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[Bug target/27827] [4.0/4.1 Regression] gcc 4 produces worse x87 code on all platforms than gcc 3
- From: "hubicka at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Aug 2006 06:15:44 -0000
- Subject: [Bug target/27827] [4.0/4.1 Regression] gcc 4 produces worse x87 code on all platforms than gcc 3
- References: <bug-27827-12761@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #46 from hubicka at gcc dot gnu dot org 2006-08-08 06:15 -------
In x86/x86-64 world one can be almost sure that the load+execute instruction
pair will execute (marginaly to noticeably) faster than move+load-and-execute
instruction pair as the more complex instructions are harder for on-chip
scheduling (they retire later).
Perhaps we can move such a transformation somewhere more generically perhaps to
post-reload copyprop?
Honza
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27827