Re: Patch for irix .globl directives

[Richard Sandiford <rsandifo at redhat dot com>]

Roger Sayle <roger@eyesopen.com> writes:
> I'm not sure that this is correct.  I suspect that in addition to the
> test for DECL_BUILT_IN, you also need the equivalent of builtin.c's
> CALLED_AS_BUILT_IN.  This is because both "sqrt" and "__builtin_sqrt"
> are marked as builtins, but you want to output the external for sqrt.
> 
> In fact, we probably want to emit an external for "sqrt" in both cases,
> checking DECL_ASSEMBLER_NAME_SET_P, which will be false for built-ins
> that don't have a library presence, and the name of the library routine
> to call otherwise.
> 
> I also think we should move that logic into the machine independent
> parts of the code, rather than bury in ASM_OUTPUT_EXTERNAL.

OK, here's a patch to do that.  It adds a new helper function to
varasm.c since the condition seems a bit too complex to check in-line.
The function is based on the builtins.c test that you mention, checking
both for alloca() and for any builtin function whose assembler name
starts with "__builtin_".

There's also the question of what should be done with target-specific
builtins.  I just left them alone on the basis that the backend should
know whether they need any declarations.  The MIPS port doesn't have
any anyway.

Bootstrapped on mips-sgi-irix6.5.  Tested gcc, g77 and objc for o32, no
regressions compared to the previous patch (so the earlier g77 and objc
execution failures stay fixed).  I checked that uses of __builtin_cos()
would still cause cos to be declared, and so on.  OK to install?

Richard


	* varasm.c (incorporeal_function_p): New.
	(assemble_external): Use it as a filter.
	* config/mips/mips.c (mips_output_external): Don't check for builtin
	functions here.

Index: varasm.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/varasm.c,v
retrieving revision 1.398
diff -c -p -F^\([(a-zA-Z0-9_]\|#define\) -r1.398 varasm.c
*** varasm.c	13 Nov 2003 02:07:52 -0000	1.398
--- varasm.c	6 Dec 2003 14:42:22 -0000
*************** static HOST_WIDE_INT const_alias_set;
*** 137,142 ****
--- 137,145 ----
  
  static const char *strip_reg_name (const char *);
  static int contains_pointers_p (tree);
+ #ifdef ASM_OUTPUT_EXTERNAL
+ static bool incorporeal_function_p (tree);
+ #endif
  static void decode_addr_const (tree, struct addr_const *);
  static hashval_t const_desc_hash (const void *);
  static int const_desc_eq (const void *, const void *);
*************** contains_pointers_p (tree type)
*** 1599,1604 ****
--- 1602,1630 ----
      }
  }
  
+ #ifdef ASM_OUTPUT_EXTERNAL
+ /* True if DECL is a function decl for which no out-of-line copy exists.
+    It is assumed that DECL's assembler name has been set.  */
+ 
+ static bool
+ incorporeal_function_p (tree decl)
+ {
+   if (TREE_CODE (decl) == FUNCTION_DECL && DECL_BUILT_IN (decl))
+     {
+       const char *name;
+ 
+       if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
+ 	  && DECL_FUNCTION_CODE (decl) == BUILT_IN_ALLOCA)
+ 	return true;
+ 
+       name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
+       if (strncmp (name, "__builtin_", strlen ("__builtin_")) == 0)
+ 	return true;
+     }
+   return false;
+ }
+ #endif
+ 
  /* Output something to declare an external symbol to the assembler.
     (Most assemblers don't need this, so we normally output nothing.)
     Do nothing if DECL is not external.  */
*************** assemble_external (tree decl ATTRIBUTE_U
*** 1619,1625 ****
        rtx rtl = DECL_RTL (decl);
  
        if (GET_CODE (rtl) == MEM && GET_CODE (XEXP (rtl, 0)) == SYMBOL_REF
! 	  && ! SYMBOL_REF_USED (XEXP (rtl, 0)))
  	{
  	  /* Some systems do require some output.  */
  	  SYMBOL_REF_USED (XEXP (rtl, 0)) = 1;
--- 1645,1652 ----
        rtx rtl = DECL_RTL (decl);
  
        if (GET_CODE (rtl) == MEM && GET_CODE (XEXP (rtl, 0)) == SYMBOL_REF
! 	  && !SYMBOL_REF_USED (XEXP (rtl, 0))
! 	  && !incorporeal_function_p (decl))
  	{
  	  /* Some systems do require some output.  */
  	  SYMBOL_REF_USED (XEXP (rtl, 0)) = 1;
Index: config/mips/mips.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/mips/mips.c,v
retrieving revision 1.347
diff -u -p -F^\([(a-zA-Z0-9_]\|#define\) -r1.347 mips.c
--- config/mips/mips.c	2 Dec 2003 22:30:28 -0000	1.347
+++ config/mips/mips.c	3 Dec 2003 22:12:08 -0000
@@ -5564,9 +5564,7 @@ mips_output_external (FILE *file ATTRIBU
       extern_head = p;
     }
 
-  if (TARGET_IRIX && mips_abi == ABI_32
-      && TREE_CODE (decl) == FUNCTION_DECL
-      && !DECL_BUILT_IN (decl))
+  if (TARGET_IRIX && mips_abi == ABI_32 && TREE_CODE (decl) == FUNCTION_DECL)
     {
       p = (struct extern_list *) ggc_alloc (sizeof (struct extern_list));
       p->next = extern_head;