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 ed4eb444e9cf7a2071fcd9285761126f92563b43..abacdb2f9b610b2592b3501930076141c0383dc0 100644 (file)
--- a/lib/Target/X86/X86FloatingPoint.cpp
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -996,7 +996,7 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
     // 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;

diff --git a/test/CodeGen/X86/inline-asm-fpstack3.ll b/test/CodeGen/X86/inline-asm-fpstack3.ll
new file mode 100644 (file)
index 0000000..ac89a1d
--- /dev/null
+++ b/test/CodeGen/X86/inline-asm-fpstack3.ll
@@ -0,0 +1,15 @@
+; RUN: llvm-as < %s | llc -march=x86 > %t
+; RUN: grep {fld       %%st(0)} %t
+; PR4459
+
+declare x86_fp80 @ceil(x86_fp80)
+
+declare void @test(x86_fp80)
+
+define void @test2(x86_fp80 %a) {
+entry:
+       %0 = call x86_fp80 @ceil(x86_fp80 %a)
+       call void asm sideeffect "fistpl $0", "{st}"( x86_fp80 %0)
+       call void @test(x86_fp80 %0 )
+        ret void
+}