[webkit-dev] get an index of array in JSC

[Filip Pizlo]

There are multiple code paths for accessing arrays, including the assembly in the LLInt but also the code in JSObject. You could instrument all of it if you wanted to. 

-Filip

> On Apr 26, 2014, at 6:09 AM, wei wang <flyingwei1986 at gmail.com> wrote:
> 
> Hello,
> 
> I wonder, is it possible to profile every read/write to an array?
> More specifically, how to get the index of JSArray according to each read/write?
> 
> Here is an example, consider the following js statement,
> 
> b = a[1],
> 
> I find that there are three relevant bytecode statements for "reading a[1]",
> 
> 
> resolve_scope    --- that is, a
> get_from_scope    --- get a's address, possibly
> get_by_val        --- get 1
> 
> 
> By following the LLint using GDB, I cannot find the corresponding methods in JSArray for accessing the value of a[1]. It seems that a[1] is accessed directly using the offset. Any suggestion will be helpful. Thanks!
> 
> 
> Wei
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