[RFC] use symbol_ref flags for rs6000

[Richard Henderson]

On Wed, Apr 23, 2003 at 04:16:48PM -0700, Janis Johnson wrote:
>   It's not correct that current_file_function_operand() always returns
>   false when SYMBOL_REF_FLAG is set; that is checked as part of an ||.

Ok, lets look again:

  funexp = XEXP (DECL_RTL (function), 0);

  SYMBOL_REF_FLAG (funexp) = 0;
  if (current_file_function_operand (funexp, VOIDmode)
  ==>
  return (GET_CODE (op) == SYMBOL_REF
          && (SYMBOL_REF_FLAG (op)
              || (op == XEXP (DECL_RTL (current_function_decl), 0)
                  && ! DECL_WEAK (current_function_decl))));

Note that function != current_function_decl during output_mi_thunk.
Ever.  If that were true we would be generating an infinite loop.
So we get:

  return (1
	  && (0
	      || (0
		  && x)));
  ==>
  return 0;

Incidentally, there is a latent buglet here.  We should *not* be
checking DECL_WEAK of current_function_decl.  Recursion always
binds locally.  (If the symbol doesn't get chosen, then we'll never
arrive in this instance of the function to begin with.)

>   The symbols that are now flagged with SYMBOL_FLAG_SMALL_V4 are treated
>   very differently from the generic small data symbols.

How's that?  Aww, nevermind.  I'll let that go for now.  We'll
let some ppc-eabi maintainer worry about it.

> -static const char * rs6000_xcoff_strip_name_encoding PARAMS ((const char *));

Bug.

> -	      SYMBOL_REF_FLAG (new_ref) = SYMBOL_REF_FLAG (operands[1]);
> +	      SYMBOL_REF_FLAGS (new_ref) = SYMBOL_REF_FLAGS (operands[1]);
>  	      SYMBOL_REF_USED (new_ref) = SYMBOL_REF_USED (operands[1]);

Should copy SYMBOL_REF_DECL here as well.

> @@ -12950,22 +12947,18 @@ rs6000_elf_encode_section_info (decl, rt
>    if (!first)
>      return;
>  
> +  default_encode_section_info (decl, rtl, first);

Should re-call default_encode_section_info (and any other bit
twiddling that doesn't depend solely on function/non-function)
even if !first.  For instance,

	extern int i;
	extern int i __attribute__((visibility("hidden")));

should result in "i" being marked LOCAL.  If we skip after first,
this won't happen.

> @@ -13643,7 +13607,7 @@ rs6000_xcoff_encode_section_info (decl, 
>  {
>    if (TREE_CODE (decl) == FUNCTION_DECL
>        && (*targetm.binds_local_p) (decl))
> -    SYMBOL_REF_FLAG (XEXP (rtl, 0)) = 1;
> +    SYMBOL_REF_FLAGS (XEXP (rtl, 0)) |= SYMBOL_FLAG_LOCAL;

You should be able to delete rs6000_xcoff_encode_section_info
entirely.  The predicate that they are checking is 

	SYMBOL_REF_LOCAL_P (x) && SYMBOL_REF_FUNCTION_P (x)

And given that this is used only in calls, you may or may not
need to check SYMBOL_REF_FUNCTION_P at all.  (Test case for this
should be does

	void foo()
	{
	  static int thunk[6];
	  ((void (*)(void))thunk)();
	}

link.)

>  #define ASM_DECLARE_FUNCTION_NAME(FILE,NAME,DECL)		\
>  { rtx sym_ref = XEXP (DECL_RTL (DECL), 0);			\
>    if ((*targetm.binds_local_p) (DECL))				\
> -    SYMBOL_REF_FLAG (sym_ref) = 1;				\
> +    SYMBOL_REF_FLAGS (sym_ref) |= SYMBOL_FLAG_LOCAL;		\

This bit frobbing should not be needed any longer.  We call
encode_section_info again during start_function, which should
set SYMBOL_FLAG_LOCAL as appropriate.



r~