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llvm-project/llvm/lib/Target/VE/VEFrameLowering.cpp

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//===-- VEFrameLowering.cpp - VE 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 VE implementation of TargetFrameLowering class.
//
// On VE, stack frames are structured as follows:
//
// The stack grows downward.
//
// All of the individual frame areas on the frame below are optional, i.e. it's
// possible to create a function so that the particular area isn't present
// in the frame.
//
// At function entry, the "frame" looks as follows:
//
// | | Higher address
// |----------------------------------------------|
// | Parameter area for this function |
// |----------------------------------------------|
// | Register save area (RSA) for this function |
// |----------------------------------------------|
// | Return address for this function |
// |----------------------------------------------|
// | Frame pointer for this function |
// |----------------------------------------------| <- sp
// | | Lower address
//
// VE doesn't use on demand stack allocation, so user code generated by LLVM
// needs to call VEOS to allocate stack frame. VE's ABI want to reduce the
// number of VEOS calls, so ABI requires to allocate not only RSA (in general
// CSR, callee saved register) area but also call frame at the prologue of
// caller function.
//
// After the prologue has run, the frame has the following general structure.
// Note that technically the last frame area (VLAs) doesn't get created until
// in the main function body, after the prologue is run. However, it's depicted
// here for completeness.
//
// | | Higher address
// |----------------------------------------------|
// | Parameter area for this function |
// |----------------------------------------------|
// | Register save area (RSA) for this function |
// |----------------------------------------------|
// | Return address for this function |
// |----------------------------------------------|
// | Frame pointer for this function |
// |----------------------------------------------| <- fp(=old sp)
// |.empty.space.to.make.part.below.aligned.in....|
// |.case.it.needs.more.than.the.standard.16-byte.| (size of this area is
// |.alignment....................................| unknown at compile time)
// |----------------------------------------------|
// | Local variables of fixed size including spill|
// | slots |
// |----------------------------------------------| <- bp(not defined by ABI,
// |.variable-sized.local.variables.(VLAs)........| LLVM chooses SX17)
// |..............................................| (size of this area is
// |..............................................| unknown at compile time)
// |----------------------------------------------| <- stack top (returned by
// | Parameter area for callee | alloca)
// |----------------------------------------------|
// | Register save area (RSA) for callee |
// |----------------------------------------------|
// | Return address for callee |
// |----------------------------------------------|
// | Frame pointer for callee |
// |----------------------------------------------| <- sp
// | | Lower address
//
// To access the data in a frame, at-compile time, a constant offset must be
// computable from one of the pointers (fp, bp, sp) to access it. The size
// of the areas with a dotted background cannot be computed at compile-time
// if they are present, making it required to have all three of fp, bp and
// sp to be set up to be able to access all contents in the frame areas,
// assuming all of the frame areas are non-empty.
//
// For most functions, some of the frame areas are empty. For those functions,
// it may not be necessary to set up fp or bp:
// * A base pointer is definitely needed when there are both VLAs and local
// variables with more-than-default alignment requirements.
// * A frame pointer is definitely needed when there are local variables with
// more-than-default alignment requirements.
//
// In addition, VE ABI defines RSA frame, return address, and frame pointer
// as follows:
//
// |----------------------------------------------| <- sp+176
// | %s18...%s33 |
// |----------------------------------------------| <- sp+48
// | Linkage area register (%s17) |
// |----------------------------------------------| <- sp+40
// | Procedure linkage table register (%plt=%s16) |
// |----------------------------------------------| <- sp+32
// | Global offset table register (%got=%s15) |
// |----------------------------------------------| <- sp+24
// | Thread pointer register (%tp=%s14) |
// |----------------------------------------------| <- sp+16
// | Return address |
// |----------------------------------------------| <- sp+8
// | Frame pointer |
// |----------------------------------------------| <- sp+0
//
// NOTE: This description is based on VE ABI and description in
// AArch64FrameLowering.cpp. Thanks a lot.
//===----------------------------------------------------------------------===//
#include "VEFrameLowering.h"
#include "VEInstrInfo.h"
#include "VEMachineFunctionInfo.h"
#include "VESubtarget.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/CodeGen/RegisterScavenging.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
VEFrameLowering::VEFrameLowering(const VESubtarget &ST)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, Align(16), 0,
Align(16)),
STI(ST) {}
void VEFrameLowering::emitPrologueInsns(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
uint64_t NumBytes,
bool RequireFPUpdate) const {
const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
DebugLoc DL;
const VEInstrInfo &TII = *STI.getInstrInfo();
// Insert following codes here as prologue
//
// st %fp, 0(, %sp) iff !isLeafProc
// st %lr, 8(, %sp) iff !isLeafProc
// st %got, 24(, %sp) iff hasGOT
// st %plt, 32(, %sp) iff hasGOT
// st %s17, 40(, %sp) iff hasBP
if (!FuncInfo->isLeafProc()) {
BuildMI(MBB, MBBI, DL, TII.get(VE::STrii))
.addReg(VE::SX11)
.addImm(0)
.addImm(0)
.addReg(VE::SX9);
BuildMI(MBB, MBBI, DL, TII.get(VE::STrii))
.addReg(VE::SX11)
.addImm(0)
.addImm(8)
.addReg(VE::SX10);
}
if (hasGOT(MF)) {
BuildMI(MBB, MBBI, DL, TII.get(VE::STrii))
.addReg(VE::SX11)
.addImm(0)
.addImm(24)
.addReg(VE::SX15);
BuildMI(MBB, MBBI, DL, TII.get(VE::STrii))
.addReg(VE::SX11)
.addImm(0)
.addImm(32)
.addReg(VE::SX16);
}
if (hasBP(MF))
BuildMI(MBB, MBBI, DL, TII.get(VE::STrii))
.addReg(VE::SX11)
.addImm(0)
.addImm(40)
.addReg(VE::SX17);
}
void VEFrameLowering::emitEpilogueInsns(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
uint64_t NumBytes,
bool RequireFPUpdate) const {
const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
DebugLoc DL;
const VEInstrInfo &TII = *STI.getInstrInfo();
// Insert following codes here as epilogue
//
// ld %s17, 40(, %sp) iff hasBP
// ld %plt, 32(, %sp) iff hasGOT
// ld %got, 24(, %sp) iff hasGOT
// ld %lr, 8(, %sp) iff !isLeafProc
// ld %fp, 0(, %sp) iff !isLeafProc
if (hasBP(MF))
BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX17)
.addReg(VE::SX11)
.addImm(0)
.addImm(40);
if (hasGOT(MF)) {
BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX16)
.addReg(VE::SX11)
.addImm(0)
.addImm(32);
BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX15)
.addReg(VE::SX11)
.addImm(0)
.addImm(24);
}
if (!FuncInfo->isLeafProc()) {
BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX10)
.addReg(VE::SX11)
.addImm(0)
.addImm(8);
BuildMI(MBB, MBBI, DL, TII.get(VE::LDrii), VE::SX9)
.addReg(VE::SX11)
.addImm(0)
.addImm(0);
}
}
void VEFrameLowering::emitSPAdjustment(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
int64_t NumBytes,
MaybeAlign MaybeAlign) const {
DebugLoc DL;
const VEInstrInfo &TII = *STI.getInstrInfo();
if (NumBytes == 0) {
// Nothing to do here.
} else if (isInt<7>(NumBytes)) {
// adds.l %s11, NumBytes@lo, %s11
BuildMI(MBB, MBBI, DL, TII.get(VE::ADDSLri), VE::SX11)
.addReg(VE::SX11)
.addImm(NumBytes);
} else if (isInt<32>(NumBytes)) {
// lea %s11, NumBytes@lo(, %s11)
BuildMI(MBB, MBBI, DL, TII.get(VE::LEArii), VE::SX11)
.addReg(VE::SX11)
.addImm(0)
.addImm(Lo_32(NumBytes));
} else {
// Emit following codes. This clobbers SX13 which we always know is
// available here.
// lea %s13, NumBytes@lo
// and %s13, %s13, (32)0
// lea.sl %sp, NumBytes@hi(%s13, %sp)
BuildMI(MBB, MBBI, DL, TII.get(VE::LEAzii), VE::SX13)
.addImm(0)
.addImm(0)
.addImm(Lo_32(NumBytes));
BuildMI(MBB, MBBI, DL, TII.get(VE::ANDrm), VE::SX13)
.addReg(VE::SX13)
.addImm(M0(32));
BuildMI(MBB, MBBI, DL, TII.get(VE::LEASLrri), VE::SX11)
.addReg(VE::SX11)
.addReg(VE::SX13)
.addImm(Hi_32(NumBytes));
}
if (MaybeAlign) {
// and %sp, %sp, Align-1
BuildMI(MBB, MBBI, DL, TII.get(VE::ANDrm), VE::SX11)
.addReg(VE::SX11)
.addImm(M1(64 - Log2_64(MaybeAlign.valueOrOne().value())));
}
}
void VEFrameLowering::emitSPExtend(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) const {
DebugLoc DL;
const VEInstrInfo &TII = *STI.getInstrInfo();
// Emit following codes. It is not possible to insert multiple
// BasicBlocks in PEI pass, so we emit two pseudo instructions here.
//
// EXTEND_STACK // pseudo instrcution
// EXTEND_STACK_GUARD // pseudo instrcution
//
// EXTEND_STACK pseudo will be converted by ExpandPostRA pass into
// following instructions with multiple basic blocks later.
//
// thisBB:
// brge.l.t %sp, %sl, sinkBB
// syscallBB:
// ld %s61, 0x18(, %tp) // load param area
// or %s62, 0, %s0 // spill the value of %s0
// lea %s63, 0x13b // syscall # of grow
// shm.l %s63, 0x0(%s61) // store syscall # at addr:0
// shm.l %sl, 0x8(%s61) // store old limit at addr:8
// shm.l %sp, 0x10(%s61) // store new limit at addr:16
// monc // call monitor
// or %s0, 0, %s62 // restore the value of %s0
// sinkBB:
//
// EXTEND_STACK_GUARD pseudo will be simply eliminated by ExpandPostRA
// pass. This pseudo is required to be at the next of EXTEND_STACK
// pseudo in order to protect iteration loop in ExpandPostRA.
BuildMI(MBB, MBBI, DL, TII.get(VE::EXTEND_STACK));
BuildMI(MBB, MBBI, DL, TII.get(VE::EXTEND_STACK_GUARD));
}
void VEFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo &MFI = MF.getFrameInfo();
const VEInstrInfo &TII = *STI.getInstrInfo();
const VERegisterInfo &RegInfo = *STI.getRegisterInfo();
MachineBasicBlock::iterator MBBI = MBB.begin();
bool NeedsStackRealignment = RegInfo.needsStackRealignment(MF);
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
DebugLoc DL;
// FIXME: unfortunately, returning false from canRealignStack
// actually just causes needsStackRealignment to return false,
// rather than reporting an error, as would be sensible. This is
// poor, but fixing that bogosity is going to be a large project.
// For now, just see if it's lied, and report an error here.
if (!NeedsStackRealignment && MFI.getMaxAlign() > getStackAlign())
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.
// This number of bytes is already aligned to ABI stack alignment.
uint64_t NumBytes = MFI.getStackSize();
// Adjust stack size if this function is not a leaf function since the
// VE ABI requires a reserved area at the top of stack as described in
// VEFrameLowering.cpp.
if (!FuncInfo->isLeafProc()) {
// NOTE: The number is aligned to ABI stack alignment after adjustment.
NumBytes = STI.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);
// Emit Prologue instructions to save multiple registers.
emitPrologueInsns(MF, MBB, MBBI, NumBytes, true);
// Emit instructions to save SP in FP as follows if this is not a leaf
// function:
// or %fp, 0, %sp
if (!FuncInfo->isLeafProc())
BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX9)
.addReg(VE::SX11)
.addImm(0);
// Emit stack adjust instructions
MaybeAlign RuntimeAlign =
NeedsStackRealignment ? MaybeAlign(MFI.getMaxAlign()) : None;
assert((RuntimeAlign == None || !FuncInfo->isLeafProc()) &&
"SP has to be saved in order to align variable sized stack object!");
emitSPAdjustment(MF, MBB, MBBI, -(int64_t)NumBytes, RuntimeAlign);
if (hasBP(MF)) {
// Copy SP to BP.
BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX17)
.addReg(VE::SX11)
.addImm(0);
}
// Emit stack extend instructions
if (NumBytes != 0)
emitSPExtend(MF, MBB, MBBI);
}
MachineBasicBlock::iterator VEFrameLowering::eliminateCallFramePseudoInstr(
MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
if (!hasReservedCallFrame(MF)) {
MachineInstr &MI = *I;
int64_t Size = MI.getOperand(0).getImm();
if (MI.getOpcode() == VE::ADJCALLSTACKDOWN)
Size = -Size;
if (Size)
emitSPAdjustment(MF, MBB, I, Size);
}
return MBB.erase(I);
}
void VEFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
DebugLoc DL;
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
MachineFrameInfo &MFI = MF.getFrameInfo();
const VEInstrInfo &TII = *STI.getInstrInfo();
uint64_t NumBytes = MFI.getStackSize();
// Emit instructions to retrieve original SP.
if (!FuncInfo->isLeafProc()) {
// If SP is saved in FP, retrieve it as follows:
// or %sp, 0, %fp iff !isLeafProc
BuildMI(MBB, MBBI, DL, TII.get(VE::ORri), VE::SX11)
.addReg(VE::SX9)
.addImm(0);
} else {
// Emit stack adjust instructions.
emitSPAdjustment(MF, MBB, MBBI, NumBytes, None);
}
// Emit Epilogue instructions to restore multiple registers.
emitEpilogueInsns(MF, MBB, MBBI, NumBytes, true);
}
// 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 VEFrameLowering::hasFP(const MachineFunction &MF) const {
const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
const MachineFrameInfo &MFI = MF.getFrameInfo();
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
RegInfo->needsStackRealignment(MF) || MFI.hasVarSizedObjects() ||
MFI.isFrameAddressTaken();
}
bool VEFrameLowering::hasBP(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
const TargetRegisterInfo *TRI = STI.getRegisterInfo();
return MFI.hasVarSizedObjects() && TRI->needsStackRealignment(MF);
}
bool VEFrameLowering::hasGOT(const MachineFunction &MF) const {
const VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
// If a global base register is assigned (!= 0), GOT is used.
return FuncInfo->getGlobalBaseReg() != 0;
}
StackOffset VEFrameLowering::getFrameIndexReference(const MachineFunction &MF,
int FI,
Register &FrameReg) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
const VERegisterInfo *RegInfo = STI.getRegisterInfo();
bool isFixed = MFI.isFixedObjectIndex(FI);
int64_t FrameOffset = MF.getFrameInfo().getObjectOffset(FI);
if (!hasFP(MF)) {
// If FP is not used, frame indexies are based on a %sp regiter.
FrameReg = VE::SX11; // %sp
return StackOffset::getFixed(FrameOffset +
MF.getFrameInfo().getStackSize());
}
if (RegInfo->needsStackRealignment(MF) && !isFixed) {
// If data on stack require realignemnt, frame indexies are based on a %sp
// or %s17 (bp) register. If there is a variable sized object, bp is used.
if (hasBP(MF))
FrameReg = VE::SX17; // %bp
else
FrameReg = VE::SX11; // %sp
return StackOffset::getFixed(FrameOffset +
MF.getFrameInfo().getStackSize());
}
// Use %fp by default.
FrameReg = RegInfo->getFrameRegister(MF);
return StackOffset::getFixed(FrameOffset);
}
bool VEFrameLowering::isLeafProc(MachineFunction &MF) const {
MachineRegisterInfo &MRI = MF.getRegInfo();
MachineFrameInfo &MFI = MF.getFrameInfo();
return !MFI.hasCalls() // No calls
&& !MRI.isPhysRegUsed(VE::SX18) // Registers within limits
// (s18 is first CSR)
&& !MRI.isPhysRegUsed(VE::SX11) // %sp un-used
&& !hasFP(MF); // Don't need %fp
}
void VEFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
// Functions having BP need to emit prologue and epilogue to allocate local
// buffer on the stack even if the function is a leaf function.
if (isLeafProc(MF) && !hasBP(MF)) {
VEMachineFunctionInfo *FuncInfo = MF.getInfo<VEMachineFunctionInfo>();
FuncInfo->setLeafProc(true);
}
}
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