1631407 - Update the JS NameResolver for Stencil

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Ted Campbell [:tcampbell]]

The NameResolver code directly accesses the JSFunctions to read and write their guessed atom names. Right now this happens in a batch process at the very end of the initial parse, but we should still support it inside Stencil.

To fix this, we need to cleanup how guessed atoms are handled in the FunctionBox. Right now we track the "explicit" name, but this should be generalized.

Some terminology:

• "explicit" name: The binding name in the source. Eg the f in function f() { }. Is exposed on fun.name in JS.
• "implicit" name: The spec defines that some grammar forms should apply a name to an otherwise anonymous function. This is exposed on fun.name and may be computed at compile time (eg. the foo in let foo = function() {};), and others cases may compute at runtime using JSOp::SetFunName (eg. the foo in let name = "foo"; let x = { [name]: function() { } }).
• "guessed" name: The engine synthesizes a name using the NameResolver. These usually have / and ^ characters. These function do not have a fun.name value, but the names may be used by the debugger to help out the user.

Comment 1

[Ted Campbell [:tcampbell]]

Attachment: Bug 1631407 - Move inferred/guessed names into FunctionBox. r?mgaudet

Use the FunctionFlags in the FunctionBox to distinguish explict, inferred,
and guessed atom types. When inter-converting between FunctionBox and
JSFunctions we now sync all types of atoms.

Note that if the function pre-exists we still propegate the name directly.
The code coverage initialization is triggered by JSScript creation which is
not fully deferred, so we need to the setInferredName to take effect before
then.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d72818f86279
Move inferred/guessed names into FunctionBox. r=mgaudet

Comment 3

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/d72818f86279