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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: "paolo dot bonzini at lu dot unisi dot ch" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Aug 2006 07:05:13 -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 #48 from paolo dot bonzini at lu dot unisi dot ch 2006-08-08 07:05 -------
Subject: Re: [4.0/4.1 Regression] gcc 4 produces worse
x87 code on all platforms than gcc 3
> 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).
Yes, so far so good and this part has already been committed. But does
a *single* load-and-execute instruction execute faster than the two
instructions in a load+execute sequence?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27827