Re: [RFA] [PR tree-optimization/79095][PATCH 2/4] Add infrastructure to detect overflow checks

[Jeff Law <law at redhat dot com>]

On 02/06/2017 05:52 AM, Richard Biener wrote:
> > +      /* Now look at the defining statement of OP1 to see if it adds
> > +        or subtracts a nonzero constant from another operand.  */
> > +      if (op1_def
> > +         && is_gimple_assign (op1_def)
> > +         && gimple_assign_rhs_code (op1_def) == PLUS_EXPR
> > +         && TREE_CODE (gimple_assign_rhs2 (op1_def)) == INTEGER_CST
> > +         && wi::ne_p (gimple_assign_rhs2 (op1_def), 0))
>
> ! integer_zerop ()
Fixed.

> > +
> > +         tree type = TREE_TYPE (op0);
> > +         wide_int max = wi::max_value (TYPE_PRECISION (type), UNSIGNED);
> > +         HOST_WIDE_INT inc = TREE_INT_CST_LOW (gimple_assign_rhs2
> > (op1_def));
>
> You nowhere tested that rhs2 fits a HOST_WIDE_INT.  You can simply make inc
> a tree and use that in the max + inc expression below.
Also fixed.

> I'll have to see where the function is used to make sense of it.
Understood.

jeff