[Bug c/43009] New: segmentation fault with -O3 when accessing byte-aligned array as dwords

[ajk dot xyz at gmail dot com]

gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu9)
Target: x86_64-linux-gnu

Resulting binary crushes with segmentation fault if gcc compile options include
-O3.

Source code:

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>

void process_buf(uint32_t *buf)
{
 int i;
 uint32_t t = 0;
 for(i = 0; i < 16; i++)
  buf[i] = ++t; // segmentation fault
}

int main(int argc, char **argv)
{
 char *buf = malloc(65);
 int n;
 process_buf((uint32_t*)(buf + 1));
 n = write(1, buf + 1, 64);
 return 0;
}


-- 
           Summary: segmentation fault with -O3 when accessing byte-aligned
                    array as dwords
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ajk dot xyz at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43009