//===-- PrologEpilogInserter.cpp - Insert Prolog/Epilog code in function --===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
//
// This pass is responsible for finalizing the functions frame layout, saving
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/STLExtras.h"
+#include <climits>
using namespace llvm;
namespace {
- struct PEI : public MachineFunctionPass {
+ struct VISIBILITY_HIDDEN PEI : public MachineFunctionPass {
+ static char ID;
+ PEI() : MachineFunctionPass((intptr_t)&ID) {}
+
const char *getPassName() const {
return "Prolog/Epilog Insertion & Frame Finalization";
}
/// frame indexes with appropriate references.
///
bool runOnMachineFunction(MachineFunction &Fn) {
- // Scan the function for modified caller saved registers and insert spill
- // code for any caller saved registers that are modified. Also calculate
+ const MRegisterInfo *MRI = Fn.getTarget().getRegisterInfo();
+ RS = MRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
+
+ // Get MachineModuleInfo so that we can track the construction of the
+ // frame.
+ if (MachineModuleInfo *MMI = getAnalysisToUpdate<MachineModuleInfo>()) {
+ Fn.getFrameInfo()->setMachineModuleInfo(MMI);
+ }
+
+ // Allow the target machine to make some adjustments to the function
+ // e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
+ MRI->processFunctionBeforeCalleeSavedScan(Fn, RS);
+
+ // Scan the function for modified callee saved registers and insert spill
+ // code for any callee saved registers that are modified. Also calculate
// the MaxCallFrameSize and HasCalls variables for the function's frame
// information and eliminates call frame pseudo instructions.
- saveCallerSavedRegisters(Fn);
+ calculateCalleeSavedRegisters(Fn);
+
+ // Add the code to save and restore the callee saved registers
+ saveCalleeSavedRegisters(Fn);
// Allow the target machine to make final modifications to the function
// before the frame layout is finalized.
// Calculate actual frame offsets for all of the abstract stack objects...
calculateFrameObjectOffsets(Fn);
- // Add prolog and epilog code to the function.
+ // Add prolog and epilog code to the function. This function is required
+ // to align the stack frame as necessary for any stack variables or
+ // called functions. Because of this, calculateCalleeSavedRegisters
+ // must be called before this function in order to set the HasCalls
+ // and MaxCallFrameSize variables.
insertPrologEpilogCode(Fn);
// Replace all MO_FrameIndex operands with physical register references
// and actual offsets.
//
replaceFrameIndices(Fn);
+
+ delete RS;
return true;
}
-
+
private:
- void saveCallerSavedRegisters(MachineFunction &Fn);
+ RegScavenger *RS;
+
+ // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved
+ // stack frame indexes.
+ unsigned MinCSFrameIndex, MaxCSFrameIndex;
+
+ void calculateCalleeSavedRegisters(MachineFunction &Fn);
+ void saveCalleeSavedRegisters(MachineFunction &Fn);
void calculateFrameObjectOffsets(MachineFunction &Fn);
void replaceFrameIndices(MachineFunction &Fn);
void insertPrologEpilogCode(MachineFunction &Fn);
};
+ char PEI::ID = 0;
}
FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); }
-/// saveCallerSavedRegisters - Scan the function for modified caller saved
-/// registers and insert spill code for any caller saved registers that are
-/// modified. Also calculate the MaxCallFrameSize and HasCalls variables for
+/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
+/// registers. Also calculate the MaxCallFrameSize and HasCalls variables for
/// the function's frame information and eliminates call frame pseudo
/// instructions.
///
-void PEI::saveCallerSavedRegisters(MachineFunction &Fn) {
+void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
- const TargetFrameInfo &FrameInfo = Fn.getTarget().getFrameInfo();
+ const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
// Get the callee saved register list...
- const unsigned *CSRegs = RegInfo->getCalleeSaveRegs();
+ const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
// Get the function call frame set-up and tear-down instruction opcode
int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
+ // These are used to keep track the callee-save area. Initialize them.
+ MinCSFrameIndex = INT_MAX;
+ MaxCSFrameIndex = 0;
+
// Early exit for targets which have no callee saved registers and no call
// frame setup/destroy pseudo instructions.
if ((CSRegs == 0 || CSRegs[0] == 0) &&
FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
return;
- // This bitset contains an entry for each physical register for the target...
- std::vector<bool> ModifiedRegs(MRegisterInfo::FirstVirtualRegister);
unsigned MaxCallFrameSize = 0;
bool HasCalls = false;
+ std::vector<MachineBasicBlock::iterator> FrameSDOps;
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
- for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); )
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
if (I->getOpcode() == FrameSetupOpcode ||
- I->getOpcode() == FrameDestroyOpcode) {
- assert(I->getNumOperands() == 1 && "Call Frame Setup/Destroy Pseudo"
- " instructions should have a single immediate argument!");
- unsigned Size = I->getOperand(0).getImmedValue();
- if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
- HasCalls = true;
- RegInfo->eliminateCallFramePseudoInstr(Fn, *BB, I++);
- } else {
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = I->getOperand(i);
- if (MO.isRegister() && MO.isDef()) {
- assert(MRegisterInfo::isPhysicalRegister(MO.getReg()) &&
- "Register allocation must be performed!");
- ModifiedRegs[MO.getReg()] = true; // Register is modified
- }
- }
- ++I;
+ I->getOpcode() == FrameDestroyOpcode) {
+ assert(I->getNumOperands() >= 1 && "Call Frame Setup/Destroy Pseudo"
+ " instructions should have a single immediate argument!");
+ unsigned Size = I->getOperand(0).getImmedValue();
+ if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
+ HasCalls = true;
+ FrameSDOps.push_back(I);
}
MachineFrameInfo *FFI = Fn.getFrameInfo();
FFI->setHasCalls(HasCalls);
FFI->setMaxCallFrameSize(MaxCallFrameSize);
+ for (unsigned i = 0, e = FrameSDOps.size(); i != e; ++i) {
+ MachineBasicBlock::iterator I = FrameSDOps[i];
+ // If call frames are not being included as part of the stack frame,
+ // and there is no dynamic allocation (therefore referencing frame slots
+ // off sp), leave the pseudo ops alone. We'll eliminate them later.
+ if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
+ RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
+ }
+
// Now figure out which *callee saved* registers are modified by the current
// function, thus needing to be saved and restored in the prolog/epilog.
//
- std::vector<unsigned> RegsToSave;
+ const TargetRegisterClass* const *CSRegClasses =
+ RegInfo->getCalleeSavedRegClasses(&Fn);
+ std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
- if (ModifiedRegs[Reg]) {
- RegsToSave.push_back(Reg); // If modified register...
+ if (Fn.isPhysRegUsed(Reg)) {
+ // If the reg is modified, save it!
+ CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
} else {
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
- *AliasSet; ++AliasSet) { // Check alias registers too...
- if (ModifiedRegs[*AliasSet]) {
- RegsToSave.push_back(Reg);
- break;
- }
+ *AliasSet; ++AliasSet) { // Check alias registers too.
+ if (Fn.isPhysRegUsed(*AliasSet)) {
+ CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
+ break;
+ }
}
}
}
- if (RegsToSave.empty())
- return; // Early exit if no caller saved registers are modified!
+ if (CSI.empty())
+ return; // Early exit if no callee saved registers are modified!
+
+ unsigned NumFixedSpillSlots;
+ const std::pair<unsigned,int> *FixedSpillSlots =
+ TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
// Now that we know which registers need to be saved and restored, allocate
// stack slots for them.
- std::vector<int> StackSlots;
- for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
- int FrameIdx = FFI->CreateStackObject(RegInfo->getRegClass(RegsToSave[i]));
- StackSlots.push_back(FrameIdx);
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ unsigned Reg = CSI[i].getReg();
+ const TargetRegisterClass *RC = CSI[i].getRegClass();
+
+ // Check to see if this physreg must be spilled to a particular stack slot
+ // on this target.
+ const std::pair<unsigned,int> *FixedSlot = FixedSpillSlots;
+ while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
+ FixedSlot->first != Reg)
+ ++FixedSlot;
+
+ int FrameIdx;
+ if (FixedSlot == FixedSpillSlots+NumFixedSpillSlots) {
+ // Nope, just spill it anywhere convenient.
+ unsigned Align = RC->getAlignment();
+ unsigned StackAlign = TFI->getStackAlignment();
+ // We may not be able to sastify the desired alignment specification of
+ // the TargetRegisterClass if the stack alignment is smaller. Use the min.
+ Align = std::min(Align, StackAlign);
+ FrameIdx = FFI->CreateStackObject(RC->getSize(), Align);
+ if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
+ if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
+ } else {
+ // Spill it to the stack where we must.
+ FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->second);
+ }
+ CSI[i].setFrameIdx(FrameIdx);
}
+ FFI->setCalleeSavedInfo(CSI);
+}
+
+/// saveCalleeSavedRegisters - Insert spill code for any callee saved registers
+/// that are modified in the function.
+///
+void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) {
+ // Get callee saved register information.
+ MachineFrameInfo *FFI = Fn.getFrameInfo();
+ const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
+
+ // Early exit if no callee saved registers are modified!
+ if (CSI.empty())
+ return;
+
+ const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+
// Now that we have a stack slot for each register to be saved, insert spill
- // code into the entry block...
+ // code into the entry block.
MachineBasicBlock *MBB = Fn.begin();
MachineBasicBlock::iterator I = MBB->begin();
- for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
- const TargetRegisterClass *RC = RegInfo->getRegClass(RegsToSave[i]);
-
- // Insert the spill to the stack frame...
- RegInfo->storeRegToStackSlot(*MBB, I, RegsToSave[i], StackSlots[i], RC);
+ if (!RegInfo->spillCalleeSavedRegisters(*MBB, I, CSI)) {
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ // Add the callee-saved register as live-in. It's killed at the spill.
+ MBB->addLiveIn(CSI[i].getReg());
+
+ // Insert the spill to the stack frame.
+ RegInfo->storeRegToStackSlot(*MBB, I, CSI[i].getReg(),
+ CSI[i].getFrameIdx(), CSI[i].getRegClass());
+ }
}
// Add code to restore the callee-save registers in each exiting block.
- const TargetInstrInfo &TII = Fn.getTarget().getInstrInfo();
- for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI) {
- // If last instruction is a return instruction, add an epilogue
+ const TargetInstrInfo &TII = *Fn.getTarget().getInstrInfo();
+ for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI)
+ // If last instruction is a return instruction, add an epilogue.
if (!FI->empty() && TII.isReturn(FI->back().getOpcode())) {
MBB = FI;
I = MBB->end(); --I;
- for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
- const TargetRegisterClass *RC = RegInfo->getRegClass(RegsToSave[i]);
- RegInfo->loadRegFromStackSlot(*MBB, I, RegsToSave[i],StackSlots[i], RC);
- --I; // Insert in reverse order
+ // Skip over all terminator instructions, which are part of the return
+ // sequence.
+ MachineBasicBlock::iterator I2 = I;
+ while (I2 != MBB->begin() && TII.isTerminatorInstr((--I2)->getOpcode()))
+ I = I2;
+
+ bool AtStart = I == MBB->begin();
+ MachineBasicBlock::iterator BeforeI = I;
+ if (!AtStart)
+ --BeforeI;
+
+ // Restore all registers immediately before the return and any terminators
+ // that preceed it.
+ if (!RegInfo->restoreCalleeSavedRegisters(*MBB, I, CSI)) {
+ for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+ RegInfo->loadRegFromStackSlot(*MBB, I, CSI[i].getReg(),
+ CSI[i].getFrameIdx(),
+ CSI[i].getRegClass());
+ assert(I != MBB->begin() &&
+ "loadRegFromStackSlot didn't insert any code!");
+ // Insert in reverse order. loadRegFromStackSlot can insert multiple
+ // instructions.
+ if (AtStart)
+ I = MBB->begin();
+ else {
+ I = BeforeI;
+ ++I;
+ }
+ }
}
}
- }
}
/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
-/// abstract stack objects...
+/// abstract stack objects.
///
void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
- const TargetFrameInfo &TFI = Fn.getTarget().getFrameInfo();
-
+ const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
+
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
- assert(StackGrowsDown && "Only tested on stack down growing targets!");
-
+
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *FFI = Fn.getFrameInfo();
- unsigned StackAlignment = TFI.getStackAlignment();
+ unsigned MaxAlign = 0;
// Start at the beginning of the local area.
- int Offset = TFI.getOffsetOfLocalArea();
-
- // Check to see if there are any fixed sized objects that are preallocated in
- // the local area. We currently don't support filling in holes in between
- // fixed sized objects, so we just skip to the end of the last fixed sized
+ // The Offset is the distance from the stack top in the direction
+ // of stack growth -- so it's always positive.
+ int64_t Offset = TFI.getOffsetOfLocalArea();
+ if (StackGrowsDown)
+ Offset = -Offset;
+ assert(Offset >= 0
+ && "Local area offset should be in direction of stack growth");
+
+ // If there are fixed sized objects that are preallocated in the local area,
+ // non-fixed objects can't be allocated right at the start of local area.
+ // We currently don't support filling in holes in between fixed sized objects,
+ // so we adjust 'Offset' to point to the end of last fixed sized
// preallocated object.
for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
- int FixedOff = -FFI->getObjectOffset(i);
+ int64_t FixedOff;
+ if (StackGrowsDown) {
+ // The maximum distance from the stack pointer is at lower address of
+ // the object -- which is given by offset. For down growing stack
+ // the offset is negative, so we negate the offset to get the distance.
+ FixedOff = -FFI->getObjectOffset(i);
+ } else {
+ // The maximum distance from the start pointer is at the upper
+ // address of the object.
+ FixedOff = FFI->getObjectOffset(i) + FFI->getObjectSize(i);
+ }
if (FixedOff > Offset) Offset = FixedOff;
}
+ // First assign frame offsets to stack objects that are used to spill
+ // callee saved registers.
+ if (StackGrowsDown) {
+ for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
+ // If stack grows down, we need to add size of find the lowest
+ // address of the object.
+ Offset += FFI->getObjectSize(i);
+
+ unsigned Align = FFI->getObjectAlignment(i);
+ // If the alignment of this object is greater than that of the stack, then
+ // increase the stack alignment to match.
+ MaxAlign = std::max(MaxAlign, Align);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ FFI->setObjectOffset(i, -Offset); // Set the computed offset
+ }
+ } else {
+ for (unsigned i = MaxCSFrameIndex; i >= MinCSFrameIndex; --i) {
+ unsigned Align = FFI->getObjectAlignment(i);
+ // If the alignment of this object is greater than that of the stack, then
+ // increase the stack alignment to match.
+ MaxAlign = std::max(MaxAlign, Align);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ FFI->setObjectOffset(i, Offset);
+ Offset += FFI->getObjectSize(i);
+ }
+ }
+
+ // Make sure the special register scavenging spill slot is closest to the
+ // frame pointer if a frame pointer is required.
+ const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+ if (RS && RegInfo->hasFP(Fn)) {
+ int SFI = RS->getScavengingFrameIndex();
+ if (SFI >= 0) {
+ // If stack grows down, we need to add size of the lowest
+ // address of the object.
+ if (StackGrowsDown)
+ Offset += FFI->getObjectSize(SFI);
+
+ unsigned Align = FFI->getObjectAlignment(SFI);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ if (StackGrowsDown) {
+ FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
+ } else {
+ FFI->setObjectOffset(SFI, Offset);
+ Offset += FFI->getObjectSize(SFI);
+ }
+ }
+ }
+
+ // Then assign frame offsets to stack objects that are not used to spill
+ // callee saved registers.
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
- Offset += FFI->getObjectSize(i); // Allocate Size bytes...
+ if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
+ continue;
+ if (RS && (int)i == RS->getScavengingFrameIndex())
+ continue;
+
+ // If stack grows down, we need to add size of find the lowest
+ // address of the object.
+ if (StackGrowsDown)
+ Offset += FFI->getObjectSize(i);
unsigned Align = FFI->getObjectAlignment(i);
- assert(Align <= StackAlignment && "Cannot align stack object to higher "
- "alignment boundary than the stack itself!");
- Offset = (Offset+Align-1)/Align*Align; // Adjust to Alignment boundary...
-
- FFI->setObjectOffset(i, -Offset); // Set the computed offset
+ // If the alignment of this object is greater than that of the stack, then
+ // increase the stack alignment to match.
+ MaxAlign = std::max(MaxAlign, Align);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ if (StackGrowsDown) {
+ FFI->setObjectOffset(i, -Offset); // Set the computed offset
+ } else {
+ FFI->setObjectOffset(i, Offset);
+ Offset += FFI->getObjectSize(i);
+ }
}
- // Align the final stack pointer offset, but only if there are calls in the
- // function. This ensures that any calls to subroutines have their stack
- // frames suitable aligned.
- if (FFI->hasCalls())
- Offset = (Offset+StackAlignment-1)/StackAlignment*StackAlignment;
+ // Make sure the special register scavenging spill slot is closest to the
+ // stack pointer.
+ if (RS && !RegInfo->hasFP(Fn)) {
+ int SFI = RS->getScavengingFrameIndex();
+ if (SFI >= 0) {
+ // If stack grows down, we need to add size of find the lowest
+ // address of the object.
+ if (StackGrowsDown)
+ Offset += FFI->getObjectSize(SFI);
+
+ unsigned Align = FFI->getObjectAlignment(SFI);
+ // Adjust to alignment boundary
+ Offset = (Offset+Align-1)/Align*Align;
+
+ if (StackGrowsDown) {
+ FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
+ } else {
+ FFI->setObjectOffset(SFI, Offset);
+ Offset += FFI->getObjectSize(SFI);
+ }
+ }
+ }
- // Set the final value of the stack pointer...
- FFI->setStackSize(Offset-TFI.getOffsetOfLocalArea());
+ // Round up the size to a multiple of the alignment, but only if there are
+ // calls or alloca's in the function. This ensures that any calls to
+ // subroutines have their stack frames suitable aligned.
+ if (!RegInfo->targetHandlesStackFrameRounding() &&
+ (FFI->hasCalls() || FFI->hasVarSizedObjects())) {
+ // If we have reserved argument space for call sites in the function
+ // immediately on entry to the current function, count it as part of the
+ // overall stack size.
+ if (RegInfo->hasReservedCallFrame(Fn))
+ Offset += FFI->getMaxCallFrameSize();
+
+ unsigned AlignMask = TFI.getStackAlignment() - 1;
+ Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
+ }
+
+ // Update frame info to pretend that this is part of the stack...
+ FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
+
+ // Remember the required stack alignment in case targets need it to perform
+ // dynamic stack alignment.
+ assert(FFI->getMaxAlignment() == MaxAlign &&
+ "Stack alignment calculation broken!");
}
-/// insertPrologEpilogCode - Scan the function for modified caller saved
-/// registers, insert spill code for these caller saved registers, then add
+/// insertPrologEpilogCode - Scan the function for modified callee saved
+/// registers, insert spill code for these callee saved registers, then add
/// prolog and epilog code to the function.
///
void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
Fn.getTarget().getRegisterInfo()->emitPrologue(Fn);
// Add epilogue to restore the callee-save registers in each exiting block
- const TargetInstrInfo &TII = Fn.getTarget().getInstrInfo();
+ const TargetInstrInfo &TII = *Fn.getTarget().getInstrInfo();
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
// If last instruction is a return instruction, add an epilogue
if (!I->empty() && TII.isReturn(I->back().getOpcode()))
const TargetMachine &TM = Fn.getTarget();
assert(TM.getRegisterInfo() && "TM::getRegisterInfo() must be implemented!");
const MRegisterInfo &MRI = *TM.getRegisterInfo();
+ const TargetFrameInfo *TFI = TM.getFrameInfo();
+ bool StackGrowsDown =
+ TFI->getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
+ int FrameSetupOpcode = MRI.getCallFrameSetupOpcode();
+ int FrameDestroyOpcode = MRI.getCallFrameDestroyOpcode();
- for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
- for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (I->getOperand(i).isFrameIndex()) {
- // If this instruction has a FrameIndex operand, we need to use that
- // target machine register info object to eliminate it.
- MRI.eliminateFrameIndex(Fn, I);
- break;
- }
+ for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
+ int SPAdj = 0; // SP offset due to call frame setup / destroy.
+ if (RS) RS->enterBasicBlock(BB);
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
+ MachineInstr *MI = I;
+
+ // Remember how much SP has been adjustment to create the call frame.
+ if (I->getOpcode() == FrameSetupOpcode ||
+ I->getOpcode() == FrameDestroyOpcode) {
+ int Size = I->getOperand(0).getImmedValue();
+ if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
+ (StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
+ Size = -Size;
+ SPAdj += Size;
+ MachineBasicBlock::iterator PrevI = prior(I);
+ MRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
+ // Visit the instructions created by eliminateCallFramePseudoInstr().
+ I = next(PrevI);
+ MI = NULL;
+ } else {
+ I++;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
+ if (MI->getOperand(i).isFrameIndex()) {
+ // If this instruction has a FrameIndex operand, we need to use that
+ // target machine register info object to eliminate it.
+ MRI.eliminateFrameIndex(MI, SPAdj, RS);
+
+ // Revisit the instruction in full. Some instructions (e.g. inline
+ // asm instructions) can have multiple frame indices.
+ --I;
+ MI = 0;
+ break;
+ }
+ }
+ // Update register states.
+ if (RS && MI) RS->forward(MI);
+ }
+ assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
+ }
}
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