[Bug tree-optimization/42944] New: errno misoptimization due to __attribute__ ((__const__)) on __errno_location()

[amodra at gmail dot com]

tst-malloc from glibc testsuite fails with 4.5.0 20100129, reporting "Error:
errno is not set correctly".  Examination of object files shows that gcc is
assuming that "save" in the following is always zero.
  errno = 0;
  p = malloc (-1);
  save = errno;

errno is defined as (*__errno_location)() with
extern int *__errno_location (void) __attribute__ ((__nothrow__)) __attribute__
((__const__));

everything looks ok up until tst-malloc.c.065t.fre


-- 
           Summary: errno misoptimization due to __attribute__ ((__const__))
                    on __errno_location()
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amodra at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42944