[Bug middle-end/52134] Does not fold (x * 4) & -4

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52134

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-02-06
     Ever Confirmed|0                           |1

--- Comment #1 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-02-06 14:08:13 UTC ---
> The above expression computes non-constant
> 
> ((ssizetype) (((sizetype) MAX_EXPR <R1b, 0> + 2) * 4) & -4) - (ssizetype)
> ((sizetype) MAX_EXPR <R1b, 0> * 4)
> 
> Not sure if such an expression cannot be reliably required to be constant
> in ada though.

Reassociation/simplification of size expressions can generally be done at will.

> Certainly this looks like a missed folding (not sure how often this
> odd BIT_AND_EXPR for sizes happen in Ada).

Quite a lot, but it's created by the folder itself (round_up).