[llvm-commits] CVS: llvm/lib/Target/X86/X86RegisterInfo.cpp

[Chris Lattner]

Does this fix PR331?

-Chris

On Tue, 13 Jun 2006, Evan Cheng wrote:

>
>
> Changes in directory llvm/lib/Target/X86:
>
> X86RegisterInfo.cpp updated: 1.157 -> 1.158
> ---
> Log message:
>
> Cygwin support: use _alloca to allocate stack if > 4k. Patch by Anton Korobeynikov.
>
> ---
> Diffs of the changes:  (+21 -4)
>
> X86RegisterInfo.cpp |   25 +++++++++++++++++++++----
> 1 files changed, 21 insertions(+), 4 deletions(-)
>
>
> Index: llvm/lib/Target/X86/X86RegisterInfo.cpp
> diff -u llvm/lib/Target/X86/X86RegisterInfo.cpp:1.157 llvm/lib/Target/X86/X86RegisterInfo.cpp:1.158
> --- llvm/lib/Target/X86/X86RegisterInfo.cpp:1.157	Tue Jun  6 18:30:24 2006
> +++ llvm/lib/Target/X86/X86RegisterInfo.cpp	Tue Jun 13 00:14:44 2006
> @@ -740,7 +740,7 @@
>   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 @@
>   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 @@
>       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);
>   }
> }
>
>
>
>
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>

-Chris

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