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Date: Wed, 28 Jul 2004 17:01:00 -0000
From: "gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040728170038.16800.steinmtz@us.ibm.com>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug other/16800] New: PowerPC - Unnecessary rldicl
X-Bugzilla-Reason: CC
X-SW-Source: 2004-07/txt/msg03361.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

Description:
A non-optimal code sequence is illustrated.  The rldicl noted below is not needed (and doesn't occur for the "==" comparison).  Duplicate using gcc 3.5 and command line:

gcc -O3 -m64 -c test.c

Testcase:
long l1,l2;
float f1,f2,f3,f4;

void logic_func4() {
  l1 = (f1 == f2);
  l2 = (f3 > f4);
}

Assembly:
.logic_func4:
	ld 8,.LC5@toc(2)
	ld 6,.LC4@toc(2)
	lfs 13,0(8)
	lfs 11,0(6)
	ld 5,.LC1@toc(2)
	ld 4,.LC2@toc(2)
	lfs 12,0(5)
	fcmpu 7,11,13
	lfs 0,0(4)
	ld 11,.LC0@toc(2)
	ld 10,.LC3@toc(2)
	fcmpu 6,12,0
	mfcr 3
	rlwinm 3,3,30,1
	rldicl 0,3,0,32 <-- Unnecessary.
	mfcr 9
	rlwinm 9,9,27,1
	std 0,0(10)
	std 9,0(11)
	blr



-- 
           Summary: PowerPC - Unnecessary rldicl
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P1
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steinmtz at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org,steinmtz at us dot ibm
                    dot com
 GCC build triplet: powerpc64-linux
  GCC host triplet: powerpc64-linux
GCC target triplet: powerpc64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16800