Re: Aliasing violation generated by fold_builtin_memcmp?

[Olivier Hainque <hainque at adacore dot com>]

Daniel Berlin wrote:
> Well, doesn't the pointed-to type have set 0 because of
> TYPE_REF_CAN_ALIAS_ALL (or whatever it's named :P)?

 Not quite: the pointer type has TYPE_REF_CAN_ALIAS_ALL, not the
 pointed-to type:

   /* Nonzero in a pointer or reference type means the data pointed to
      by this type can alias anything.  */
   #define TYPE_REF_CAN_ALIAS_ALL(NODE) \
     (PTR_OR_REF_CHECK (NODE)->common.static_flag)

 It seems to me that get_tmt does not do the right thing today
 because it assigns the tag alias set from the alias set of the
 pointed-to type, even if CAN_ALIAS_ALL is set on the pointer type.

 Here is an example input tree out of an Ada testcase:

 <var_decl 0x4022f370 ksubint.2
    type <pointer_type 0x4025fbdc p2__integer_access
        type <integer_type 0x4025fb80 integer type <integer_type integer>
            sizes-gimplified public SI
            user align 32 symtab 0 alias set 3 

        sizes-gimplified public static unsigned SI
                                ^^^^^^
        user align 32 symtab 0 alias set -1>

 This is a pointer to integer which is declared "can actually alias anything".