X86: Custom lower zext v16i8 to v16i16.

On sandy bridge (PR17654) we now get
	vpxor	%xmm1, %xmm1, %xmm1
	vpunpckhbw	%xmm1, %xmm0, %xmm2
	vpunpcklbw	%xmm1, %xmm0, %xmm0
	vinsertf128	$1, %xmm2, %ymm0, %ymm0

On haswell it's a simple
	vpmovzxbw	%xmm0, %ymm0

There is a maze of duplicated and dead transforms and patterns in this
area. Remove the dead custom lowering of zext v8i16 to v8i32, that's
already handled by LowerAVXExtend.

llvm-svn: 193262

2 files changed, 8 insertions, 19 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 7dddb49beee..5f29f4f8ce3 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1160,6 +1160,7 @@ void X86TargetLowering::resetOperationActions() {
     setOperationAction(ISD::SINT_TO_FP,         MVT::v8i32, Legal);
     setOperationAction(ISD::FP_ROUND,           MVT::v4f32, Legal);
 
+    setOperationAction(ISD::ZERO_EXTEND,        MVT::v16i16, Custom);
     setOperationAction(ISD::ZERO_EXTEND,        MVT::v8i32, Custom);
     setOperationAction(ISD::UINT_TO_FP,         MVT::v8i8,  Custom);
     setOperationAction(ISD::UINT_TO_FP,         MVT::v8i16, Custom);
@@ -8864,7 +8865,8 @@ static SDValue LowerAVXExtend(SDValue Op, SelectionDAG &DAG,
   //   Concat upper and lower parts.
   //
 
-  if (((VT != MVT::v8i32) || (InVT != MVT::v8i16)) &&
+  if (((VT != MVT::v16i16) || (InVT != MVT::v16i8)) &&
+      ((VT != MVT::v8i32) || (InVT != MVT::v8i16)) &&
       ((VT != MVT::v4i64) || (InVT != MVT::v4i32)))
     return SDValue();
 
@@ -8944,24 +8946,9 @@ static SDValue LowerZERO_EXTEND(SDValue Op, const X86Subtarget *Subtarget,
       return Res;
   }
 
-  if (!VT.is256BitVector() || !SVT.is128BitVector() ||
-      VT.getVectorNumElements() != SVT.getVectorNumElements())
-    return SDValue();
-
-  assert(Subtarget->hasFp256() && "256-bit vector is observed without AVX!");
-
-  // AVX2 has better support of integer extending.
-  if (Subtarget->hasInt256())
-    return DAG.getNode(X86ISD::VZEXT, DL, VT, In);
-
-  SDValue Lo = DAG.getNode(X86ISD::VZEXT, DL, MVT::v4i32, In);
-  static const int Mask[] = {4, 5, 6, 7, -1, -1, -1, -1};
-  SDValue Hi = DAG.getNode(X86ISD::VZEXT, DL, MVT::v4i32,
-                           DAG.getVectorShuffle(MVT::v8i16, DL, In,
-                                                DAG.getUNDEF(MVT::v8i16),
-                                                &Mask[0]));
-
-  return DAG.getNode(ISD::CONCAT_VECTORS, DL, MVT::v8i32, Lo, Hi);
+  assert(!VT.is256BitVector() || !SVT.is128BitVector() ||
+         VT.getVectorNumElements() != SVT.getVectorNumElements());
+  return SDValue();
 }
 
 SDValue X86TargetLowering::LowerTRUNCATE(SDValue Op, SelectionDAG &DAG) const {
diff --git a/llvm/lib/Target/X86/X86InstrSSE.td b/llvm/lib/Target/X86/X86InstrSSE.td
index bf091919549..004710b67cc 100644
--- a/llvm/lib/Target/X86/X86InstrSSE.td
+++ b/llvm/lib/Target/X86/X86InstrSSE.td
@@ -5596,6 +5596,8 @@ let Predicates = [HasAVX2] in {
               (VPMOVZXDQYrr VR128:$src)>;
     def : Pat<(v8i32 (X86vzmovly (v8i16 VR128:$src))),
               (VPMOVZXWDYrr VR128:$src)>;
+    def : Pat<(v16i16 (X86vzmovly (v16i8 VR128:$src))),
+              (VPMOVZXBWYrr VR128:$src)>;
   }
 
   def : Pat<(v4i64 (X86vsmovl (v4i32 VR128:$src))), (VPMOVSXDQYrr VR128:$src)>;