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Cranelift: GVN uadd_overflow_trap#5520

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fitzgen merged 4 commits into
bytecodealliance:mainfrom
fitzgen:gvn-uadd-overflow-trap
Jan 5, 2023
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Cranelift: GVN uadd_overflow_trap#5520
fitzgen merged 4 commits into
bytecodealliance:mainfrom
fitzgen:gvn-uadd-overflow-trap

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@fitzgen fitzgen commented Jan 5, 2023

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This test was accidentally hitting a special case for bounds checks for when we
know that `offset + access_size < min_size` and can skip some steps. This
commit changes the `min_size` of the memory to zero so that we are forced to do
fully general bounds checks.
Although this improves our test sequence for duplicate loads with dynamic
memories, it unfortunately doesn't have any effect on sightglass benchmarks:

```
instantiation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm

  No difference in performance.

  [34448 35607.23 37158] gvn_uadd_overflow_trap.so
  [34566 35734.05 36585] main.so

instantiation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm

  No difference in performance.

  [44101 60449.62 92712] gvn_uadd_overflow_trap.so
  [44011 60436.37 92690] main.so

instantiation :: instructions-retired :: benchmarks/bz2/benchmark.wasm

  No difference in performance.

  [35595 36675.72 38153] gvn_uadd_overflow_trap.so
  [35440 36670.42 37993] main.so

compilation :: instructions-retired :: benchmarks/bz2/benchmark.wasm

  No difference in performance.

  [17370195 17405125.62 17471222] gvn_uadd_overflow_trap.so
  [17369324 17404859.43 17470725] main.so

execution :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm

  No difference in performance.

  [7055720520 7055886880.32 7056265930] gvn_uadd_overflow_trap.so
  [7055719554 7055843809.33 7056193289] main.so

compilation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm

  No difference in performance.

  [683589861 683767276.00 684098366] gvn_uadd_overflow_trap.so
  [683590024 683767998.02 684097885] main.so

execution :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm

  No difference in performance.

  [46436883 46437135.10 46437823] gvn_uadd_overflow_trap.so
  [46436883 46437087.67 46437785] main.so

compilation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm

  No difference in performance.

  [126522461 126565812.58 126647044] gvn_uadd_overflow_trap.so
  [126522176 126565757.75 126647522] main.so

execution :: instructions-retired :: benchmarks/bz2/benchmark.wasm

  No difference in performance.

  [653010531 653010533.03 653010544] gvn_uadd_overflow_trap.so
  [653010531 653010533.18 653010537] main.so
```
@fitzgen fitzgen requested a review from elliottt January 5, 2023 00:01
@github-actions github-actions Bot added cranelift Issues related to the Cranelift code generator cranelift:meta Everything related to the meta-language. labels Jan 5, 2023
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@elliottt elliottt left a comment

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Looks good to me!

@fitzgen fitzgen merged commit f4a2d53 into bytecodealliance:main Jan 5, 2023
@fitzgen fitzgen deleted the gvn-uadd-overflow-trap branch January 5, 2023 06:03
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