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Re: Identifying global state within GCC
- From: Jeff Law <law at redhat dot com>
- To: David Malcolm <dmalcolm at redhat dot com>
- Cc: gcc at gcc dot gnu dot org, "gcc-python-plugin at lists dot fedorahosted dot org" <gcc-python-plugin at lists dot fedorahosted dot org>
- Date: Thu, 02 May 2013 07:20:40 -0600
- Subject: Re: Identifying global state within GCC
- References: <1367440332 dot 21297 dot 10 dot camel at surprise>
On 05/01/2013 02:32 PM, David Malcolm wrote:
I had a go at writing a custom pass to try to locate places where GCC
makes use of global state.
You can see the pass here (which I implemented using gcc-python-plugin):
https://gcc-python-plugin.readthedocs.org/en/latest/working-with-c.html#finding-global-variables
A build log from recompiling gcc using this pass can be seen at:
http://fedorapeople.org/~dmalcolm/gcc/2013-05-01/make.log
(about 12MB in size; I killed it when I saw that stage 1 was done).
I'm sure there are quite a few false positives in there.
Hope this is helpful. FWIW I had an earlier version of the pass which
merely gave *declaration* sites for global variables, rather than all
*uses* of such variables.
I wonder how useful it would be to filter out the source line
information, then produce a histogram of which global state is hit the
most often across the build. That'd give us an interesting hitlist as
we start trying to remove the global state.
jeff