Bug 130755 – Repatch should inline trivial getters into the stub by doing pattern recognition to realize that it will behave trivially

• Status: NEW
• Component: JavaScriptCore

[Filip Pizlo]

If you have a getter like:

    function() { return this._f; }

Then inside the getter stub we know the structure of 'this' - because we just checked it - so we can inspect what _f is and if it's a simple field then we can prove that the outcome of executing this function is exactly equivalent to just loading the field from 'this'.

The only hard parts are:

- Proving that the getter is what you thought it was.  The structure doesn't tell you that so this will be an extra check.

- Inspecting the getter to recognize this pattern.  This should hopefully be relatively easy.