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Re: [Bug fortran/32732] [Bind C] Character scalars are passed as arrays
- From: Steve Ellcey <sje at cup dot hp dot com>
- To: crickett at lanl dot gov
- Cc: burnus at net-b dot de, fortran at gcc dot gnu dot org
- Date: Mon, 30 Jul 2007 14:12:40 -0700 (PDT)
- Subject: Re: [Bug fortran/32732] [Bind C] Character scalars are passed as arrays
> first, a comment on the code snippet you gave: the reason you have to add
> -fno-underscoring is because your main program forgets to say 'use
> c_char_tests', so sub0 gets implicitly declared.
Ah yes, I added that and I can compile without the -fno-underscoring.
> second, i think i've tracked down what was causing the problem with the
> code snippet. the call to sub0 gets converted (gfc_conv_function_call)
> before the generate_local_decls runs for param_test. this means that the
> symbols for the dummy args in the call still say they're an array_type, so
> the actuals given by sub0() are converted to array_type. i think this
> means that the fixup done for by-value character dummies in
> generate_local_decl must also be done when mapping actuals to formals in
> gfc_conv_function_call. i've attached a patch that does this. it's been
> bootstrapped and regtested on x86 and x86_64 linux with no new failures,
> but the real test is whether they'll work for you. :-)
It doesn't look like it is working. I put in your patch (after removing
the previous trans-decl.c patch) Then I rebuilt and tested my program
and it still failed. Looking at the assembly language, there are still
shifts of the characters in sub0 before it calls param_test so it looks
like sub0 is still passing the arguments as arrays.
I am not sure why this is, I do hit the new code in trans-expr.c, before
calling gfc_conv_scalar_char_value I have:
<parm_decl 7d6cc2d8 my_char
type <array_type 7d76e230
type <integer_type 7d6d8150 char public unsigned string-flag QI
size <integer_cst 7d6c51b8 constant invariant 8>
unit size <integer_cst 7d6c51e0 constant invariant 1>
align 8 symtab 0 alias set -1 canonical type 7d6d8150 precision 8 min <integer_cst 7d6c5208 0> max <integer_cst 7d6c5230 255>
pointer_to_this <pointer_type 7d6e0690>>
string-flag QI size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
align 8 symtab 0 alias set -1 canonical type 7d76e230
domain <integer_type 7d76e1c0 type <integer_type 7d6d8310 int4>
SI
size <integer_cst 7d6c53e8 constant invariant 32>
unit size <integer_cst 7d6c50f0 constant invariant 4>
align 32 symtab 0 alias set -1 canonical type 7d76e1c0 precision 32 min <integer_cst 7d6c5898 1> max <integer_cst 7d6c5898 1>>>
readonly QI file x.f90 line 5 size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
align 8 context <function_decl 7d76dd20 param_test> initial <array_type 7d76e230> arg-type <array_type 7d76e230> chain <parm_decl 7d6cc3a8 my_char_2>>
And after calling gfc_conv_scalar_char_value I have:
<parm_decl 7d6cc2d8 my_char
type <integer_type 7d6d8150 char public unsigned string-flag QI
size <integer_cst 7d6c51b8 constant invariant 8>
unit size <integer_cst 7d6c51e0 constant invariant 1>
align 8 symtab 0 alias set -1 canonical type 7d6d8150 precision 8 min <integer_cst 7d6c5208 0> max <integer_cst 7d6c5230 255>
pointer_to_this <pointer_type 7d6e0690>>
readonly QI file x.f90 line 5 size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
align 8 context <function_decl 7d76dd20 param_test> initial <integer_type 7d6d8150 char> arg-type <integer_type 7d6d8150 char> chain <parm_decl 7d6cc3a8 my_char_2>>
But the arguments are still shifted before being passed from sub0 to
param_test. I don't know why.
Steve Ellcey
sje@cup.hp.com