760258 - IonMonkey: Add MIR instruction MBreakpoint

Status: NEW

(Core :: JavaScript Engine, enhancement, P5)

Description

[Eric Faust [:efaust]]

It would be nice to have an instruction internally for testing purposes which assembled to a breakpoint from the MIR level.

Comment 1

[Felix S. Klock II [:pnkfelix, :fklock]]

I was just talking about wanting this.  At least something that would get compiled into a |masm.breakpoint()|.

(I assume that's what this is describing, though its possible efaust was talking about breakpoints visible to JS devtools and not a machine code level debugger like gdb.)

Comment 2

[Felix S. Klock II [:pnkfelix, :fklock]]

I have one version working that just emits a non-moveable nullary instruction into the codegen output for the basic block.

I think it is useful.

We may also want another version that acts like a unary mov instruction that could *move* along with the code it is attached to.