[llvm-commits] CVS: llvm/lib/Target/X86/X86ISelLowering.cpp

[Anton Korobeynikov]

Changes in directory llvm/lib/Target/X86:

X86ISelLowering.cpp updated: 1.392 -> 1.393
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Diffs of the changes:  (+9 -0)

 X86ISelLowering.cpp |    9 +++++++++
 1 files changed, 9 insertions(+)


Index: llvm/lib/Target/X86/X86ISelLowering.cpp
diff -u llvm/lib/Target/X86/X86ISelLowering.cpp:1.392 llvm/lib/Target/X86/X86ISelLowering.cpp:1.393
--- llvm/lib/Target/X86/X86ISelLowering.cpp:1.392	Tue Apr 17 12:21:52 2007
+++ llvm/lib/Target/X86/X86ISelLowering.cpp	Tue Apr 17 14:34:00 2007
@@ -3406,8 +3406,17 @@
     }
 }
 
+
+// Lower dynamic stack allocation to _alloca call for Cygwin/Mingw targets.
+// Calls to _alloca is needed 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.
 SDOperand X86TargetLowering::LowerDYNAMIC_STACKALLOC(SDOperand Op,
                                                      SelectionDAG &DAG) {
+  assert(Subtarget->isTargetCygMing() &&
+         "This should be used only on Cygwin/Mingw targets");
+  
   // Get the inputs.
   SDOperand Chain = Op.getOperand(0);
   SDOperand Size  = Op.getOperand(1);