Fix PR4185.
Handle FpSET_ST0_80 being used when ST0 is still alive.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73850 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp
index 0f2fbcc..ed4eb44 100644
--- a/lib/Target/X86/X86FloatingPoint.cpp
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -991,8 +991,13 @@
case X86::FpSET_ST0_32:
case X86::FpSET_ST0_64:
case X86::FpSET_ST0_80:
- assert((StackTop == 1 || StackTop == 2)
- && "Stack should have one or two element on it to return!");
+ // FpSET_ST0_80 is generated by copyRegToReg for both function return
+ // and inline assembly with the "st" constrain. In the latter case,
+ // it is possible for FP0 to be alive after this instruction.
+ if (!MI->killsRegister(X86::FP0)) {
+ // Duplicate ST0
+ duplicateToTop(0, 0, I);
+ }
--StackTop; // "Forget" we have something on the top of stack!
break;
case X86::FpSET_ST1_32: