On Mon, 11 Aug 2014, Steve Ellcey 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.
There is still a table in opts.c, with entries that look like:
{ OPT_LEVELS_2_PLUS, OPT_ftree_vrp, NULL, 1 },
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
appreciated.
--
Marc Glisse
