This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: [PATCH] fold-const.c use of BRANCH_COST

From: Geoff Keating <geoffk at geoffk dot org>
To: Andrew Pinski <pinskia at physics dot uc dot edu>
Cc: David Edelsohn <dje at watson dot ibm dot com>, gcc-patches at gcc dot gnu dot org
Date: 11 Apr 2003 10:46:13 -0700
Subject: Re: [PATCH] fold-const.c use of BRANCH_COST
References: <20030411040929.GN4350@redhat.com><4C775C4C-6BD5-11D7-9089-000393A6D2F2@physics.uc.edu>

Andrew Pinski <pinskia at physics dot uc dot edu> writes:

> Because with BRANCH_COST set to 3, gcc on PPC produces
> serializing instructions (adde, subfe, subfme, subfze) on some
> processors, like 750 and 7400.
> It also sometimes produces smaller code.

If these instructions are serializing, it's probably not useful for
GCC to be producing them at all on these processors; they'll always be
slower than a branch.

-- 
- Geoffrey Keating <geoffk at geoffk dot org>

Follow-Ups:
- Re: [PATCH] fold-const.c use of BRANCH_COST
  - From: Segher Boessenkool

References:
- Re: [PATCH] fold-const.c use of BRANCH_COST
  - From: Richard Henderson
- Re: [PATCH] fold-const.c use of BRANCH_COST
  - From: Andrew Pinski

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]