1473894 - (seqrec) Automatically reverse engineer CodeGenerator, SharedIC, and others stacks form a crash-dump

Status: ASSIGNED

(Core :: JavaScript Engine, enhancement, P5)

Description

[Nicolas B. Pierron [:nbp]]

When crashing in Just-In-Time compiled code, such as in Bug 858032, it is hard to guess what were the code path taken by the JIT compiler to generate the code.

The idea is to make a tool which works in 3 steps:
  1/ Instrument SpiderMonkey to record all stacks which are producing bytes.
  2/ Create a tool which ""learn"" from these backtraces which stacks we should be looking for and what are their names / symbols.
  3/ Create a tool which given a sequence of bytes will infer the sequences of stack frames required to generate these sequences of bytes.

Comment 1

[Nicolas B. Pierron [:nbp]]

Attachment: Dump stack frames for each byte written by the Assembler.

This code corresponds to the instrumentation required for working with
https://github.com/nbp/seqrec .

At the moment it is not ready to land, as it does not have the proper guard
mechanism to toogle it off by default in normal builds, and that this
instrumentation is costly.