PR3739, part 1: Disable the red zone on Win64.

llvm-svn: 72830

llvm/lib/Target/X86/X86RegisterInfo.cpp

@@ -754,7 +754,8 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
   if (Is64Bit && !DisableRedZone &&
       !needsStackRealignment(MF) &&
       !MFI->hasVarSizedObjects() &&                // No dynamic alloca.
-      !MFI->hasCalls()) {                          // No calls.
+      !MFI->hasCalls() &&                          // No calls.
+      !Subtarget->isTargetWin64()) {               // Win64 has no Red Zone
     uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
     if (hasFP(MF)) MinSize += SlotSize;
     StackSize = std::max(MinSize,

llvm/test/CodeGen/X86/2009-06-03-Win64DisableRedZone.ll

@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s | llc | grep "subq.*\\\$8, \\\%rsp"
+target triple = "x86_64-mingw64"
+
+define x86_fp80 @a(i64 %x) nounwind readnone {
+entry:
+	%conv = sitofp i64 %x to x86_fp80		; <x86_fp80> [#uses=1]
+	ret x86_fp80 %conv
+}
+