My previous commit had an incomplete message, it should have been:

make the 'fp return in ST(0)' optimization smart enough to
look through token factor nodes.  THis allows us to compile
testcases like CodeGen/X86/fp-stack-retcopy.ll into:

_carg:
	subl	$12, %esp
	call	L_foo$stub
	fstpl	(%esp)
	fldl	(%esp)
	addl	$12, %esp
	ret

instead of:

_carg:
	subl	$28, %esp
	call	L_foo$stub
	fstpl	16(%esp)
	movsd	16(%esp), %xmm0
	movsd	%xmm0, 8(%esp)
	fldl	8(%esp)
	addl	$28, %esp
	ret

Still not optimal, but much better and this is a trivial patch.  Fixing
the rest requires invasive surgery that is is not llvm 2.2 material.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46054 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index eb8e5e3832063fbaba7c3eae77c1bed665a4472e..de55a7c6f4b2157ce7018a75ba84b5c757cda66e 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -767,7 +767,7 @@ SDOperand X86TargetLowering::LowerRET(SDOperand Op, SelectionDAG &DAG) {
       // If this is a load into a scalarsse value, don't store the loaded value
       // back to the stack, only to reload it: just replace the scalar-sse load.
       if (ISD::isNON_EXTLoad(Value.Val) &&
-          Chain.reachesChainWithoutSideEffects(Value.getOperand(0))) {
+           Chain.reachesChainWithoutSideEffects(Value.getOperand(0))) {
         Chain  = Value.getOperand(0);
         MemLoc = Value.getOperand(1);
       } else {

diff --git a/test/CodeGen/X86/fp-stack-retcopy.ll b/test/CodeGen/X86/fp-stack-retcopy.ll
new file mode 100644 (file)
index 0000000..997f8df
--- /dev/null
+++ b/test/CodeGen/X86/fp-stack-retcopy.ll
@@ -0,0 +1,12 @@
+; This should not copy the result of foo into an xmm register.
+; RUN: llvm-as < %s | llc -march=x86 -mcpu=yonah -mtriple=i686-apple-darwin9 | not grep xmm
+; rdar://5689903
+
+declare double @foo()
+
+define double @carg({ double, double }* byval  %z) nounwind  {
+entry:
+       %tmp5 = tail call double @foo() nounwind                ; <double> [#uses=1]
+       ret double %tmp5
+}
+