v8-print-code-filter

Filter V8 dump generated by --print-code or --print-opt-code by name, source position, optimization id and so on.

Example

$ v8-print-code-filter --name fs.writeSync example/print_code
$ node --print-code example/source.js |v8-print-code-filter --optimization-id=1
$ v8-print-code-filter --source-position=96 example/print_opt_code

CLI

Usage:  v8-print-code-filter [filter_expr]... [file]

Each filter_expr is a combination of an option key and value and describes a single attribute line.

E.g. --source-position=96 matches the following code section:

--- Raw source ---
...

--- Optimized code ---
optimization_id = 1
source_position = 96
kind = OPTIMIZED_FUNCTION
name = add
...

Two special values for numeric attributes are available:

• max removes from selection all but entries with maximum value;
• min removes all but entries with minimum value.

Multiple expressions are applied in sequence, so that --source-position=96 --optimization-id=max selects entries with source_position equal to 96 and, among those, with maximum possible optimization_id.

API

sections = printCodeFilter(sections, filters, [opts])

• sections — parse tree in v8-code-dump-parser format.
• filters — array of {key: 'key', value: 'value'} objects.
• opts.onWarning(warning) — optional callback for warning handling.

Returns new section tree.

Related

• v8-print-code-highlighter — dual JavaScript + ASM syntax highlighter for V8 dumps.

Install

npm install -g v8-print-code-filter

License

MIT