https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103964
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|UNCONFIRMED |RESOLVED
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
And for the curious it's indeed
static bool
indirect_ref_may_alias_decl_p (tree ref1...
...
/* If only one reference is based on a variable, they cannot alias if
the pointer access is beyond the extent of the variable access.
(the pointer base cannot validly point to an offset less than zero
of the variable).
??? IVOPTs creates bases that do not honor this restriction,
so do not apply this optimization for TARGET_MEM_REFs. */
if (TREE_CODE (base1) != TARGET_MEM_REF
&& !ranges_maybe_overlap_p (offset1 + moff, -1, offset2, max_size2))
return false;
the IVOPTs reference is likely due to the fact that while IVOPTs uses
uintptrs to create the base pointer the TARGET_MEM_REF contained arithmetic
itself is still considered pointer arithmetic (like also here the embedded
MEM_REF pointer offsetting) and the base "pointer" cannot be a non-pointer
to disable that behavior.
Not a bug btw. There's no flag to make violating the C pointer offsetting
rules well-defined.
