Procedure Pointers: a first patch

[Paul Richard Thomas]

Hi Steven,

I'm glad that you are still about - how are you?

I for one am feeling a bit lost with this:)

Where do I find documentation to unravel what you mean?

To Tobias and FX:  I added some debugging functions gfc_show_symbol_n
and gfc_show_expr_n but these have been removed.  There is no
ChangeLog entry to mark their passing. Do you know when and where they
went?

Cheers

Paul

On 5/4/08, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
> xf. http://gcc.gnu.org/ml/fortran/2008-05/msg00029.html
>
> Hi Janus,
>
> Just for comparison, look at the gimple for the following C test case
> with your Fortran tree:
>
> ================
> extern void foo (void);
> void bar (void) {
>   typedef void (*funptr) (void);
>   funptr ptr = foo;
> }
> ================
> This gives the following statement to the gimplifier:
>
> Breakpoint 5, gimplify_stmt (stmt_p=0x22c760) at
> ../../vanilla/gcc/gimplify.c:4660
> 4660	  gimplify_expr (stmt_p, NULL, NULL, is_gimple_stmt, fb_none);
> (gdb) p debug_tree(*stmt_p)
>  <init_expr 0x7ff40208
>     type <void_type 0x7ff81248 void VOID
>         align 8 symtab 0 alias set -1 canonical type 0x7ff81248
>         pointer_to_this <pointer_type 0x7ff812b0>>
>     side-effects
>     arg 0 <var_decl 0x7fdf0000 ptr
>         type <pointer_type 0x7ff8f908 funptr type <function_type 0x7ff837a8>
>             sizes-gimplified unsigned SI
>             size <integer_cst 0x7ff00700 constant 32>
>             unit size <integer_cst 0x7ff004a0 constant 4>
>             align 32 symtab 0 alias set -1 canonical type 0x7ff8f838>
>         unsigned SI file t.c line 6 col 10 size <integer_cst
> 0x7ff00700 32> unit size <integer_cst 0x7ff004a0 4>
>         align 32 context <function_decl 0x7fdbf340 bar>>
>     arg 1 <addr_expr 0x7fde2500
>         type <pointer_type 0x7ff8f838 type <function_type 0x7ff837a8>
>             sizes-gimplified unsigned SI size <integer_cst 0x7ff00700
> 32> unit size <integer_cst 0x7ff004a0 4>
>             align 32 symtab 0 alias set -1 canonical type 0x7ff8f838>
>         constant
>         arg 0 <function_decl 0x7fdbf2d0 foo type <function_type 0x7ff837a8>
>             addressable used public external decl_5 QI defer-output
> file t.c line 1 col 13 align 8>>>
>
> Note how the rhs of the assignment arg0 (INIT_EXPR is gimplified to a
> simple assignment) is a var decl.
>
> For your test case, otoh, I get an ADDR_EXPR on the rhs:
>
> #4  0x007876cd in gimplify_stmt (stmt_p=0x7ff33c08) at
> ../../vanilla/gcc/gimplify.c:4660
> 4660	  gimplify_expr (stmt_p, NULL, NULL, is_gimple_stmt, fb_none);
> (gdb) p debug_tree(*stmt_p)
>  <modify_expr 0x7ff401e0
>     type <void_type 0x7ff808f0 void VOID
>         align 8 symtab 0 alias set -1 canonical type 0x7ff808f0
>         pointer_to_this <pointer_type 0x7ff80958>>
>     side-effects
>     arg 0 <addr_expr 0x7fdb0bc0
>         type <pointer_type 0x7ff82be0 type <function_type 0x7ff82b78>
>             unsigned SI
>             size <integer_cst 0x7ff006e0 constant 32>
>             unit size <integer_cst 0x7ff00480 constant 4>
>             align 32 symtab 0 alias set -1 canonical type 0x7ff82be0>
>         constant
>         arg 0 <function_decl 0x7ff9c1d0 ptr type <function_type 0x7ff82b78>
>             addressable public external QI file procptr.f90 line 13
> col 0 align 8 chain <function_decl 0x7ff9c160 procptrtest>>>
>     arg 1 <addr_expr 0x7fdb0c00 type <pointer_type 0x7ff82be0>
>         constant
>         arg 0 <function_decl 0x7ff9c240 proc type <function_type 0x7ff82b78>
>             addressable public external QI file procptr.f90 line 13
> col 0 align 8 chain <function_decl 0x7ff9c1d0 ptr>>>
>     procptr.f90:20:0>
>
>
> Full GDB output is attached for your convenience.
> Hope this helps!
>
> Gr.
> Steven
>


-- 
The knack of flying is learning how to throw yourself at the ground and miss.
       --Hitchhikers Guide to the Galaxy