[Bug c/113555] New: Yet another failure in verify_ssa

[Bug c/113555] New: Yet another failure in verify_ssa

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

            Bug ID: 113555
           Summary: Yet another failure in verify_ssa
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Today's gcc trunk says:

$ ~/gcc/results.20240123.asan.ubsan/bin/gcc -c -O3 -w bug1000.c
$ ~/gcc/results.20240123.asan.ubsan/bin/gcc -c -O3 -w -march=znver3 bug1000.c
bug1000.c: In function ‘net_roa_check_ip4_trie_tab’:
bug1000.c:20:6: error: definition in block 4 does not dominate use in block 5
   20 | void net_roa_check_ip4_trie_tab() {
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~
for SSA_NAME: vect__14.32_111 in statement:
vect__14.32_112 = PHI <vect__14.32_111(5)>
PHI argument
vect__14.32_111
for PHI node
vect__14.32_112 = PHI <vect__14.32_111(5)>
during GIMPLE pass: vect
bug1000.c:20:6: internal compiler error: verify_ssa failed

Reduced source code is

int ip4_getbit_a, ip4_getbit_pos, ip4_clrbit_pos;
void ip4_clrbit(int *a) { *a &= ip4_clrbit_pos; }
typedef struct {
  char pxlen;
  int prefix
} net_addr_ip4;
void fib_get_chain();
int trie_match_longest_ip4();
int trie_match_next_longest_ip4(net_addr_ip4 *n) {
  int __trans_tmp_1;
  while (n->pxlen) {
    n->pxlen--;
    ip4_clrbit(&n->prefix);
    __trans_tmp_1 = ip4_getbit_a >> ip4_getbit_pos;
    if (__trans_tmp_1)
      return 1;
  }
  return 0;
}
void net_roa_check_ip4_trie_tab() {
  net_addr_ip4 px0;
  for (int _n = trie_match_longest_ip4(&px0); _n;
       _n = trie_match_next_longest_ip4(&px0))
    fib_get_chain();
}

The bug seems to have existed since at least 20231227.

On a side note, 1000 bug reports and enhancement requests in 11 years.

[Bug c/113555] Yet another failure in verify_ssa

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> ---
Second test case:

char LZ4_decompress_generic_source;
void LZ4_decompress_generic_endOnInput() {
  char *ip = &LZ4_decompress_generic_source;
  while (1) {
    long length;
    if (length) {
      unsigned s;
      do {
        if (ip > -5)
          goto _output_error;
        s = *ip++;
        length += s;
      } while (s);
    }
  }
_output_error:
}

cvise $ ~/gcc/results/bin/gcc -c -w -O3 bug1000B.c
cvise $ ~/gcc/results/bin/gcc -c -w -O3 -march=znver3 bug1000B.c
bug1000B.c: In function ‘LZ4_decompress_generic_endOnInput’:
bug1000B.c:2:6: error: definition in block 7 does not dominate use in block 5
    2 | void LZ4_decompress_generic_endOnInput() {
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Bug c/113555] Yet another failure in verify_ssa

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

--- Comment #2 from David Binderman <dcb314 at hotmail dot com> ---
For the first source code, the bug seems to exist sometime between 20231119
and 20231227.

Git hashes are g:eaeaad3fcac4d7a3 and g:f19ceb2d49afdfa5

Please ignore the second source code - it is a separate bug.

[Bug tree-optimization/113555] Yet another failure in verify_ssa

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
                 CC|                            |rguenth at gcc dot gnu.org,
                   |                            |tnfchris at gcc dot gnu.org
          Component|c                           |tree-optimization

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
possibly a duplicate

[Bug tree-optimization/113555] Yet another failure in verify_ssa

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=113364

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The proposed fix for PR113364 resolves the ICE

[Bug tree-optimization/113555] Yet another failure in verify_ssa

[tnfchris at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113555

Tamar Christina <tnfchris at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #5 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
Both cases fixed by fix for PR113364

*** This bug has been marked as a duplicate of bug 113364 ***