[X86][SSE] Pull out duplicate EXTRW lowering code. NFCI.

As requested on D22509, I've pulled out the v8i16 extraction lowering as the SSE41 and pre-SSE41 implementations are effectively the same.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276285 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c82888a..cf6e970 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -12373,21 +12373,6 @@ static SDValue LowerEXTRACT_VECTOR_ELT_SSE4(SDValue Op, SelectionDAG &DAG) {
     return DAG.getNode(ISD::TRUNCATE, dl, VT, Assert);
   }
 
-  if (VT.getSizeInBits() == 16) {
-    // If Idx is 0, it's cheaper to do a move instead of a pextrw.
-    if (isNullConstant(Op.getOperand(1)))
-      return DAG.getNode(
-          ISD::TRUNCATE, dl, MVT::i16,
-          DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, MVT::i32,
-                      DAG.getBitcast(MVT::v4i32, Op.getOperand(0)),
-                      Op.getOperand(1)));
-    SDValue Extract = DAG.getNode(X86ISD::PEXTRW, dl, MVT::i32,
-                                  Op.getOperand(0), Op.getOperand(1));
-    SDValue Assert  = DAG.getNode(ISD::AssertZext, dl, MVT::i32, Extract,
-                                  DAG.getValueType(VT));
-    return DAG.getNode(ISD::TRUNCATE, dl, VT, Assert);
-  }
-
   if (VT == MVT::f32) {
     // EXTRACTPS outputs to a GPR32 register which will require a movd to copy
     // the result back to FR32 register. It's only worth matching if the
@@ -12413,6 +12398,7 @@ static SDValue LowerEXTRACT_VECTOR_ELT_SSE4(SDValue Op, SelectionDAG &DAG) {
     if (isa<ConstantSDNode>(Op.getOperand(1)))
       return Op;
   }
+
   return SDValue();
 }
 
@@ -12512,26 +12498,30 @@ X86TargetLowering::LowerEXTRACT_VECTOR_ELT(SDValue Op,
 
   assert(VecVT.is128BitVector() && "Unexpected vector length");
 
-  if (Subtarget.hasSSE41())
-    if (SDValue Res = LowerEXTRACT_VECTOR_ELT_SSE4(Op, DAG))
-      return Res;
-
   MVT VT = Op.getSimpleValueType();
-  // TODO: handle v16i8.
+
   if (VT.getSizeInBits() == 16) {
+    // If IdxVal is 0, it's cheaper to do a move instead of a pextrw.
     if (IdxVal == 0)
-      return DAG.getNode(ISD::TRUNCATE, dl, MVT::i16,
-                         DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, MVT::i32,
-                                     DAG.getBitcast(MVT::v4i32, Vec), Idx));
+      return DAG.getNode(
+          ISD::TRUNCATE, dl, MVT::i16,
+          DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, MVT::i32,
+                      DAG.getBitcast(MVT::v4i32, Vec), Idx));
 
     // Transform it so it match pextrw which produces a 32-bit result.
-    MVT EltVT = MVT::i32;
-    SDValue Extract = DAG.getNode(X86ISD::PEXTRW, dl, EltVT, Vec, Idx);
-    SDValue Assert  = DAG.getNode(ISD::AssertZext, dl, EltVT, Extract,
+    SDValue Extract = DAG.getNode(X86ISD::PEXTRW, dl, MVT::i32,
+                                  Op.getOperand(0), Op.getOperand(1));
+    SDValue Assert  = DAG.getNode(ISD::AssertZext, dl, MVT::i32, Extract,
                                   DAG.getValueType(VT));
     return DAG.getNode(ISD::TRUNCATE, dl, VT, Assert);
   }
 
+  if (Subtarget.hasSSE41())
+    if (SDValue Res = LowerEXTRACT_VECTOR_ELT_SSE4(Op, DAG))
+      return Res;
+
+  // TODO: handle v16i8.
+
   if (VT.getSizeInBits() == 32) {
     if (IdxVal == 0)
       return Op;