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llvm-project/llvm/lib/Target/Sparc/SparcFrameLowering.cpp

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//===-- SparcFrameLowering.cpp - Sparc Frame Information ------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the Sparc implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "SparcFrameLowering.h"
#include "SparcInstrInfo.h"
#include "SparcMachineFunctionInfo.h"
#include "SparcSubtarget.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static cl::opt<bool>
DisableLeafProc("disable-sparc-leaf-proc",
cl::init(false),
cl::desc("Disable Sparc leaf procedure optimization."),
cl::Hidden);
SparcFrameLowering::SparcFrameLowering(const SparcSubtarget &ST)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown,
ST.is64Bit() ? Align(16) : Align(8), 0,
ST.is64Bit() ? Align(16) : Align(8)) {}
void SparcFrameLowering::emitSPAdjustment(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
int NumBytes,
unsigned ADDrr,
unsigned ADDri) const {
DebugLoc dl;
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
if (NumBytes >= -4096 && NumBytes < 4096) {
BuildMI(MBB, MBBI, dl, TII.get(ADDri), SP::O6)
.addReg(SP::O6).addImm(NumBytes);
return;
}
// Emit this the hard way. This clobbers G1 which we always know is
// available here.
if (NumBytes >= 0) {
// Emit nonnegative numbers with sethi + or.
// sethi %hi(NumBytes), %g1
// or %g1, %lo(NumBytes), %g1
// add %sp, %g1, %sp
BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
.addImm(HI22(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(SP::ORri), SP::G1)
.addReg(SP::G1).addImm(LO10(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
.addReg(SP::O6).addReg(SP::G1);
return ;
}
// Emit negative numbers with sethi + xor.
// sethi %hix(NumBytes), %g1
// xor %g1, %lox(NumBytes), %g1
// add %sp, %g1, %sp
BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
.addImm(HIX22(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(SP::XORri), SP::G1)
.addReg(SP::G1).addImm(LOX10(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
.addReg(SP::O6).addReg(SP::G1);
}
void SparcFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo &MFI = MF.getFrameInfo();
const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(Subtarget.getInstrInfo());
const SparcRegisterInfo &RegInfo =
*static_cast<const SparcRegisterInfo *>(Subtarget.getRegisterInfo());
MachineBasicBlock::iterator MBBI = MBB.begin();
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
DebugLoc dl;
bool NeedsStackRealignment = RegInfo.shouldRealignStack(MF);
if (NeedsStackRealignment && !RegInfo.canRealignStack(MF))
report_fatal_error("Function \"" + Twine(MF.getName()) + "\" required "
"stack re-alignment, but LLVM couldn't handle it "
"(probably because it has a dynamic alloca).");
// Get the number of bytes to allocate from the FrameInfo
int NumBytes = (int) MFI.getStackSize();
unsigned SAVEri = SP::SAVEri;
unsigned SAVErr = SP::SAVErr;
if (FuncInfo->isLeafProc()) {
if (NumBytes == 0)
return;
SAVEri = SP::ADDri;
SAVErr = SP::ADDrr;
}
// The SPARC ABI is a bit odd in that it requires a reserved 92-byte
// (128 in v9) area in the user's stack, starting at %sp. Thus, the
// first part of the stack that can actually be used is located at
// %sp + 92.
//
// We therefore need to add that offset to the total stack size
// after all the stack objects are placed by
// PrologEpilogInserter calculateFrameObjectOffsets. However, since the stack needs to be
// aligned *after* the extra size is added, we need to disable
// calculateFrameObjectOffsets's built-in stack alignment, by having
// targetHandlesStackFrameRounding return true.
// Add the extra call frame stack size, if needed. (This is the same
// code as in PrologEpilogInserter, but also gets disabled by
// targetHandlesStackFrameRounding)
if (MFI.adjustsStack() && hasReservedCallFrame(MF))
NumBytes += MFI.getMaxCallFrameSize();
// Adds the SPARC subtarget-specific spill area to the stack
// size. Also ensures target-required alignment.
NumBytes = Subtarget.getAdjustedFrameSize(NumBytes);
// Finally, ensure that the size is sufficiently aligned for the
// data on the stack.
NumBytes = alignTo(NumBytes, MFI.getMaxAlign());
// Update stack size with corrected value.
MFI.setStackSize(NumBytes);
emitSPAdjustment(MF, MBB, MBBI, -NumBytes, SAVErr, SAVEri);
unsigned regFP = RegInfo.getDwarfRegNum(SP::I6, true);
// Emit ".cfi_def_cfa_register 30".
unsigned CFIIndex =
MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(nullptr, regFP));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
// Emit ".cfi_window_save".
CFIIndex = MF.addFrameInst(MCCFIInstruction::createWindowSave(nullptr));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
unsigned regInRA = RegInfo.getDwarfRegNum(SP::I7, true);
unsigned regOutRA = RegInfo.getDwarfRegNum(SP::O7, true);
// Emit ".cfi_register 15, 31".
CFIIndex = MF.addFrameInst(
MCCFIInstruction::createRegister(nullptr, regOutRA, regInRA));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (NeedsStackRealignment) {
int64_t Bias = Subtarget.getStackPointerBias();
unsigned regUnbiased;
if (Bias) {
// This clobbers G1 which we always know is available here.
regUnbiased = SP::G1;
// add %o6, BIAS, %g1
BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), regUnbiased)
.addReg(SP::O6).addImm(Bias);
} else
regUnbiased = SP::O6;
// andn %regUnbiased, MaxAlign-1, %regUnbiased
Align MaxAlign = MFI.getMaxAlign();
BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), regUnbiased)
.addReg(regUnbiased)
.addImm(MaxAlign.value() - 1U);
if (Bias) {
// add %g1, -BIAS, %o6
BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), SP::O6)
.addReg(regUnbiased).addImm(-Bias);
}
}
}
MachineBasicBlock::iterator SparcFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
if (!hasReservedCallFrame(MF)) {
MachineInstr &MI = *I;
int Size = MI.getOperand(0).getImm();
if (MI.getOpcode() == SP::ADJCALLSTACKDOWN)
Size = -Size;
if (Size)
emitSPAdjustment(MF, MBB, I, Size, SP::ADDrr, SP::ADDri);
}
return MBB.erase(I);
}
void SparcFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
assert(MBBI->getOpcode() == SP::RETL &&
"Can only put epilog before 'retl' instruction!");
if (!FuncInfo->isLeafProc()) {
BuildMI(MBB, MBBI, dl, TII.get(SP::RESTORErr), SP::G0).addReg(SP::G0)
.addReg(SP::G0);
return;
}
MachineFrameInfo &MFI = MF.getFrameInfo();
int NumBytes = (int) MFI.getStackSize();
if (NumBytes == 0)
return;
emitSPAdjustment(MF, MBB, MBBI, NumBytes, SP::ADDrr, SP::ADDri);
}
bool SparcFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
// Reserve call frame if there are no variable sized objects on the stack.
return !MF.getFrameInfo().hasVarSizedObjects();
}
// hasFP - Return true if the specified function should have a dedicated frame
// pointer register. This is true if the function has variable sized allocas or
// if frame pointer elimination is disabled.
bool SparcFrameLowering::hasFP(const MachineFunction &MF) const {
const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
const MachineFrameInfo &MFI = MF.getFrameInfo();
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
RegInfo->hasStackRealignment(MF) || MFI.hasVarSizedObjects() ||
MFI.isFrameAddressTaken();
}
StackOffset
SparcFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const {
const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();
const MachineFrameInfo &MFI = MF.getFrameInfo();
const SparcRegisterInfo *RegInfo = Subtarget.getRegisterInfo();
const SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
bool isFixed = MFI.isFixedObjectIndex(FI);
// Addressable stack objects are accessed using neg. offsets from
// %fp, or positive offsets from %sp.
bool UseFP;
// Sparc uses FP-based references in general, even when "hasFP" is
// false. That function is rather a misnomer, because %fp is
// actually always available, unless isLeafProc.
if (FuncInfo->isLeafProc()) {
// If there's a leaf proc, all offsets need to be %sp-based,
// because we haven't caused %fp to actually point to our frame.
UseFP = false;
} else if (isFixed) {
// Otherwise, argument access should always use %fp.
UseFP = true;
} else if (RegInfo->hasStackRealignment(MF)) {
// If there is dynamic stack realignment, all local object
// references need to be via %sp, to take account of the
// re-alignment.
UseFP = false;
} else {
// Finally, default to using %fp.
UseFP = true;
}
int64_t FrameOffset = MF.getFrameInfo().getObjectOffset(FI) +
Subtarget.getStackPointerBias();
if (UseFP) {
FrameReg = RegInfo->getFrameRegister(MF);
return StackOffset::getFixed(FrameOffset);
} else {
FrameReg = SP::O6; // %sp
return StackOffset::getFixed(FrameOffset + MF.getFrameInfo().getStackSize());
}
}
static bool LLVM_ATTRIBUTE_UNUSED verifyLeafProcRegUse(MachineRegisterInfo *MRI)
{
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
if (MRI->isPhysRegUsed(reg))
return false;
for (unsigned reg = SP::L0; reg <= SP::L7; ++reg)
if (MRI->isPhysRegUsed(reg))
return false;
return true;
}
bool SparcFrameLowering::isLeafProc(MachineFunction &MF) const
{
MachineRegisterInfo &MRI = MF.getRegInfo();
MachineFrameInfo &MFI = MF.getFrameInfo();
return !(MFI.hasCalls() // has calls
|| MRI.isPhysRegUsed(SP::L0) // Too many registers needed
|| MRI.isPhysRegUsed(SP::O6) // %sp is used
|| hasFP(MF)); // need %fp
}
void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
MachineRegisterInfo &MRI = MF.getRegInfo();
// Remap %i[0-7] to %o[0-7].
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
if (!MRI.isPhysRegUsed(reg))
continue;
unsigned mapped_reg = reg - SP::I0 + SP::O0;
// Replace I register with O register.
MRI.replaceRegWith(reg, mapped_reg);
// Also replace register pair super-registers.
if ((reg - SP::I0) % 2 == 0) {
unsigned preg = (reg - SP::I0) / 2 + SP::I0_I1;
unsigned mapped_preg = preg - SP::I0_I1 + SP::O0_O1;
MRI.replaceRegWith(preg, mapped_preg);
}
}
// Rewrite MBB's Live-ins.
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB) {
for (unsigned reg = SP::I0_I1; reg <= SP::I6_I7; ++reg) {
if (!MBB->isLiveIn(reg))
continue;
MBB->removeLiveIn(reg);
MBB->addLiveIn(reg - SP::I0_I1 + SP::O0_O1);
}
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
if (!MBB->isLiveIn(reg))
continue;
MBB->removeLiveIn(reg);
MBB->addLiveIn(reg - SP::I0 + SP::O0);
}
}
assert(verifyLeafProcRegUse(&MRI));
#ifdef EXPENSIVE_CHECKS
MF.verify(0, "After LeafProc Remapping");
#endif
}
void SparcFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
if (!DisableLeafProc && isLeafProc(MF)) {
SparcMachineFunctionInfo *MFI = MF.getInfo<SparcMachineFunctionInfo>();
MFI->setLeafProc(true);
remapRegsForLeafProc(MF);
}
}
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