[all-commits] [llvm/llvm-project] ac9e67: [ValueTracking][NFC] Early exit when enumerating g...

[Yingwei Zheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ac9e67756e0157793d565c2cceaf82e4403f58ba
      https://github.com/llvm/llvm-project/commit/ac9e67756e0157793d565c2cceaf82e4403f58ba
  Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
  Date:   2024-02-26 (Mon, 26 Feb 2024)

  Changed paths:
    M llvm/lib/Analysis/ValueTracking.cpp

  Log Message:
  -----------
  [ValueTracking][NFC] Early exit when enumerating guaranteed well-defined/non-poison operands. (#82812)

According to the [coverage
result](https://dtcxzyw.github.io/llvm-opt-benchmark/coverage/home/dtcxzyw/llvm-project/llvm/lib/Analysis/ValueTracking.cpp.html#L7193)
on my benchmark, `llvm::mustTriggerUB` returns true with an average of
35.0M/12.3M=2.85 matches. I think we can stop enumerating when one of
the matches succeeds to avoid filling the temporary buffer
`NonPoisonOps`.

This patch introduces two template functions
`handleGuaranteedWellDefinedOps/handleGuaranteedNonPoisonOps`. They will
pass well-defined/non-poison operands to inlinable callbacks `Handle`.
If the callback returns true, stop processing and return true.
Otherwise, return false.

Compile-time improvement:
https://llvm-compile-time-tracker.com/compare.php?from=13acb3af5ad48e850cf37dcf02270ede3f267bd4&to=2b55f513c1b6dd2732cb79a25f3eaf6c5e4d6619&stat=instructions:u

|stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang|
|--|--|--|--|--|--|--|
|-0.03%|-0.04%|-0.06%|-0.03%|-0.05%|+0.03%|-0.02%|



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