Change how wasm DWARF is inserted into artifacts #5358
Merged
Conversation
This file contains 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
This commit fixes a bug with components by changing how DWARF information from a wasm binary is copied over to the final compiled artifact. Note that this is not the Wasmtime-generated DWARF but rather the native wasm DWARF itself used in backtraces. Previously the wasm dwarf was inserted into sections `.*.wasm` where `*` was `debug_info`, `debug_str`, etc -- one per `gimli::SectionId` as found in the original wasm module. This does not work with components, however, where modules did not correctly separate their debug information into separate sections or otherwise disambiguate. The fix in this commit is to instead smash all the debug information together into one large section and store offsets into that giant section. This is similar to the `name`-section scraping or the trap metadata section where one section contains all the data for all the modules in a component. This simplifies the object file parsing by only looking for one section name and doesn't add all that much complexity to serializing and looking up dwarf information as well.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
This commit fixes a bug with components by changing how DWARF information from a wasm binary is copied over to the final compiled artifact. Note that this is not the Wasmtime-generated DWARF but rather the native wasm DWARF itself used in backtraces.
Previously the wasm dwarf was inserted into sections
.*.wasmwhere*wasdebug_info,debug_str, etc -- one pergimli::SectionIdas found in the original wasm module. This does not work with components, however, where modules did not correctly separate their debug information into separate sections or otherwise disambiguate. The fix in this commit is to instead smash all the debug information together into one large section and store offsets into that giant section. This is similar to thename-section scraping or the trap metadata section where one section contains all the data for all the modules in a component.This simplifies the object file parsing by only looking for one section name and doesn't add all that much complexity to serializing and looking up dwarf information as well.