[llvm] r216241 - Minor refactor to make applying patches from 'Add a "probe-stack" attribute' review thread out of order easier.

[Philip Reames]

Author: reames
Date: Thu Aug 21 17:53:49 2014
New Revision: 216241

URL: http://llvm.org/viewvc/llvm-project?rev=216241&view=rev
Log:
Minor refactor to make applying patches from 'Add a "probe-stack" attribute' review thread out of order easier.


Modified:
    llvm/trunk/lib/Target/X86/X86FrameLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=216241&r1=216240&r2=216241&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Thu Aug 21 17:53:49 2014
@@ -502,6 +502,8 @@ void X86FrameLowering::emitPrologue(Mach
     X86FI->setCalleeSavedFrameSize(
       X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta);
 
+  bool UseStackProbe = (STI.isOSWindows() && !STI.isTargetMacho());
+  
   // If this is x86-64 and the Red Zone is not disabled, if we are a leaf
   // function, and use up to 128 bytes of stack space, don't have a frame
   // pointer, calls, or dynamic alloca then we do not need to adjust the
@@ -675,6 +677,8 @@ void X86FrameLowering::emitPrologue(Mach
 
   // Adjust stack pointer: ESP -= numbytes.
 
+  static const size_t PageSize = 4096;
+
   // Windows and cygwin/mingw require a prologue helper routine when allocating
   // more than 4K bytes on the stack.  Windows uses __chkstk and cygwin/mingw
   // uses __alloca.  __alloca and the 32-bit version of __chkstk will probe the
@@ -683,7 +687,7 @@ void X86FrameLowering::emitPrologue(Mach
   // responsible for adjusting the stack pointer.  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.
-  if (NumBytes >= 4096 && STI.isOSWindows() && !STI.isTargetMacho()) {
+  if (NumBytes >= PageSize && UseStackProbe) {
     const char *StackProbeSymbol;
     unsigned CallOp;