[CostModel] getInstructionCost - match SK_InsertSubvector shuffle patterns before SK_Select (#145920)

More closely match improveShuffleKindFromMask's shuffle ordering by
trying to match a SK_InsertSubvector shuffles patterns before SK_Select
- both can match many of the same patterns, but its much easier to
recognise when a SK_InsertSubvector can be converted to SK_Select than
vice-versa.

Another step towards #145335 - which I'm hoping will allow us to
generalise improveShuffleKindFromMask and remove getInstructionCost's
shuffle matching entirely.

Author: RKSimon

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -1538,7 +1538,7 @@ class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
       if (Shuffle->changesLength()) {
         // Treat a 'subvector widening' as a free shuffle.
         if (Shuffle->increasesLength() && Shuffle->isIdentityWithPadding())
-          return 0;
+          return TTI::TCC_Free;
 
         if (Shuffle->isExtractSubvectorMask(SubIndex))
           return TargetTTI->getShuffleCost(TTI::SK_ExtractSubvector, VecTy,
@@ -1599,18 +1599,13 @@ class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
       }
 
       if (Shuffle->isIdentity())
-        return 0;
+        return TTI::TCC_Free;
 
       if (Shuffle->isReverse())
         return TargetTTI->getShuffleCost(TTI::SK_Reverse, VecTy, VecSrcTy, Mask,
                                          CostKind, 0, nullptr, Operands,
                                          Shuffle);
 
-      if (Shuffle->isSelect())
-        return TargetTTI->getShuffleCost(TTI::SK_Select, VecTy, VecSrcTy, Mask,
-                                         CostKind, 0, nullptr, Operands,
-                                         Shuffle);
-
       if (Shuffle->isTranspose())
         return TargetTTI->getShuffleCost(TTI::SK_Transpose, VecTy, VecSrcTy,
                                          Mask, CostKind, 0, nullptr, Operands,
@@ -1632,6 +1627,11 @@ class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
             FixedVectorType::get(VecTy->getScalarType(), NumSubElts), Operands,
             Shuffle);
 
+      if (Shuffle->isSelect())
+        return TargetTTI->getShuffleCost(TTI::SK_Select, VecTy, VecSrcTy, Mask,
+                                         CostKind, 0, nullptr, Operands,
+                                         Shuffle);
+
       if (Shuffle->isSplice(SubIndex))
         return TargetTTI->getShuffleCost(TTI::SK_Splice, VecTy, VecSrcTy, Mask,
                                          CostKind, SubIndex, nullptr, Operands,

llvm/test/Analysis/CostModel/AArch64/shuffle-other.ll

@@ -87,21 +87,21 @@ define void @concat() {
 
 define void @insert_subvec() {
 ; CHECK-LABEL: 'insert_subvec'
-; CHECK-NEXT:  Cost Model: Found costs of RThru:12 CodeSize:6 Lat:12 SizeLat:12 for: %v4i8_2_0 = shufflevector <4 x i8> undef, <4 x i8> undef, <4 x i32> <i32 0, i32 1, i32 6, i32 7>
+; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v4i8_2_0 = shufflevector <4 x i8> undef, <4 x i8> undef, <4 x i32> <i32 0, i32 1, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v4i8_2_1 = shufflevector <4 x i8> undef, <4 x i8> undef, <4 x i32> <i32 4, i32 5, i32 0, i32 1>
-; CHECK-NEXT:  Cost Model: Found costs of RThru:28 CodeSize:14 Lat:28 SizeLat:28 for: %v8i8_2_0 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 8, i32 9, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i8_2_0 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 8, i32 9, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i8_2_1 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 0, i32 1, i32 8, i32 9, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i8_2_2 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i8_2_3 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 8, i32 9>
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:6 CodeSize:3 Lat:6 SizeLat:6 for: %v8i8_2_05 = shufflevector <8 x i8> undef, <8 x i8> undef, <8 x i32> <i32 0, i32 8, i32 9, i32 3, i32 4, i32 5, i32 6, i32 7>
-; CHECK-NEXT:  Cost Model: Found costs of RThru:60 CodeSize:30 Lat:60 SizeLat:60 for: %v16i8_4_0 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 16, i32 17, i32 18, i32 19, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
+; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i8_4_0 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 16, i32 17, i32 18, i32 19, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i8_4_1 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 16, i32 17, i32 18, i32 19, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i8_4_2 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 16, i32 17, i32 18, i32 19, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i8_4_3 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 16, i32 17, i32 18, i32 19>
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:14 CodeSize:7 Lat:14 SizeLat:14 for: %v16i8_4_05 = shufflevector <16 x i8> undef, <16 x i8> undef, <16 x i32> <i32 0, i32 1, i32 16, i32 17, i32 18, i32 19, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v4i16_2_0 = shufflevector <4 x i16> undef, <4 x i16> undef, <4 x i32> <i32 0, i32 1, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v4i16_2_1 = shufflevector <4 x i16> undef, <4 x i16> undef, <4 x i32> <i32 4, i32 5, i32 0, i32 1>
-; CHECK-NEXT:  Cost Model: Found costs of RThru:28 CodeSize:14 Lat:28 SizeLat:28 for: %v8i16_2_0 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 8, i32 9, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i16_2_0 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 8, i32 9, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i16_2_1 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 0, i32 1, i32 8, i32 9, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i16_2_2 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i16_2_3 = shufflevector <8 x i16> undef, <8 x i16> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 8, i32 9>
@@ -118,7 +118,7 @@ define void @insert_subvec() {
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i32_2_2 = shufflevector <8 x i32> undef, <8 x i32> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 6, i32 7>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v8i32_2_3 = shufflevector <8 x i32> undef, <8 x i32> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 8, i32 9>
 ; CHECK-NEXT:  Cost Model: Found costs of RThru:6 CodeSize:3 Lat:6 SizeLat:6 for: %v8i32_2_05 = shufflevector <8 x i32> undef, <8 x i32> undef, <8 x i32> <i32 0, i32 8, i32 9, i32 3, i32 4, i32 5, i32 6, i32 7>
-; CHECK-NEXT:  Cost Model: Found costs of 0 for: %v16i32_4_0 = shufflevector <16 x i32> undef, <16 x i32> undef, <16 x i32> <i32 16, i32 17, i32 18, i32 19, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
+; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i32_4_0 = shufflevector <16 x i32> undef, <16 x i32> undef, <16 x i32> <i32 16, i32 17, i32 18, i32 19, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i32_4_1 = shufflevector <16 x i32> undef, <16 x i32> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 16, i32 17, i32 18, i32 19, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i32_4_2 = shufflevector <16 x i32> undef, <16 x i32> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 16, i32 17, i32 18, i32 19, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:  Cost Model: Found costs of 1 for: %v16i32_4_3 = shufflevector <16 x i32> undef, <16 x i32> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 16, i32 17, i32 18, i32 19>