[RISCV][TTI] Scale the cost of intrinsic stepvector with LMUL #87301

arcbbb · 2024-04-02T02:03:31Z

Use the return type to measure the LMUL size for latency/throughput cost

Use the destination data type to measure the LMUL size for latency/throughput cost

llvmbot · 2024-04-02T02:04:01Z

@llvm/pr-subscribers-llvm-analysis

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

Author: Shih-Po Hung (arcbbb)

Changes

Use the return type to measure the LMUL size for latency/throughput cost

Full diff: https://github.com/llvm/llvm-project/pull/87301.diff

2 Files Affected:

(modified) llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp (+7-5)
(modified) llvm/test/Analysis/CostModel/RISCV/stepvector.ll (+31-31)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index 38304ff90252f0..424e79ef26a83d 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -860,11 +860,13 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
     break;
   }
   // TODO: add more intrinsic
-  case Intrinsic::experimental_stepvector: {
-    unsigned Cost = 1; // vid
-    auto LT = getTypeLegalizationCost(RetTy);
-    return Cost + (LT.first - 1);
-  }
+  case Intrinsic::experimental_stepvector:
+    if (ST->hasVInstructions()) {
+      auto LT = getTypeLegalizationCost(RetTy);
+      return LT.first *
+             getRISCVInstructionCost(RISCV::VID_V, LT.second, CostKind);
+    }
+    break;
   case Intrinsic::vp_rint: {
     // RISC-V target uses at least 5 instructions to lower rounding intrinsics.
     unsigned Cost = 5;
diff --git a/llvm/test/Analysis/CostModel/RISCV/stepvector.ll b/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
index 7d29d2c0cfa628..c540208df6ff39 100644
--- a/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
+++ b/llvm/test/Analysis/CostModel/RISCV/stepvector.ll
@@ -12,43 +12,43 @@ define void @stepvector() {
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %5 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %6 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %7 = call <vscale x 8 x i8> @llvm.experimental.stepvector.nxv8i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %8 = call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %9 = call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %10 = call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %8 = call <vscale x 16 x i8> @llvm.experimental.stepvector.nxv16i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %9 = call <vscale x 32 x i8> @llvm.experimental.stepvector.nxv32i8()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %10 = call <vscale x 64 x i8> @llvm.experimental.stepvector.nxv64i8()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %11 = call <vscale x 1 x i16> @llvm.experimental.stepvector.nxv1i16()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %12 = call <vscale x 2 x i16> @llvm.experimental.stepvector.nxv2i16()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %13 = call <vscale x 4 x i16> @llvm.experimental.stepvector.nxv4i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %14 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %15 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %16 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %17 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %18 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %19 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %20 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %14 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %15 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %16 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %17 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %18 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %19 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %20 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %21 = call <vscale x 1 x i32> @llvm.experimental.stepvector.nxv1i32()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %22 = call <vscale x 2 x i32> @llvm.experimental.stepvector.nxv2i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %23 = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %24 = call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %25 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %26 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %27 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %28 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %29 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %23 = call <vscale x 4 x i32> @llvm.experimental.stepvector.nxv4i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %24 = call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %25 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %26 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %27 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %28 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %29 = call <vscale x 16 x i32> @llvm.experimental.stepvector.nxv16i32()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %30 = call <vscale x 1 x i64> @llvm.experimental.stepvector.nxv1i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %31 = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %32 = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %33 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %34 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %35 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %36 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %37 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %38 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %39 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %40 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %41 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %42 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %43 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %44 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %31 = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %32 = call <vscale x 4 x i64> @llvm.experimental.stepvector.nxv4i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %33 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %34 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %35 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %36 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %37 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %38 = call <vscale x 8 x i64> @llvm.experimental.stepvector.nxv8i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %39 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %40 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %41 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %42 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %43 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %44 = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
   %zero = call <vscale x 1 x i8> @llvm.experimental.stepvector.nxv1i8()

lukel97 · 2024-04-02T03:33:42Z

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

-  }
+  case Intrinsic::experimental_stepvector:
+    if (ST->hasVInstructions()) {
+      auto LT = getTypeLegalizationCost(RetTy);


Do we ever reach here without +v and need to return the scalarized cost?

No, not typically. I just recalled the case in #83294

If that's the case then should we still return 1 + (getTypeLegalizationCost(RetTy).First - 1) for the scalar case so it's the same as before?

lukel97

LGTM

topperc · 2024-04-02T20:55:46Z

llvm/test/Analysis/CostModel/RISCV/stepvector.ll

-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %19 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %20 = call <vscale x 32 x i16> @llvm.experimental.stepvector.nxv32i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %14 = call <vscale x 8 x i16> @llvm.experimental.stepvector.nxv8i16()
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %15 = call <vscale x 16 x i16> @llvm.experimental.stepvector.nxv16i16()


Why are we repeatedly costing the nxv16i16? This happens for 16i32 and 8i64 too.

It looks like those duplicated cases have existed since the original post https://reviews.llvm.org/D122782
I clean them in the update patch.

topperc · 2024-04-02T20:57:12Z

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

    auto LT = getTypeLegalizationCost(RetTy);
-    return Cost + (LT.first - 1);
+    if (ST->hasVInstructions())
+      return LT.first *


This isn't correct. If LT.first is greater than 1, then there is 1 vid.v and LT.first-1 vadd.vx/vi instructions.

Thanks for catching that!! Fixed.

topperc

LGTM

[RISCV][TTI] Scale the cost of intrinsic stepvector with LMUL

0700688

Use the destination data type to measure the LMUL size for latency/throughput cost

arcbbb requested review from ChunyuLiao, lukel97, preames and topperc April 2, 2024 02:03

llvmbot added backend:RISC-V llvm:analysis Includes value tracking, cost tables and constant folding labels Apr 2, 2024

lukel97 reviewed Apr 2, 2024

View reviewed changes

keep scalar case when V is not supported

34d7939

arcbbb force-pushed the tti-intrinsic-stepvector branch from 763b3a9 to 34d7939 Compare April 2, 2024 07:56

lukel97 approved these changes Apr 2, 2024

View reviewed changes

topperc reviewed Apr 2, 2024

View reviewed changes

topperc requested changes Apr 2, 2024

View reviewed changes

arcbbb added 2 commits April 3, 2024 00:40

Add legalization cost for illegal type

a2f7a33

Remove duplicated test cases

6f99212

topperc approved these changes Apr 3, 2024

View reviewed changes

arcbbb merged commit 97523e5 into llvm:main Apr 4, 2024

arcbbb deleted the tti-intrinsic-stepvector branch April 4, 2024 00:30

arcbbb mentioned this pull request Apr 5, 2024

[RISCV] Fix missing scaling by LMUL in cost model #73342

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[RISCV][TTI] Scale the cost of intrinsic stepvector with LMUL #87301

[RISCV][TTI] Scale the cost of intrinsic stepvector with LMUL #87301

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[RISCV][TTI] Scale the cost of intrinsic stepvector with LMUL #87301

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