https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108757
--- Comment #22 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #21)
> (In reply to Jiu Fu Guo from comment #20)
> > Interesting thing:
> > the VR is always VR_VARYING, even for the below simple case:
> >
> > typedef unsigned long INT;
> > INT __attribute__ ((noinline)) foo (INT x)
> > {
> > if (x < 4)
> > return 0;
> > INT a = x + 18446744073709551612ULL;
> > INT b = a >> 2;
> > return b + 1;
> > }
>
> Yes that is because x does not have a "global" range.
I also tried "get_range_query (cfun)->range_of_expr (vr0, @0)",
>
> You could try the following testcase:
> ```
> typedef unsigned long INT;
> INT __attribute__ ((noinline)) foo (INT x)
> {
> if (x < 4)
> __builtin_unreachable();
> INT a = x + 18446744073709551612ULL;
> INT b = a >> 2;
> return b + 1;
> }
> ```
>
> Which gets a (global) range for x_1(D) during forwprop3:
> # RANGE [irange] INT [4, +INF]
> INTD.2750 x_1(D) = xD.2751;
(In reply to Andrew Pinski from comment #21)
> (In reply to Jiu Fu Guo from comment #20)
> > Interesting thing:
> > the VR is always VR_VARYING, even for the below simple case:
> >
> > typedef unsigned long INT;
> > INT __attribute__ ((noinline)) foo (INT x)
> > {
> > if (x < 4)
> > return 0;
> > INT a = x + 18446744073709551612ULL;
> > INT b = a >> 2;
> > return b + 1;
> > }
>
> Yes that is because x does not have a "global" range.
>
> You could try the following testcase:
> ```
> typedef unsigned long INT;
> INT __attribute__ ((noinline)) foo (INT x)
> {
> if (x < 4)
> __builtin_unreachable();
> INT a = x + 18446744073709551612ULL;
> INT b = a >> 2;
> return b + 1;
> }
> ```
>
> Which gets a (global) range for x_1(D) during forwprop3:
> # RANGE [irange] INT [4, +INF]
> INTD.2750 x_1(D) = xD.2751;
Thanks so much!
"get_range_query (cfun)->range_of_expr (vr0, @0)" works for both the case!
