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
--
http://nondot.org/sabre/
http://llvm.org/
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