Re-commit r269828 "X86: Avoid using _chkstk when lowering WIN_ALLOCA instructions"
with an additional fix to make RegAllocFast ignore undef physreg uses. It would
previously get confused about the "push %eax" instruction's use of eax. That
method for adjusting the stack pointer is used in X86FrameLowering::emitSPUpdate
as well, but since that runs after register-allocation, we didn't run into the
RegAllocFast issue before.
llvm-svn: 269949
diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index cde3197..1fe98a6 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -266,6 +266,7 @@
addPass(createX86OptimizeLEAs());
addPass(createX86CallFrameOptimization());
+ addPass(createX86WinAllocaExpander());
}
void X86PassConfig::addPostRegAlloc() {