3 files changed, 14 insertions, 5 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index aa7009a..5548318 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1128,12 +1128,9 @@ void SelectionDAGBuilder::visitRet(const ReturnInst &I) {
         else if (F->paramHasAttr(0, Attribute::ZExt))
           ExtendKind = ISD::ZERO_EXTEND;
 
-        // FIXME: C calling convention requires the return type to be promoted
-        // to at least 32-bit. But this is not necessary for non-C calling
-        // conventions. The frontend should mark functions whose return values
-        // require promoting with signext or zeroext attributes.
         if (ExtendKind != ISD::ANY_EXTEND && VT.isInteger()) {
-          EVT MinVT = TLI.getRegisterType(*DAG.getContext(), MVT::i32);
+          MVT ReturnMVT = TLI.getTypeForExtendedInteger(VT, ExtendKind);
+          EVT MinVT = TLI.getRegisterType(*DAG.getContext(), ReturnMVT);
           if (VT.bitsLT(MinVT))
             VT = MinVT;
         }
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 910ed2a..c1aa720 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1448,6 +1448,15 @@ bool X86TargetLowering::isUsedByReturnOnly(SDNode *N) const {
   return HasRet;
 }
 
+MVT
+X86TargetLowering::getTypeForExtendedInteger(EVT VT,
+                                             ISD::NodeType ExtendKind) const {
+  // TODO: Is this also valid on 32-bit?
+  if (Subtarget->is64Bit() && VT == MVT::i1 && ExtendKind == ISD::ZERO_EXTEND)
+    return MVT::i8;
+  return MVT::i32;
+}
+
 /// LowerCallResult - Lower the result values of a call into the
 /// appropriate copies out of appropriate physical registers.
 ///
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index 551884b..0857c59 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -843,6 +843,9 @@ namespace llvm {
 
     virtual bool isUsedByReturnOnly(SDNode *N) const;
 
+    virtual MVT
+    getTypeForExtendedInteger(EVT VT, ISD::NodeType ExtendKind) const;
+
     virtual bool
       CanLowerReturn(CallingConv::ID CallConv, bool isVarArg,
                      const SmallVectorImpl<ISD::OutputArg> &Outs,