Subzero. X8664. Fix broken call sequence.

Makefile.standalone

@@ -497,12 +497,21 @@ check-presubmit presubmit:
 # Run lit tests, cross tests, unit tests, and spec2k/x86-32.
 	+make -f Makefile.standalone \
           check check-spec
+# Run spec2k/x86-64.
+	+make -f Makefile.standalone \
+          TARGET=x8664 check-spec
 # Build spec2k under -Om1/x86-32, to check for liveness errors.
 	+make -f Makefile.standalone \
           SPECFLAGS='-Om1' SPECBUILDONLY=true check-spec
+# Build spec2k under -Om1/x86-64, to check for liveness errors.
+	+make -f Makefile.standalone \
+          SPECFLAGS='-Om1' TARGET=x8664 SPECBUILDONLY=true check-spec
 # Run spec2k for x86-32 without advanced phi lowering.
 	+make -f Makefile.standalone \
           SPECFLAGS='--sz=--phi-edge-split=0' check-spec
+# Run spec2k for x86-64 without advanced phi lowering.
+	+make -f Makefile.standalone \
+          SPECFLAGS='--sz=--phi-edge-split=0' TARGET=x8664 check-spec
 # Run cross tests and lit tests to validate filetype=asm output.
 	+make -f Makefile.standalone \
           FORCEASM=1 check-xtest check-lit

src/IceTargetLoweringX86BaseImpl.h

@@ -2152,7 +2152,7 @@ void TargetX86Base<TraitsType>::lowerCall(const InstCall *Instr) {
   // Ensure there is enough space for the fstp/movs for floating returns.
   Variable *Dest = Instr->getDest();
   const Type DestTy = Dest ? Dest->getType() : IceType_void;
-  if (Traits::X86_PASS_SCALAR_FP_IN_XMM) {
+  if (!Traits::X86_PASS_SCALAR_FP_IN_XMM) {
     if (isScalarFloatingType(DestTy)) {
       ParameterAreaSizeBytes =
           std::max(static_cast<size_t>(ParameterAreaSizeBytes),