This implements generating source maps for the generated Wasm files.
Copying dart2js's command line interface, a source map file with the
name `<program name>.wasm.map` is generated unless `--no-source-maps` is
passed.
When a source map is generated, the generated .wasm file gets a new
section `sourceMappingURL` with the contents `<program name>.wasm.map`.
This section seems to be undocumented, but Chrome and binaryen recognize
it as the URI to the source map file. Chrome is then loads it
automatically in the DevTools.
## Implementation
- `wasm_builder` package is updated with the new `source_map` library,
which describes the source mapping entries.
- `wasm_builder`'s `InstructionsBuilder` is updated with the new public
members:
- `startSourceMapping`: starts mapping the instructions generated to
the given source code.
- `stopSourceMapping`: stops mapping the instructions generated to a
source code. These instructions won't have a mapping in the source
map.
- `CodeGenerator` sets the source file URI and location in the file
when:
- Starting compiling a new member
- Compiling an expression and statement
Change-Id: Ic8f723f7a154402c0d34710689db57d640b83b86
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/370500
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Ömer Ağacan <omersa@google.com>
Ömer Sinan Ağacan
10742d9a12