X86: Use push-pop for materializing 8-bit immediates for minsize (take 2)

This is the same as r255936, with added logic for avoiding clobbering of the
red zone (PR26023).

Differential Revision: http://reviews.llvm.org/D18246

llvm-svn: 264375

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index dd8b8134c43..9beb916d23d 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -958,6 +958,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
       !MF.shouldSplitStack()) {                 // Regular stack
     uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
     if (HasFP) MinSize += SlotSize;
+    X86FI->setUsesRedZone(MinSize > 0 || StackSize > 0);
     StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0);
     MFI->setStackSize(StackSize);
   }