[X86][AVX512] Only lower to VPALIGNR if we have BWI (PR48322)

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -17270,12 +17270,14 @@ static SDValue lowerV8I64Shuffle(const SDLoc &DL, ArrayRef<int> Mask,
     return Rotate;
 
   // Try to use PALIGNR.
-  if (SDValue Rotate = lowerShuffleAsByteRotate(DL, MVT::v8i64, V1, V2, Mask,
-                                                Subtarget, DAG))
-    return Rotate;
+  if (Subtarget.hasBWI())
+    if (SDValue Rotate = lowerShuffleAsByteRotate(DL, MVT::v8i64, V1, V2, Mask,
+                                                  Subtarget, DAG))
+      return Rotate;
 
   if (SDValue Unpck = lowerShuffleWithUNPCK(DL, MVT::v8i64, Mask, V1, V2, DAG))
     return Unpck;
+
   // If we have AVX512F support, we can use VEXPAND.
   if (SDValue V = lowerShuffleToEXPAND(DL, MVT::v8i64, Zeroable, Mask, V1, V2,
                                        DAG, Subtarget))

llvm/test/CodeGen/X86/vector-shuffle-512-v16.ll

@@ -167,6 +167,16 @@ define <16 x float> @shuffle_v16f32_00_17_02_19_04_21_06_23_08_25_10_27_12_29_14
   ret <16 x float> %tmp2
 }
 
+; PR48322
+define <16 x float> @shuffle_v16f32_02_03_16_17_06_07_20_21_10_11_24_25_14_15_28_29(<16 x float> %a, <16 x float> %b) {
+; ALL-LABEL: shuffle_v16f32_02_03_16_17_06_07_20_21_10_11_24_25_14_15_28_29:
+; ALL:       # %bb.0:
+; ALL-NEXT:    vshufpd {{.*#+}} zmm0 = zmm0[1],zmm1[0],zmm0[3],zmm1[2],zmm0[5],zmm1[4],zmm0[7],zmm1[6]
+; ALL-NEXT:    retq
+  %shuffle = shufflevector <16 x float> %a, <16 x float> %b, <16 x i32> <i32 2, i32 3, i32 16, i32 17, i32 6, i32 7, i32 20, i32 21, i32 10, i32 11, i32 24, i32 25, i32 14, i32 15, i32 28, i32 29>
+  ret <16 x float> %shuffle
+}
+
 define <16 x i32> @shuffle_v16i32_00_00_00_00_00_00_00_00_00_00_00_00_00_00_00_00(<16 x i32> %a, <16 x i32> %b) {
 ; ALL-LABEL: shuffle_v16i32_00_00_00_00_00_00_00_00_00_00_00_00_00_00_00_00:
 ; ALL:       # %bb.0:
@@ -506,6 +516,22 @@ define <16 x i32> @shuffle_v16i32_16_16_02_03_20_20_06_07_24_24_10_11_28_28_uu_u
   ret <16 x i32> %shuffle
 }
 
+; PR48322
+define <16 x i32> @shuffle_v16i32_02_03_16_17_06_07_20_21_10_11_24_25_14_15_28_29(<16 x i32> %a, <16 x i32> %b) {
+; AVX512F-LABEL: shuffle_v16i32_02_03_16_17_06_07_20_21_10_11_24_25_14_15_28_29:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovdqa64 {{.*#+}} zmm2 = [1,8,3,10,5,12,7,14]
+; AVX512F-NEXT:    vpermt2q %zmm1, %zmm2, %zmm0
+; AVX512F-NEXT:    retq
+;
+; AVX512BW-LABEL: shuffle_v16i32_02_03_16_17_06_07_20_21_10_11_24_25_14_15_28_29:
+; AVX512BW:       # %bb.0:
+; AVX512BW-NEXT:    vpalignr {{.*#+}} zmm0 = zmm0[8,9,10,11,12,13,14,15],zmm1[0,1,2,3,4,5,6,7],zmm0[24,25,26,27,28,29,30,31],zmm1[16,17,18,19,20,21,22,23],zmm0[40,41,42,43,44,45,46,47],zmm1[32,33,34,35,36,37,38,39],zmm0[56,57,58,59,60,61,62,63],zmm1[48,49,50,51,52,53,54,55]
+; AVX512BW-NEXT:    retq
+  %shuffle = shufflevector <16 x i32> %a, <16 x i32> %b, <16 x i32> <i32 2, i32 3, i32 16, i32 17, i32 6, i32 7, i32 20, i32 21, i32 10, i32 11, i32 24, i32 25, i32 14, i32 15, i32 28, i32 29>
+  ret <16 x i32> %shuffle
+}
+
 define <16 x i32> @shuffle_v8i32_17_16_01_00_21_20_05_04_25_24_09_08_29_28_13_12(<16 x i32> %a, <16 x i32> %b) {
 ; ALL-LABEL: shuffle_v8i32_17_16_01_00_21_20_05_04_25_24_09_08_29_28_13_12:
 ; ALL:       # %bb.0: