[Bug c/112346] New: Wrong code produced with -O2

[Bug c/112346] New: Wrong code produced with -O2

[fchelnokov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112346

            Bug ID: 112346
           Summary: Wrong code produced with -O2
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fchelnokov at gmail dot com
  Target Milestone: ---

This program

#include <ctype.h>

char *SkipAName(char *s) {
  if (('A' <= *s && *s <= 'Z') || ('a' <= *s && *s <= 'z') ) {
    while (isalnum(*s)) {
      s++;
    }
  }
  return s;
}

int TestName(char *name) {
  while (*name)
    name++;
  return 0;
}

int StrICmp(char *s1, char *s2) {
  while (*s1 && *s1 == *s2) {
    s1++;
    s2++;
  }
  return *s1 - *s2;
}

int DoTable(char *s) {
    char *name, c;
    name = s;
    s = SkipAName(s);
    c = *s;
    *s = 0;
    TestName(name);
    *s = c;
    if (*s == '(')
      return 3;
    if (*s != ',')
      return 2;
    *s = 0;
    return StrICmp(name, "sparse");
}

int main() {
  char buf[] = "sparse,C(1)";
  return DoTable(buf);
}

shall return 0, but in GCC 13 with -O2 it returns 44. Online demo:
https://gcc.godbolt.org/z/c6W33T1zK

Related discussion: https://stackoverflow.com/q/77407156/7325599

[Bug tree-optimization/112346] [13 Regression] Wrong code produced with -O2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112346

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

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

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 111519 which will be included in the GCC 13.3.0 release.

*** This bug has been marked as a duplicate of bug 111519 ***

[Bug tree-optimization/112346] [13 Regression] Wrong code produced with -O2

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112346

Shaohua Li <shaohua.li at inf dot ethz.ch> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |shaohua.li at inf dot ethz.ch

--- Comment #2 from Shaohua Li <shaohua.li at inf dot ethz.ch> ---
(In reply to Fedor Chelnokov from comment #0)
> This program
> 
> #include <ctype.h>
> 
> char *SkipAName(char *s) {
>   if (('A' <= *s && *s <= 'Z') || ('a' <= *s && *s <= 'z') ) {
>     while (isalnum(*s)) {
>       s++;
>     }
>   }
>   return s;
> }
> 
> int TestName(char *name) {
>   while (*name)
>     name++;
>   return 0;
> }
> 
> int StrICmp(char *s1, char *s2) {
>   while (*s1 && *s1 == *s2) {
>     s1++;
>     s2++;
>   }
>   return *s1 - *s2;
> }
> 
> int DoTable(char *s) {
>     char *name, c;
>     name = s;
>     s = SkipAName(s);
>     c = *s;
>     *s = 0;
>     TestName(name);
>     *s = c;
>     if (*s == '(')
>       return 3;
>     if (*s != ',')
>       return 2;
>     *s = 0;
>     return StrICmp(name, "sparse");
> }
> 
> int main() {
>   char buf[] = "sparse,C(1)";
>   return DoTable(buf);
> }
> 
> shall return 0, but in GCC 13 with -O2 it returns 44. Online demo:
> https://gcc.godbolt.org/z/c6W33T1zK
> 
> Related discussion: https://stackoverflow.com/q/77407156/7325599

Hi, it seems that this test case is reduced from a real project. Could you tell
me which project it is from?

[Bug tree-optimization/112346] [13 Regression] Wrong code produced with -O2

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112346

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sjames at gcc dot gnu.org

--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
Yes, if allowed/able, please do always mention where something got derived
from. It can be useful data.

[Bug tree-optimization/112346] [13 Regression] Wrong code produced with -O2

[fchelnokov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112346

--- Comment #4 from Fedor Chelnokov <fchelnokov at gmail dot com> ---
According to referenced stackoverflow discussion, the code is reduced from 
https://github.com/vermaseren/form see
https://github.com/vermaseren/form/issues/461