On Wed, Jun 3, 2009 at 12:41 PM, Bingfeng Mei <bmei@broadcom.com> wrote:
> Hello,
> I noticed that the restrict doesn't work fully on 4.4.0 (used to work on
>  our port based on 4.3 branch). The problem is that tree optimizer can do a
> lot of optimization regarding pointer, e.g., at -O3. The alias set property
> is not propagated accordingly.
>
> Is the following RTL expansion correct? Both read and write address are
> converted to a restrict pointer, but the both mem rtx have the same alias set (2).
>
> ;; *(int * restrict) (D.1768 + 4) = *(int * restrict) (D.1770 + 4);

restrict only works if there is a restrict qualified pointer decl in
your source.

I will re-implement restrict support completely for 4.5.

You can try the attached hack which might help (but also cause
weird effects ...).

Richard.

> (insn 56 55 57 tst.c:7 (set (reg:SI 124)
>        (mem:SI (plus:SI (reg:SI 103 [ D.1770 ])
>                (const_int 4 [0x4])) [2 S4 A32])) -1 (nil))
>
> (insn 57 56 0 tst.c:7 (set (mem:SI (plus:SI (reg:SI 104 [ D.1768 ])
>                (const_int 4 [0x4])) [2 S4 A32])
>        (reg:SI 124)) -1 (nil))
>
>
> The alias set property is copied from tree node:
>  <indirect_ref 0xf7f09d40
>    type <integer_type 0xf7f122f4 int sizes-gimplified public SI
>        size <integer_cst 0xf7f0f9d8 constant 32>
>        unit size <integer_cst 0xf7f0f7c4 constant 4>
>        align 32 symtab 0 alias set 2 canonical type 0xf7f122f4 precision 32 min <integer_cst 0xf7f0f984 -2147483648> max <integer_cst 0xf7f0f9a0 2147483647>
>        pointer_to_this <pointer_type 0xf7f18798>>
>
>    arg 0 <nop_expr 0xf7fc7400
>        type <pointer_type 0xf7fa6870 type <integer_type 0xf7f122f4 int>
>            sizes-gimplified public unsigned restrict SI size <integer_cst 0xf7f0f9d8 32> unit size <integer_cst 0xf7f0f7c4 4>
>            align 32 symtab 0 alias set -1 canonical type 0xf7fa6870>
>
>        arg 0 <plus_expr 0xf7fc95e8 type <integer_type 0xf7f12438 long unsigned int>
>            arg 0 <var_decl 0xf7fc4a6c D.1768>
>            arg 1 <integer_cst 0xf7fb7bec constant 4>
>            tst.c:7:5>
>        tst.c:7:5>
>    tst.c:7:5>
>
> Is the RTL expansion wrong or the orginal tree node is constructed incorrectly?
>
> Thanks,
> Bingfeng Mei
>
> Broadcom UK
>