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Cygwin support: use _alloca to allocate stack if > 4k. Patch by Anton Korobeynikov.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28764 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2006-06-13 05:14:44 +00:00
parent 9686ae7f4e
commit 004fb92615
1 changed files with 21 additions and 4 deletions
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25
lib/Target/X86/X86RegisterInfo.cpp
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@ -740,7 +740,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
const Function* Fn = MF.getFunction();
const X86Subtarget* Subtarget = &MF.getTarget().getSubtarget<X86Subtarget>();
MachineInstr *MI;
// Get the number of bytes to allocate from the FrameInfo
unsigned NumBytes = MFI->getStackSize();
if (MFI->hasCalls() || MF.getFrameInfo()->hasVarSizedObjects()) {
@ -760,9 +760,20 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
MFI->setStackSize(NumBytes);
if (NumBytes) { // adjust stack pointer: ESP -= numbytes
unsigned Opc = NumBytes < 128 ? X86::SUB32ri8 : X86::SUB32ri;
MI = BuildMI(Opc, 1, X86::ESP,MachineOperand::UseAndDef).addImm(NumBytes);
MBB.insert(MBBI, MI);
if (NumBytes >= 4096 && Subtarget->TargetType == X86Subtarget::isCygwin) {
// Function prologue calls _alloca to probe the stack when allocating
// more than 4k bytes in one go. Touching the stack at 4K increments is
// necessary to ensure that the guard pages used by the OS virtual memory
// manager are allocated in correct sequence.
MI = BuildMI(X86::MOV32ri, 2, X86::EAX).addImm(NumBytes);
MBB.insert(MBBI, MI);
MI = BuildMI(X86::CALLpcrel32, 1).addExternalSymbol("_alloca");
MBB.insert(MBBI, MI);
} else {
unsigned Opc = NumBytes < 128 ? X86::SUB32ri8 : X86::SUB32ri;
MI = BuildMI(Opc, 1, X86::ESP,MachineOperand::UseAndDef).addImm(NumBytes);
MBB.insert(MBBI, MI);
}
}
if (hasFP(MF)) {
@ -789,6 +800,12 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
Subtarget->TargetType == X86Subtarget::isCygwin) {
MI = BuildMI(X86::AND32ri, 2, X86::ESP).addImm(-Align);
MBB.insert(MBBI, MI);
// Probe the stack
MI = BuildMI(X86::MOV32ri, 2, X86::EAX).addImm(Align);
MBB.insert(MBBI, MI);
MI = BuildMI(X86::CALLpcrel32, 1).addExternalSymbol("_alloca");
MBB.insert(MBBI, MI);
}
}