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@arcbbb arcbbb commented Jan 25, 2024

It is split off from #77342.
InstCombine transform min/max reduction with i1 into arithmetic reduction,
so this patch reuses the cost logic in arithmetic reduction cost function.

InstCombine transform min/max reduction with i1 into arithmetic
reduction.
This patch reuse the cost logic in arithmetic reduction cost function.
@llvmbot llvmbot added backend:RISC-V llvm:analysis Includes value tracking, cost tables and constant folding labels Jan 25, 2024
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llvmbot commented Jan 25, 2024

@llvm/pr-subscribers-llvm-analysis

@llvm/pr-subscribers-backend-risc-v

Author: Shih-Po Hung (arcbbb)

Changes

It is split off from #77342.
InstCombine transform min/max reduction with i1 into arithmetic reduction,
so this patch reuses the cost logic in arithmetic reduction cost function.


Full diff: https://github.com/llvm/llvm-project/pull/79401.diff

3 Files Affected:

  • (modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+9-4)
  • (modified) llvm/test/Analysis/CostModel/RISCV/reduce-max.ll (+16-16)
  • (modified) llvm/test/Analysis/CostModel/RISCV/reduce-min.ll (+16-16)
diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 0799af0a7bad550..87b36b15a900562 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -936,10 +936,15 @@ RISCVTTIImpl::getMinMaxReductionCost(Intrinsic::ID IID, VectorType *Ty,
     return BaseT::getMinMaxReductionCost(IID, Ty, FMF, CostKind);
 
   std::pair<InstructionCost, MVT> LT = getTypeLegalizationCost(Ty);
-  if (Ty->getElementType()->isIntegerTy(1))
-    // vcpop sequences, see vreduction-mask.ll.  umax, smin actually only
-    // cost 2, but we don't have enough info here so we slightly over cost.
-    return (LT.first - 1) + 3;
+  if (Ty->getElementType()->isIntegerTy(1)) {
+    // InstCombine does following transform:
+    // vector_reduce_u{min,max}(<n x i1>) --> vector_reduce_{and,or}(<n x i1>)
+    // vector_reduce_s{min,max}(<n x i1>) --> vector_reduce_{or,and}(<n x i1>)
+    if ((IID == Intrinsic::umax) || (IID == Intrinsic::smin))
+      return getArithmeticReductionCost(Instruction::Or, Ty, FMF, CostKind);
+    else
+      return getArithmeticReductionCost(Instruction::And, Ty, FMF, CostKind);
+  }
 
   // IR Reduction is composed by two vmv and one rvv reduction instruction.
   InstructionCost BaseCost = 2;
diff --git a/llvm/test/Analysis/CostModel/RISCV/reduce-max.ll b/llvm/test/Analysis/CostModel/RISCV/reduce-max.ll
index c21b8520112cf88..f3436b54df90ab2 100644
--- a/llvm/test/Analysis/CostModel/RISCV/reduce-max.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/reduce-max.ll
@@ -6,25 +6,25 @@
 
 define i32 @reduce_umin_i1(i32 %arg) {
 ; CHECK-LABEL: 'reduce_umin_i1'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V1 = call i1 @llvm.vector.reduce.umax.v1i1(<1 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V2 = call i1 @llvm.vector.reduce.umax.v2i1(<2 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V4 = call i1 @llvm.vector.reduce.umax.v4i1(<4 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V8 = call i1 @llvm.vector.reduce.umax.v8i1(<8 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V16 = call i1 @llvm.vector.reduce.umax.v16i1(<16 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V32 = call i1 @llvm.vector.reduce.umax.v32i1(<32 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V64 = call i1 @llvm.vector.reduce.umax.v64i1(<64 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V128 = call i1 @llvm.vector.reduce.umax.v128i1(<128 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V1 = call i1 @llvm.vector.reduce.umax.v1i1(<1 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V2 = call i1 @llvm.vector.reduce.umax.v2i1(<2 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V4 = call i1 @llvm.vector.reduce.umax.v4i1(<4 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V8 = call i1 @llvm.vector.reduce.umax.v8i1(<8 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V16 = call i1 @llvm.vector.reduce.umax.v16i1(<16 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V32 = call i1 @llvm.vector.reduce.umax.v32i1(<32 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V64 = call i1 @llvm.vector.reduce.umax.v64i1(<64 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V128 = call i1 @llvm.vector.reduce.umax.v128i1(<128 x i1> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret i32 undef
 ;
 ; SIZE-LABEL: 'reduce_umin_i1'
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V1 = call i1 @llvm.vector.reduce.umax.v1i1(<1 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V2 = call i1 @llvm.vector.reduce.umax.v2i1(<2 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V4 = call i1 @llvm.vector.reduce.umax.v4i1(<4 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V8 = call i1 @llvm.vector.reduce.umax.v8i1(<8 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V16 = call i1 @llvm.vector.reduce.umax.v16i1(<16 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V32 = call i1 @llvm.vector.reduce.umax.v32i1(<32 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V64 = call i1 @llvm.vector.reduce.umax.v64i1(<64 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V128 = call i1 @llvm.vector.reduce.umax.v128i1(<128 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V1 = call i1 @llvm.vector.reduce.umax.v1i1(<1 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V2 = call i1 @llvm.vector.reduce.umax.v2i1(<2 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V4 = call i1 @llvm.vector.reduce.umax.v4i1(<4 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V8 = call i1 @llvm.vector.reduce.umax.v8i1(<8 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V16 = call i1 @llvm.vector.reduce.umax.v16i1(<16 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V32 = call i1 @llvm.vector.reduce.umax.v32i1(<32 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V64 = call i1 @llvm.vector.reduce.umax.v64i1(<64 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V128 = call i1 @llvm.vector.reduce.umax.v128i1(<128 x i1> undef)
 ; SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret i32 undef
 ;
   %V1   = call i1 @llvm.vector.reduce.umax.v1i1(<1 x i1> undef)
diff --git a/llvm/test/Analysis/CostModel/RISCV/reduce-min.ll b/llvm/test/Analysis/CostModel/RISCV/reduce-min.ll
index 941c3cf8a999c87..1964e35b81b1a65 100644
--- a/llvm/test/Analysis/CostModel/RISCV/reduce-min.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/reduce-min.ll
@@ -176,25 +176,25 @@ define i32 @reduce_umin_i64(i32 %arg) {
 
 define i32 @reduce_smin_i1(i32 %arg) {
 ; CHECK-LABEL: 'reduce_smin_i1'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V1 = call i1 @llvm.vector.reduce.smin.v1i1(<1 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V2 = call i1 @llvm.vector.reduce.smin.v2i1(<2 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V4 = call i1 @llvm.vector.reduce.smin.v4i1(<4 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V8 = call i1 @llvm.vector.reduce.smin.v8i1(<8 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V16 = call i1 @llvm.vector.reduce.smin.v16i1(<16 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V32 = call i1 @llvm.vector.reduce.smin.v32i1(<32 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V64 = call i1 @llvm.vector.reduce.smin.v64i1(<64 x i1> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V128 = call i1 @llvm.vector.reduce.smin.v128i1(<128 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V1 = call i1 @llvm.vector.reduce.smin.v1i1(<1 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V2 = call i1 @llvm.vector.reduce.smin.v2i1(<2 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V4 = call i1 @llvm.vector.reduce.smin.v4i1(<4 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V8 = call i1 @llvm.vector.reduce.smin.v8i1(<8 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V16 = call i1 @llvm.vector.reduce.smin.v16i1(<16 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V32 = call i1 @llvm.vector.reduce.smin.v32i1(<32 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V64 = call i1 @llvm.vector.reduce.smin.v64i1(<64 x i1> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V128 = call i1 @llvm.vector.reduce.smin.v128i1(<128 x i1> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret i32 undef
 ;
 ; SIZE-LABEL: 'reduce_smin_i1'
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V1 = call i1 @llvm.vector.reduce.smin.v1i1(<1 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V2 = call i1 @llvm.vector.reduce.smin.v2i1(<2 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V4 = call i1 @llvm.vector.reduce.smin.v4i1(<4 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V8 = call i1 @llvm.vector.reduce.smin.v8i1(<8 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V16 = call i1 @llvm.vector.reduce.smin.v16i1(<16 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V32 = call i1 @llvm.vector.reduce.smin.v32i1(<32 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V64 = call i1 @llvm.vector.reduce.smin.v64i1(<64 x i1> undef)
-; SIZE-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %V128 = call i1 @llvm.vector.reduce.smin.v128i1(<128 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V1 = call i1 @llvm.vector.reduce.smin.v1i1(<1 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V2 = call i1 @llvm.vector.reduce.smin.v2i1(<2 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V4 = call i1 @llvm.vector.reduce.smin.v4i1(<4 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V8 = call i1 @llvm.vector.reduce.smin.v8i1(<8 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V16 = call i1 @llvm.vector.reduce.smin.v16i1(<16 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V32 = call i1 @llvm.vector.reduce.smin.v32i1(<32 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V64 = call i1 @llvm.vector.reduce.smin.v64i1(<64 x i1> undef)
+; SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %V128 = call i1 @llvm.vector.reduce.smin.v128i1(<128 x i1> undef)
 ; SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret i32 undef
 ;
   %V1   = call i1 @llvm.vector.reduce.smin.v1i1(<1 x i1> undef)

// InstCombine does following transform:
// vector_reduce_u{min,max}(<n x i1>) --> vector_reduce_{and,or}(<n x i1>)
// vector_reduce_s{min,max}(<n x i1>) --> vector_reduce_{or,and}(<n x i1>)
if ((IID == Intrinsic::umax) || (IID == Intrinsic::smin))
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Nit, I think you can drop the parentheses?

Suggested change
if ((IID == Intrinsic::umax) || (IID == Intrinsic::smin))
if (IID == Intrinsic::umax || IID == Intrinsic::smin)

// cost 2, but we don't have enough info here so we slightly over cost.
return (LT.first - 1) + 3;
if (Ty->getElementType()->isIntegerTy(1)) {
// InstCombine does following transform:
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I ran instcombine on some test examples and it didn't seem to be transforming the reductions. But the incoming selection dag uses vecreduce_or/vecreduce_and before any sort of legalization. Do you know if this is coming from SelectionDAGBuilder or something?

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Sorry my comment was misleading. I looked at it again and found it at SelectionDAG::getNode

  case ISD::VECREDUCE_SMIN:
  case ISD::VECREDUCE_UMAX:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNode(ISD::VECREDUCE_OR, DL, VT, N1);
    break;
  case ISD::VECREDUCE_SMAX:
  case ISD::VECREDUCE_UMIN:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNode(ISD::VECREDUCE_AND, DL, VT, N1);

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LGTM

@arcbbb arcbbb merged commit bf716fb into llvm:main Jan 26, 2024
@arcbbb arcbbb deleted the cost-minmax-i1 branch January 26, 2024 11:35
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