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Do proper book-keeping of offsets and prologue/epilogue code for stack realignment

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50163 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anton Korobeynikov 2008-04-23 18:21:27 +00:00
parent 8e91ec5e29
commit 2c430cbf03
1 changed files with 81 additions and 44 deletions
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125
lib/Target/X86/X86RegisterInfo.cpp
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@ -249,6 +249,19 @@ BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
// Stack Frame Processing methods
//===----------------------------------------------------------------------===//
static unsigned calculateMaxStackAlignment(const MachineFrameInfo *FFI) {
unsigned MaxAlign = 0;
for (int i = FFI->getObjectIndexBegin(),
e = FFI->getObjectIndexEnd(); i != e; ++i) {
if (FFI->isDeadObjectIndex(i))
continue;
unsigned Align = FFI->getObjectAlignment(i);
MaxAlign = std::max(MaxAlign, Align);
}
return MaxAlign;
}
// 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.
@ -267,10 +280,16 @@ bool X86RegisterInfo::hasFP(const MachineFunction &MF) const {
bool X86RegisterInfo::needsStackRealignment(const MachineFunction &MF) const {
MachineFrameInfo *MFI = MF.getFrameInfo();;
// FIXME: This is really really ugly, but it seems we need to decide, whether
// we will need stack realignment or not too early (during RA stage).
unsigned MaxAlign = MFI->getMaxAlignment();
if (!MaxAlign)
MaxAlign = calculateMaxStackAlignment(MFI);
// FIXME: Currently we don't support stack realignment for functions with
// variable-sized allocas
return (RealignStack &&
(MFI->getMaxAlignment() > StackAlign &&
(MaxAlign > StackAlign &&
!MFI->hasVarSizedObjects()));
}
@ -281,18 +300,24 @@ bool X86RegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
int
X86RegisterInfo::getFrameIndexOffset(MachineFunction &MF, int FI) const {
int Offset = MF.getFrameInfo()->getObjectOffset(FI) + SlotSize;
uint64_t StackSize = MF.getFrameInfo()->getStackSize();
if (needsStackRealignment(MF)) {
if (FI < 0)
// Skip the saved EBP
Offset += SlotSize;
else
return Offset + MF.getFrameInfo()->getStackSize();
else {
unsigned MaxAlign = MF.getFrameInfo()->getMaxAlignment();
uint64_t FrameSize =
(StackSize - SlotSize + MaxAlign - 1)/MaxAlign*MaxAlign;
return Offset + FrameSize - SlotSize;
}
// FIXME: Support tail calls
} else {
if (!hasFP(MF))
return Offset + MF.getFrameInfo()->getStackSize();
return Offset + StackSize;
// Skip the saved EBP
Offset += SlotSize;
@ -397,14 +422,7 @@ X86RegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
// Calculate and set max stack object alignment early, so we can decide
// whether we will need stack realignment (and thus FP).
unsigned MaxAlign = 0;
for (int i = FFI->getObjectIndexBegin(),
e = FFI->getObjectIndexEnd(); i != e; ++i) {
if (FFI->isDeadObjectIndex(i))
continue;
unsigned Align = FFI->getObjectAlignment(i);
MaxAlign = std::max(MaxAlign, Align);
}
unsigned MaxAlign = calculateMaxStackAlignment(FFI);
FFI->setMaxAlignment(MaxAlign);
}
@ -641,12 +659,14 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Get the number of bytes to allocate from the FrameInfo.
uint64_t StackSize = MFI->getStackSize();
// Get desired stack alignment
uint64_t MaxAlign = MFI->getMaxAlignment();
// Add RETADDR move area to callee saved frame size.
int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
if (TailCallReturnAddrDelta < 0)
X86FI->setCalleeSavedFrameSize(
X86FI->getCalleeSavedFrameSize() +(-TailCallReturnAddrDelta));
uint64_t NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
// Insert stack pointer adjustment for later moving of return addr. Only
// applies to tail call optimized functions where the callee argument stack
@ -656,16 +676,23 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
StackPtr).addReg(StackPtr).addImm(-TailCallReturnAddrDelta);
}
uint64_t NumBytes = 0;
if (hasFP(MF)) {
// Calculate required stack adjustment
uint64_t FrameSize = StackSize - SlotSize;
if (needsStackRealignment(MF))
FrameSize = (FrameSize + MaxAlign - 1)/MaxAlign*MaxAlign;
NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize();
// 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.
MFI->setOffsetAdjustment(SlotSize-NumBytes);
MFI->setOffsetAdjustment(-NumBytes);
// Save EBP into the appropriate stack slot...
BuildMI(MBB, MBBI, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r))
.addReg(FramePtr);
NumBytes -= SlotSize;
if (needsFrameMoves) {
// Mark effective beginning of when frame pointer becomes valid.
@ -676,7 +703,14 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Update EBP with the new base value...
BuildMI(MBB, MBBI, TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), FramePtr)
.addReg(StackPtr);
}
// Realign stack
if (needsStackRealignment(MF))
BuildMI(MBB, MBBI,
TII.get(Is64Bit ? X86::AND64ri32 : X86::AND32ri),
StackPtr).addReg(StackPtr).addImm(-MaxAlign);
} else
NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
unsigned ReadyLabelId = 0;
if (needsFrameMoves) {
@ -740,25 +774,12 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
if (needsFrameMoves)
emitFrameMoves(MF, FrameLabelId, ReadyLabelId);
// If it's main() on Cygwin\Mingw32 we should align stack as well
if (Fn->hasExternalLinkage() && Fn->getName() == "main" &&
Subtarget->isTargetCygMing()) {
BuildMI(MBB, MBBI, TII.get(X86::AND32ri), X86::ESP)
.addReg(X86::ESP).addImm(-StackAlign);
// Probe the stack
BuildMI(MBB, MBBI, TII.get(X86::MOV32ri), X86::EAX).addImm(StackAlign);
BuildMI(MBB, MBBI, TII.get(X86::CALLpcrel32)).addExternalSymbol("_alloca");
}
}
void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const Function* Fn = MF.getFunction();
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
const X86Subtarget* Subtarget = &MF.getTarget().getSubtarget<X86Subtarget>();
MachineBasicBlock::iterator MBBI = prior(MBB.end());
unsigned RetOpcode = MBBI->getOpcode();
@ -779,16 +800,25 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
// Get the number of bytes to allocate from the FrameInfo
uint64_t StackSize = MFI->getStackSize();
uint64_t MaxAlign = MFI->getMaxAlignment();
unsigned CSSize = X86FI->getCalleeSavedFrameSize();
uint64_t NumBytes = StackSize - CSSize;
uint64_t NumBytes = 0;
if (hasFP(MF)) {
// Calculate required stack adjustment
uint64_t FrameSize = StackSize - SlotSize;
if (needsStackRealignment(MF))
FrameSize = (FrameSize + MaxAlign - 1)/MaxAlign*MaxAlign;
NumBytes = FrameSize - CSSize;
// pop EBP.
BuildMI(MBB, MBBI, TII.get(Is64Bit ? X86::POP64r : X86::POP32r), FramePtr);
NumBytes -= SlotSize;
}
} else
NumBytes = StackSize - CSSize;
// Skip the callee-saved pop instructions.
MachineBasicBlock::iterator LastCSPop = MBBI;
while (MBBI != MBB.begin()) {
MachineBasicBlock::iterator PI = prior(MBBI);
unsigned Opc = PI->getOpcode();
@ -804,14 +834,22 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes);
// If dynamic alloca is used, then reset esp to point to the last callee-saved
// slot before popping them off! Also, if it's main() on Cygwin/Mingw32 we
// aligned stack in the prologue, - revert stack changes back. Note: we're
// assuming, that frame pointer was forced for main()
if (MFI->hasVarSizedObjects() ||
(Fn->hasExternalLinkage() && Fn->getName() == "main" &&
Subtarget->isTargetCygMing())) {
unsigned Opc = Is64Bit ? X86::LEA64r : X86::LEA32r;
// slot before popping them off! Same applies for the case, when stack was
// realigned
if (needsStackRealignment(MF)) {
// We cannot use LEA here, because stack pointer was realigned. We need to
// deallocate local frame back
if (CSSize) {
emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, TII);
MBBI = prior(LastCSPop);
}
BuildMI(MBB, MBBI,
TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr),
StackPtr).addReg(FramePtr);
} else if (MFI->hasVarSizedObjects()) {
if (CSSize) {
unsigned Opc = Is64Bit ? X86::LEA64r : X86::LEA32r;
MachineInstr *MI = addRegOffset(BuildMI(TII.get(Opc), StackPtr),
FramePtr, -CSSize);
MBB.insert(MBBI, MI);
@ -819,13 +857,12 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
BuildMI(MBB, MBBI, TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr),StackPtr).
addReg(FramePtr);
NumBytes = 0;
} else {
// adjust stack pointer back: ESP += numbytes
if (NumBytes)
emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, TII);
}
// adjust stack pointer back: ESP += numbytes
if (NumBytes)
emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, TII);
// We're returning from function via eh_return.
if (RetOpcode == X86::EH_RETURN) {
MBBI = prior(MBB.end());