[PATCH] D127141: [RISCV] Add cost model for reverse shuffle

[Philip Reames via Phabricator via llvm-commits]

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The majority of the cost appears to be forming the indices vector.

This is my first costing patch, so please check for all the silly mistakes.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D127141

Files:
  llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
  llvm/test/Analysis/CostModel/RISCV/rvv-shuffle.ll


Index: llvm/test/Analysis/CostModel/RISCV/rvv-shuffle.ll
===================================================================
--- llvm/test/Analysis/CostModel/RISCV/rvv-shuffle.ll
+++ llvm/test/Analysis/CostModel/RISCV/rvv-shuffle.ll
@@ -55,20 +55,20 @@
 
 define void @vector_reverse() {
 ; CHECK-LABEL: 'vector_reverse'
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv16i8 = call <vscale x 16 x i8> @llvm.experimental.vector.reverse.nxv16i8(<vscale x 16 x i8> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv32i8 = call <vscale x 32 x i8> @llvm.experimental.vector.reverse.nxv32i8(<vscale x 32 x i8> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv2i16 = call <vscale x 2 x i16> @llvm.experimental.vector.reverse.nxv2i16(<vscale x 2 x i16> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv4i16 = call <vscale x 4 x i16> @llvm.experimental.vector.reverse.nxv4i16(<vscale x 4 x i16> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv8i16 = call <vscale x 8 x i16> @llvm.experimental.vector.reverse.nxv8i16(<vscale x 8 x i16> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv16i16 = call <vscale x 16 x i16> @llvm.experimental.vector.reverse.nxv16i16(<vscale x 16 x i16> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv4i32 = call <vscale x 4 x i32> @llvm.experimental.vector.reverse.nxv4i32(<vscale x 4 x i32> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv8i32 = call <vscale x 8 x i32> @llvm.experimental.vector.reverse.nxv8i32(<vscale x 8 x i32> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv2i64 = call <vscale x 2 x i64> @llvm.experimental.vector.reverse.nxv2i64(<vscale x 2 x i64> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv4i64 = call <vscale x 4 x i64> @llvm.experimental.vector.reverse.nxv4i64(<vscale x 4 x i64> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv16i1 = call <vscale x 16 x i1> @llvm.experimental.vector.reverse.nxv16i1(<vscale x 16 x i1> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv8i1 = call <vscale x 8 x i1> @llvm.experimental.vector.reverse.nxv8i1(<vscale x 8 x i1> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv4i1 = call <vscale x 4 x i1> @llvm.experimental.vector.reverse.nxv4i1(<vscale x 4 x i1> undef)
-; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %reverse_nxv2i1 = call <vscale x 2 x i1> @llvm.experimental.vector.reverse.nxv2i1(<vscale x 2 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv16i8 = call <vscale x 16 x i8> @llvm.experimental.vector.reverse.nxv16i8(<vscale x 16 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv32i8 = call <vscale x 32 x i8> @llvm.experimental.vector.reverse.nxv32i8(<vscale x 32 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv2i16 = call <vscale x 2 x i16> @llvm.experimental.vector.reverse.nxv2i16(<vscale x 2 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv4i16 = call <vscale x 4 x i16> @llvm.experimental.vector.reverse.nxv4i16(<vscale x 4 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv8i16 = call <vscale x 8 x i16> @llvm.experimental.vector.reverse.nxv8i16(<vscale x 8 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv16i16 = call <vscale x 16 x i16> @llvm.experimental.vector.reverse.nxv16i16(<vscale x 16 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv4i32 = call <vscale x 4 x i32> @llvm.experimental.vector.reverse.nxv4i32(<vscale x 4 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv8i32 = call <vscale x 8 x i32> @llvm.experimental.vector.reverse.nxv8i32(<vscale x 8 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv2i64 = call <vscale x 2 x i64> @llvm.experimental.vector.reverse.nxv2i64(<vscale x 2 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv4i64 = call <vscale x 4 x i64> @llvm.experimental.vector.reverse.nxv4i64(<vscale x 4 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv16i1 = call <vscale x 16 x i1> @llvm.experimental.vector.reverse.nxv16i1(<vscale x 16 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv8i1 = call <vscale x 8 x i1> @llvm.experimental.vector.reverse.nxv8i1(<vscale x 8 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv4i1 = call <vscale x 4 x i1> @llvm.experimental.vector.reverse.nxv4i1(<vscale x 4 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %reverse_nxv2i1 = call <vscale x 2 x i1> @llvm.experimental.vector.reverse.nxv2i1(<vscale x 2 x i1> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
   %reverse_nxv16i8 = call <vscale x 16 x i8> @llvm.experimental.vector.reverse.nxv16i8(<vscale x 16 x i8> undef)
Index: llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -178,6 +178,7 @@
                                              int Index, VectorType *SubTp,
                                              ArrayRef<const Value *> Args) {
   if (isa<ScalableVectorType>(Tp)) {
+    std::pair<InstructionCost, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
     switch (Kind) {
     default:
       // Fallthrough to generic handling.
@@ -185,11 +186,21 @@
       // must be implemented here.
       break;
     case TTI::SK_Broadcast: {
-      std::pair<InstructionCost, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
       return LT.first * 1;
     }
     case TTI::SK_Splice:
       return getSpliceCost(Tp, Index);
+    case TTI::SK_Reverse:
+      // Most of the cost here is producing the vrgather index register
+      // Example sequence:
+      //   csrr a0, vlenb
+      //   rli a0, a0, 3
+      //   addi a0, a0, -1
+      //   vsetvli a1, zero, e8, mf8, ta, mu (ignored)
+      //   vid.v v9
+      //   vrsub.vx v10, v9, a0
+      //   vrgather.vv v9, v8, v10
+      return LT.first * 6;
     }
   }
 


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