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llvm-project/llvm/lib/Target/MBlaze/MBlazeFrameLowering.cpp

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//===-- MBlazeFrameLowering.cpp - MBlaze Frame Information ---------------====//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the MBlaze implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mblaze-frame-lowering"
#include "MBlazeFrameLowering.h"
#include "InstPrinter/MBlazeInstPrinter.h"
#include "MBlazeInstrInfo.h"
#include "MBlazeMachineFunction.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/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static cl::opt<bool> MBDisableStackAdjust(
"disable-mblaze-stack-adjust",
cl::init(false),
cl::desc("Disable MBlaze stack layout adjustment."),
cl::Hidden);
static void replaceFrameIndexes(MachineFunction &MF,
SmallVector<std::pair<int,int64_t>, 16> &FR) {
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
const SmallVector<std::pair<int,int64_t>, 16>::iterator FRB = FR.begin();
const SmallVector<std::pair<int,int64_t>, 16>::iterator FRE = FR.end();
SmallVector<std::pair<int,int64_t>, 16>::iterator FRI = FRB;
for (; FRI != FRE; ++FRI) {
MFI->RemoveStackObject(FRI->first);
int NFI = MFI->CreateFixedObject(4, FRI->second, true);
MBlazeFI->recordReplacement(FRI->first, NFI);
for (MachineFunction::iterator MB=MF.begin(), ME=MF.end(); MB!=ME; ++MB) {
MachineBasicBlock::iterator MBB = MB->begin();
const MachineBasicBlock::iterator MBE = MB->end();
for (; MBB != MBE; ++MBB) {
MachineInstr::mop_iterator MIB = MBB->operands_begin();
const MachineInstr::mop_iterator MIE = MBB->operands_end();
for (MachineInstr::mop_iterator MII = MIB; MII != MIE; ++MII) {
if (!MII->isFI() || MII->getIndex() != FRI->first) continue;
DEBUG(dbgs() << "FOUND FI#" << MII->getIndex() << "\n");
MII->setIndex(NFI);
}
}
}
}
}
//===----------------------------------------------------------------------===//
//
// Stack Frame Processing methods
// +----------------------------+
//
// The stack is allocated decrementing the stack pointer on
// the first instruction of a function prologue. Once decremented,
// all stack references are are done through a positive offset
// from the stack/frame pointer, so the stack is considered
// to grow up.
//
//===----------------------------------------------------------------------===//
static void analyzeFrameIndexes(MachineFunction &MF) {
if (MBDisableStackAdjust) return;
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
const MachineRegisterInfo &MRI = MF.getRegInfo();
MachineRegisterInfo::livein_iterator LII = MRI.livein_begin();
MachineRegisterInfo::livein_iterator LIE = MRI.livein_end();
const SmallVector<int, 16> &LiveInFI = MBlazeFI->getLiveIn();
SmallVector<MachineInstr*, 16> EraseInstr;
SmallVector<std::pair<int,int64_t>, 16> FrameRelocate;
MachineBasicBlock *MBB = MF.getBlockNumbered(0);
MachineBasicBlock::iterator MIB = MBB->begin();
MachineBasicBlock::iterator MIE = MBB->end();
int StackAdjust = 0;
int StackOffset = -28;
// In this loop we are searching frame indexes that corrospond to incoming
// arguments that are already in the stack. We look for instruction sequences
// like the following:
//
// LWI REG, FI1, 0
// ...
// SWI REG, FI2, 0
//
// As long as there are no defs of REG in the ... part, we can eliminate
// the SWI instruction because the value has already been stored to the
// stack by the caller. All we need to do is locate FI at the correct
// stack location according to the calling convensions.
//
// Additionally, if the SWI operation kills the def of REG then we don't
// need the LWI operation so we can erase it as well.
for (unsigned i = 0, e = LiveInFI.size(); i < e; ++i) {
for (MachineBasicBlock::iterator I=MIB; I != MIE; ++I) {
if (I->getOpcode() != MBlaze::LWI || I->getNumOperands() != 3 ||
!I->getOperand(1).isFI() || !I->getOperand(0).isReg() ||
I->getOperand(1).getIndex() != LiveInFI[i]) continue;
unsigned FIReg = I->getOperand(0).getReg();
MachineBasicBlock::iterator SI = I;
for (SI++; SI != MIE; ++SI) {
if (!SI->getOperand(0).isReg() ||
!SI->getOperand(1).isFI() ||
SI->getOpcode() != MBlaze::SWI) continue;
int FI = SI->getOperand(1).getIndex();
if (SI->getOperand(0).getReg() != FIReg ||
MFI->isFixedObjectIndex(FI) ||
MFI->getObjectSize(FI) != 4) continue;
if (SI->getOperand(0).isDef()) break;
if (SI->getOperand(0).isKill()) {
DEBUG(dbgs() << "LWI for FI#" << I->getOperand(1).getIndex()
<< " removed\n");
EraseInstr.push_back(I);
}
EraseInstr.push_back(SI);
DEBUG(dbgs() << "SWI for FI#" << FI << " removed\n");
FrameRelocate.push_back(std::make_pair(FI,StackOffset));
DEBUG(dbgs() << "FI#" << FI << " relocated to " << StackOffset << "\n");
StackOffset -= 4;
StackAdjust += 4;
break;
}
}
}
// In this loop we are searching for frame indexes that corrospond to
// incoming arguments that are in registers. We look for instruction
// sequences like the following:
//
// ... SWI REG, FI, 0
//
// As long as the ... part does not define REG and if REG is an incoming
// parameter register then we know that, according to ABI convensions, the
// caller has allocated stack space for it already. Instead of allocating
// stack space on our frame, we record the correct location in the callers
// frame.
for (MachineRegisterInfo::livein_iterator LI = LII; LI != LIE; ++LI) {
for (MachineBasicBlock::iterator I=MIB; I != MIE; ++I) {
if (I->definesRegister(LI->first))
break;
if (I->getOpcode() != MBlaze::SWI || I->getNumOperands() != 3 ||
!I->getOperand(1).isFI() || !I->getOperand(0).isReg() ||
I->getOperand(1).getIndex() < 0) continue;
if (I->getOperand(0).getReg() == LI->first) {
int FI = I->getOperand(1).getIndex();
MBlazeFI->recordLiveIn(FI);
int FILoc = 0;
switch (LI->first) {
default: llvm_unreachable("invalid incoming parameter!");
case MBlaze::R5: FILoc = -4; break;
case MBlaze::R6: FILoc = -8; break;
case MBlaze::R7: FILoc = -12; break;
case MBlaze::R8: FILoc = -16; break;
case MBlaze::R9: FILoc = -20; break;
case MBlaze::R10: FILoc = -24; break;
}
StackAdjust += 4;
FrameRelocate.push_back(std::make_pair(FI,FILoc));
DEBUG(dbgs() << "FI#" << FI << " relocated to " << FILoc << "\n");
break;
}
}
}
// Go ahead and erase all of the instructions that we determined were
// no longer needed.
for (int i = 0, e = EraseInstr.size(); i < e; ++i)
MBB->erase(EraseInstr[i]);
// Replace all of the frame indexes that we have relocated with new
// fixed object frame indexes.
replaceFrameIndexes(MF, FrameRelocate);
}
static void interruptFrameLayout(MachineFunction &MF) {
const Function *F = MF.getFunction();
CallingConv::ID CallConv = F->getCallingConv();
// If this function is not using either the interrupt_handler
// calling convention or the save_volatiles calling convention
// then we don't need to do any additional frame layout.
if (CallConv != CallingConv::MBLAZE_INTR &&
CallConv != CallingConv::MBLAZE_SVOL)
return;
MachineFrameInfo *MFI = MF.getFrameInfo();
const MachineRegisterInfo &MRI = MF.getRegInfo();
const MBlazeInstrInfo &TII =
*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
// Determine if the calling convention is the interrupt_handler
// calling convention. Some pieces of the prologue and epilogue
// only need to be emitted if we are lowering and interrupt handler.
bool isIntr = CallConv == CallingConv::MBLAZE_INTR;
// Determine where to put prologue and epilogue additions
MachineBasicBlock &MENT = MF.front();
MachineBasicBlock &MEXT = MF.back();
MachineBasicBlock::iterator MENTI = MENT.begin();
MachineBasicBlock::iterator MEXTI = prior(MEXT.end());
DebugLoc ENTDL = MENTI != MENT.end() ? MENTI->getDebugLoc() : DebugLoc();
DebugLoc EXTDL = MEXTI != MEXT.end() ? MEXTI->getDebugLoc() : DebugLoc();
// Store the frame indexes generated during prologue additions for use
// when we are generating the epilogue additions.
SmallVector<int, 10> VFI;
// Build the prologue SWI for R3 - R12 if needed. Note that R11 must
// always have a SWI because it is used when processing RMSR.
for (unsigned r = MBlaze::R3; r <= MBlaze::R12; ++r) {
if (!MRI.isPhysRegUsed(r) && !(isIntr && r == MBlaze::R11)) continue;
int FI = MFI->CreateStackObject(4,4,false,false);
VFI.push_back(FI);
BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), r)
.addFrameIndex(FI).addImm(0);
}
// Build the prologue SWI for R17, R18
int R17FI = MFI->CreateStackObject(4,4,false,false);
int R18FI = MFI->CreateStackObject(4,4,false,false);
BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R17)
.addFrameIndex(R17FI).addImm(0);
BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R18)
.addFrameIndex(R18FI).addImm(0);
// Buid the prologue SWI and the epilogue LWI for RMSR if needed
if (isIntr) {
int MSRFI = MFI->CreateStackObject(4,4,false,false);
BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::MFS), MBlaze::R11)
.addReg(MBlaze::RMSR);
BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R11)
.addFrameIndex(MSRFI).addImm(0);
BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R11)
.addFrameIndex(MSRFI).addImm(0);
BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::MTS), MBlaze::RMSR)
.addReg(MBlaze::R11);
}
// Build the epilogue LWI for R17, R18
BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R18)
.addFrameIndex(R18FI).addImm(0);
BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R17)
.addFrameIndex(R17FI).addImm(0);
// Build the epilogue LWI for R3 - R12 if needed
for (unsigned r = MBlaze::R12, i = VFI.size(); r >= MBlaze::R3; --r) {
if (!MRI.isPhysRegUsed(r)) continue;
BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), r)
.addFrameIndex(VFI[--i]).addImm(0);
}
}
static void determineFrameLayout(MachineFunction &MF) {
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
// Replace the dummy '0' SPOffset by the negative offsets, as explained on
// LowerFORMAL_ARGUMENTS. Leaving '0' for while is necessary to avoid
// the approach done by calculateFrameObjectOffsets to the stack frame.
MBlazeFI->adjustLoadArgsFI(MFI);
MBlazeFI->adjustStoreVarArgsFI(MFI);
// Get the number of bytes to allocate from the FrameInfo
unsigned FrameSize = MFI->getStackSize();
DEBUG(dbgs() << "Original Frame Size: " << FrameSize << "\n" );
// Get the alignments provided by the target, and the maximum alignment
// (if any) of the fixed frame objects.
// unsigned MaxAlign = MFI->getMaxAlignment();
unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
unsigned AlignMask = TargetAlign - 1;
// Make sure the frame is aligned.
FrameSize = (FrameSize + AlignMask) & ~AlignMask;
MFI->setStackSize(FrameSize);
DEBUG(dbgs() << "Aligned Frame Size: " << FrameSize << "\n" );
}
int MBlazeFrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI)
const {
const MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
if (MBlazeFI->hasReplacement(FI))
FI = MBlazeFI->getReplacement(FI);
return TargetFrameLowering::getFrameIndexOffset(MF,FI);
}
// 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 MBlazeFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
MFI->hasVarSizedObjects();
}
void MBlazeFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
const MBlazeInstrInfo &TII =
*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;
// Determine the correct frame layout
determineFrameLayout(MF);
// Get the number of bytes to allocate from the FrameInfo.
unsigned StackSize = MFI->getStackSize();
// No need to allocate space on the stack.
if (StackSize == 0 && !MFI->adjustsStack() && !requiresRA) return;
int FPOffset = MBlazeFI->getFPStackOffset();
int RAOffset = MBlazeFI->getRAStackOffset();
// Adjust stack : addi R1, R1, -imm
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADDIK), MBlaze::R1)
.addReg(MBlaze::R1).addImm(-StackSize);
// swi R15, R1, stack_loc
if (MFI->adjustsStack() || requiresRA) {
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
.addReg(MBlaze::R15).addReg(MBlaze::R1).addImm(RAOffset);
}
if (hasFP(MF)) {
// swi R19, R1, stack_loc
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
.addReg(MBlaze::R19).addReg(MBlaze::R1).addImm(FPOffset);
// add R19, R1, R0
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADD), MBlaze::R19)
.addReg(MBlaze::R1).addReg(MBlaze::R0);
}
}
void MBlazeFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
const MBlazeInstrInfo &TII =
*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;
// Get the FI's where RA and FP are saved.
int FPOffset = MBlazeFI->getFPStackOffset();
int RAOffset = MBlazeFI->getRAStackOffset();
if (hasFP(MF)) {
// add R1, R19, R0
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADD), MBlaze::R1)
.addReg(MBlaze::R19).addReg(MBlaze::R0);
// lwi R19, R1, stack_loc
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R19)
.addReg(MBlaze::R1).addImm(FPOffset);
}
// lwi R15, R1, stack_loc
if (MFI->adjustsStack() || requiresRA) {
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R15)
.addReg(MBlaze::R1).addImm(RAOffset);
}
// Get the number of bytes from FrameInfo
int StackSize = (int) MFI->getStackSize();
// addi R1, R1, imm
if (StackSize) {
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADDIK), MBlaze::R1)
.addReg(MBlaze::R1).addImm(StackSize);
}
}
void MBlazeFrameLowering::
processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;
if (MFI->adjustsStack() || requiresRA) {
MBlazeFI->setRAStackOffset(0);
MFI->CreateFixedObject(4,0,true);
}
if (hasFP(MF)) {
MBlazeFI->setFPStackOffset(4);
MFI->CreateFixedObject(4,4,true);
}
interruptFrameLayout(MF);
analyzeFrameIndexes(MF);
}
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