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From: matthieu.moy@ensimag.imag.fr To: gcc-gnats@gcc.gnu.org Subject: c/2600: gcc fails to increment a signed int variable by one with -O2 Date: Fri, 20 Apr 2001 07:26:00 -0000 [thread overview] Message-ID: <20010420142241.17758.qmail@sourceware.cygnus.com> (raw) >Number: 2600 >Category: c >Synopsis: gcc fails to increment a signed int variable by one with -O2 >Confidential: no >Severity: non-critical >Priority: low >Responsible: unassigned >State: open >Class: wrong-code >Submitter-Id: net >Arrival-Date: Fri Apr 20 07:26:00 PDT 2001 >Closed-Date: >Last-Modified: >Originator: Matthieu Moy >Release: gcc version 2.95.3 >Organization: >Environment: AIX on bull (8 procs) >Description: A variable plus one operation is not done if the program is compiled with optimisation -O2 in a very simple c program. example of output : $ gcc -O1 bug-gcc.c $ a.out i = 1; plus_one = 2 $ gcc -O2 bug-gcc.c $ a.out i = 1; plus_one = 1 >How-To-Repeat: compile with -O1 and -O2 >Fix: I didn't make any patch >Release-Note: >Audit-Trail: >Unformatted: ----gnatsweb-attachment---- Content-Type: application/octet-stream; name="bug-gcc.c" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="bug-gcc.c" I2luY2x1ZGU8c3RkaW8uaD4KCnR5cGVkZWYgc2lnbmVkIGNoYXIgVDsKCmludCBtYWluKCkKewog IFQgaSA9IDAsIHBsdXNfb25lOwogIGludCB5OwogIGZvcih5PTA7IHk8MTsgKyt5KQogICAgewog ICAgICBpPWkrMTsKICAgICAgcHJpbnRmKCJpID0gJWQ7ICIsIGkpOwogICAgICBwbHVzX29uZSA9 IGkgKyAxOwogICAgICBwcmludGYoInBsdXNfb25lID0gJWRcbiIsIHBsdXNfb25lKTsKICAgIH0K ICByZXR1cm4gMDsKfQo=
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