[Microbenchmarks] Benchmark for vXi8 shift add/sub optimization#316
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grodranlorth wants to merge 1 commit intollvm:mainfrom
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[Microbenchmarks] Benchmark for vXi8 shift add/sub optimization#316grodranlorth wants to merge 1 commit intollvm:mainfrom
grodranlorth wants to merge 1 commit intollvm:mainfrom
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RKSimon
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Mar 11, 2026
Fixes #164200 ~~I will create a separate PR to the `llvm-test-suite` repo for the microbenchmark for this change.~~ The benchmark is in llvm/llvm-test-suite#316 In my experiments on an EC2 `c6i.4xl`, the change gives a small improvement for the `x86-64`, `x86-64-v2`, and `x86-64-v3` targets. It regresses performance on `x86-64-v4` (in particular, when the constant decomposes into two shifts). The performance summary follows: ``` $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v1.json results-opt-generic-v1.json |tail -n1 OVERALL_GEOMEAN -0.2846 -0.2846 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v2.json results-opt-generic-v2.json |tail -n1 OVERALL_GEOMEAN -0.0907 -0.0907 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v3.json results-opt-generic-v3.json |tail -n1 OVERALL_GEOMEAN -0.1821 -0.1821 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v4.json results-opt-generic-v4.json |tail -n1 OVERALL_GEOMEAN +0.0190 +0.0190 0 0 0 0 ```
llvm-sync bot
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Mar 11, 2026
Fixes #164200 ~~I will create a separate PR to the `llvm-test-suite` repo for the microbenchmark for this change.~~ The benchmark is in llvm/llvm-test-suite#316 In my experiments on an EC2 `c6i.4xl`, the change gives a small improvement for the `x86-64`, `x86-64-v2`, and `x86-64-v3` targets. It regresses performance on `x86-64-v4` (in particular, when the constant decomposes into two shifts). The performance summary follows: ``` $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v1.json results-opt-generic-v1.json |tail -n1 OVERALL_GEOMEAN -0.2846 -0.2846 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v2.json results-opt-generic-v2.json |tail -n1 OVERALL_GEOMEAN -0.0907 -0.0907 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v3.json results-opt-generic-v3.json |tail -n1 OVERALL_GEOMEAN -0.1821 -0.1821 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v4.json results-opt-generic-v4.json |tail -n1 OVERALL_GEOMEAN +0.0190 +0.0190 0 0 0 0 ```
shermpay
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Mar 12, 2026
Fixes llvm#164200 ~~I will create a separate PR to the `llvm-test-suite` repo for the microbenchmark for this change.~~ The benchmark is in llvm/llvm-test-suite#316 In my experiments on an EC2 `c6i.4xl`, the change gives a small improvement for the `x86-64`, `x86-64-v2`, and `x86-64-v3` targets. It regresses performance on `x86-64-v4` (in particular, when the constant decomposes into two shifts). The performance summary follows: ``` $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v1.json results-opt-generic-v1.json |tail -n1 OVERALL_GEOMEAN -0.2846 -0.2846 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v2.json results-opt-generic-v2.json |tail -n1 OVERALL_GEOMEAN -0.0907 -0.0907 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v3.json results-opt-generic-v3.json |tail -n1 OVERALL_GEOMEAN -0.1821 -0.1821 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v4.json results-opt-generic-v4.json |tail -n1 OVERALL_GEOMEAN +0.0190 +0.0190 0 0 0 0 ```
albertbolt1
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Mar 13, 2026
Fixes llvm#164200 ~~I will create a separate PR to the `llvm-test-suite` repo for the microbenchmark for this change.~~ The benchmark is in llvm/llvm-test-suite#316 In my experiments on an EC2 `c6i.4xl`, the change gives a small improvement for the `x86-64`, `x86-64-v2`, and `x86-64-v3` targets. It regresses performance on `x86-64-v4` (in particular, when the constant decomposes into two shifts). The performance summary follows: ``` $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v1.json results-opt-generic-v1.json |tail -n1 OVERALL_GEOMEAN -0.2846 -0.2846 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v2.json results-opt-generic-v2.json |tail -n1 OVERALL_GEOMEAN -0.0907 -0.0907 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v3.json results-opt-generic-v3.json |tail -n1 OVERALL_GEOMEAN -0.1821 -0.1821 0 0 0 0 $ ../MicroBenchmarks/libs/benchmark/tools/compare.py benchmarks results-baseline-generic-v4.json results-opt-generic-v4.json |tail -n1 OVERALL_GEOMEAN +0.0190 +0.0190 0 0 0 0 ```
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A benchmark for evaluating the optimization in llvm/llvm-project#164200