[PATCH] D108292: [Analysis][AArch64] Make fixed-width ordered reductions slightly more expensive

[David Sherwood via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
david-arm marked an inline comment as done.
Closed by commit rG219d4518fce9: [Analysis][AArch64] Make fixed-width ordered reductions slightly more expensive (authored by david-arm).

Changed prior to commit:
  https://reviews.llvm.org/D108292?vs=367176&id=367230#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108292/new/

https://reviews.llvm.org/D108292

Files:
  llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
  llvm/test/Analysis/CostModel/AArch64/reduce-fadd.ll
  llvm/test/Transforms/LoopVectorize/AArch64/strict-fadd-cost.ll


Index: llvm/test/Transforms/LoopVectorize/AArch64/strict-fadd-cost.ll
===================================================================
--- llvm/test/Transforms/LoopVectorize/AArch64/strict-fadd-cost.ll
+++ llvm/test/Transforms/LoopVectorize/AArch64/strict-fadd-cost.ll
@@ -6,8 +6,8 @@
 
 target triple="aarch64-unknown-linux-gnu"
 
-; CHECK-VF4: Found an estimated cost of 17 for VF 4 For instruction:   %add = fadd float %0, %sum.07
-; CHECK-VF8: Found an estimated cost of 34 for VF 8 For instruction:   %add = fadd float %0, %sum.07
+; CHECK-VF4: Found an estimated cost of 21 for VF 4 For instruction:   %add = fadd float %0, %sum.07
+; CHECK-VF8: Found an estimated cost of 42 for VF 8 For instruction:   %add = fadd float %0, %sum.07
 
 define float @fadd_strict32(float* noalias nocapture readonly %a, i64 %n) {
 entry:
@@ -28,8 +28,8 @@
 }
 
 
-; CHECK-VF4: Found an estimated cost of 14 for VF 4 For instruction:   %add = fadd double %0, %sum.07
-; CHECK-VF8: Found an estimated cost of 28 for VF 8 For instruction:   %add = fadd double %0, %sum.07
+; CHECK-VF4: Found an estimated cost of 18 for VF 4 For instruction:   %add = fadd double %0, %sum.07
+; CHECK-VF8: Found an estimated cost of 36 for VF 8 For instruction:   %add = fadd double %0, %sum.07
 
 define double @fadd_strict64(double* noalias nocapture readonly %a, i64 %n) {
 entry:
Index: llvm/test/Analysis/CostModel/AArch64/reduce-fadd.ll
===================================================================
--- llvm/test/Analysis/CostModel/AArch64/reduce-fadd.ll
+++ llvm/test/Analysis/CostModel/AArch64/reduce-fadd.ll
@@ -2,10 +2,10 @@
 
 define void @strict_fp_reductions() {
 ; CHECK-LABEL: strict_fp_reductions
-; CHECK-NEXT: Cost Model: Found an estimated cost of 17 for instruction: %fadd_v4f32 = call float @llvm.vector.reduce.fadd.v4f32(float 0.000000e+00, <4 x float> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 34 for instruction: %fadd_v8f32 = call float @llvm.vector.reduce.fadd.v8f32(float 0.000000e+00, <8 x float> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 7 for instruction: %fadd_v2f64 = call double @llvm.vector.reduce.fadd.v2f64(double 0.000000e+00, <2 x double> undef)
-; CHECK-NEXT: Cost Model: Found an estimated cost of 14 for instruction: %fadd_v4f64 = call double @llvm.vector.reduce.fadd.v4f64(double 0.000000e+00, <4 x double> undef)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 21 for instruction: %fadd_v4f32 = call float @llvm.vector.reduce.fadd.v4f32(float 0.000000e+00, <4 x float> undef)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 42 for instruction: %fadd_v8f32 = call float @llvm.vector.reduce.fadd.v8f32(float 0.000000e+00, <8 x float> undef)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 9 for instruction: %fadd_v2f64 = call double @llvm.vector.reduce.fadd.v2f64(double 0.000000e+00, <2 x double> undef)
+; CHECK-NEXT: Cost Model: Found an estimated cost of 18 for instruction: %fadd_v4f64 = call double @llvm.vector.reduce.fadd.v4f64(double 0.000000e+00, <4 x double> undef)
   %fadd_v4f32 = call float @llvm.vector.reduce.fadd.v4f32(float 0.0, <4 x float> undef)
   %fadd_v8f32 = call float @llvm.vector.reduce.fadd.v8f32(float 0.0, <8 x float> undef)
   %fadd_v2f64 = call double @llvm.vector.reduce.fadd.v2f64(double 0.0, <2 x double> undef)
Index: llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -1999,8 +1999,13 @@
                                            Optional<FastMathFlags> FMF,
                                            TTI::TargetCostKind CostKind) {
   if (TTI::requiresOrderedReduction(FMF)) {
-    if (!isa<ScalableVectorType>(ValTy))
-      return BaseT::getArithmeticReductionCost(Opcode, ValTy, FMF, CostKind);
+    if (auto *FixedVTy = dyn_cast<FixedVectorType>(ValTy)) {
+      InstructionCost BaseCost =
+          BaseT::getArithmeticReductionCost(Opcode, ValTy, FMF, CostKind);
+      // Add on extra cost to reflect the extra overhead on some CPUs. We still
+      // end up vectorizing for more computationally intensive loops.
+      return BaseCost + FixedVTy->getNumElements();
+    }
 
     if (Opcode != Instruction::FAdd)
       return InstructionCost::getInvalid();


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