Repository navigation
Conversation
array.new_data is not a constant expression, which blocks optimizations such as hoisting array literals into immutable globals, and passes like Precompute, Heap2Local, GUFA and SimplifyGlobals don't understand it. When the offset and size are constant and in bounds of a passive segment, lower it to: * array.new_default, if all elements are zero * array.new, if all elements are equal * array.new_fixed, if there are at most 64 elements Non-empty slices are only lowered with --traps-never-happen, since array.new_data traps if the segment was dropped. An empty slice at offset 0 can never trap, so it is always lowered. The 64-element limit exists because array.new_fixed costs a full *.const per element, while a data segment stores raw bytes. On large J2Wasm applications this removes over 99.7% of passive data segments and reduces binary size by ~1.8% (~1.3% gzipped).
This branch has not been deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
array.new_data is not a constant expression, which blocks optimizations
such as hoisting array literals into immutable globals, and passes like
Precompute, Heap2Local, GUFA and SimplifyGlobals don't understand it.
When the offset and size are constant and in bounds of a passive
segment, lower it to:
Non-empty slices are only lowered with --traps-never-happen, since
array.new_data traps if the segment was dropped. An empty slice at
offset 0 can never trap, so it is always lowered.
The 64-element limit exists because array.new_fixed costs a full
*.const per element, while a data segment stores raw bytes. On large
J2Wasm applications this removes over 99.7% of passive data segments and
reduces binary size by ~1.8% (~1.3% gzipped).