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[Bug target/18141] mips64-none-elf-gcc: Excessive NOPs with -march=r3000
- From: "rsandifo at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 27 Oct 2004 14:49:00 -0000
- Subject: [Bug target/18141] mips64-none-elf-gcc: Excessive NOPs with -march=r3000
- References: <20041025112436.18141.niva@niisi.msk.ru>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From rsandifo at gcc dot gnu dot org 2004-10-27 14:48 -------
This is a known problem, and is due to the fact that paired
FP registers can't be treated as separate entities. This leads
to an internal representation of double loads that appears to
indicate a read-after-write dependency between the first lwc1
and the second.
In many cases, the scheduler will be able to fill the gap between
two lwc1s with something else, so the nop should be avoided more
often than not.
This is something I hope to fix one day, but it's quite low down
my list of priorities. Marking as suspended/enhancement for now.
I'll assign it to myself later if I think I'll have time to work
on a fix.
--
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2004-10-27 14:48:59
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18141