FIX PR 4459.

Not sure I understand how the temp register gets used,
but this fixes a bug and introduces no regressions.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74446 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp
index ed4eb44..abacdb2 100644
--- a/lib/Target/X86/X86FloatingPoint.cpp
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -996,7 +996,7 @@
     // it is possible for FP0 to be alive after this instruction.
     if (!MI->killsRegister(X86::FP0)) {
       // Duplicate ST0
-      duplicateToTop(0, 0, I);
+      duplicateToTop(0, 7 /*temp register*/, I);
     }
     --StackTop;   // "Forget" we have something on the top of stack!
     break;