Red Hat Bugzilla – Bug 106900
gcc miscompiles postfix increment on structure member when used as array index
Last modified: 2007-11-30 17:06:58 EST
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User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.5a) Gecko/20031010
Description of problem:
gcc miscompiles the following attachment on ppc with -O1 or higher, in both 32
and 64-bit mode.
A similar case in real world code trips up ia64 as well, but works fine with
this simple test case. I'm hoping a fix will address the problems on both targets.
x86 and amd64 are not affected.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. gcc -O2 -o gccbug gccbug.c
Actual Results: prints 0
Expected Results: should've printed 1
Created attachment 95127 [details]
Testing with cross-compiler from i686:
Fails with head-of-branch of gcc-3.2-rh as of 20041002.
Succeeds with head-of-branch of gcc-3.3.
Compilation goes wonky during .15.life. Without digging too deeply,
it looks like it might be pre-subreg-rationalization confusion. If
true, it's likely that the hinted ia64 problem is different, as this
would only affect big-endian targets.
This bug is filed against RHEL 3, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
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