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Re: Where does GCC pick passes for different opt. levels
- From: Andrew Pinski <pinskia at gmail dot com>
- To: Steve Ellcey <sellcey at mips dot com>
- Cc: GCC Mailing List <gcc at gcc dot gnu dot org>
- Date: Mon, 11 Aug 2014 14:18:37 -0700
- Subject: Re: Where does GCC pick passes for different opt. levels
- Authentication-results: sourceware.org; auth=none
- References: <42bd6319-2c9b-4c0d-b04d-aed54d8a43ec at BAMAIL02 dot ba dot imgtec dot org>
On Mon, Aug 11, 2014 at 1:58 PM, Steve Ellcey <email@example.com> wrote:
> I have a basic question about optimization selection in GCC. There used to
> be some code in GCC (passes.c?) that would set various optimize pass flags
> depending on if the 'optimize' flag was > 0, > 1, or > 2; later I think
> there may have been a table. This code seems gone now and I can't figure
> out how GCC is selecting what optimization passes to run at what optimization
> levels (-O1 vs. -O2 vs. -O3). How is this handled in the top-of-tree GCC code?
> I see passes.def but there doesn't seem to be anything in there to tie
> specific passes to specific optimization levels. Likewise in common.opt
> I see flags for various optimization passes but nothing to tie them to
> -O1 or -O2, etc.
> I'm probably missing something obvious, but a pointer would be much
default_options_table in opts.c.
> Steve Ellcey