[llvm] r274474 - [X86][AVX2] Merge unary permute matching behind the same V2.isUndef() condition. NFCI.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sun Jul  3 15:39:42 2016
New Revision: 274474

URL: http://llvm.org/viewvc/llvm-project?rev=274474&view=rev
Log:
[X86][AVX2] Merge unary permute matching behind the same V2.isUndef() condition. NFCI.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=274474&r1=274473&r2=274474&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sun Jul  3 15:39:42 2016
@@ -11216,11 +11216,11 @@ static SDValue lowerV4I64VectorShuffle(c
                                                         Mask, Subtarget, DAG))
     return Broadcast;
 
-  // When the shuffle is mirrored between the 128-bit lanes of the unit, we can
-  // use lower latency instructions that will operate on both 128-bit lanes.
-  SmallVector<int, 2> RepeatedMask;
-  if (is128BitLaneRepeatedShuffleMask(MVT::v4i64, Mask, RepeatedMask)) {
-    if (V2.isUndef()) {
+  if (V2.isUndef()) {
+    // When the shuffle is mirrored between the 128-bit lanes of the unit, we
+    // can use lower latency instructions that will operate on both lanes.
+    SmallVector<int, 2> RepeatedMask;
+    if (is128BitLaneRepeatedShuffleMask(MVT::v4i64, Mask, RepeatedMask)) {
       int PSHUFDMask[] = {-1, -1, -1, -1};
       for (int i = 0; i < 2; ++i)
         if (RepeatedMask[i] >= 0) {
@@ -11233,13 +11233,12 @@ static SDValue lowerV4I64VectorShuffle(c
                       DAG.getBitcast(MVT::v8i32, V1),
                       getV4X86ShuffleImm8ForMask(PSHUFDMask, DL, DAG)));
     }
-  }
 
-  // AVX2 provides a direct instruction for permuting a single input across
-  // lanes.
-  if (V2.isUndef())
+    // AVX2 provides a direct instruction for permuting a single input across
+    // lanes.
     return DAG.getNode(X86ISD::VPERMI, DL, MVT::v4i64, V1,
                        getV4X86ShuffleImm8ForMask(Mask, DL, DAG));
+  }
 
   // Try to use shift instructions.
   if (SDValue Shift = lowerVectorShuffleAsShift(DL, MVT::v4i64, V1, V2, Mask,