https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104356
--- Comment #34 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> For the X / bool_range_Y is X. case I think just !flag_non_call_exceptions
> would be better. If @1 has boolean range and is known to be non-zero, it is
> known to be 1, so we should be optimizing it elsewhere, that is the constant
> case.
OK, adjusted and successfully tested on x86-64/Linux.
> path isolation is already guarding is_divmod_with_given_divisor calls with
> !cfun->can_throw_non_call_exceptions.
Indeed.
> Can you try to rewrite the
> unsigned
> foo (unsigned x, unsigned y)
> {
> if (x >= 2)
> return 0;
> if (x == 1)
> y += 4;
> return y / x;
> }
>
> testcase I've posted into Ada and see if it will optimize away the division
> in evrp or vrp?
For:
with System.Unsigned_Types; use System.Unsigned_Types;
function F (X, Y : Unsigned) return Unsigned is
begin
if X >=2 then
return 0;
elsif X = 1 then
return 2 * Y;
else
return Y / X;
end if;
end;
I get with -O2 -gnatp:
_ada_f:
.LFB1:
.cfi_startproc
cmpl $1, %edi
ja .L4
je .L6
ud2
.p2align 4,,10
.p2align 3
.L4:
xorl %eax, %eax
ret
.p2align 4,,10
.p2align 3
.L6:
leal (%rsi,%rsi), %eax
ret
