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[Bug target/87079] nios2 optimization for size - case of regression relatively to 5.3.0
- From: "sandra at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 02 Nov 2018 04:17:13 +0000
- Subject: [Bug target/87079] nios2 optimization for size - case of regression relatively to 5.3.0
- Auto-submitted: auto-generated
- References: <bug-87079-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87079
sandra at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2018-11-02
CC| |sandra at gcc dot gnu.org
Assignee|unassigned at gcc dot gnu.org |sandra at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from sandra at gcc dot gnu.org ---
This looks like a problem with the nios2 instruction costs. Things are going
wrong in expand_widening_mult (in expmed.c); compiling with -O2 takes the
expand_binop path at the end to use the provided umulsidi3 expander, but with
-Os it thinks the expand_mult_const path is better. I'll try to poke at this
some more and come up with a patch.