[x86] As a follow-up to r217819, don't check for VSELECT legality now

that we don't use VSELECT and directly emit an addsub synthetic node.
Also remove a stale comment referencing VSELECT.

The test case is updated to use 'core2' which only has SSE3, not SSE4.1,
and it still passes. Previously it would not because we lacked
sufficient blend support to legalize the VSELECT.

llvm-svn: 217849

1 files changed, 1 insertions, 7 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index b5bf866b22d..6465fececc8 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -6485,11 +6485,6 @@ static SDValue matchAddSub(const BuildVectorSDNode *BV, SelectionDAG &DAG,
   assert((VT == MVT::v8f32 || VT == MVT::v4f64 || VT == MVT::v4f32 ||
           VT == MVT::v2f64) && "build_vector with an invalid type found!");
 
-  // Don't try to emit a VSELECT that cannot be lowered into a blend.
-  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
-  if (!TLI.isOperationLegalOrCustom(ISD::VSELECT, VT))
-    return SDValue();
-
   // Odd-numbered elements in the input build vector are obtained from
   // adding two integer/float elements.
   // Even-numbered elements in the input build vector are obtained from
@@ -6562,8 +6557,7 @@ static SDValue matchAddSub(const BuildVectorSDNode *BV, SelectionDAG &DAG,
     std::swap(ExpectedOpcode, NextExpectedOpcode);
   }
 
-  // Don't try to fold this build_vector into a VSELECT if it has
-  // too many UNDEF operands.
+  // Don't try to fold this build_vector into an ADDSUB if the inputs are undef.
   if (AddFound && SubFound && InVec0.getOpcode() != ISD::UNDEF &&
       InVec1.getOpcode() != ISD::UNDEF)
     return DAG.getNode(X86ISD::ADDSUB, DL, VT, InVec0, InVec1);