commit bea3f74a546a7adab7fd4362914d608631488001
author Alexander Markov <alexmarkov@google.com> Wed Oct 02 15:41:20 2024 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Oct 02 15:41:20 2024 +0000
tree e738d3a282be96da89fa137976096c7447df0f95
parent 1b6fe3406ae23854d63a875232edff5536bb2691

[vm, aot] Improve canonicalization of branch comparisons

Canonicalization

  v1 <- comparison(...)
  Branch if (StrictCompare(===, v1, true))
=>
  Branch if (comparison(...)

was not applied if comparison has unmatched representations.
However, checking for unmatched representations matters only
if comparison is speculative (in JIT mode).

Fixing this canonicalization rule improves range analysis in AOT.
As a result, range analysis can eliminate bounds check in a loop when
iterating over list using its iterator.

Also, add useful tracing to bounds check elimination code
under --trace_range_analysis.

In addition, BranchInstr::SpeculativeModeOfInput is fixed -
it should delegate to its comparison instead of returning
kGuardInputs default in order to support non-speculative
comparisons folded into branch.

Also, EqualityCompare canonicalization is now applied to
BranchInstr comparison, in order to keep optimizations which
were applied when EqualityCompare was not folded into
branches.

TEST=runtime/tests/vm/dart/regress_56807_il_test.dart
Fixes https://github.com/dart-lang/sdk/issues/56807

Change-Id: Ib69294d7ccf30b63dd3ff7ae5a47c0a238824952
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/387622
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>