Fix assertion in OptimizeInstructions for exact refs - #7354
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Update the finalization of all instructions whose types (or sent types) depend on their operand reference types to handle exact references correctly. Specifically, update `ref.as_non_null`, `br_on_null`, `br_on_non_null`, `br_on_cast`, and `br_on_cast_fail`. Also add TODOs on all instructions that allocate new heap objects to remind us to make their types exact in the future.
When optimizing a cast to an exact reference to a bottom type, OptimizeInstructions previously triggered an assertion that expected the cast type to be inexact. Fix the assertion and surrounding code to be more robust to the presence of exact reference types and add a test.
kripken
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Mar 10, 2025
tlively
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Mar 26, 2025
We decided that Custom Descriptors should introduce exact heap types rather than exact reference types. Although these new features are very similar, the APIs we need to change for them are completely different. One option would have been to keep the existing exact reference type implementation while additionally implementing exact heap types, but there are not enough free bits in the type implementation to have both at once without increasing the alignment of HeapTypeInfo allocations. Portably increasing the alignment is annoying enough that it's easier to just eagerly remove exact reference types to free up the bit for use with exact heap types. Fully or partially revert the following PRs: - #7371 - #7365 - #7360 - #7357 - #7356 - #7355 - #7354 - #7353 - #7347 - #7342 - #7328 Keep the new `.with(...)` Type APIs and the relevant parts of the type relations gtest that were introduced as part of the reverted work.
tlively
added a commit
that referenced
this pull request
Mar 26, 2025
We decided that Custom Descriptors should introduce exact heap types rather than exact reference types. Although these new features are very similar, the APIs we need to change for them are completely different. One option would have been to keep the existing exact reference type implementation while additionally implementing exact heap types, but there are not enough free bits in the type implementation to have both at once without increasing the alignment of HeapTypeInfo allocations. Portably increasing the alignment is annoying enough that it's easier to just eagerly remove exact reference types to free up the bit for use with exact heap types. Fully or partially revert the following PRs: - #7371 - #7365 - #7360 - #7357 - #7356 - #7355 - #7354 - #7353 - #7347 - #7342 - #7328 Keep the new `.with(...)` Type APIs and the relevant parts of the type relations gtest that were introduced as part of the reverted work.
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When optimizing a cast to an exact reference to a bottom type,
OptimizeInstructions previously triggered an assertion that expected the
cast type to be inexact. Fix the assertion and surrounding code to be
more robust to the presence of exact reference types and add a test.