[Bug tree-optimization/18703] New: [4.0 regression] ICE with negative array index of VLA in loop

["falk at debian dot org" <gcc-bugzilla at gcc dot gnu dot org>]

falk@juist:/tmp% cat ffv1.c
void encode_rgb_frame(int ring_size)
{
    int sample[3][ring_size];
    int i;
    for (i = 0; i < 2; i++)
        sample[1][-1] = sample[1][0];
}
falk@juist:/tmp% gcc -O -c -v  ffv1.c
Reading specs from
/usr/local/stow/gcc-2004.11.11/bin/../lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/specs
Configured with: ../configure --disable-nls --enable-languags=c++ :
(reconfigured) ../configure --disable-nls --enable-languages=c++
Thread model: posix
gcc version 4.0.0 20041111 (experimental)
 /usr/local/stow/gcc-2004.11.11/bin/../libexec/gcc/alphaev68-unknown-linux-gnu/4.0.0/cc1
-quiet -v -iprefix
/usr/local/stow/gcc-2004.11.11/bin/../lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/
ffv1.c -quiet -dumpbase ffv1.c -mcpu=ev67 -auxbase ffv1 -O -version -o
/tmp/ccJUOdLe.s
ignoring nonexistent directory
"/usr/local/stow/gcc-2004.11.11/bin/../lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/../../../../alphaev68-unknown-linux-gnu/include"
ignoring nonexistent directory "NONE/include"
ignoring duplicate directory
"/usr/local/lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/include"
ignoring nonexistent directory
"/usr/local/lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/../../../../alphaev68-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/stow/gcc-2004.11.11/bin/../lib/gcc/alphaev68-unknown-linux-gnu/4.0.0/include
 /usr/local/include
 /usr/include
End of search list.
GNU C version 4.0.0 20041111 (experimental) (alphaev68-unknown-linux-gnu)
        compiled by GNU C version 4.0.0 20041009 (experimental).
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ffv1.c: In function 'encode_rgb_frame':
ffv1.c:2: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

-- 
           Summary: [4.0 regression] ICE with negative array index of VLA in
                    loop
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: critical
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: falk at debian dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: alphaev68-unknown-linux-gnu
  GCC host triplet: alphaev68-unknown-linux-gnu
GCC target triplet: alphaev68-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18703