Revert r169638 because it broke Mesa llvmpipe tests.

Fix PR15239.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175985 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelLowering.cpp

@@ -16248,11 +16248,6 @@ static SDValue PerformOrCombine(SDNode *N, SelectionDAG &DAG,
 
       DebugLoc DL = N->getDebugLoc();
 
-      // We are going to replace the AND, OR, NAND with either BLEND
-      // or PSIGN, which only look at the MSB. The VSRAI instruction
-      // does not affect the highest bit, so we can get rid of it.
-      Mask = Mask.getOperand(0);
-
       // Now we know we at least have a plendvb with the mask val.  See if
       // we can form a psignb/w/d.
       // psign = x.type == y.type == mask.type && y = sub(0, x);
@@ -16261,7 +16256,7 @@ static SDValue PerformOrCombine(SDNode *N, SelectionDAG &DAG,
           X.getValueType() == MaskVT && Y.getValueType() == MaskVT) {
         assert((EltBits == 8 || EltBits == 16 || EltBits == 32) &&
                "Unsupported VT for PSIGN");
-        Mask = DAG.getNode(X86ISD::PSIGN, DL, MaskVT, X, Mask);
+        Mask = DAG.getNode(X86ISD::PSIGN, DL, MaskVT, X, Mask.getOperand(0));
         return DAG.getNode(ISD::BITCAST, DL, VT, Mask);
       }
       // PBLENDVB only available on SSE 4.1

test/CodeGen/X86/2011-12-28-vselecti8.ll

@@ -5,7 +5,7 @@ target triple = "x86_64-apple-darwin11.2.0"
 
 ; CHECK: @foo8
 ; CHECK: psll
-; CHECK-NOT: psraw
+; CHECK: psraw
 ; CHECK: pblendvb
 ; CHECK: ret
 define void @foo8(float* nocapture %RET) nounwind {

test/CodeGen/X86/blend-msb.ll

@@ -30,7 +30,7 @@ define <4 x i8> @vsel_4xi8(<4 x i8> %v1, <4 x i8> %v2) {
 ; reduce the mask in this case.
 ;CHECK: vsel_8xi16
 ;CHECK: psllw
-;CHECK-NOT: psraw
+;CHECK: psraw
 ;CHECK: pblendvb
 ;CHECK: ret
 define <8 x i16> @vsel_8xi16(<8 x i16> %v1, <8 x i16> %v2) {