> Well, the comment for that folding is totally odd - of _course_ > unsigned sizetype things can overflow (we hid that issue merely > by pretending all unsigned sizetype constants (yes, only constants) > are signed. Huh.)
It's again the special semantics of sizetypes whereby we pretend that they don't overflow. I know your opinion about this, but this is documented: /* In an INTEGER_TYPE, it means the type represents a size. We use this both for validity checking and to permit optimizations that are unsafe for other types. Note that the C `size_t' type should *not* have this flag set. The `size_t' type is simply a typedef for an ordinary integer type that happens to be the type of an expression returned by `sizeof'; `size_t' has no special properties. Expressions whose type have TYPE_IS_SIZETYPE set are always actual sizes. */ #define TYPE_IS_SIZETYPE(NODE) \ (INTEGER_TYPE_CHECK (NODE)->type_common.no_force_blk_flag) and we rely on these optimizations to simplify size computations in Ada. > 2011-08-31 Richard Guenther <rguent...@suse.de> > > * fold-const.c (extract_muldiv_1): Remove bogus TYPE_IS_SIZETYPE > special-casing. IMO you shouldn't commit this kind of patchlets without the final big patch. -- Eric Botcazou
