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From: "wouter.vermaelen at scarlet dot be" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug 45764] (tree-optimization) New: wrong code  -O2 vs -O3    (problem in vectorizer???)
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45764

           Summary: wrong code  -O2 vs -O3    (problem in vectorizer???)
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: wouter.vermaelen@scarlet.be


> cat bug.cc
int result[64][16];

int main()
{
        double dbuf[1000] = {0.0};
        int ibuf[900];

        double d1 = 0.0;
        double d2 = 0.0;
        for (int i = 0; i < 900; ++i) {
                ibuf[i] = int(d2 - d1);
                d1 += dbuf[i];
                d2 += dbuf[i + 64];
        }

        for (int i = 0; i < 64; ++i) {
                for (int j = 0; j < 8; ++j) {
                        result[i][     j] = ibuf[64 - i + 64 * j];
                        result[i][15 - j] = ibuf[     i + 64 * j];
                }
        }
}

> g++ -O2 bug.cc
> ./a.out
> g++ -O3 bug.cc
> ./a.out
Segmentation fault (core dumped)

I'm using SVN revision 164570 on linux_x86_64.

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