[llvm] r365044 - [X86][AVX] Combine vpermi(bitcast(x)) -> bitcast(vpermi(x))

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Wed Jul  3 07:34:16 2019
New Revision: 365044

URL: http://llvm.org/viewvc/llvm-project?rev=365044&view=rev
Log:
[X86][AVX] Combine vpermi(bitcast(x)) -> bitcast(vpermi(x))

iff the number of elements doesn't change.

This gets around an issue with combineX86ShuffleChain not being able to hint which domain is preferred for shuffles that can be done with either.

Fixes regression introduced in rL365041

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/avx512-shuffles/partial_permute.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=365044&r1=365043&r2=365044&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Jul  3 07:34:16 2019
@@ -31946,6 +31946,7 @@ static SDValue combineX86ShuffleChain(Ar
 
   // Which shuffle domains are permitted?
   // Permit domain crossing at higher combine depths.
+  // TODO: Should we indicate which domain is preferred if both are allowed?
   bool AllowFloatDomain = FloatDomain || (Depth > 3);
   bool AllowIntDomain = (!FloatDomain || (Depth > 3)) && Subtarget.hasSSE2() &&
                         (!MaskVT.is256BitVector() || Subtarget.hasAVX2());
@@ -33057,6 +33058,21 @@ static SDValue combineTargetShuffle(SDVa
     }
     return SDValue();
   }
+  case X86ISD::VPERMI: {
+    // vpermi(bitcast(x)) -> bitcast(vpermi(x)) for same number of elements.
+    // TODO: Remove when we have preferred domains in combineX86ShuffleChain.
+    SDValue N0 = N.getOperand(0);
+    SDValue N1 = N.getOperand(1);
+    unsigned EltSizeInBits = VT.getScalarSizeInBits();
+    if (N0.getOpcode() == ISD::BITCAST &&
+        N0.getOperand(0).getScalarValueSizeInBits() == EltSizeInBits) {
+      SDValue Src = N0.getOperand(0);
+      EVT SrcVT = Src.getValueType();
+      SDValue Res = DAG.getNode(X86ISD::VPERMI, DL, SrcVT, Src, N1);
+      return DAG.getBitcast(VT, Res);
+    }
+    return SDValue();
+  }
   case X86ISD::PSHUFD:
   case X86ISD::PSHUFLW:
   case X86ISD::PSHUFHW:

Modified: llvm/trunk/test/CodeGen/X86/avx512-shuffles/partial_permute.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx512-shuffles/partial_permute.ll?rev=365044&r1=365043&r2=365044&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/avx512-shuffles/partial_permute.ll (original)
+++ llvm/trunk/test/CodeGen/X86/avx512-shuffles/partial_permute.ll Wed Jul  3 07:34:16 2019
@@ -2216,9 +2216,9 @@ define <2 x i64> @test_masked_8xi64_to_2
 define <2 x i64> @test_masked_z_8xi64_to_2xi64_perm_mask0(<8 x i64> %vec, <2 x i64> %mask) {
 ; CHECK-LABEL: test_masked_z_8xi64_to_2xi64_perm_mask0:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vpermq {{.*#+}} zmm0 = zmm0[3,0,2,3,7,4,6,7]
 ; CHECK-NEXT:    vptestnmq %xmm1, %xmm1, %k1
-; CHECK-NEXT:    vmovdqa64 %xmm0, %xmm0 {%k1} {z}
+; CHECK-NEXT:    vpermq {{.*#+}} zmm0 {%k1} {z} = zmm0[3,0,2,3,7,4,6,7]
+; CHECK-NEXT:    # kill: def $xmm0 killed $xmm0 killed $zmm0
 ; CHECK-NEXT:    vzeroupper
 ; CHECK-NEXT:    retq
   %shuf = shufflevector <8 x i64> %vec, <8 x i64> undef, <2 x i32> <i32 3, i32 0>