[X86][MMX] Added custom lowering action for MMX SELECT (PR30418)

Fix for pr30418 - error in backend: Cannot select: t17: x86mmx = select_cc t2, Constant:i64<0>, t7, t8, seteq:ch
Differential Revision: https://reviews.llvm.org/D34661

llvm-svn: 309614

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 081b711a145..e1dd6d03550 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -419,6 +419,11 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
     setOperationAction(ISD::SELECT, VT, Custom);
     setOperationAction(ISD::SETCC,  VT, Custom);
   }
+
+  // Custom action for SELECT MMX and expand action for SELECT_CC MMX
+  setOperationAction(ISD::SELECT, MVT::x86mmx, Custom);
+  setOperationAction(ISD::SELECT_CC, MVT::x86mmx, Expand);
+
   setOperationAction(ISD::EH_RETURN       , MVT::Other, Custom);
   // NOTE: EH_SJLJ_SETJMP/_LONGJMP supported here is NOT intended to support
   // SjLj exception handling but a light-weight setjmp/longjmp replacement to
@@ -30631,6 +30636,14 @@ static SDValue combineSelect(SDNode *N, SelectionDAG &DAG,
       return SDValue(N, 0);
   }
 
+  // Custom action for SELECT MMX
+  if (VT == MVT::x86mmx) {
+    LHS = DAG.getBitcast(MVT::i64, LHS);
+    RHS = DAG.getBitcast(MVT::i64, RHS);
+    SDValue newSelect = DAG.getNode(ISD::SELECT, DL, MVT::i64, Cond, LHS, RHS);
+    return DAG.getBitcast(VT, newSelect);
+  }
+
   return SDValue();
 }