[webkit-dev] How to dump SquirrelFish opcode and machine code

Zoltan Herczeg zherczeg at inf.u-szeged.hu
Wed May 27 11:42:26 PDT 2009

> Hi,
> How to dump SquirrelFish opcode and machine code?
> Here is what I would like to do, for each JS file that WebCore passes to
> SquirrelFish, configure SquirrelFish to dump opcode and machine code.
> Thank you for any tips.

I am not sure you can do SF byte code dump out of the box since SF opcode
dump is only availible if you build your standalone JavaScriptCore in
debug mode. In that case you just have to pass -d option to jsc.
Fortunately, all neccessary helper functions can be found here:

JavaScriptCore/bytecode/CodeBlock.cpp : CodeBlock::dump

You only need to do some hand coding to make it available under WebCore,
and perhaps dump the output into a file instead of the console.

Machine code dump is not supported by JavaScriptCore. However, all machine
code goes through this function:

JavaScriptCore/assembler/AssemblerBuffer.h : AssemblerBuffer::executableCopy

You can dump the raw x86 code here, and a disassembler can do the rest of
the work.


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