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From: mark.odonohue@cytopia.com.au To: gcc-gnats@gcc.gnu.org Subject: optimization/8613: -O3 optimisation of ++ generates wrong code Date: Fri, 22 Nov 2002 11:23:00 -0000 [thread overview] Message-ID: <20021117133942.7556.qmail@sources.redhat.com> (raw) >Number: 8613 >Category: optimization >Synopsis: -O3 optimisation of ++ generates wrong code >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Sun Nov 17 05:46:06 PST 2002 >Closed-Date: >Last-Modified: >Originator: mark.odonohue@cytopia.com.au >Release: gcc 3.2 >Organization: >Environment: mandrake linux 9.0 >Description: In the provided code, *dpb++ = strlen(userName) dpb is incorrectly incremented by two bytes, not one. The output buffer should result in: 1, 35, 6, 'sysdba'. Instead it results in: 1, 35, 6, x, 'sysdba' where x is random. Tracing in gdb shows that dpb is incremented by a value of two. >How-To-Repeat: g++ -O2 -march=i686 -fPIC test1.cpp ./a.out 1 >Fix: -O1 seems to work. >Release-Note: >Audit-Trail: >Unformatted: ----gnatsweb-attachment---- Content-Type: application/octet-stream; name="test1.cpp" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="test1.cpp" CgojaW5jbHVkZSA8c3RkaW8uaD4KI2luY2x1ZGUgPHN0ZGxpYi5oPgojaW5jbHVkZSA8c3RyaW5n PgojaW5jbHVkZSA8aW9zdHJlYW0+CgppbnQgbWFpbihpbnQgYXJnYywgY2hhciogYXJndltdKSB7 CgogIGludCBhdmFsdWUgPSAwOwogIGNoYXIgZHBiX2J1ZmZlclsyNTZdLCAqZHBiOwoKICBjaGFy IHVzZXJOYW1lMVsyNTZdOwogIGNvbnN0IGNoYXIqIHVzZXJOYW1lID0gInN5c2RiYSI7CiAgY29u c3QgY2hhciogcGFzc3dkID0gIm1hc3RlcmtleSI7CgogIHN0cmNweSh1c2VyTmFtZTEsIHVzZXJO YW1lKTsKICAKICBhdmFsdWUgPSBhdG9pKGFyZ3ZbMV0pOwogIGRwYiA9IGRwYl9idWZmZXI7Cgog ICpkcGIrKyA9IDB4MTsKICAqZHBiKysgPSAweDM1OwogIC8vcHJpbnRmKCIleFxuIiwgZHBiKTsK ICBpZiAoIGF2YWx1ZSkgewogICAgICpkcGIrKyA9IHN0cmxlbih1c2VyTmFtZTEpOwogIC8vcHJp bnRmKCIleFxuIiwgZHBiKTsKICAgICBmb3IgKGNoYXIqIHA9dXNlck5hbWUxOyAqcDspIHsKICAg ICAgICAqZHBiKysgPSAqcCsrOwogICAgIH0KICB9CiAgCiAgZm9yIChpbnQgaSA9MDsgaSA8IDEw OyBpKyspIHsKICAgICAgcHJpbnRmKCIlZCwgJWMsIGNoYXIgPSAleFxuIiwgaSwgZHBiX2J1ZmZl cltpXSwgZHBiX2J1ZmZlcltpXSk7CiAgfQogIC8vcHJpbnRmKCJjaGFyID0gJWNcbiIsIGRwYl9i dWZmZXJbMl0pOwoKICByZXR1cm4gMDsKfQoK
next reply other threads:[~2002-11-17 13:46 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-11-22 11:23 mark.odonohue [this message] 2002-11-22 13:33 Mark O'Donohue
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