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c/4214: powerpc64: wrong code from optimized mask and shift
- To: gcc-gnats at gcc dot gnu dot org
- Subject: c/4214: powerpc64: wrong code from optimized mask and shift
- From: Kevin Ryde <user42 at zip dot com dot au>
- Date: 04 Sep 2001 09:39:45 +1000
>Number: 4214
>Category: c
>Synopsis: powerpc64: wrong code from optimized mask and shift
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: wrong-code
>Submitter-Id: net
>Arrival-Date: Mon Sep 03 16:46:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:
>Release: 3.0
>Organization:
>Environment:
System: AIX panther 3 4 000785504C00
host: powerpc-ibm-aix4.3.2.0
build: powerpc-ibm-aix4.3.2.0
target: powerpc-ibm-aix4.3.2.0
configured with: ../gcc-3.0/configure
>Description:
A certain mask and shift combination produces a wrong answer when
compiled with optimization.
>How-To-Repeat:
A program foo.c,
int n = 3;
int
main (void)
{
printf ("%d\n", (n & 2) << 1);
return 0;
}
when compiled with
gcc -O -maix64 -mpowerpc64 foo.c
and run just as "./a.out", prints 6 whereas I think it should print 4
(and which it does if compiled without the -O).
For what it's worth, it seems this only happens under "-maix64
-mpowerpc64", not in 32-bit mode.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: