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From: "eplondke at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/29274]  New: 4.1, 4.2 (possibly 4.0?) not using mulsidi3
Date: Thu, 28 Sep 2006 16:43:00 -0000	[thread overview]
Message-ID: <bug-29274-9933@http.gcc.gnu.org/bugzilla/> (raw)

GCC 4.x tree optimization decides to put int values into long long int
temporaries.  When RTL expansion comes around, the expander sees only a DImode
multiply and so generates three SImode multiplies to deal with the problem.

GCC 3.x sees that the source values are SImode and uses mulsidi3 to generate
32x32->64 multiplies, which are much more efficient.  It also picks up the
accumulation.

(using -O3 for all compilations)

GCC 3.4 has an 84-byte stack frame, and a body of 372 instructions.
GCC 4.1 has a 1416-byte stack frame, and a body of 1668 instructions.
GCC 4.2 has a 1320-byte stack frame, and a body of 1565 instructions.


-- 
           Summary: 4.1, 4.2 (possibly 4.0?) not using mulsidi3
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: eplondke at gmail dot com
  GCC host triplet: x86_64-suse-linux
GCC target triplet: arm-unkown-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29274


             reply	other threads:[~2006-09-28 16:43 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-28 16:43 eplondke at gmail dot com [this message]
2006-09-28 16:46 ` [Bug c/29274] " eplondke at gmail dot com
2006-09-28 16:46 ` eplondke at gmail dot com
2009-03-27 17:12 ` [Bug target/29274] " ramana at gcc dot gnu dot org
2009-03-27 17:26 ` [Bug middle-end/29274] [4.2/4.3/4.4 Regression] " rguenth at gcc dot gnu dot org
2009-03-27 17:27 ` rguenth at gcc dot gnu dot org
2009-03-30 14:44 ` [Bug middle-end/29274] [4.2/4.3/4.4/4.5 " rguenth at gcc dot gnu dot org
2009-03-31 19:46 ` [Bug middle-end/29274] [4.3/4.4/4.5 " jsm28 at gcc dot gnu dot org
2009-08-04 12:41 ` rguenth at gcc dot gnu dot org
2009-08-26 15:50 ` froydnj at gcc dot gnu dot org
2009-08-26 18:35 ` rguenth at gcc dot gnu dot org
2009-12-29 23:21 ` ramana at gcc dot gnu dot org
2010-04-22  9:31 ` [Bug middle-end/29274] [4.3/4.4/4.5/4.6 " bernds at gcc dot gnu dot org
2010-04-22 10:12 ` [Bug middle-end/29274] [4.3/4.4/4.5 " rguenth at gcc dot gnu dot org
2010-04-22 11:26 ` bernds at gcc dot gnu dot org
2010-05-22 18:24 ` rguenth at gcc dot gnu dot org

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