(this is a corrected patch)

Calling _chkstk is required on ELF as well as COFF on Windows. Without 
_chkstk, functions requiring large stack crash in initialization code.

Previous code tested for COFF format but not Mach-O and this patch modifies 
the code to test for Windows OS (both Windows target and MingW target) 
but not Mach-O object format: Looks like macho environment was used to 
build some EFI code.
 
Credits to Andrew MacPherson.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193289 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index cc409fb..31ff797 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -631,7 +631,7 @@
   setOperationAction(ISD::STACKSAVE,          MVT::Other, Expand);
   setOperationAction(ISD::STACKRESTORE,       MVT::Other, Expand);
 
-  if (Subtarget->isTargetCOFF() && !Subtarget->isTargetEnvMacho())
+  if (Subtarget->isOSWindows() && !Subtarget->isTargetEnvMacho())
     setOperationAction(ISD::DYNAMIC_STACKALLOC, Subtarget->is64Bit() ?
                        MVT::i64 : MVT::i32, Custom);
   else if (TM.Options.EnableSegmentedStacks)