https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106422
--- Comment #7 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
I think item 2 from comment #3 (jump threading) still needs to be solved
independently of what is decided about item 1 (leaf functions resuming earlier
returns_twice call).
---
The problem with 'leaf' is that Glibc is taking the longjmp stipulation from
the docs ("a leaf function is not allowed to [...] longjmp into the unit")
literally:
/* All functions, except those with callbacks or those that
synchronize memory, are leaf functions. */
# if __GNUC_PREREQ (4, 6) && !defined _LIBC
# define __LEAF , __leaf__
# define __LEAF_ATTR __attribute__ ((__leaf__))
# else
# define __LEAF
# define __LEAF_ATTR
# endif
and marks many, many functions including 'execve' leaf, while 'execve'
obviously resumes an earlier vfork (if successful).
---
In the original testcase we have 'free' which arguably should not resume any
returns_twice function, so GIMPLE representation is correct and jump threading
needs a fix (or can_duplicate_block_p if we decide it's too conservative and
ought to check presence of abnormal edges). Please let me know if I should
split off the problem with leaf functions in a separate bug.
