forked from OSchip/llvm-project
2863 lines
108 KiB
C++
2863 lines
108 KiB
C++
//===-- X86FrameLowering.cpp - X86 Frame Information ----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the X86 implementation of TargetFrameLowering class.
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//
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//===----------------------------------------------------------------------===//
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#include "X86FrameLowering.h"
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#include "X86InstrBuilder.h"
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#include "X86InstrInfo.h"
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#include "X86MachineFunctionInfo.h"
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#include "X86Subtarget.h"
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#include "X86TargetMachine.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/Analysis/EHPersonalities.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/WinEHFuncInfo.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Function.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Support/Debug.h"
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#include <cstdlib>
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using namespace llvm;
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X86FrameLowering::X86FrameLowering(const X86Subtarget &STI,
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unsigned StackAlignOverride)
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: TargetFrameLowering(StackGrowsDown, StackAlignOverride,
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STI.is64Bit() ? -8 : -4),
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STI(STI), TII(*STI.getInstrInfo()), TRI(STI.getRegisterInfo()) {
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// Cache a bunch of frame-related predicates for this subtarget.
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SlotSize = TRI->getSlotSize();
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Is64Bit = STI.is64Bit();
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IsLP64 = STI.isTarget64BitLP64();
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// standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
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Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64();
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StackPtr = TRI->getStackRegister();
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}
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bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
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return !MF.getFrameInfo()->hasVarSizedObjects() &&
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!MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences();
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}
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/// canSimplifyCallFramePseudos - If there is a reserved call frame, the
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/// call frame pseudos can be simplified. Having a FP, as in the default
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/// implementation, is not sufficient here since we can't always use it.
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/// Use a more nuanced condition.
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bool
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X86FrameLowering::canSimplifyCallFramePseudos(const MachineFunction &MF) const {
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return hasReservedCallFrame(MF) ||
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(hasFP(MF) && !TRI->needsStackRealignment(MF)) ||
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TRI->hasBasePointer(MF);
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}
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// needsFrameIndexResolution - Do we need to perform FI resolution for
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// this function. Normally, this is required only when the function
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// has any stack objects. However, FI resolution actually has another job,
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// not apparent from the title - it resolves callframesetup/destroy
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// that were not simplified earlier.
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// So, this is required for x86 functions that have push sequences even
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// when there are no stack objects.
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bool
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X86FrameLowering::needsFrameIndexResolution(const MachineFunction &MF) const {
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return MF.getFrameInfo()->hasStackObjects() ||
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MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences();
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}
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/// hasFP - Return true if the specified function should have a dedicated frame
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/// pointer register. This is true if the function has variable sized allocas
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/// or if frame pointer elimination is disabled.
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bool X86FrameLowering::hasFP(const MachineFunction &MF) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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const MachineModuleInfo &MMI = MF.getMMI();
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return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
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TRI->needsStackRealignment(MF) ||
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MFI->hasVarSizedObjects() ||
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MFI->isFrameAddressTaken() || MFI->hasOpaqueSPAdjustment() ||
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MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() ||
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MMI.callsUnwindInit() || MMI.hasEHFunclets() || MMI.callsEHReturn() ||
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MFI->hasStackMap() || MFI->hasPatchPoint() ||
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MFI->hasCopyImplyingStackAdjustment());
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}
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static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) {
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if (IsLP64) {
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if (isInt<8>(Imm))
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return X86::SUB64ri8;
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return X86::SUB64ri32;
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} else {
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if (isInt<8>(Imm))
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return X86::SUB32ri8;
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return X86::SUB32ri;
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}
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}
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static unsigned getADDriOpcode(unsigned IsLP64, int64_t Imm) {
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if (IsLP64) {
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if (isInt<8>(Imm))
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return X86::ADD64ri8;
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return X86::ADD64ri32;
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} else {
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if (isInt<8>(Imm))
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return X86::ADD32ri8;
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return X86::ADD32ri;
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}
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}
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static unsigned getSUBrrOpcode(unsigned isLP64) {
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return isLP64 ? X86::SUB64rr : X86::SUB32rr;
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}
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static unsigned getADDrrOpcode(unsigned isLP64) {
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return isLP64 ? X86::ADD64rr : X86::ADD32rr;
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}
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static unsigned getANDriOpcode(bool IsLP64, int64_t Imm) {
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if (IsLP64) {
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if (isInt<8>(Imm))
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return X86::AND64ri8;
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return X86::AND64ri32;
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}
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if (isInt<8>(Imm))
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return X86::AND32ri8;
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return X86::AND32ri;
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}
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static unsigned getLEArOpcode(unsigned IsLP64) {
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return IsLP64 ? X86::LEA64r : X86::LEA32r;
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}
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/// findDeadCallerSavedReg - Return a caller-saved register that isn't live
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/// when it reaches the "return" instruction. We can then pop a stack object
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/// to this register without worry about clobbering it.
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static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MBBI,
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const X86RegisterInfo *TRI,
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bool Is64Bit) {
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const MachineFunction *MF = MBB.getParent();
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const Function *F = MF->getFunction();
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if (!F || MF->getMMI().callsEHReturn())
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return 0;
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const TargetRegisterClass &AvailableRegs = *TRI->getGPRsForTailCall(*MF);
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unsigned Opc = MBBI->getOpcode();
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switch (Opc) {
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default: return 0;
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case X86::RETL:
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case X86::RETQ:
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case X86::RETIL:
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case X86::RETIQ:
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case X86::TCRETURNdi:
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case X86::TCRETURNri:
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case X86::TCRETURNmi:
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case X86::TCRETURNdi64:
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case X86::TCRETURNri64:
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case X86::TCRETURNmi64:
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case X86::EH_RETURN:
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case X86::EH_RETURN64: {
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SmallSet<uint16_t, 8> Uses;
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for (unsigned i = 0, e = MBBI->getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MBBI->getOperand(i);
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if (!MO.isReg() || MO.isDef())
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continue;
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unsigned Reg = MO.getReg();
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if (!Reg)
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continue;
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for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
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Uses.insert(*AI);
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}
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for (auto CS : AvailableRegs)
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if (!Uses.count(CS) && CS != X86::RIP)
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return CS;
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}
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}
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return 0;
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}
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static bool isEAXLiveIn(MachineBasicBlock &MBB) {
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for (MachineBasicBlock::RegisterMaskPair RegMask : MBB.liveins()) {
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unsigned Reg = RegMask.PhysReg;
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if (Reg == X86::RAX || Reg == X86::EAX || Reg == X86::AX ||
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Reg == X86::AH || Reg == X86::AL)
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return true;
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}
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return false;
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}
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/// Check if the flags need to be preserved before the terminators.
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/// This would be the case, if the eflags is live-in of the region
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/// composed by the terminators or live-out of that region, without
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/// being defined by a terminator.
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static bool
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flagsNeedToBePreservedBeforeTheTerminators(const MachineBasicBlock &MBB) {
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for (const MachineInstr &MI : MBB.terminators()) {
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bool BreakNext = false;
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for (const MachineOperand &MO : MI.operands()) {
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if (!MO.isReg())
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continue;
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unsigned Reg = MO.getReg();
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if (Reg != X86::EFLAGS)
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continue;
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// This terminator needs an eflags that is not defined
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// by a previous another terminator:
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// EFLAGS is live-in of the region composed by the terminators.
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if (!MO.isDef())
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return true;
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// This terminator defines the eflags, i.e., we don't need to preserve it.
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// However, we still need to check this specific terminator does not
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// read a live-in value.
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BreakNext = true;
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}
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// We found a definition of the eflags, no need to preserve them.
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if (BreakNext)
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return false;
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}
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// None of the terminators use or define the eflags.
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// Check if they are live-out, that would imply we need to preserve them.
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for (const MachineBasicBlock *Succ : MBB.successors())
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if (Succ->isLiveIn(X86::EFLAGS))
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return true;
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return false;
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}
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/// emitSPUpdate - Emit a series of instructions to increment / decrement the
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/// stack pointer by a constant value.
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void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MBBI,
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int64_t NumBytes, bool InEpilogue) const {
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bool isSub = NumBytes < 0;
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uint64_t Offset = isSub ? -NumBytes : NumBytes;
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uint64_t Chunk = (1LL << 31) - 1;
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DebugLoc DL = MBB.findDebugLoc(MBBI);
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while (Offset) {
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if (Offset > Chunk) {
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// Rather than emit a long series of instructions for large offsets,
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// load the offset into a register and do one sub/add
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unsigned Reg = 0;
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if (isSub && !isEAXLiveIn(MBB))
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Reg = (unsigned)(Is64Bit ? X86::RAX : X86::EAX);
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else
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Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit);
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if (Reg) {
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unsigned Opc = Is64Bit ? X86::MOV64ri : X86::MOV32ri;
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BuildMI(MBB, MBBI, DL, TII.get(Opc), Reg)
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.addImm(Offset);
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Opc = isSub
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? getSUBrrOpcode(Is64Bit)
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: getADDrrOpcode(Is64Bit);
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MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
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.addReg(StackPtr)
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.addReg(Reg);
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MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
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Offset = 0;
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continue;
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}
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}
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uint64_t ThisVal = std::min(Offset, Chunk);
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if (ThisVal == (Is64Bit ? 8 : 4)) {
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// Use push / pop instead.
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unsigned Reg = isSub
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? (unsigned)(Is64Bit ? X86::RAX : X86::EAX)
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: findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit);
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if (Reg) {
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unsigned Opc = isSub
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? (Is64Bit ? X86::PUSH64r : X86::PUSH32r)
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: (Is64Bit ? X86::POP64r : X86::POP32r);
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MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc))
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.addReg(Reg, getDefRegState(!isSub) | getUndefRegState(isSub));
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if (isSub)
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MI->setFlag(MachineInstr::FrameSetup);
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else
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MI->setFlag(MachineInstr::FrameDestroy);
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Offset -= ThisVal;
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continue;
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}
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}
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MachineInstrBuilder MI = BuildStackAdjustment(
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MBB, MBBI, DL, isSub ? -ThisVal : ThisVal, InEpilogue);
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if (isSub)
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MI.setMIFlag(MachineInstr::FrameSetup);
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else
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MI.setMIFlag(MachineInstr::FrameDestroy);
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Offset -= ThisVal;
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}
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}
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MachineInstrBuilder X86FrameLowering::BuildStackAdjustment(
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MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, DebugLoc DL,
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int64_t Offset, bool InEpilogue) const {
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assert(Offset != 0 && "zero offset stack adjustment requested");
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// On Atom, using LEA to adjust SP is preferred, but using it in the epilogue
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// is tricky.
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bool UseLEA;
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if (!InEpilogue) {
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// Check if inserting the prologue at the beginning
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// of MBB would require to use LEA operations.
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// We need to use LEA operations if EFLAGS is live in, because
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// it means an instruction will read it before it gets defined.
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UseLEA = STI.useLeaForSP() || MBB.isLiveIn(X86::EFLAGS);
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} else {
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// If we can use LEA for SP but we shouldn't, check that none
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// of the terminators uses the eflags. Otherwise we will insert
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// a ADD that will redefine the eflags and break the condition.
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// Alternatively, we could move the ADD, but this may not be possible
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// and is an optimization anyway.
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UseLEA = canUseLEAForSPInEpilogue(*MBB.getParent());
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if (UseLEA && !STI.useLeaForSP())
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UseLEA = flagsNeedToBePreservedBeforeTheTerminators(MBB);
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// If that assert breaks, that means we do not do the right thing
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// in canUseAsEpilogue.
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assert((UseLEA || !flagsNeedToBePreservedBeforeTheTerminators(MBB)) &&
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"We shouldn't have allowed this insertion point");
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}
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MachineInstrBuilder MI;
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if (UseLEA) {
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MI = addRegOffset(BuildMI(MBB, MBBI, DL,
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TII.get(getLEArOpcode(Uses64BitFramePtr)),
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StackPtr),
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StackPtr, false, Offset);
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} else {
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bool IsSub = Offset < 0;
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uint64_t AbsOffset = IsSub ? -Offset : Offset;
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unsigned Opc = IsSub ? getSUBriOpcode(Uses64BitFramePtr, AbsOffset)
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: getADDriOpcode(Uses64BitFramePtr, AbsOffset);
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MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
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.addReg(StackPtr)
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.addImm(AbsOffset);
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MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
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}
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return MI;
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}
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int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MBBI,
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bool doMergeWithPrevious) const {
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if ((doMergeWithPrevious && MBBI == MBB.begin()) ||
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(!doMergeWithPrevious && MBBI == MBB.end()))
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return 0;
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MachineBasicBlock::iterator PI = doMergeWithPrevious ? std::prev(MBBI) : MBBI;
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MachineBasicBlock::iterator NI = doMergeWithPrevious ? nullptr
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: std::next(MBBI);
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unsigned Opc = PI->getOpcode();
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int Offset = 0;
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if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 ||
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Opc == X86::ADD32ri || Opc == X86::ADD32ri8) &&
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PI->getOperand(0).getReg() == StackPtr){
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Offset += PI->getOperand(2).getImm();
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MBB.erase(PI);
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if (!doMergeWithPrevious) MBBI = NI;
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} else if ((Opc == X86::LEA32r || Opc == X86::LEA64_32r) &&
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PI->getOperand(0).getReg() == StackPtr) {
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// For LEAs we have: def = lea SP, FI, noreg, Offset, noreg.
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Offset += PI->getOperand(4).getImm();
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MBB.erase(PI);
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if (!doMergeWithPrevious) MBBI = NI;
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} else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 ||
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Opc == X86::SUB32ri || Opc == X86::SUB32ri8) &&
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PI->getOperand(0).getReg() == StackPtr) {
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Offset -= PI->getOperand(2).getImm();
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MBB.erase(PI);
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if (!doMergeWithPrevious) MBBI = NI;
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}
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return Offset;
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}
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void X86FrameLowering::BuildCFI(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI, DebugLoc DL,
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MCCFIInstruction CFIInst) const {
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MachineFunction &MF = *MBB.getParent();
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unsigned CFIIndex = MF.getMMI().addFrameInst(CFIInst);
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BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
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.addCFIIndex(CFIIndex);
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}
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void
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X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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DebugLoc DL) const {
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MachineFunction &MF = *MBB.getParent();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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MachineModuleInfo &MMI = MF.getMMI();
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const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
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// Add callee saved registers to move list.
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const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
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if (CSI.empty()) return;
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// Calculate offsets.
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for (std::vector<CalleeSavedInfo>::const_iterator
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I = CSI.begin(), E = CSI.end(); I != E; ++I) {
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int64_t Offset = MFI->getObjectOffset(I->getFrameIdx());
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unsigned Reg = I->getReg();
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unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true);
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BuildCFI(MBB, MBBI, DL,
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MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset));
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}
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}
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MachineInstr *X86FrameLowering::emitStackProbe(MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MBBI,
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DebugLoc DL,
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bool InProlog) const {
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const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
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if (STI.isTargetWindowsCoreCLR()) {
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if (InProlog) {
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return emitStackProbeInlineStub(MF, MBB, MBBI, DL, true);
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} else {
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return emitStackProbeInline(MF, MBB, MBBI, DL, false);
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}
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} else {
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return emitStackProbeCall(MF, MBB, MBBI, DL, InProlog);
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}
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}
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void X86FrameLowering::inlineStackProbe(MachineFunction &MF,
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MachineBasicBlock &PrologMBB) const {
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const StringRef ChkStkStubSymbol = "__chkstk_stub";
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MachineInstr *ChkStkStub = nullptr;
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for (MachineInstr &MI : PrologMBB) {
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if (MI.isCall() && MI.getOperand(0).isSymbol() &&
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ChkStkStubSymbol == MI.getOperand(0).getSymbolName()) {
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ChkStkStub = &MI;
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break;
|
|
}
|
|
}
|
|
|
|
if (ChkStkStub != nullptr) {
|
|
// FIXME: MBBI is a bundle iterator. Should this be getBundleIterator()?
|
|
MachineBasicBlock::iterator MBBI =
|
|
std::next(ChkStkStub->getInstrIterator());
|
|
assert(std::prev(MBBI).operator==(ChkStkStub) &&
|
|
"MBBI expected after __chkstk_stub.");
|
|
DebugLoc DL = PrologMBB.findDebugLoc(MBBI);
|
|
emitStackProbeInline(MF, PrologMBB, MBBI, DL, true);
|
|
ChkStkStub->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
MachineInstr *X86FrameLowering::emitStackProbeInline(
|
|
MachineFunction &MF, MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const {
|
|
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
|
|
assert(STI.is64Bit() && "different expansion needed for 32 bit");
|
|
assert(STI.isTargetWindowsCoreCLR() && "custom expansion expects CoreCLR");
|
|
const TargetInstrInfo &TII = *STI.getInstrInfo();
|
|
const BasicBlock *LLVM_BB = MBB.getBasicBlock();
|
|
|
|
// RAX contains the number of bytes of desired stack adjustment.
|
|
// The handling here assumes this value has already been updated so as to
|
|
// maintain stack alignment.
|
|
//
|
|
// We need to exit with RSP modified by this amount and execute suitable
|
|
// page touches to notify the OS that we're growing the stack responsibly.
|
|
// All stack probing must be done without modifying RSP.
|
|
//
|
|
// MBB:
|
|
// SizeReg = RAX;
|
|
// ZeroReg = 0
|
|
// CopyReg = RSP
|
|
// Flags, TestReg = CopyReg - SizeReg
|
|
// FinalReg = !Flags.Ovf ? TestReg : ZeroReg
|
|
// LimitReg = gs magic thread env access
|
|
// if FinalReg >= LimitReg goto ContinueMBB
|
|
// RoundBB:
|
|
// RoundReg = page address of FinalReg
|
|
// LoopMBB:
|
|
// LoopReg = PHI(LimitReg,ProbeReg)
|
|
// ProbeReg = LoopReg - PageSize
|
|
// [ProbeReg] = 0
|
|
// if (ProbeReg > RoundReg) goto LoopMBB
|
|
// ContinueMBB:
|
|
// RSP = RSP - RAX
|
|
// [rest of original MBB]
|
|
|
|
// Set up the new basic blocks
|
|
MachineBasicBlock *RoundMBB = MF.CreateMachineBasicBlock(LLVM_BB);
|
|
MachineBasicBlock *LoopMBB = MF.CreateMachineBasicBlock(LLVM_BB);
|
|
MachineBasicBlock *ContinueMBB = MF.CreateMachineBasicBlock(LLVM_BB);
|
|
|
|
MachineFunction::iterator MBBIter = std::next(MBB.getIterator());
|
|
MF.insert(MBBIter, RoundMBB);
|
|
MF.insert(MBBIter, LoopMBB);
|
|
MF.insert(MBBIter, ContinueMBB);
|
|
|
|
// Split MBB and move the tail portion down to ContinueMBB.
|
|
MachineBasicBlock::iterator BeforeMBBI = std::prev(MBBI);
|
|
ContinueMBB->splice(ContinueMBB->begin(), &MBB, MBBI, MBB.end());
|
|
ContinueMBB->transferSuccessorsAndUpdatePHIs(&MBB);
|
|
|
|
// Some useful constants
|
|
const int64_t ThreadEnvironmentStackLimit = 0x10;
|
|
const int64_t PageSize = 0x1000;
|
|
const int64_t PageMask = ~(PageSize - 1);
|
|
|
|
// Registers we need. For the normal case we use virtual
|
|
// registers. For the prolog expansion we use RAX, RCX and RDX.
|
|
MachineRegisterInfo &MRI = MF.getRegInfo();
|
|
const TargetRegisterClass *RegClass = &X86::GR64RegClass;
|
|
const unsigned SizeReg = InProlog ? (unsigned)X86::RAX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
ZeroReg = InProlog ? (unsigned)X86::RCX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
CopyReg = InProlog ? (unsigned)X86::RDX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
TestReg = InProlog ? (unsigned)X86::RDX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
FinalReg = InProlog ? (unsigned)X86::RDX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
RoundedReg = InProlog ? (unsigned)X86::RDX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
LimitReg = InProlog ? (unsigned)X86::RCX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
JoinReg = InProlog ? (unsigned)X86::RCX
|
|
: MRI.createVirtualRegister(RegClass),
|
|
ProbeReg = InProlog ? (unsigned)X86::RCX
|
|
: MRI.createVirtualRegister(RegClass);
|
|
|
|
// SP-relative offsets where we can save RCX and RDX.
|
|
int64_t RCXShadowSlot = 0;
|
|
int64_t RDXShadowSlot = 0;
|
|
|
|
// If inlining in the prolog, save RCX and RDX.
|
|
// Future optimization: don't save or restore if not live in.
|
|
if (InProlog) {
|
|
// Compute the offsets. We need to account for things already
|
|
// pushed onto the stack at this point: return address, frame
|
|
// pointer (if used), and callee saves.
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
const int64_t CalleeSaveSize = X86FI->getCalleeSavedFrameSize();
|
|
const bool HasFP = hasFP(MF);
|
|
RCXShadowSlot = 8 + CalleeSaveSize + (HasFP ? 8 : 0);
|
|
RDXShadowSlot = RCXShadowSlot + 8;
|
|
// Emit the saves.
|
|
addRegOffset(BuildMI(&MBB, DL, TII.get(X86::MOV64mr)), X86::RSP, false,
|
|
RCXShadowSlot)
|
|
.addReg(X86::RCX);
|
|
addRegOffset(BuildMI(&MBB, DL, TII.get(X86::MOV64mr)), X86::RSP, false,
|
|
RDXShadowSlot)
|
|
.addReg(X86::RDX);
|
|
} else {
|
|
// Not in the prolog. Copy RAX to a virtual reg.
|
|
BuildMI(&MBB, DL, TII.get(X86::MOV64rr), SizeReg).addReg(X86::RAX);
|
|
}
|
|
|
|
// Add code to MBB to check for overflow and set the new target stack pointer
|
|
// to zero if so.
|
|
BuildMI(&MBB, DL, TII.get(X86::XOR64rr), ZeroReg)
|
|
.addReg(ZeroReg, RegState::Undef)
|
|
.addReg(ZeroReg, RegState::Undef);
|
|
BuildMI(&MBB, DL, TII.get(X86::MOV64rr), CopyReg).addReg(X86::RSP);
|
|
BuildMI(&MBB, DL, TII.get(X86::SUB64rr), TestReg)
|
|
.addReg(CopyReg)
|
|
.addReg(SizeReg);
|
|
BuildMI(&MBB, DL, TII.get(X86::CMOVB64rr), FinalReg)
|
|
.addReg(TestReg)
|
|
.addReg(ZeroReg);
|
|
|
|
// FinalReg now holds final stack pointer value, or zero if
|
|
// allocation would overflow. Compare against the current stack
|
|
// limit from the thread environment block. Note this limit is the
|
|
// lowest touched page on the stack, not the point at which the OS
|
|
// will cause an overflow exception, so this is just an optimization
|
|
// to avoid unnecessarily touching pages that are below the current
|
|
// SP but already commited to the stack by the OS.
|
|
BuildMI(&MBB, DL, TII.get(X86::MOV64rm), LimitReg)
|
|
.addReg(0)
|
|
.addImm(1)
|
|
.addReg(0)
|
|
.addImm(ThreadEnvironmentStackLimit)
|
|
.addReg(X86::GS);
|
|
BuildMI(&MBB, DL, TII.get(X86::CMP64rr)).addReg(FinalReg).addReg(LimitReg);
|
|
// Jump if the desired stack pointer is at or above the stack limit.
|
|
BuildMI(&MBB, DL, TII.get(X86::JAE_1)).addMBB(ContinueMBB);
|
|
|
|
// Add code to roundMBB to round the final stack pointer to a page boundary.
|
|
BuildMI(RoundMBB, DL, TII.get(X86::AND64ri32), RoundedReg)
|
|
.addReg(FinalReg)
|
|
.addImm(PageMask);
|
|
BuildMI(RoundMBB, DL, TII.get(X86::JMP_1)).addMBB(LoopMBB);
|
|
|
|
// LimitReg now holds the current stack limit, RoundedReg page-rounded
|
|
// final RSP value. Add code to loopMBB to decrement LimitReg page-by-page
|
|
// and probe until we reach RoundedReg.
|
|
if (!InProlog) {
|
|
BuildMI(LoopMBB, DL, TII.get(X86::PHI), JoinReg)
|
|
.addReg(LimitReg)
|
|
.addMBB(RoundMBB)
|
|
.addReg(ProbeReg)
|
|
.addMBB(LoopMBB);
|
|
}
|
|
|
|
addRegOffset(BuildMI(LoopMBB, DL, TII.get(X86::LEA64r), ProbeReg), JoinReg,
|
|
false, -PageSize);
|
|
|
|
// Probe by storing a byte onto the stack.
|
|
BuildMI(LoopMBB, DL, TII.get(X86::MOV8mi))
|
|
.addReg(ProbeReg)
|
|
.addImm(1)
|
|
.addReg(0)
|
|
.addImm(0)
|
|
.addReg(0)
|
|
.addImm(0);
|
|
BuildMI(LoopMBB, DL, TII.get(X86::CMP64rr))
|
|
.addReg(RoundedReg)
|
|
.addReg(ProbeReg);
|
|
BuildMI(LoopMBB, DL, TII.get(X86::JNE_1)).addMBB(LoopMBB);
|
|
|
|
MachineBasicBlock::iterator ContinueMBBI = ContinueMBB->getFirstNonPHI();
|
|
|
|
// If in prolog, restore RDX and RCX.
|
|
if (InProlog) {
|
|
addRegOffset(BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::MOV64rm),
|
|
X86::RCX),
|
|
X86::RSP, false, RCXShadowSlot);
|
|
addRegOffset(BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::MOV64rm),
|
|
X86::RDX),
|
|
X86::RSP, false, RDXShadowSlot);
|
|
}
|
|
|
|
// Now that the probing is done, add code to continueMBB to update
|
|
// the stack pointer for real.
|
|
BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
|
|
.addReg(X86::RSP)
|
|
.addReg(SizeReg);
|
|
|
|
// Add the control flow edges we need.
|
|
MBB.addSuccessor(ContinueMBB);
|
|
MBB.addSuccessor(RoundMBB);
|
|
RoundMBB->addSuccessor(LoopMBB);
|
|
LoopMBB->addSuccessor(ContinueMBB);
|
|
LoopMBB->addSuccessor(LoopMBB);
|
|
|
|
// Mark all the instructions added to the prolog as frame setup.
|
|
if (InProlog) {
|
|
for (++BeforeMBBI; BeforeMBBI != MBB.end(); ++BeforeMBBI) {
|
|
BeforeMBBI->setFlag(MachineInstr::FrameSetup);
|
|
}
|
|
for (MachineInstr &MI : *RoundMBB) {
|
|
MI.setFlag(MachineInstr::FrameSetup);
|
|
}
|
|
for (MachineInstr &MI : *LoopMBB) {
|
|
MI.setFlag(MachineInstr::FrameSetup);
|
|
}
|
|
for (MachineBasicBlock::iterator CMBBI = ContinueMBB->begin();
|
|
CMBBI != ContinueMBBI; ++CMBBI) {
|
|
CMBBI->setFlag(MachineInstr::FrameSetup);
|
|
}
|
|
}
|
|
|
|
// Possible TODO: physreg liveness for InProlog case.
|
|
|
|
return ContinueMBBI;
|
|
}
|
|
|
|
MachineInstr *X86FrameLowering::emitStackProbeCall(
|
|
MachineFunction &MF, MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const {
|
|
bool IsLargeCodeModel = MF.getTarget().getCodeModel() == CodeModel::Large;
|
|
|
|
unsigned CallOp;
|
|
if (Is64Bit)
|
|
CallOp = IsLargeCodeModel ? X86::CALL64r : X86::CALL64pcrel32;
|
|
else
|
|
CallOp = X86::CALLpcrel32;
|
|
|
|
const char *Symbol;
|
|
if (Is64Bit) {
|
|
if (STI.isTargetCygMing()) {
|
|
Symbol = "___chkstk_ms";
|
|
} else {
|
|
Symbol = "__chkstk";
|
|
}
|
|
} else if (STI.isTargetCygMing())
|
|
Symbol = "_alloca";
|
|
else
|
|
Symbol = "_chkstk";
|
|
|
|
MachineInstrBuilder CI;
|
|
MachineBasicBlock::iterator ExpansionMBBI = std::prev(MBBI);
|
|
|
|
// All current stack probes take AX and SP as input, clobber flags, and
|
|
// preserve all registers. x86_64 probes leave RSP unmodified.
|
|
if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) {
|
|
// For the large code model, we have to call through a register. Use R11,
|
|
// as it is scratch in all supported calling conventions.
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::R11)
|
|
.addExternalSymbol(Symbol);
|
|
CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addReg(X86::R11);
|
|
} else {
|
|
CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addExternalSymbol(Symbol);
|
|
}
|
|
|
|
unsigned AX = Is64Bit ? X86::RAX : X86::EAX;
|
|
unsigned SP = Is64Bit ? X86::RSP : X86::ESP;
|
|
CI.addReg(AX, RegState::Implicit)
|
|
.addReg(SP, RegState::Implicit)
|
|
.addReg(AX, RegState::Define | RegState::Implicit)
|
|
.addReg(SP, RegState::Define | RegState::Implicit)
|
|
.addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
|
|
|
|
if (Is64Bit) {
|
|
// MSVC x64's __chkstk and cygwin/mingw's ___chkstk_ms do not adjust %rsp
|
|
// themselves. It also does not clobber %rax so we can reuse it when
|
|
// adjusting %rsp.
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
|
|
.addReg(X86::RSP)
|
|
.addReg(X86::RAX);
|
|
}
|
|
|
|
if (InProlog) {
|
|
// Apply the frame setup flag to all inserted instrs.
|
|
for (++ExpansionMBBI; ExpansionMBBI != MBBI; ++ExpansionMBBI)
|
|
ExpansionMBBI->setFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
return MBBI;
|
|
}
|
|
|
|
MachineInstr *X86FrameLowering::emitStackProbeInlineStub(
|
|
MachineFunction &MF, MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const {
|
|
|
|
assert(InProlog && "ChkStkStub called outside prolog!");
|
|
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32))
|
|
.addExternalSymbol("__chkstk_stub");
|
|
|
|
return MBBI;
|
|
}
|
|
|
|
static unsigned calculateSetFPREG(uint64_t SPAdjust) {
|
|
// Win64 ABI has a less restrictive limitation of 240; 128 works equally well
|
|
// and might require smaller successive adjustments.
|
|
const uint64_t Win64MaxSEHOffset = 128;
|
|
uint64_t SEHFrameOffset = std::min(SPAdjust, Win64MaxSEHOffset);
|
|
// Win64 ABI requires 16-byte alignment for the UWOP_SET_FPREG opcode.
|
|
return SEHFrameOffset & -16;
|
|
}
|
|
|
|
// If we're forcing a stack realignment we can't rely on just the frame
|
|
// info, we need to know the ABI stack alignment as well in case we
|
|
// have a call out. Otherwise just make sure we have some alignment - we'll
|
|
// go with the minimum SlotSize.
|
|
uint64_t X86FrameLowering::calculateMaxStackAlign(const MachineFunction &MF) const {
|
|
const MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment.
|
|
unsigned StackAlign = getStackAlignment();
|
|
if (MF.getFunction()->hasFnAttribute("stackrealign")) {
|
|
if (MFI->hasCalls())
|
|
MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign;
|
|
else if (MaxAlign < SlotSize)
|
|
MaxAlign = SlotSize;
|
|
}
|
|
return MaxAlign;
|
|
}
|
|
|
|
void X86FrameLowering::BuildStackAlignAND(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MBBI,
|
|
DebugLoc DL, unsigned Reg,
|
|
uint64_t MaxAlign) const {
|
|
uint64_t Val = -MaxAlign;
|
|
unsigned AndOp = getANDriOpcode(Uses64BitFramePtr, Val);
|
|
MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(AndOp), Reg)
|
|
.addReg(Reg)
|
|
.addImm(Val)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
// The EFLAGS implicit def is dead.
|
|
MI->getOperand(3).setIsDead();
|
|
}
|
|
|
|
/// emitPrologue - Push callee-saved registers onto the stack, which
|
|
/// automatically adjust the stack pointer. Adjust the stack pointer to allocate
|
|
/// space for local variables. Also emit labels used by the exception handler to
|
|
/// generate the exception handling frames.
|
|
|
|
/*
|
|
Here's a gist of what gets emitted:
|
|
|
|
; Establish frame pointer, if needed
|
|
[if needs FP]
|
|
push %rbp
|
|
.cfi_def_cfa_offset 16
|
|
.cfi_offset %rbp, -16
|
|
.seh_pushreg %rpb
|
|
mov %rsp, %rbp
|
|
.cfi_def_cfa_register %rbp
|
|
|
|
; Spill general-purpose registers
|
|
[for all callee-saved GPRs]
|
|
pushq %<reg>
|
|
[if not needs FP]
|
|
.cfi_def_cfa_offset (offset from RETADDR)
|
|
.seh_pushreg %<reg>
|
|
|
|
; If the required stack alignment > default stack alignment
|
|
; rsp needs to be re-aligned. This creates a "re-alignment gap"
|
|
; of unknown size in the stack frame.
|
|
[if stack needs re-alignment]
|
|
and $MASK, %rsp
|
|
|
|
; Allocate space for locals
|
|
[if target is Windows and allocated space > 4096 bytes]
|
|
; Windows needs special care for allocations larger
|
|
; than one page.
|
|
mov $NNN, %rax
|
|
call ___chkstk_ms/___chkstk
|
|
sub %rax, %rsp
|
|
[else]
|
|
sub $NNN, %rsp
|
|
|
|
[if needs FP]
|
|
.seh_stackalloc (size of XMM spill slots)
|
|
.seh_setframe %rbp, SEHFrameOffset ; = size of all spill slots
|
|
[else]
|
|
.seh_stackalloc NNN
|
|
|
|
; Spill XMMs
|
|
; Note, that while only Windows 64 ABI specifies XMMs as callee-preserved,
|
|
; they may get spilled on any platform, if the current function
|
|
; calls @llvm.eh.unwind.init
|
|
[if needs FP]
|
|
[for all callee-saved XMM registers]
|
|
movaps %<xmm reg>, -MMM(%rbp)
|
|
[for all callee-saved XMM registers]
|
|
.seh_savexmm %<xmm reg>, (-MMM + SEHFrameOffset)
|
|
; i.e. the offset relative to (%rbp - SEHFrameOffset)
|
|
[else]
|
|
[for all callee-saved XMM registers]
|
|
movaps %<xmm reg>, KKK(%rsp)
|
|
[for all callee-saved XMM registers]
|
|
.seh_savexmm %<xmm reg>, KKK
|
|
|
|
.seh_endprologue
|
|
|
|
[if needs base pointer]
|
|
mov %rsp, %rbx
|
|
[if needs to restore base pointer]
|
|
mov %rsp, -MMM(%rbp)
|
|
|
|
; Emit CFI info
|
|
[if needs FP]
|
|
[for all callee-saved registers]
|
|
.cfi_offset %<reg>, (offset from %rbp)
|
|
[else]
|
|
.cfi_def_cfa_offset (offset from RETADDR)
|
|
[for all callee-saved registers]
|
|
.cfi_offset %<reg>, (offset from %rsp)
|
|
|
|
Notes:
|
|
- .seh directives are emitted only for Windows 64 ABI
|
|
- .cfi directives are emitted for all other ABIs
|
|
- for 32-bit code, substitute %e?? registers for %r??
|
|
*/
|
|
|
|
void X86FrameLowering::emitPrologue(MachineFunction &MF,
|
|
MachineBasicBlock &MBB) const {
|
|
assert(&STI == &MF.getSubtarget<X86Subtarget>() &&
|
|
"MF used frame lowering for wrong subtarget");
|
|
MachineBasicBlock::iterator MBBI = MBB.begin();
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
const Function *Fn = MF.getFunction();
|
|
MachineModuleInfo &MMI = MF.getMMI();
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
uint64_t MaxAlign = calculateMaxStackAlign(MF); // Desired stack alignment.
|
|
uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate.
|
|
bool IsFunclet = MBB.isEHFuncletEntry();
|
|
EHPersonality Personality = EHPersonality::Unknown;
|
|
if (Fn->hasPersonalityFn())
|
|
Personality = classifyEHPersonality(Fn->getPersonalityFn());
|
|
bool FnHasClrFunclet =
|
|
MMI.hasEHFunclets() && Personality == EHPersonality::CoreCLR;
|
|
bool IsClrFunclet = IsFunclet && FnHasClrFunclet;
|
|
bool HasFP = hasFP(MF);
|
|
bool IsWin64CC = STI.isCallingConvWin64(Fn->getCallingConv());
|
|
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
|
|
bool NeedsWinCFI = IsWin64Prologue && Fn->needsUnwindTableEntry();
|
|
bool NeedsDwarfCFI =
|
|
!IsWin64Prologue && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry());
|
|
unsigned FramePtr = TRI->getFrameRegister(MF);
|
|
const unsigned MachineFramePtr =
|
|
STI.isTarget64BitILP32()
|
|
? getX86SubSuperRegister(FramePtr, 64) : FramePtr;
|
|
unsigned BasePtr = TRI->getBaseRegister();
|
|
|
|
// Debug location must be unknown since the first debug location is used
|
|
// to determine the end of the prologue.
|
|
DebugLoc DL;
|
|
|
|
// Add RETADDR move area to callee saved frame size.
|
|
int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
|
|
if (TailCallReturnAddrDelta && IsWin64Prologue)
|
|
report_fatal_error("Can't handle guaranteed tail call under win64 yet");
|
|
|
|
if (TailCallReturnAddrDelta < 0)
|
|
X86FI->setCalleeSavedFrameSize(
|
|
X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta);
|
|
|
|
bool UseStackProbe = (STI.isOSWindows() && !STI.isTargetMachO());
|
|
|
|
// The default stack probe size is 4096 if the function has no stackprobesize
|
|
// attribute.
|
|
unsigned StackProbeSize = 4096;
|
|
if (Fn->hasFnAttribute("stack-probe-size"))
|
|
Fn->getFnAttribute("stack-probe-size")
|
|
.getValueAsString()
|
|
.getAsInteger(0, StackProbeSize);
|
|
|
|
// If this is x86-64 and the Red Zone is not disabled, if we are a leaf
|
|
// function, and use up to 128 bytes of stack space, don't have a frame
|
|
// pointer, calls, or dynamic alloca then we do not need to adjust the
|
|
// stack pointer (we fit in the Red Zone). We also check that we don't
|
|
// push and pop from the stack.
|
|
if (Is64Bit && !Fn->hasFnAttribute(Attribute::NoRedZone) &&
|
|
!TRI->needsStackRealignment(MF) &&
|
|
!MFI->hasVarSizedObjects() && // No dynamic alloca.
|
|
!MFI->adjustsStack() && // No calls.
|
|
!IsWin64CC && // Win64 has no Red Zone
|
|
!MFI->hasCopyImplyingStackAdjustment() && // Don't push and pop.
|
|
!MF.shouldSplitStack()) { // Regular stack
|
|
uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
|
|
if (HasFP) MinSize += SlotSize;
|
|
StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0);
|
|
MFI->setStackSize(StackSize);
|
|
}
|
|
|
|
// Insert stack pointer adjustment for later moving of return addr. Only
|
|
// applies to tail call optimized functions where the callee argument stack
|
|
// size is bigger than the callers.
|
|
if (TailCallReturnAddrDelta < 0) {
|
|
BuildStackAdjustment(MBB, MBBI, DL, TailCallReturnAddrDelta,
|
|
/*InEpilogue=*/false)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
// Mapping for machine moves:
|
|
//
|
|
// DST: VirtualFP AND
|
|
// SRC: VirtualFP => DW_CFA_def_cfa_offset
|
|
// ELSE => DW_CFA_def_cfa
|
|
//
|
|
// SRC: VirtualFP AND
|
|
// DST: Register => DW_CFA_def_cfa_register
|
|
//
|
|
// ELSE
|
|
// OFFSET < 0 => DW_CFA_offset_extended_sf
|
|
// REG < 64 => DW_CFA_offset + Reg
|
|
// ELSE => DW_CFA_offset_extended
|
|
|
|
uint64_t NumBytes = 0;
|
|
int stackGrowth = -SlotSize;
|
|
|
|
// Find the funclet establisher parameter
|
|
unsigned Establisher = X86::NoRegister;
|
|
if (IsClrFunclet)
|
|
Establisher = Uses64BitFramePtr ? X86::RCX : X86::ECX;
|
|
else if (IsFunclet)
|
|
Establisher = Uses64BitFramePtr ? X86::RDX : X86::EDX;
|
|
|
|
if (IsWin64Prologue && IsFunclet && !IsClrFunclet) {
|
|
// Immediately spill establisher into the home slot.
|
|
// The runtime cares about this.
|
|
// MOV64mr %rdx, 16(%rsp)
|
|
unsigned MOVmr = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(MOVmr)), StackPtr, true, 16)
|
|
.addReg(Establisher)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
MBB.addLiveIn(Establisher);
|
|
}
|
|
|
|
if (HasFP) {
|
|
// Calculate required stack adjustment.
|
|
uint64_t FrameSize = StackSize - SlotSize;
|
|
// If required, include space for extra hidden slot for stashing base pointer.
|
|
if (X86FI->getRestoreBasePointer())
|
|
FrameSize += SlotSize;
|
|
|
|
NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize();
|
|
|
|
// Callee-saved registers are pushed on stack before the stack is realigned.
|
|
if (TRI->needsStackRealignment(MF) && !IsWin64Prologue)
|
|
NumBytes = alignTo(NumBytes, MaxAlign);
|
|
|
|
// Get the offset of the stack slot for the EBP register, which is
|
|
// guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
|
|
// Update the frame offset adjustment.
|
|
if (!IsFunclet)
|
|
MFI->setOffsetAdjustment(-NumBytes);
|
|
else
|
|
assert(MFI->getOffsetAdjustment() == -(int)NumBytes &&
|
|
"should calculate same local variable offset for funclets");
|
|
|
|
// Save EBP/RBP into the appropriate stack slot.
|
|
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r))
|
|
.addReg(MachineFramePtr, RegState::Kill)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
if (NeedsDwarfCFI) {
|
|
// Mark the place where EBP/RBP was saved.
|
|
// Define the current CFA rule to use the provided offset.
|
|
assert(StackSize);
|
|
BuildCFI(MBB, MBBI, DL,
|
|
MCCFIInstruction::createDefCfaOffset(nullptr, 2 * stackGrowth));
|
|
|
|
// Change the rule for the FramePtr to be an "offset" rule.
|
|
unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true);
|
|
BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createOffset(
|
|
nullptr, DwarfFramePtr, 2 * stackGrowth));
|
|
}
|
|
|
|
if (NeedsWinCFI) {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg))
|
|
.addImm(FramePtr)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
if (!IsWin64Prologue && !IsFunclet) {
|
|
// Update EBP with the new base value.
|
|
BuildMI(MBB, MBBI, DL,
|
|
TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr),
|
|
FramePtr)
|
|
.addReg(StackPtr)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
if (NeedsDwarfCFI) {
|
|
// Mark effective beginning of when frame pointer becomes valid.
|
|
// Define the current CFA to use the EBP/RBP register.
|
|
unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true);
|
|
BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaRegister(
|
|
nullptr, DwarfFramePtr));
|
|
}
|
|
}
|
|
|
|
// Mark the FramePtr as live-in in every block. Don't do this again for
|
|
// funclet prologues.
|
|
if (!IsFunclet) {
|
|
for (MachineBasicBlock &EveryMBB : MF)
|
|
EveryMBB.addLiveIn(MachineFramePtr);
|
|
}
|
|
} else {
|
|
assert(!IsFunclet && "funclets without FPs not yet implemented");
|
|
NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
|
|
}
|
|
|
|
// For EH funclets, only allocate enough space for outgoing calls. Save the
|
|
// NumBytes value that we would've used for the parent frame.
|
|
unsigned ParentFrameNumBytes = NumBytes;
|
|
if (IsFunclet)
|
|
NumBytes = getWinEHFuncletFrameSize(MF);
|
|
|
|
// Skip the callee-saved push instructions.
|
|
bool PushedRegs = false;
|
|
int StackOffset = 2 * stackGrowth;
|
|
|
|
while (MBBI != MBB.end() &&
|
|
MBBI->getFlag(MachineInstr::FrameSetup) &&
|
|
(MBBI->getOpcode() == X86::PUSH32r ||
|
|
MBBI->getOpcode() == X86::PUSH64r)) {
|
|
PushedRegs = true;
|
|
unsigned Reg = MBBI->getOperand(0).getReg();
|
|
++MBBI;
|
|
|
|
if (!HasFP && NeedsDwarfCFI) {
|
|
// Mark callee-saved push instruction.
|
|
// Define the current CFA rule to use the provided offset.
|
|
assert(StackSize);
|
|
BuildCFI(MBB, MBBI, DL,
|
|
MCCFIInstruction::createDefCfaOffset(nullptr, StackOffset));
|
|
StackOffset += stackGrowth;
|
|
}
|
|
|
|
if (NeedsWinCFI) {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)).addImm(Reg).setMIFlag(
|
|
MachineInstr::FrameSetup);
|
|
}
|
|
}
|
|
|
|
// Realign stack after we pushed callee-saved registers (so that we'll be
|
|
// able to calculate their offsets from the frame pointer).
|
|
// Don't do this for Win64, it needs to realign the stack after the prologue.
|
|
if (!IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF)) {
|
|
assert(HasFP && "There should be a frame pointer if stack is realigned.");
|
|
BuildStackAlignAND(MBB, MBBI, DL, StackPtr, MaxAlign);
|
|
}
|
|
|
|
// If there is an SUB32ri of ESP immediately before this instruction, merge
|
|
// the two. This can be the case when tail call elimination is enabled and
|
|
// the callee has more arguments then the caller.
|
|
NumBytes -= mergeSPUpdates(MBB, MBBI, true);
|
|
|
|
// Adjust stack pointer: ESP -= numbytes.
|
|
|
|
// Windows and cygwin/mingw require a prologue helper routine when allocating
|
|
// more than 4K bytes on the stack. Windows uses __chkstk and cygwin/mingw
|
|
// uses __alloca. __alloca and the 32-bit version of __chkstk will probe the
|
|
// stack and adjust the stack pointer in one go. The 64-bit version of
|
|
// __chkstk is only responsible for probing the stack. The 64-bit prologue is
|
|
// responsible for adjusting the stack pointer. Touching the stack at 4K
|
|
// increments is necessary to ensure that the guard pages used by the OS
|
|
// virtual memory manager are allocated in correct sequence.
|
|
uint64_t AlignedNumBytes = NumBytes;
|
|
if (IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF))
|
|
AlignedNumBytes = alignTo(AlignedNumBytes, MaxAlign);
|
|
if (AlignedNumBytes >= StackProbeSize && UseStackProbe) {
|
|
// Check whether EAX is livein for this block.
|
|
bool isEAXAlive = isEAXLiveIn(MBB);
|
|
|
|
if (isEAXAlive) {
|
|
// Sanity check that EAX is not livein for this function.
|
|
// It should not be, so throw an assert.
|
|
assert(!Is64Bit && "EAX is livein in x64 case!");
|
|
|
|
// Save EAX
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
|
|
.addReg(X86::EAX, RegState::Kill)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
if (Is64Bit) {
|
|
// Handle the 64-bit Windows ABI case where we need to call __chkstk.
|
|
// Function prologue is responsible for adjusting the stack pointer.
|
|
if (isUInt<32>(NumBytes)) {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
|
|
.addImm(NumBytes)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
} else if (isInt<32>(NumBytes)) {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri32), X86::RAX)
|
|
.addImm(NumBytes)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
} else {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX)
|
|
.addImm(NumBytes)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
} else {
|
|
// Allocate NumBytes-4 bytes on stack in case of isEAXAlive.
|
|
// We'll also use 4 already allocated bytes for EAX.
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
|
|
.addImm(isEAXAlive ? NumBytes - 4 : NumBytes)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
// Call __chkstk, __chkstk_ms, or __alloca.
|
|
emitStackProbe(MF, MBB, MBBI, DL, true);
|
|
|
|
if (isEAXAlive) {
|
|
// Restore EAX
|
|
MachineInstr *MI =
|
|
addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), X86::EAX),
|
|
StackPtr, false, NumBytes - 4);
|
|
MI->setFlag(MachineInstr::FrameSetup);
|
|
MBB.insert(MBBI, MI);
|
|
}
|
|
} else if (NumBytes) {
|
|
emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, /*InEpilogue=*/false);
|
|
}
|
|
|
|
if (NeedsWinCFI && NumBytes)
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc))
|
|
.addImm(NumBytes)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
int SEHFrameOffset = 0;
|
|
unsigned SPOrEstablisher;
|
|
if (IsFunclet) {
|
|
if (IsClrFunclet) {
|
|
// The establisher parameter passed to a CLR funclet is actually a pointer
|
|
// to the (mostly empty) frame of its nearest enclosing funclet; we have
|
|
// to find the root function establisher frame by loading the PSPSym from
|
|
// the intermediate frame.
|
|
unsigned PSPSlotOffset = getPSPSlotOffsetFromSP(MF);
|
|
MachinePointerInfo NoInfo;
|
|
MBB.addLiveIn(Establisher);
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rm), Establisher),
|
|
Establisher, false, PSPSlotOffset)
|
|
.addMemOperand(MF.getMachineMemOperand(
|
|
NoInfo, MachineMemOperand::MOLoad, SlotSize, SlotSize));
|
|
;
|
|
// Save the root establisher back into the current funclet's (mostly
|
|
// empty) frame, in case a sub-funclet or the GC needs it.
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mr)), StackPtr,
|
|
false, PSPSlotOffset)
|
|
.addReg(Establisher)
|
|
.addMemOperand(
|
|
MF.getMachineMemOperand(NoInfo, MachineMemOperand::MOStore |
|
|
MachineMemOperand::MOVolatile,
|
|
SlotSize, SlotSize));
|
|
}
|
|
SPOrEstablisher = Establisher;
|
|
} else {
|
|
SPOrEstablisher = StackPtr;
|
|
}
|
|
|
|
if (IsWin64Prologue && HasFP) {
|
|
// Set RBP to a small fixed offset from RSP. In the funclet case, we base
|
|
// this calculation on the incoming establisher, which holds the value of
|
|
// RSP from the parent frame at the end of the prologue.
|
|
SEHFrameOffset = calculateSetFPREG(ParentFrameNumBytes);
|
|
if (SEHFrameOffset)
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
|
|
SPOrEstablisher, false, SEHFrameOffset);
|
|
else
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr)
|
|
.addReg(SPOrEstablisher);
|
|
|
|
// If this is not a funclet, emit the CFI describing our frame pointer.
|
|
if (NeedsWinCFI && !IsFunclet) {
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame))
|
|
.addImm(FramePtr)
|
|
.addImm(SEHFrameOffset)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
if (isAsynchronousEHPersonality(Personality))
|
|
MF.getWinEHFuncInfo()->SEHSetFrameOffset = SEHFrameOffset;
|
|
}
|
|
} else if (IsFunclet && STI.is32Bit()) {
|
|
// Reset EBP / ESI to something good for funclets.
|
|
MBBI = restoreWin32EHStackPointers(MBB, MBBI, DL);
|
|
// If we're a catch funclet, we can be returned to via catchret. Save ESP
|
|
// into the registration node so that the runtime will restore it for us.
|
|
if (!MBB.isCleanupFuncletEntry()) {
|
|
assert(Personality == EHPersonality::MSVC_CXX);
|
|
unsigned FrameReg;
|
|
int FI = MF.getWinEHFuncInfo()->EHRegNodeFrameIndex;
|
|
int64_t EHRegOffset = getFrameIndexReference(MF, FI, FrameReg);
|
|
// ESP is the first field, so no extra displacement is needed.
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32mr)), FrameReg,
|
|
false, EHRegOffset)
|
|
.addReg(X86::ESP);
|
|
}
|
|
}
|
|
|
|
while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) {
|
|
const MachineInstr *FrameInstr = &*MBBI;
|
|
++MBBI;
|
|
|
|
if (NeedsWinCFI) {
|
|
int FI;
|
|
if (unsigned Reg = TII.isStoreToStackSlot(FrameInstr, FI)) {
|
|
if (X86::FR64RegClass.contains(Reg)) {
|
|
unsigned IgnoredFrameReg;
|
|
int Offset = getFrameIndexReference(MF, FI, IgnoredFrameReg);
|
|
Offset += SEHFrameOffset;
|
|
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SaveXMM))
|
|
.addImm(Reg)
|
|
.addImm(Offset)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (NeedsWinCFI)
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_EndPrologue))
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
if (FnHasClrFunclet && !IsFunclet) {
|
|
// Save the so-called Initial-SP (i.e. the value of the stack pointer
|
|
// immediately after the prolog) into the PSPSlot so that funclets
|
|
// and the GC can recover it.
|
|
unsigned PSPSlotOffset = getPSPSlotOffsetFromSP(MF);
|
|
auto PSPInfo = MachinePointerInfo::getFixedStack(
|
|
MF, MF.getWinEHFuncInfo()->PSPSymFrameIdx);
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mr)), StackPtr, false,
|
|
PSPSlotOffset)
|
|
.addReg(StackPtr)
|
|
.addMemOperand(MF.getMachineMemOperand(
|
|
PSPInfo, MachineMemOperand::MOStore | MachineMemOperand::MOVolatile,
|
|
SlotSize, SlotSize));
|
|
}
|
|
|
|
// Realign stack after we spilled callee-saved registers (so that we'll be
|
|
// able to calculate their offsets from the frame pointer).
|
|
// Win64 requires aligning the stack after the prologue.
|
|
if (IsWin64Prologue && TRI->needsStackRealignment(MF)) {
|
|
assert(HasFP && "There should be a frame pointer if stack is realigned.");
|
|
BuildStackAlignAND(MBB, MBBI, DL, SPOrEstablisher, MaxAlign);
|
|
}
|
|
|
|
// We already dealt with stack realignment and funclets above.
|
|
if (IsFunclet && STI.is32Bit())
|
|
return;
|
|
|
|
// If we need a base pointer, set it up here. It's whatever the value
|
|
// of the stack pointer is at this point. Any variable size objects
|
|
// will be allocated after this, so we can still use the base pointer
|
|
// to reference locals.
|
|
if (TRI->hasBasePointer(MF)) {
|
|
// Update the base pointer with the current stack pointer.
|
|
unsigned Opc = Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr;
|
|
BuildMI(MBB, MBBI, DL, TII.get(Opc), BasePtr)
|
|
.addReg(SPOrEstablisher)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
if (X86FI->getRestoreBasePointer()) {
|
|
// Stash value of base pointer. Saving RSP instead of EBP shortens
|
|
// dependence chain. Used by SjLj EH.
|
|
unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)),
|
|
FramePtr, true, X86FI->getRestoreBasePointerOffset())
|
|
.addReg(SPOrEstablisher)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
if (X86FI->getHasSEHFramePtrSave() && !IsFunclet) {
|
|
// Stash the value of the frame pointer relative to the base pointer for
|
|
// Win32 EH. This supports Win32 EH, which does the inverse of the above:
|
|
// it recovers the frame pointer from the base pointer rather than the
|
|
// other way around.
|
|
unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
|
|
unsigned UsedReg;
|
|
int Offset =
|
|
getFrameIndexReference(MF, X86FI->getSEHFramePtrSaveIndex(), UsedReg);
|
|
assert(UsedReg == BasePtr);
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)), UsedReg, true, Offset)
|
|
.addReg(FramePtr)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
}
|
|
|
|
if (((!HasFP && NumBytes) || PushedRegs) && NeedsDwarfCFI) {
|
|
// Mark end of stack pointer adjustment.
|
|
if (!HasFP && NumBytes) {
|
|
// Define the current CFA rule to use the provided offset.
|
|
assert(StackSize);
|
|
BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaOffset(
|
|
nullptr, -StackSize + stackGrowth));
|
|
}
|
|
|
|
// Emit DWARF info specifying the offsets of the callee-saved registers.
|
|
if (PushedRegs)
|
|
emitCalleeSavedFrameMoves(MBB, MBBI, DL);
|
|
}
|
|
}
|
|
|
|
bool X86FrameLowering::canUseLEAForSPInEpilogue(
|
|
const MachineFunction &MF) const {
|
|
// We can't use LEA instructions for adjusting the stack pointer if this is a
|
|
// leaf function in the Win64 ABI. Only ADD instructions may be used to
|
|
// deallocate the stack.
|
|
// This means that we can use LEA for SP in two situations:
|
|
// 1. We *aren't* using the Win64 ABI which means we are free to use LEA.
|
|
// 2. We *have* a frame pointer which means we are permitted to use LEA.
|
|
return !MF.getTarget().getMCAsmInfo()->usesWindowsCFI() || hasFP(MF);
|
|
}
|
|
|
|
static bool isFuncletReturnInstr(MachineInstr *MI) {
|
|
switch (MI->getOpcode()) {
|
|
case X86::CATCHRET:
|
|
case X86::CLEANUPRET:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
llvm_unreachable("impossible");
|
|
}
|
|
|
|
// CLR funclets use a special "Previous Stack Pointer Symbol" slot on the
|
|
// stack. It holds a pointer to the bottom of the root function frame. The
|
|
// establisher frame pointer passed to a nested funclet may point to the
|
|
// (mostly empty) frame of its parent funclet, but it will need to find
|
|
// the frame of the root function to access locals. To facilitate this,
|
|
// every funclet copies the pointer to the bottom of the root function
|
|
// frame into a PSPSym slot in its own (mostly empty) stack frame. Using the
|
|
// same offset for the PSPSym in the root function frame that's used in the
|
|
// funclets' frames allows each funclet to dynamically accept any ancestor
|
|
// frame as its establisher argument (the runtime doesn't guarantee the
|
|
// immediate parent for some reason lost to history), and also allows the GC,
|
|
// which uses the PSPSym for some bookkeeping, to find it in any funclet's
|
|
// frame with only a single offset reported for the entire method.
|
|
unsigned
|
|
X86FrameLowering::getPSPSlotOffsetFromSP(const MachineFunction &MF) const {
|
|
const WinEHFuncInfo &Info = *MF.getWinEHFuncInfo();
|
|
// getFrameIndexReferenceFromSP has an out ref parameter for the stack
|
|
// pointer register; pass a dummy that we ignore
|
|
unsigned SPReg;
|
|
int Offset = getFrameIndexReferenceFromSP(MF, Info.PSPSymFrameIdx, SPReg);
|
|
assert(Offset >= 0);
|
|
return static_cast<unsigned>(Offset);
|
|
}
|
|
|
|
unsigned
|
|
X86FrameLowering::getWinEHFuncletFrameSize(const MachineFunction &MF) const {
|
|
// This is the size of the pushed CSRs.
|
|
unsigned CSSize =
|
|
MF.getInfo<X86MachineFunctionInfo>()->getCalleeSavedFrameSize();
|
|
// This is the amount of stack a funclet needs to allocate.
|
|
unsigned UsedSize;
|
|
EHPersonality Personality =
|
|
classifyEHPersonality(MF.getFunction()->getPersonalityFn());
|
|
if (Personality == EHPersonality::CoreCLR) {
|
|
// CLR funclets need to hold enough space to include the PSPSym, at the
|
|
// same offset from the stack pointer (immediately after the prolog) as it
|
|
// resides at in the main function.
|
|
UsedSize = getPSPSlotOffsetFromSP(MF) + SlotSize;
|
|
} else {
|
|
// Other funclets just need enough stack for outgoing call arguments.
|
|
UsedSize = MF.getFrameInfo()->getMaxCallFrameSize();
|
|
}
|
|
// RBP is not included in the callee saved register block. After pushing RBP,
|
|
// everything is 16 byte aligned. Everything we allocate before an outgoing
|
|
// call must also be 16 byte aligned.
|
|
unsigned FrameSizeMinusRBP = alignTo(CSSize + UsedSize, getStackAlignment());
|
|
// Subtract out the size of the callee saved registers. This is how much stack
|
|
// each funclet will allocate.
|
|
return FrameSizeMinusRBP - CSSize;
|
|
}
|
|
|
|
void X86FrameLowering::emitEpilogue(MachineFunction &MF,
|
|
MachineBasicBlock &MBB) const {
|
|
const MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
|
|
DebugLoc DL;
|
|
if (MBBI != MBB.end())
|
|
DL = MBBI->getDebugLoc();
|
|
// standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
|
|
const bool Is64BitILP32 = STI.isTarget64BitILP32();
|
|
unsigned FramePtr = TRI->getFrameRegister(MF);
|
|
unsigned MachineFramePtr =
|
|
Is64BitILP32 ? getX86SubSuperRegister(FramePtr, 64) : FramePtr;
|
|
|
|
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
|
|
bool NeedsWinCFI =
|
|
IsWin64Prologue && MF.getFunction()->needsUnwindTableEntry();
|
|
bool IsFunclet = isFuncletReturnInstr(MBBI);
|
|
MachineBasicBlock *TargetMBB = nullptr;
|
|
|
|
// Get the number of bytes to allocate from the FrameInfo.
|
|
uint64_t StackSize = MFI->getStackSize();
|
|
uint64_t MaxAlign = calculateMaxStackAlign(MF);
|
|
unsigned CSSize = X86FI->getCalleeSavedFrameSize();
|
|
uint64_t NumBytes = 0;
|
|
|
|
if (MBBI->getOpcode() == X86::CATCHRET) {
|
|
// SEH shouldn't use catchret.
|
|
assert(!isAsynchronousEHPersonality(
|
|
classifyEHPersonality(MF.getFunction()->getPersonalityFn())) &&
|
|
"SEH should not use CATCHRET");
|
|
|
|
NumBytes = getWinEHFuncletFrameSize(MF);
|
|
assert(hasFP(MF) && "EH funclets without FP not yet implemented");
|
|
TargetMBB = MBBI->getOperand(0).getMBB();
|
|
|
|
// Pop EBP.
|
|
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r),
|
|
MachineFramePtr)
|
|
.setMIFlag(MachineInstr::FrameDestroy);
|
|
} else if (MBBI->getOpcode() == X86::CLEANUPRET) {
|
|
NumBytes = getWinEHFuncletFrameSize(MF);
|
|
assert(hasFP(MF) && "EH funclets without FP not yet implemented");
|
|
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r),
|
|
MachineFramePtr)
|
|
.setMIFlag(MachineInstr::FrameDestroy);
|
|
} else if (hasFP(MF)) {
|
|
// Calculate required stack adjustment.
|
|
uint64_t FrameSize = StackSize - SlotSize;
|
|
NumBytes = FrameSize - CSSize;
|
|
|
|
// Callee-saved registers were pushed on stack before the stack was
|
|
// realigned.
|
|
if (TRI->needsStackRealignment(MF) && !IsWin64Prologue)
|
|
NumBytes = alignTo(FrameSize, MaxAlign);
|
|
|
|
// Pop EBP.
|
|
BuildMI(MBB, MBBI, DL,
|
|
TII.get(Is64Bit ? X86::POP64r : X86::POP32r), MachineFramePtr)
|
|
.setMIFlag(MachineInstr::FrameDestroy);
|
|
} else {
|
|
NumBytes = StackSize - CSSize;
|
|
}
|
|
uint64_t SEHStackAllocAmt = NumBytes;
|
|
|
|
// Skip the callee-saved pop instructions.
|
|
while (MBBI != MBB.begin()) {
|
|
MachineBasicBlock::iterator PI = std::prev(MBBI);
|
|
unsigned Opc = PI->getOpcode();
|
|
|
|
if ((Opc != X86::POP32r || !PI->getFlag(MachineInstr::FrameDestroy)) &&
|
|
(Opc != X86::POP64r || !PI->getFlag(MachineInstr::FrameDestroy)) &&
|
|
Opc != X86::DBG_VALUE && !PI->isTerminator())
|
|
break;
|
|
|
|
--MBBI;
|
|
}
|
|
MachineBasicBlock::iterator FirstCSPop = MBBI;
|
|
|
|
if (TargetMBB) {
|
|
// Fill EAX/RAX with the address of the target block.
|
|
unsigned ReturnReg = STI.is64Bit() ? X86::RAX : X86::EAX;
|
|
if (STI.is64Bit()) {
|
|
// LEA64r TargetMBB(%rip), %rax
|
|
BuildMI(MBB, FirstCSPop, DL, TII.get(X86::LEA64r), ReturnReg)
|
|
.addReg(X86::RIP)
|
|
.addImm(0)
|
|
.addReg(0)
|
|
.addMBB(TargetMBB)
|
|
.addReg(0);
|
|
} else {
|
|
// MOV32ri $TargetMBB, %eax
|
|
BuildMI(MBB, FirstCSPop, DL, TII.get(X86::MOV32ri), ReturnReg)
|
|
.addMBB(TargetMBB);
|
|
}
|
|
// Record that we've taken the address of TargetMBB and no longer just
|
|
// reference it in a terminator.
|
|
TargetMBB->setHasAddressTaken();
|
|
}
|
|
|
|
if (MBBI != MBB.end())
|
|
DL = MBBI->getDebugLoc();
|
|
|
|
// If there is an ADD32ri or SUB32ri of ESP immediately before this
|
|
// instruction, merge the two instructions.
|
|
if (NumBytes || MFI->hasVarSizedObjects())
|
|
NumBytes += mergeSPUpdates(MBB, MBBI, true);
|
|
|
|
// If dynamic alloca is used, then reset esp to point to the last callee-saved
|
|
// slot before popping them off! Same applies for the case, when stack was
|
|
// realigned. Don't do this if this was a funclet epilogue, since the funclets
|
|
// will not do realignment or dynamic stack allocation.
|
|
if ((TRI->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) &&
|
|
!IsFunclet) {
|
|
if (TRI->needsStackRealignment(MF))
|
|
MBBI = FirstCSPop;
|
|
unsigned SEHFrameOffset = calculateSetFPREG(SEHStackAllocAmt);
|
|
uint64_t LEAAmount =
|
|
IsWin64Prologue ? SEHStackAllocAmt - SEHFrameOffset : -CSSize;
|
|
|
|
// There are only two legal forms of epilogue:
|
|
// - add SEHAllocationSize, %rsp
|
|
// - lea SEHAllocationSize(%FramePtr), %rsp
|
|
//
|
|
// 'mov %FramePtr, %rsp' will not be recognized as an epilogue sequence.
|
|
// However, we may use this sequence if we have a frame pointer because the
|
|
// effects of the prologue can safely be undone.
|
|
if (LEAAmount != 0) {
|
|
unsigned Opc = getLEArOpcode(Uses64BitFramePtr);
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr),
|
|
FramePtr, false, LEAAmount);
|
|
--MBBI;
|
|
} else {
|
|
unsigned Opc = (Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr);
|
|
BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
|
|
.addReg(FramePtr);
|
|
--MBBI;
|
|
}
|
|
} else if (NumBytes) {
|
|
// Adjust stack pointer back: ESP += numbytes.
|
|
emitSPUpdate(MBB, MBBI, NumBytes, /*InEpilogue=*/true);
|
|
--MBBI;
|
|
}
|
|
|
|
// Windows unwinder will not invoke function's exception handler if IP is
|
|
// either in prologue or in epilogue. This behavior causes a problem when a
|
|
// call immediately precedes an epilogue, because the return address points
|
|
// into the epilogue. To cope with that, we insert an epilogue marker here,
|
|
// then replace it with a 'nop' if it ends up immediately after a CALL in the
|
|
// final emitted code.
|
|
if (NeedsWinCFI)
|
|
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue));
|
|
|
|
// Add the return addr area delta back since we are not tail calling.
|
|
int Offset = -1 * X86FI->getTCReturnAddrDelta();
|
|
assert(Offset >= 0 && "TCDelta should never be positive");
|
|
if (Offset) {
|
|
MBBI = MBB.getFirstTerminator();
|
|
|
|
// Check for possible merge with preceding ADD instruction.
|
|
Offset += mergeSPUpdates(MBB, MBBI, true);
|
|
emitSPUpdate(MBB, MBBI, Offset, /*InEpilogue=*/true);
|
|
}
|
|
}
|
|
|
|
// NOTE: this only has a subset of the full frame index logic. In
|
|
// particular, the FI < 0 and AfterFPPop logic is handled in
|
|
// X86RegisterInfo::eliminateFrameIndex, but not here. Possibly
|
|
// (probably?) it should be moved into here.
|
|
int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
|
|
unsigned &FrameReg) const {
|
|
const MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
|
|
// We can't calculate offset from frame pointer if the stack is realigned,
|
|
// so enforce usage of stack/base pointer. The base pointer is used when we
|
|
// have dynamic allocas in addition to dynamic realignment.
|
|
if (TRI->hasBasePointer(MF))
|
|
FrameReg = TRI->getBaseRegister();
|
|
else if (TRI->needsStackRealignment(MF))
|
|
FrameReg = TRI->getStackRegister();
|
|
else
|
|
FrameReg = TRI->getFrameRegister(MF);
|
|
|
|
// Offset will hold the offset from the stack pointer at function entry to the
|
|
// object.
|
|
// We need to factor in additional offsets applied during the prologue to the
|
|
// frame, base, and stack pointer depending on which is used.
|
|
int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea();
|
|
const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
unsigned CSSize = X86FI->getCalleeSavedFrameSize();
|
|
uint64_t StackSize = MFI->getStackSize();
|
|
bool HasFP = hasFP(MF);
|
|
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
|
|
int64_t FPDelta = 0;
|
|
|
|
if (IsWin64Prologue) {
|
|
assert(!MFI->hasCalls() || (StackSize % 16) == 8);
|
|
|
|
// Calculate required stack adjustment.
|
|
uint64_t FrameSize = StackSize - SlotSize;
|
|
// If required, include space for extra hidden slot for stashing base pointer.
|
|
if (X86FI->getRestoreBasePointer())
|
|
FrameSize += SlotSize;
|
|
uint64_t NumBytes = FrameSize - CSSize;
|
|
|
|
uint64_t SEHFrameOffset = calculateSetFPREG(NumBytes);
|
|
if (FI && FI == X86FI->getFAIndex())
|
|
return -SEHFrameOffset;
|
|
|
|
// FPDelta is the offset from the "traditional" FP location of the old base
|
|
// pointer followed by return address and the location required by the
|
|
// restricted Win64 prologue.
|
|
// Add FPDelta to all offsets below that go through the frame pointer.
|
|
FPDelta = FrameSize - SEHFrameOffset;
|
|
assert((!MFI->hasCalls() || (FPDelta % 16) == 0) &&
|
|
"FPDelta isn't aligned per the Win64 ABI!");
|
|
}
|
|
|
|
|
|
if (TRI->hasBasePointer(MF)) {
|
|
assert(HasFP && "VLAs and dynamic stack realign, but no FP?!");
|
|
if (FI < 0) {
|
|
// Skip the saved EBP.
|
|
return Offset + SlotSize + FPDelta;
|
|
} else {
|
|
assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
|
|
return Offset + StackSize;
|
|
}
|
|
} else if (TRI->needsStackRealignment(MF)) {
|
|
if (FI < 0) {
|
|
// Skip the saved EBP.
|
|
return Offset + SlotSize + FPDelta;
|
|
} else {
|
|
assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
|
|
return Offset + StackSize;
|
|
}
|
|
// FIXME: Support tail calls
|
|
} else {
|
|
if (!HasFP)
|
|
return Offset + StackSize;
|
|
|
|
// Skip the saved EBP.
|
|
Offset += SlotSize;
|
|
|
|
// Skip the RETADDR move area
|
|
int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
|
|
if (TailCallReturnAddrDelta < 0)
|
|
Offset -= TailCallReturnAddrDelta;
|
|
}
|
|
|
|
return Offset + FPDelta;
|
|
}
|
|
|
|
// Simplified from getFrameIndexReference keeping only StackPointer cases
|
|
int X86FrameLowering::getFrameIndexReferenceFromSP(const MachineFunction &MF,
|
|
int FI,
|
|
unsigned &FrameReg) const {
|
|
const MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
// Does not include any dynamic realign.
|
|
const uint64_t StackSize = MFI->getStackSize();
|
|
{
|
|
#ifndef NDEBUG
|
|
// LLVM arranges the stack as follows:
|
|
// ...
|
|
// ARG2
|
|
// ARG1
|
|
// RETADDR
|
|
// PUSH RBP <-- RBP points here
|
|
// PUSH CSRs
|
|
// ~~~~~~~ <-- possible stack realignment (non-win64)
|
|
// ...
|
|
// STACK OBJECTS
|
|
// ... <-- RSP after prologue points here
|
|
// ~~~~~~~ <-- possible stack realignment (win64)
|
|
//
|
|
// if (hasVarSizedObjects()):
|
|
// ... <-- "base pointer" (ESI/RBX) points here
|
|
// DYNAMIC ALLOCAS
|
|
// ... <-- RSP points here
|
|
//
|
|
// Case 1: In the simple case of no stack realignment and no dynamic
|
|
// allocas, both "fixed" stack objects (arguments and CSRs) are addressable
|
|
// with fixed offsets from RSP.
|
|
//
|
|
// Case 2: In the case of stack realignment with no dynamic allocas, fixed
|
|
// stack objects are addressed with RBP and regular stack objects with RSP.
|
|
//
|
|
// Case 3: In the case of dynamic allocas and stack realignment, RSP is used
|
|
// to address stack arguments for outgoing calls and nothing else. The "base
|
|
// pointer" points to local variables, and RBP points to fixed objects.
|
|
//
|
|
// In cases 2 and 3, we can only answer for non-fixed stack objects, and the
|
|
// answer we give is relative to the SP after the prologue, and not the
|
|
// SP in the middle of the function.
|
|
|
|
assert((!MFI->isFixedObjectIndex(FI) || !TRI->needsStackRealignment(MF) ||
|
|
STI.isTargetWin64()) &&
|
|
"offset from fixed object to SP is not static");
|
|
|
|
// We don't handle tail calls, and shouldn't be seeing them either.
|
|
int TailCallReturnAddrDelta =
|
|
MF.getInfo<X86MachineFunctionInfo>()->getTCReturnAddrDelta();
|
|
assert(!(TailCallReturnAddrDelta < 0) && "we don't handle this case!");
|
|
#endif
|
|
}
|
|
|
|
// Fill in FrameReg output argument.
|
|
FrameReg = TRI->getStackRegister();
|
|
|
|
// This is how the math works out:
|
|
//
|
|
// %rsp grows (i.e. gets lower) left to right. Each box below is
|
|
// one word (eight bytes). Obj0 is the stack slot we're trying to
|
|
// get to.
|
|
//
|
|
// ----------------------------------
|
|
// | BP | Obj0 | Obj1 | ... | ObjN |
|
|
// ----------------------------------
|
|
// ^ ^ ^ ^
|
|
// A B C E
|
|
//
|
|
// A is the incoming stack pointer.
|
|
// (B - A) is the local area offset (-8 for x86-64) [1]
|
|
// (C - A) is the Offset returned by MFI->getObjectOffset for Obj0 [2]
|
|
//
|
|
// |(E - B)| is the StackSize (absolute value, positive). For a
|
|
// stack that grown down, this works out to be (B - E). [3]
|
|
//
|
|
// E is also the value of %rsp after stack has been set up, and we
|
|
// want (C - E) -- the value we can add to %rsp to get to Obj0. Now
|
|
// (C - E) == (C - A) - (B - A) + (B - E)
|
|
// { Using [1], [2] and [3] above }
|
|
// == getObjectOffset - LocalAreaOffset + StackSize
|
|
//
|
|
|
|
// Get the Offset from the StackPointer
|
|
int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea();
|
|
|
|
return Offset + StackSize;
|
|
}
|
|
|
|
bool X86FrameLowering::assignCalleeSavedSpillSlots(
|
|
MachineFunction &MF, const TargetRegisterInfo *TRI,
|
|
std::vector<CalleeSavedInfo> &CSI) const {
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
|
|
unsigned CalleeSavedFrameSize = 0;
|
|
int SpillSlotOffset = getOffsetOfLocalArea() + X86FI->getTCReturnAddrDelta();
|
|
|
|
if (hasFP(MF)) {
|
|
// emitPrologue always spills frame register the first thing.
|
|
SpillSlotOffset -= SlotSize;
|
|
MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset);
|
|
|
|
// Since emitPrologue and emitEpilogue will handle spilling and restoring of
|
|
// the frame register, we can delete it from CSI list and not have to worry
|
|
// about avoiding it later.
|
|
unsigned FPReg = TRI->getFrameRegister(MF);
|
|
for (unsigned i = 0; i < CSI.size(); ++i) {
|
|
if (TRI->regsOverlap(CSI[i].getReg(),FPReg)) {
|
|
CSI.erase(CSI.begin() + i);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Assign slots for GPRs. It increases frame size.
|
|
for (unsigned i = CSI.size(); i != 0; --i) {
|
|
unsigned Reg = CSI[i - 1].getReg();
|
|
|
|
if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
|
|
SpillSlotOffset -= SlotSize;
|
|
CalleeSavedFrameSize += SlotSize;
|
|
|
|
int SlotIndex = MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset);
|
|
CSI[i - 1].setFrameIdx(SlotIndex);
|
|
}
|
|
|
|
X86FI->setCalleeSavedFrameSize(CalleeSavedFrameSize);
|
|
|
|
// Assign slots for XMMs.
|
|
for (unsigned i = CSI.size(); i != 0; --i) {
|
|
unsigned Reg = CSI[i - 1].getReg();
|
|
if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
|
|
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
|
|
// ensure alignment
|
|
SpillSlotOffset -= std::abs(SpillSlotOffset) % RC->getAlignment();
|
|
// spill into slot
|
|
SpillSlotOffset -= RC->getSize();
|
|
int SlotIndex =
|
|
MFI->CreateFixedSpillStackObject(RC->getSize(), SpillSlotOffset);
|
|
CSI[i - 1].setFrameIdx(SlotIndex);
|
|
MFI->ensureMaxAlignment(RC->getAlignment());
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool X86FrameLowering::spillCalleeSavedRegisters(
|
|
MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
|
|
const std::vector<CalleeSavedInfo> &CSI,
|
|
const TargetRegisterInfo *TRI) const {
|
|
DebugLoc DL = MBB.findDebugLoc(MI);
|
|
|
|
// Don't save CSRs in 32-bit EH funclets. The caller saves EBX, EBP, ESI, EDI
|
|
// for us, and there are no XMM CSRs on Win32.
|
|
if (MBB.isEHFuncletEntry() && STI.is32Bit() && STI.isOSWindows())
|
|
return true;
|
|
|
|
// Push GPRs. It increases frame size.
|
|
unsigned Opc = STI.is64Bit() ? X86::PUSH64r : X86::PUSH32r;
|
|
for (unsigned i = CSI.size(); i != 0; --i) {
|
|
unsigned Reg = CSI[i - 1].getReg();
|
|
|
|
if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
// Add the callee-saved register as live-in. It's killed at the spill.
|
|
MBB.addLiveIn(Reg);
|
|
|
|
BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, RegState::Kill)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
// Make XMM regs spilled. X86 does not have ability of push/pop XMM.
|
|
// It can be done by spilling XMMs to stack frame.
|
|
for (unsigned i = CSI.size(); i != 0; --i) {
|
|
unsigned Reg = CSI[i-1].getReg();
|
|
if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
// Add the callee-saved register as live-in. It's killed at the spill.
|
|
MBB.addLiveIn(Reg);
|
|
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
|
|
|
|
TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i - 1].getFrameIdx(), RC,
|
|
TRI);
|
|
--MI;
|
|
MI->setFlag(MachineInstr::FrameSetup);
|
|
++MI;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MI,
|
|
const std::vector<CalleeSavedInfo> &CSI,
|
|
const TargetRegisterInfo *TRI) const {
|
|
if (CSI.empty())
|
|
return false;
|
|
|
|
if (isFuncletReturnInstr(MI) && STI.isOSWindows()) {
|
|
// Don't restore CSRs in 32-bit EH funclets. Matches
|
|
// spillCalleeSavedRegisters.
|
|
if (STI.is32Bit())
|
|
return true;
|
|
// Don't restore CSRs before an SEH catchret. SEH except blocks do not form
|
|
// funclets. emitEpilogue transforms these to normal jumps.
|
|
if (MI->getOpcode() == X86::CATCHRET) {
|
|
const Function *Func = MBB.getParent()->getFunction();
|
|
bool IsSEH = isAsynchronousEHPersonality(
|
|
classifyEHPersonality(Func->getPersonalityFn()));
|
|
if (IsSEH)
|
|
return true;
|
|
}
|
|
}
|
|
|
|
DebugLoc DL = MBB.findDebugLoc(MI);
|
|
|
|
// Reload XMMs from stack frame.
|
|
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
|
|
unsigned Reg = CSI[i].getReg();
|
|
if (X86::GR64RegClass.contains(Reg) ||
|
|
X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
|
|
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
|
|
TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
|
|
}
|
|
|
|
// POP GPRs.
|
|
unsigned Opc = STI.is64Bit() ? X86::POP64r : X86::POP32r;
|
|
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
|
|
unsigned Reg = CSI[i].getReg();
|
|
if (!X86::GR64RegClass.contains(Reg) &&
|
|
!X86::GR32RegClass.contains(Reg))
|
|
continue;
|
|
|
|
BuildMI(MBB, MI, DL, TII.get(Opc), Reg)
|
|
.setMIFlag(MachineInstr::FrameDestroy);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
void X86FrameLowering::determineCalleeSaves(MachineFunction &MF,
|
|
BitVector &SavedRegs,
|
|
RegScavenger *RS) const {
|
|
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
|
|
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
int64_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
|
|
|
|
if (TailCallReturnAddrDelta < 0) {
|
|
// create RETURNADDR area
|
|
// arg
|
|
// arg
|
|
// RETADDR
|
|
// { ...
|
|
// RETADDR area
|
|
// ...
|
|
// }
|
|
// [EBP]
|
|
MFI->CreateFixedObject(-TailCallReturnAddrDelta,
|
|
TailCallReturnAddrDelta - SlotSize, true);
|
|
}
|
|
|
|
// Spill the BasePtr if it's used.
|
|
if (TRI->hasBasePointer(MF)) {
|
|
SavedRegs.set(TRI->getBaseRegister());
|
|
|
|
// Allocate a spill slot for EBP if we have a base pointer and EH funclets.
|
|
if (MF.getMMI().hasEHFunclets()) {
|
|
int FI = MFI->CreateSpillStackObject(SlotSize, SlotSize);
|
|
X86FI->setHasSEHFramePtrSave(true);
|
|
X86FI->setSEHFramePtrSaveIndex(FI);
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool
|
|
HasNestArgument(const MachineFunction *MF) {
|
|
const Function *F = MF->getFunction();
|
|
for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
|
|
I != E; I++) {
|
|
if (I->hasNestAttr())
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// GetScratchRegister - Get a temp register for performing work in the
|
|
/// segmented stack and the Erlang/HiPE stack prologue. Depending on platform
|
|
/// and the properties of the function either one or two registers will be
|
|
/// needed. Set primary to true for the first register, false for the second.
|
|
static unsigned
|
|
GetScratchRegister(bool Is64Bit, bool IsLP64, const MachineFunction &MF, bool Primary) {
|
|
CallingConv::ID CallingConvention = MF.getFunction()->getCallingConv();
|
|
|
|
// Erlang stuff.
|
|
if (CallingConvention == CallingConv::HiPE) {
|
|
if (Is64Bit)
|
|
return Primary ? X86::R14 : X86::R13;
|
|
else
|
|
return Primary ? X86::EBX : X86::EDI;
|
|
}
|
|
|
|
if (Is64Bit) {
|
|
if (IsLP64)
|
|
return Primary ? X86::R11 : X86::R12;
|
|
else
|
|
return Primary ? X86::R11D : X86::R12D;
|
|
}
|
|
|
|
bool IsNested = HasNestArgument(&MF);
|
|
|
|
if (CallingConvention == CallingConv::X86_FastCall ||
|
|
CallingConvention == CallingConv::Fast) {
|
|
if (IsNested)
|
|
report_fatal_error("Segmented stacks does not support fastcall with "
|
|
"nested function.");
|
|
return Primary ? X86::EAX : X86::ECX;
|
|
}
|
|
if (IsNested)
|
|
return Primary ? X86::EDX : X86::EAX;
|
|
return Primary ? X86::ECX : X86::EAX;
|
|
}
|
|
|
|
// The stack limit in the TCB is set to this many bytes above the actual stack
|
|
// limit.
|
|
static const uint64_t kSplitStackAvailable = 256;
|
|
|
|
void X86FrameLowering::adjustForSegmentedStacks(
|
|
MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
uint64_t StackSize;
|
|
unsigned TlsReg, TlsOffset;
|
|
DebugLoc DL;
|
|
|
|
// To support shrink-wrapping we would need to insert the new blocks
|
|
// at the right place and update the branches to PrologueMBB.
|
|
assert(&(*MF.begin()) == &PrologueMBB && "Shrink-wrapping not supported yet");
|
|
|
|
unsigned ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true);
|
|
assert(!MF.getRegInfo().isLiveIn(ScratchReg) &&
|
|
"Scratch register is live-in");
|
|
|
|
if (MF.getFunction()->isVarArg())
|
|
report_fatal_error("Segmented stacks do not support vararg functions.");
|
|
if (!STI.isTargetLinux() && !STI.isTargetDarwin() && !STI.isTargetWin32() &&
|
|
!STI.isTargetWin64() && !STI.isTargetFreeBSD() &&
|
|
!STI.isTargetDragonFly())
|
|
report_fatal_error("Segmented stacks not supported on this platform.");
|
|
|
|
// Eventually StackSize will be calculated by a link-time pass; which will
|
|
// also decide whether checking code needs to be injected into this particular
|
|
// prologue.
|
|
StackSize = MFI->getStackSize();
|
|
|
|
// Do not generate a prologue for functions with a stack of size zero
|
|
if (StackSize == 0)
|
|
return;
|
|
|
|
MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock();
|
|
MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock();
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
bool IsNested = false;
|
|
|
|
// We need to know if the function has a nest argument only in 64 bit mode.
|
|
if (Is64Bit)
|
|
IsNested = HasNestArgument(&MF);
|
|
|
|
// The MOV R10, RAX needs to be in a different block, since the RET we emit in
|
|
// allocMBB needs to be last (terminating) instruction.
|
|
|
|
for (const auto &LI : PrologueMBB.liveins()) {
|
|
allocMBB->addLiveIn(LI);
|
|
checkMBB->addLiveIn(LI);
|
|
}
|
|
|
|
if (IsNested)
|
|
allocMBB->addLiveIn(IsLP64 ? X86::R10 : X86::R10D);
|
|
|
|
MF.push_front(allocMBB);
|
|
MF.push_front(checkMBB);
|
|
|
|
// When the frame size is less than 256 we just compare the stack
|
|
// boundary directly to the value of the stack pointer, per gcc.
|
|
bool CompareStackPointer = StackSize < kSplitStackAvailable;
|
|
|
|
// Read the limit off the current stacklet off the stack_guard location.
|
|
if (Is64Bit) {
|
|
if (STI.isTargetLinux()) {
|
|
TlsReg = X86::FS;
|
|
TlsOffset = IsLP64 ? 0x70 : 0x40;
|
|
} else if (STI.isTargetDarwin()) {
|
|
TlsReg = X86::GS;
|
|
TlsOffset = 0x60 + 90*8; // See pthread_machdep.h. Steal TLS slot 90.
|
|
} else if (STI.isTargetWin64()) {
|
|
TlsReg = X86::GS;
|
|
TlsOffset = 0x28; // pvArbitrary, reserved for application use
|
|
} else if (STI.isTargetFreeBSD()) {
|
|
TlsReg = X86::FS;
|
|
TlsOffset = 0x18;
|
|
} else if (STI.isTargetDragonFly()) {
|
|
TlsReg = X86::FS;
|
|
TlsOffset = 0x20; // use tls_tcb.tcb_segstack
|
|
} else {
|
|
report_fatal_error("Segmented stacks not supported on this platform.");
|
|
}
|
|
|
|
if (CompareStackPointer)
|
|
ScratchReg = IsLP64 ? X86::RSP : X86::ESP;
|
|
else
|
|
BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::LEA64r : X86::LEA64_32r), ScratchReg).addReg(X86::RSP)
|
|
.addImm(1).addReg(0).addImm(-StackSize).addReg(0);
|
|
|
|
BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::CMP64rm : X86::CMP32rm)).addReg(ScratchReg)
|
|
.addReg(0).addImm(1).addReg(0).addImm(TlsOffset).addReg(TlsReg);
|
|
} else {
|
|
if (STI.isTargetLinux()) {
|
|
TlsReg = X86::GS;
|
|
TlsOffset = 0x30;
|
|
} else if (STI.isTargetDarwin()) {
|
|
TlsReg = X86::GS;
|
|
TlsOffset = 0x48 + 90*4;
|
|
} else if (STI.isTargetWin32()) {
|
|
TlsReg = X86::FS;
|
|
TlsOffset = 0x14; // pvArbitrary, reserved for application use
|
|
} else if (STI.isTargetDragonFly()) {
|
|
TlsReg = X86::FS;
|
|
TlsOffset = 0x10; // use tls_tcb.tcb_segstack
|
|
} else if (STI.isTargetFreeBSD()) {
|
|
report_fatal_error("Segmented stacks not supported on FreeBSD i386.");
|
|
} else {
|
|
report_fatal_error("Segmented stacks not supported on this platform.");
|
|
}
|
|
|
|
if (CompareStackPointer)
|
|
ScratchReg = X86::ESP;
|
|
else
|
|
BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP)
|
|
.addImm(1).addReg(0).addImm(-StackSize).addReg(0);
|
|
|
|
if (STI.isTargetLinux() || STI.isTargetWin32() || STI.isTargetWin64() ||
|
|
STI.isTargetDragonFly()) {
|
|
BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)).addReg(ScratchReg)
|
|
.addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg);
|
|
} else if (STI.isTargetDarwin()) {
|
|
|
|
// TlsOffset doesn't fit into a mod r/m byte so we need an extra register.
|
|
unsigned ScratchReg2;
|
|
bool SaveScratch2;
|
|
if (CompareStackPointer) {
|
|
// The primary scratch register is available for holding the TLS offset.
|
|
ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, true);
|
|
SaveScratch2 = false;
|
|
} else {
|
|
// Need to use a second register to hold the TLS offset
|
|
ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, false);
|
|
|
|
// Unfortunately, with fastcc the second scratch register may hold an
|
|
// argument.
|
|
SaveScratch2 = MF.getRegInfo().isLiveIn(ScratchReg2);
|
|
}
|
|
|
|
// If Scratch2 is live-in then it needs to be saved.
|
|
assert((!MF.getRegInfo().isLiveIn(ScratchReg2) || SaveScratch2) &&
|
|
"Scratch register is live-in and not saved");
|
|
|
|
if (SaveScratch2)
|
|
BuildMI(checkMBB, DL, TII.get(X86::PUSH32r))
|
|
.addReg(ScratchReg2, RegState::Kill);
|
|
|
|
BuildMI(checkMBB, DL, TII.get(X86::MOV32ri), ScratchReg2)
|
|
.addImm(TlsOffset);
|
|
BuildMI(checkMBB, DL, TII.get(X86::CMP32rm))
|
|
.addReg(ScratchReg)
|
|
.addReg(ScratchReg2).addImm(1).addReg(0)
|
|
.addImm(0)
|
|
.addReg(TlsReg);
|
|
|
|
if (SaveScratch2)
|
|
BuildMI(checkMBB, DL, TII.get(X86::POP32r), ScratchReg2);
|
|
}
|
|
}
|
|
|
|
// This jump is taken if SP >= (Stacklet Limit + Stack Space required).
|
|
// It jumps to normal execution of the function body.
|
|
BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&PrologueMBB);
|
|
|
|
// On 32 bit we first push the arguments size and then the frame size. On 64
|
|
// bit, we pass the stack frame size in r10 and the argument size in r11.
|
|
if (Is64Bit) {
|
|
// Functions with nested arguments use R10, so it needs to be saved across
|
|
// the call to _morestack
|
|
|
|
const unsigned RegAX = IsLP64 ? X86::RAX : X86::EAX;
|
|
const unsigned Reg10 = IsLP64 ? X86::R10 : X86::R10D;
|
|
const unsigned Reg11 = IsLP64 ? X86::R11 : X86::R11D;
|
|
const unsigned MOVrr = IsLP64 ? X86::MOV64rr : X86::MOV32rr;
|
|
const unsigned MOVri = IsLP64 ? X86::MOV64ri : X86::MOV32ri;
|
|
|
|
if (IsNested)
|
|
BuildMI(allocMBB, DL, TII.get(MOVrr), RegAX).addReg(Reg10);
|
|
|
|
BuildMI(allocMBB, DL, TII.get(MOVri), Reg10)
|
|
.addImm(StackSize);
|
|
BuildMI(allocMBB, DL, TII.get(MOVri), Reg11)
|
|
.addImm(X86FI->getArgumentStackSize());
|
|
} else {
|
|
BuildMI(allocMBB, DL, TII.get(X86::PUSHi32))
|
|
.addImm(X86FI->getArgumentStackSize());
|
|
BuildMI(allocMBB, DL, TII.get(X86::PUSHi32))
|
|
.addImm(StackSize);
|
|
}
|
|
|
|
// __morestack is in libgcc
|
|
if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) {
|
|
// Under the large code model, we cannot assume that __morestack lives
|
|
// within 2^31 bytes of the call site, so we cannot use pc-relative
|
|
// addressing. We cannot perform the call via a temporary register,
|
|
// as the rax register may be used to store the static chain, and all
|
|
// other suitable registers may be either callee-save or used for
|
|
// parameter passing. We cannot use the stack at this point either
|
|
// because __morestack manipulates the stack directly.
|
|
//
|
|
// To avoid these issues, perform an indirect call via a read-only memory
|
|
// location containing the address.
|
|
//
|
|
// This solution is not perfect, as it assumes that the .rodata section
|
|
// is laid out within 2^31 bytes of each function body, but this seems
|
|
// to be sufficient for JIT.
|
|
BuildMI(allocMBB, DL, TII.get(X86::CALL64m))
|
|
.addReg(X86::RIP)
|
|
.addImm(0)
|
|
.addReg(0)
|
|
.addExternalSymbol("__morestack_addr")
|
|
.addReg(0);
|
|
MF.getMMI().setUsesMorestackAddr(true);
|
|
} else {
|
|
if (Is64Bit)
|
|
BuildMI(allocMBB, DL, TII.get(X86::CALL64pcrel32))
|
|
.addExternalSymbol("__morestack");
|
|
else
|
|
BuildMI(allocMBB, DL, TII.get(X86::CALLpcrel32))
|
|
.addExternalSymbol("__morestack");
|
|
}
|
|
|
|
if (IsNested)
|
|
BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET_RESTORE_R10));
|
|
else
|
|
BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET));
|
|
|
|
allocMBB->addSuccessor(&PrologueMBB);
|
|
|
|
checkMBB->addSuccessor(allocMBB);
|
|
checkMBB->addSuccessor(&PrologueMBB);
|
|
|
|
#ifdef XDEBUG
|
|
MF.verify();
|
|
#endif
|
|
}
|
|
|
|
/// Erlang programs may need a special prologue to handle the stack size they
|
|
/// might need at runtime. That is because Erlang/OTP does not implement a C
|
|
/// stack but uses a custom implementation of hybrid stack/heap architecture.
|
|
/// (for more information see Eric Stenman's Ph.D. thesis:
|
|
/// http://publications.uu.se/uu/fulltext/nbn_se_uu_diva-2688.pdf)
|
|
///
|
|
/// CheckStack:
|
|
/// temp0 = sp - MaxStack
|
|
/// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart
|
|
/// OldStart:
|
|
/// ...
|
|
/// IncStack:
|
|
/// call inc_stack # doubles the stack space
|
|
/// temp0 = sp - MaxStack
|
|
/// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart
|
|
void X86FrameLowering::adjustForHiPEPrologue(
|
|
MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
DebugLoc DL;
|
|
|
|
// To support shrink-wrapping we would need to insert the new blocks
|
|
// at the right place and update the branches to PrologueMBB.
|
|
assert(&(*MF.begin()) == &PrologueMBB && "Shrink-wrapping not supported yet");
|
|
|
|
// HiPE-specific values
|
|
const unsigned HipeLeafWords = 24;
|
|
const unsigned CCRegisteredArgs = Is64Bit ? 6 : 5;
|
|
const unsigned Guaranteed = HipeLeafWords * SlotSize;
|
|
unsigned CallerStkArity = MF.getFunction()->arg_size() > CCRegisteredArgs ?
|
|
MF.getFunction()->arg_size() - CCRegisteredArgs : 0;
|
|
unsigned MaxStack = MFI->getStackSize() + CallerStkArity*SlotSize + SlotSize;
|
|
|
|
assert(STI.isTargetLinux() &&
|
|
"HiPE prologue is only supported on Linux operating systems.");
|
|
|
|
// Compute the largest caller's frame that is needed to fit the callees'
|
|
// frames. This 'MaxStack' is computed from:
|
|
//
|
|
// a) the fixed frame size, which is the space needed for all spilled temps,
|
|
// b) outgoing on-stack parameter areas, and
|
|
// c) the minimum stack space this function needs to make available for the
|
|
// functions it calls (a tunable ABI property).
|
|
if (MFI->hasCalls()) {
|
|
unsigned MoreStackForCalls = 0;
|
|
|
|
for (MachineFunction::iterator MBBI = MF.begin(), MBBE = MF.end();
|
|
MBBI != MBBE; ++MBBI)
|
|
for (MachineBasicBlock::iterator MI = MBBI->begin(), ME = MBBI->end();
|
|
MI != ME; ++MI) {
|
|
if (!MI->isCall())
|
|
continue;
|
|
|
|
// Get callee operand.
|
|
const MachineOperand &MO = MI->getOperand(0);
|
|
|
|
// Only take account of global function calls (no closures etc.).
|
|
if (!MO.isGlobal())
|
|
continue;
|
|
|
|
const Function *F = dyn_cast<Function>(MO.getGlobal());
|
|
if (!F)
|
|
continue;
|
|
|
|
// Do not update 'MaxStack' for primitive and built-in functions
|
|
// (encoded with names either starting with "erlang."/"bif_" or not
|
|
// having a ".", such as a simple <Module>.<Function>.<Arity>, or an
|
|
// "_", such as the BIF "suspend_0") as they are executed on another
|
|
// stack.
|
|
if (F->getName().find("erlang.") != StringRef::npos ||
|
|
F->getName().find("bif_") != StringRef::npos ||
|
|
F->getName().find_first_of("._") == StringRef::npos)
|
|
continue;
|
|
|
|
unsigned CalleeStkArity =
|
|
F->arg_size() > CCRegisteredArgs ? F->arg_size()-CCRegisteredArgs : 0;
|
|
if (HipeLeafWords - 1 > CalleeStkArity)
|
|
MoreStackForCalls = std::max(MoreStackForCalls,
|
|
(HipeLeafWords - 1 - CalleeStkArity) * SlotSize);
|
|
}
|
|
MaxStack += MoreStackForCalls;
|
|
}
|
|
|
|
// If the stack frame needed is larger than the guaranteed then runtime checks
|
|
// and calls to "inc_stack_0" BIF should be inserted in the assembly prologue.
|
|
if (MaxStack > Guaranteed) {
|
|
MachineBasicBlock *stackCheckMBB = MF.CreateMachineBasicBlock();
|
|
MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock();
|
|
|
|
for (const auto &LI : PrologueMBB.liveins()) {
|
|
stackCheckMBB->addLiveIn(LI);
|
|
incStackMBB->addLiveIn(LI);
|
|
}
|
|
|
|
MF.push_front(incStackMBB);
|
|
MF.push_front(stackCheckMBB);
|
|
|
|
unsigned ScratchReg, SPReg, PReg, SPLimitOffset;
|
|
unsigned LEAop, CMPop, CALLop;
|
|
if (Is64Bit) {
|
|
SPReg = X86::RSP;
|
|
PReg = X86::RBP;
|
|
LEAop = X86::LEA64r;
|
|
CMPop = X86::CMP64rm;
|
|
CALLop = X86::CALL64pcrel32;
|
|
SPLimitOffset = 0x90;
|
|
} else {
|
|
SPReg = X86::ESP;
|
|
PReg = X86::EBP;
|
|
LEAop = X86::LEA32r;
|
|
CMPop = X86::CMP32rm;
|
|
CALLop = X86::CALLpcrel32;
|
|
SPLimitOffset = 0x4c;
|
|
}
|
|
|
|
ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true);
|
|
assert(!MF.getRegInfo().isLiveIn(ScratchReg) &&
|
|
"HiPE prologue scratch register is live-in");
|
|
|
|
// Create new MBB for StackCheck:
|
|
addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(LEAop), ScratchReg),
|
|
SPReg, false, -MaxStack);
|
|
// SPLimitOffset is in a fixed heap location (pointed by BP).
|
|
addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(CMPop))
|
|
.addReg(ScratchReg), PReg, false, SPLimitOffset);
|
|
BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&PrologueMBB);
|
|
|
|
// Create new MBB for IncStack:
|
|
BuildMI(incStackMBB, DL, TII.get(CALLop)).
|
|
addExternalSymbol("inc_stack_0");
|
|
addRegOffset(BuildMI(incStackMBB, DL, TII.get(LEAop), ScratchReg),
|
|
SPReg, false, -MaxStack);
|
|
addRegOffset(BuildMI(incStackMBB, DL, TII.get(CMPop))
|
|
.addReg(ScratchReg), PReg, false, SPLimitOffset);
|
|
BuildMI(incStackMBB, DL, TII.get(X86::JLE_1)).addMBB(incStackMBB);
|
|
|
|
stackCheckMBB->addSuccessor(&PrologueMBB, {99, 100});
|
|
stackCheckMBB->addSuccessor(incStackMBB, {1, 100});
|
|
incStackMBB->addSuccessor(&PrologueMBB, {99, 100});
|
|
incStackMBB->addSuccessor(incStackMBB, {1, 100});
|
|
}
|
|
#ifdef XDEBUG
|
|
MF.verify();
|
|
#endif
|
|
}
|
|
|
|
bool X86FrameLowering::adjustStackWithPops(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator MBBI, DebugLoc DL, int Offset) const {
|
|
|
|
if (Offset <= 0)
|
|
return false;
|
|
|
|
if (Offset % SlotSize)
|
|
return false;
|
|
|
|
int NumPops = Offset / SlotSize;
|
|
// This is only worth it if we have at most 2 pops.
|
|
if (NumPops != 1 && NumPops != 2)
|
|
return false;
|
|
|
|
// Handle only the trivial case where the adjustment directly follows
|
|
// a call. This is the most common one, anyway.
|
|
if (MBBI == MBB.begin())
|
|
return false;
|
|
MachineBasicBlock::iterator Prev = std::prev(MBBI);
|
|
if (!Prev->isCall() || !Prev->getOperand(1).isRegMask())
|
|
return false;
|
|
|
|
unsigned Regs[2];
|
|
unsigned FoundRegs = 0;
|
|
|
|
auto RegMask = Prev->getOperand(1);
|
|
|
|
auto &RegClass =
|
|
Is64Bit ? X86::GR64_NOREX_NOSPRegClass : X86::GR32_NOREX_NOSPRegClass;
|
|
// Try to find up to NumPops free registers.
|
|
for (auto Candidate : RegClass) {
|
|
|
|
// Poor man's liveness:
|
|
// Since we're immediately after a call, any register that is clobbered
|
|
// by the call and not defined by it can be considered dead.
|
|
if (!RegMask.clobbersPhysReg(Candidate))
|
|
continue;
|
|
|
|
bool IsDef = false;
|
|
for (const MachineOperand &MO : Prev->implicit_operands()) {
|
|
if (MO.isReg() && MO.isDef() && MO.getReg() == Candidate) {
|
|
IsDef = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (IsDef)
|
|
continue;
|
|
|
|
Regs[FoundRegs++] = Candidate;
|
|
if (FoundRegs == (unsigned)NumPops)
|
|
break;
|
|
}
|
|
|
|
if (FoundRegs == 0)
|
|
return false;
|
|
|
|
// If we found only one free register, but need two, reuse the same one twice.
|
|
while (FoundRegs < (unsigned)NumPops)
|
|
Regs[FoundRegs++] = Regs[0];
|
|
|
|
for (int i = 0; i < NumPops; ++i)
|
|
BuildMI(MBB, MBBI, DL,
|
|
TII.get(STI.is64Bit() ? X86::POP64r : X86::POP32r), Regs[i]);
|
|
|
|
return true;
|
|
}
|
|
|
|
void X86FrameLowering::
|
|
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator I) const {
|
|
bool reserveCallFrame = hasReservedCallFrame(MF);
|
|
unsigned Opcode = I->getOpcode();
|
|
bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode();
|
|
DebugLoc DL = I->getDebugLoc();
|
|
uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0;
|
|
uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0;
|
|
I = MBB.erase(I);
|
|
|
|
if (!reserveCallFrame) {
|
|
// If the stack pointer can be changed after prologue, turn the
|
|
// adjcallstackup instruction into a 'sub ESP, <amt>' and the
|
|
// adjcallstackdown instruction into 'add ESP, <amt>'
|
|
|
|
// We need to keep the stack aligned properly. To do this, we round the
|
|
// amount of space needed for the outgoing arguments up to the next
|
|
// alignment boundary.
|
|
unsigned StackAlign = getStackAlignment();
|
|
Amount = alignTo(Amount, StackAlign);
|
|
|
|
MachineModuleInfo &MMI = MF.getMMI();
|
|
const Function *Fn = MF.getFunction();
|
|
bool WindowsCFI = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
|
|
bool DwarfCFI = !WindowsCFI &&
|
|
(MMI.hasDebugInfo() || Fn->needsUnwindTableEntry());
|
|
|
|
// If we have any exception handlers in this function, and we adjust
|
|
// the SP before calls, we may need to indicate this to the unwinder
|
|
// using GNU_ARGS_SIZE. Note that this may be necessary even when
|
|
// Amount == 0, because the preceding function may have set a non-0
|
|
// GNU_ARGS_SIZE.
|
|
// TODO: We don't need to reset this between subsequent functions,
|
|
// if it didn't change.
|
|
bool HasDwarfEHHandlers = !WindowsCFI &&
|
|
!MF.getMMI().getLandingPads().empty();
|
|
|
|
if (HasDwarfEHHandlers && !isDestroy &&
|
|
MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences())
|
|
BuildCFI(MBB, I, DL,
|
|
MCCFIInstruction::createGnuArgsSize(nullptr, Amount));
|
|
|
|
if (Amount == 0)
|
|
return;
|
|
|
|
// Factor out the amount that gets handled inside the sequence
|
|
// (Pushes of argument for frame setup, callee pops for frame destroy)
|
|
Amount -= InternalAmt;
|
|
|
|
// TODO: This is needed only if we require precise CFA.
|
|
// If this is a callee-pop calling convention, emit a CFA adjust for
|
|
// the amount the callee popped.
|
|
if (isDestroy && InternalAmt && DwarfCFI && !hasFP(MF))
|
|
BuildCFI(MBB, I, DL,
|
|
MCCFIInstruction::createAdjustCfaOffset(nullptr, -InternalAmt));
|
|
|
|
if (Amount) {
|
|
// Add Amount to SP to destroy a frame, and subtract to setup.
|
|
int Offset = isDestroy ? Amount : -Amount;
|
|
|
|
if (!(Fn->optForMinSize() &&
|
|
adjustStackWithPops(MBB, I, DL, Offset)))
|
|
BuildStackAdjustment(MBB, I, DL, Offset, /*InEpilogue=*/false);
|
|
}
|
|
|
|
if (DwarfCFI && !hasFP(MF)) {
|
|
// If we don't have FP, but need to generate unwind information,
|
|
// we need to set the correct CFA offset after the stack adjustment.
|
|
// How much we adjust the CFA offset depends on whether we're emitting
|
|
// CFI only for EH purposes or for debugging. EH only requires the CFA
|
|
// offset to be correct at each call site, while for debugging we want
|
|
// it to be more precise.
|
|
int CFAOffset = Amount;
|
|
// TODO: When not using precise CFA, we also need to adjust for the
|
|
// InternalAmt here.
|
|
|
|
if (CFAOffset) {
|
|
CFAOffset = isDestroy ? -CFAOffset : CFAOffset;
|
|
BuildCFI(MBB, I, DL,
|
|
MCCFIInstruction::createAdjustCfaOffset(nullptr, CFAOffset));
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
if (isDestroy && InternalAmt) {
|
|
// If we are performing frame pointer elimination and if the callee pops
|
|
// something off the stack pointer, add it back. We do this until we have
|
|
// more advanced stack pointer tracking ability.
|
|
// We are not tracking the stack pointer adjustment by the callee, so make
|
|
// sure we restore the stack pointer immediately after the call, there may
|
|
// be spill code inserted between the CALL and ADJCALLSTACKUP instructions.
|
|
MachineBasicBlock::iterator B = MBB.begin();
|
|
while (I != B && !std::prev(I)->isCall())
|
|
--I;
|
|
BuildStackAdjustment(MBB, I, DL, -InternalAmt, /*InEpilogue=*/false);
|
|
}
|
|
}
|
|
|
|
bool X86FrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const {
|
|
assert(MBB.getParent() && "Block is not attached to a function!");
|
|
|
|
// Win64 has strict requirements in terms of epilogue and we are
|
|
// not taking a chance at messing with them.
|
|
// I.e., unless this block is already an exit block, we can't use
|
|
// it as an epilogue.
|
|
if (STI.isTargetWin64() && !MBB.succ_empty() && !MBB.isReturnBlock())
|
|
return false;
|
|
|
|
if (canUseLEAForSPInEpilogue(*MBB.getParent()))
|
|
return true;
|
|
|
|
// If we cannot use LEA to adjust SP, we may need to use ADD, which
|
|
// clobbers the EFLAGS. Check that we do not need to preserve it,
|
|
// otherwise, conservatively assume this is not
|
|
// safe to insert the epilogue here.
|
|
return !flagsNeedToBePreservedBeforeTheTerminators(MBB);
|
|
}
|
|
|
|
bool X86FrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
|
|
// If we may need to emit frameless compact unwind information, give
|
|
// up as this is currently broken: PR25614.
|
|
return (MF.getFunction()->hasFnAttribute(Attribute::NoUnwind) || hasFP(MF)) &&
|
|
// The lowering of segmented stack and HiPE only support entry blocks
|
|
// as prologue blocks: PR26107.
|
|
// This limitation may be lifted if we fix:
|
|
// - adjustForSegmentedStacks
|
|
// - adjustForHiPEPrologue
|
|
MF.getFunction()->getCallingConv() != CallingConv::HiPE &&
|
|
!MF.shouldSplitStack();
|
|
}
|
|
|
|
MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(
|
|
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
|
|
DebugLoc DL, bool RestoreSP) const {
|
|
assert(STI.isTargetWindowsMSVC() && "funclets only supported in MSVC env");
|
|
assert(STI.isTargetWin32() && "EBP/ESI restoration only required on win32");
|
|
assert(STI.is32Bit() && !Uses64BitFramePtr &&
|
|
"restoring EBP/ESI on non-32-bit target");
|
|
|
|
MachineFunction &MF = *MBB.getParent();
|
|
unsigned FramePtr = TRI->getFrameRegister(MF);
|
|
unsigned BasePtr = TRI->getBaseRegister();
|
|
WinEHFuncInfo &FuncInfo = *MF.getWinEHFuncInfo();
|
|
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
|
|
MachineFrameInfo *MFI = MF.getFrameInfo();
|
|
|
|
// FIXME: Don't set FrameSetup flag in catchret case.
|
|
|
|
int FI = FuncInfo.EHRegNodeFrameIndex;
|
|
int EHRegSize = MFI->getObjectSize(FI);
|
|
|
|
if (RestoreSP) {
|
|
// MOV32rm -EHRegSize(%ebp), %esp
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32rm), X86::ESP),
|
|
X86::EBP, true, -EHRegSize)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
unsigned UsedReg;
|
|
int EHRegOffset = getFrameIndexReference(MF, FI, UsedReg);
|
|
int EndOffset = -EHRegOffset - EHRegSize;
|
|
FuncInfo.EHRegNodeEndOffset = EndOffset;
|
|
|
|
if (UsedReg == FramePtr) {
|
|
// ADD $offset, %ebp
|
|
unsigned ADDri = getADDriOpcode(false, EndOffset);
|
|
BuildMI(MBB, MBBI, DL, TII.get(ADDri), FramePtr)
|
|
.addReg(FramePtr)
|
|
.addImm(EndOffset)
|
|
.setMIFlag(MachineInstr::FrameSetup)
|
|
->getOperand(3)
|
|
.setIsDead();
|
|
assert(EndOffset >= 0 &&
|
|
"end of registration object above normal EBP position!");
|
|
} else if (UsedReg == BasePtr) {
|
|
// LEA offset(%ebp), %esi
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA32r), BasePtr),
|
|
FramePtr, false, EndOffset)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
// MOV32rm SavedEBPOffset(%esi), %ebp
|
|
assert(X86FI->getHasSEHFramePtrSave());
|
|
int Offset =
|
|
getFrameIndexReference(MF, X86FI->getSEHFramePtrSaveIndex(), UsedReg);
|
|
assert(UsedReg == BasePtr);
|
|
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32rm), FramePtr),
|
|
UsedReg, true, Offset)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
} else {
|
|
llvm_unreachable("32-bit frames with WinEH must use FramePtr or BasePtr");
|
|
}
|
|
return MBBI;
|
|
}
|
|
|
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namespace {
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// Struct used by orderFrameObjects to help sort the stack objects.
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struct X86FrameSortingObject {
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bool IsValid = false; // true if we care about this Object.
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unsigned ObjectIndex = 0; // Index of Object into MFI list.
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unsigned ObjectSize = 0; // Size of Object in bytes.
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unsigned ObjectAlignment = 1; // Alignment of Object in bytes.
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unsigned ObjectNumUses = 0; // Object static number of uses.
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};
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// The comparison function we use for std::sort to order our local
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// stack symbols. The current algorithm is to use an estimated
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// "density". This takes into consideration the size and number of
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// uses each object has in order to roughly minimize code size.
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// So, for example, an object of size 16B that is referenced 5 times
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// will get higher priority than 4 4B objects referenced 1 time each.
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// It's not perfect and we may be able to squeeze a few more bytes out of
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// it (for example : 0(esp) requires fewer bytes, symbols allocated at the
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// fringe end can have special consideration, given their size is less
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// important, etc.), but the algorithmic complexity grows too much to be
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// worth the extra gains we get. This gets us pretty close.
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// The final order leaves us with objects with highest priority going
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// at the end of our list.
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struct X86FrameSortingComparator {
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inline bool operator()(const X86FrameSortingObject &A,
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const X86FrameSortingObject &B) {
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uint64_t DensityAScaled, DensityBScaled;
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// For consistency in our comparison, all invalid objects are placed
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// at the end. This also allows us to stop walking when we hit the
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// first invalid item after it's all sorted.
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if (!A.IsValid)
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return false;
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if (!B.IsValid)
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return true;
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// The density is calculated by doing :
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// (double)DensityA = A.ObjectNumUses / A.ObjectSize
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// (double)DensityB = B.ObjectNumUses / B.ObjectSize
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// Since this approach may cause inconsistencies in
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// the floating point <, >, == comparisons, depending on the floating
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// point model with which the compiler was built, we're going
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// to scale both sides by multiplying with
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// A.ObjectSize * B.ObjectSize. This ends up factoring away
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// the division and, with it, the need for any floating point
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// arithmetic.
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DensityAScaled = static_cast<uint64_t>(A.ObjectNumUses) *
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static_cast<uint64_t>(B.ObjectSize);
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DensityBScaled = static_cast<uint64_t>(B.ObjectNumUses) *
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static_cast<uint64_t>(A.ObjectSize);
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// If the two densities are equal, prioritize highest alignment
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// objects. This allows for similar alignment objects
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// to be packed together (given the same density).
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// There's room for improvement here, also, since we can pack
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// similar alignment (different density) objects next to each
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// other to save padding. This will also require further
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// complexity/iterations, and the overall gain isn't worth it,
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// in general. Something to keep in mind, though.
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if (DensityAScaled == DensityBScaled)
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return A.ObjectAlignment < B.ObjectAlignment;
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return DensityAScaled < DensityBScaled;
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}
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};
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} // namespace
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// Order the symbols in the local stack.
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// We want to place the local stack objects in some sort of sensible order.
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// The heuristic we use is to try and pack them according to static number
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// of uses and size of object in order to minimize code size.
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void X86FrameLowering::orderFrameObjects(
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const MachineFunction &MF, SmallVectorImpl<int> &ObjectsToAllocate) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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// Don't waste time if there's nothing to do.
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if (ObjectsToAllocate.empty())
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return;
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// Create an array of all MFI objects. We won't need all of these
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// objects, but we're going to create a full array of them to make
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// it easier to index into when we're counting "uses" down below.
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// We want to be able to easily/cheaply access an object by simply
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// indexing into it, instead of having to search for it every time.
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std::vector<X86FrameSortingObject> SortingObjects(MFI->getObjectIndexEnd());
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// Walk the objects we care about and mark them as such in our working
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// struct.
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for (auto &Obj : ObjectsToAllocate) {
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SortingObjects[Obj].IsValid = true;
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SortingObjects[Obj].ObjectIndex = Obj;
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SortingObjects[Obj].ObjectAlignment = MFI->getObjectAlignment(Obj);
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// Set the size.
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int ObjectSize = MFI->getObjectSize(Obj);
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if (ObjectSize == 0)
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// Variable size. Just use 4.
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SortingObjects[Obj].ObjectSize = 4;
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else
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SortingObjects[Obj].ObjectSize = ObjectSize;
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}
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// Count the number of uses for each object.
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for (auto &MBB : MF) {
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for (auto &MI : MBB) {
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for (const MachineOperand &MO : MI.operands()) {
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// Check to see if it's a local stack symbol.
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if (!MO.isFI())
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continue;
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int Index = MO.getIndex();
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// Check to see if it falls within our range, and is tagged
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// to require ordering.
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if (Index >= 0 && Index < MFI->getObjectIndexEnd() &&
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SortingObjects[Index].IsValid)
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SortingObjects[Index].ObjectNumUses++;
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}
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}
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}
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// Sort the objects using X86FrameSortingAlgorithm (see its comment for
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// info).
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std::stable_sort(SortingObjects.begin(), SortingObjects.end(),
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X86FrameSortingComparator());
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// Now modify the original list to represent the final order that
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// we want. The order will depend on whether we're going to access them
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// from the stack pointer or the frame pointer. For SP, the list should
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// end up with the END containing objects that we want with smaller offsets.
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// For FP, it should be flipped.
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int i = 0;
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for (auto &Obj : SortingObjects) {
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// All invalid items are sorted at the end, so it's safe to stop.
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if (!Obj.IsValid)
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break;
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ObjectsToAllocate[i++] = Obj.ObjectIndex;
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}
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// Flip it if we're accessing off of the FP.
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if (!TRI->needsStackRealignment(MF) && hasFP(MF))
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std::reverse(ObjectsToAllocate.begin(), ObjectsToAllocate.end());
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}
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unsigned X86FrameLowering::getWinEHParentFrameOffset(const MachineFunction &MF) const {
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// RDX, the parent frame pointer, is homed into 16(%rsp) in the prologue.
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unsigned Offset = 16;
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// RBP is immediately pushed.
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Offset += SlotSize;
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// All callee-saved registers are then pushed.
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Offset += MF.getInfo<X86MachineFunctionInfo>()->getCalleeSavedFrameSize();
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// Every funclet allocates enough stack space for the largest outgoing call.
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Offset += getWinEHFuncletFrameSize(MF);
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return Offset;
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}
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void X86FrameLowering::processFunctionBeforeFrameFinalized(
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MachineFunction &MF, RegScavenger *RS) const {
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// If this function isn't doing Win64-style C++ EH, we don't need to do
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// anything.
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const Function *Fn = MF.getFunction();
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if (!STI.is64Bit() || !MF.getMMI().hasEHFunclets() ||
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classifyEHPersonality(Fn->getPersonalityFn()) != EHPersonality::MSVC_CXX)
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return;
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// Win64 C++ EH needs to allocate the UnwindHelp object at some fixed offset
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// relative to RSP after the prologue. Find the offset of the last fixed
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// object, so that we can allocate a slot immediately following it. If there
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// were no fixed objects, use offset -SlotSize, which is immediately after the
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// return address. Fixed objects have negative frame indices.
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MachineFrameInfo *MFI = MF.getFrameInfo();
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int64_t MinFixedObjOffset = -SlotSize;
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for (int I = MFI->getObjectIndexBegin(); I < 0; ++I)
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MinFixedObjOffset = std::min(MinFixedObjOffset, MFI->getObjectOffset(I));
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int64_t UnwindHelpOffset = MinFixedObjOffset - SlotSize;
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int UnwindHelpFI =
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MFI->CreateFixedObject(SlotSize, UnwindHelpOffset, /*Immutable=*/false);
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MF.getWinEHFuncInfo()->UnwindHelpFrameIdx = UnwindHelpFI;
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// Store -2 into UnwindHelp on function entry. We have to scan forwards past
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// other frame setup instructions.
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MachineBasicBlock &MBB = MF.front();
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auto MBBI = MBB.begin();
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while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup))
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++MBBI;
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DebugLoc DL = MBB.findDebugLoc(MBBI);
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addFrameReference(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mi32)),
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UnwindHelpFI)
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.addImm(-2);
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}
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