On Wed, Oct 21, 2015 at 9:24 AM, Eric Botcazou <ebotca...@adacore.com> wrote: >> So the only question is whether or not the CEIL_MOD_EXPR and >> ROUND_MOD_EXPR bits are right. I'm confident the change to >> FLOOR_MOD_EXPR is right. > > OK. > >> Do we have any reasonable way to test CEIL_MOD_EXPR & ROUND_MOD_EXPR? > > Note that the patch makes the function punt on those 2 so it can do no harm. > The sign of CEIL_MOD_EXPR is predictable (opposite of that of the divisor) but > you cannot use that in the context; and finally the sign of ROUND_MOD_EXPR > isn't predictable. > > I can add a few more comments:
Maybe add the comments to tree.def instead. > Index: fold-const.c > =================================================================== > --- fold-const.c (revision 229022) > +++ fold-const.c (working copy) > @@ -12982,11 +12982,18 @@ tree_binary_nonnegative_warnv_p (enum tr > return RECURSE (op0) && RECURSE (op1); > > case TRUNC_MOD_EXPR: > - case CEIL_MOD_EXPR: > - case FLOOR_MOD_EXPR: > - case ROUND_MOD_EXPR: > + /* The sign of the remainder is that of the dividend. */ > return RECURSE (op0); > > + case FLOOR_MOD_EXPR: > + /* The sign of the remainder is that of the divisor. */ > + return RECURSE (op1); > + > + case CEIL_MOD_EXPR: > + /* The sign of the remainder is the opposite of that of the divisor, > + but this cannot be used in this context. */ > + case ROUND_MOD_EXPR: > + /* The sign of the remainder is not predictable. */ > default: > return tree_simple_nonnegative_warnv_p (code, type); > } > > > -- > Eric Botcazou
