Fix use of section encoding info on Darwin

[Stan Shebs]

I've checked in a rewrite of Darwin section encoding to fix the many
bugs noticed by rth (and no, there wasn't anybody else trying to
modify the result of ggc_alloc_string).  Bootstrapped and tested on
powerpc-apple-darwin1.3.3, committed to mainline only.

Stan

2001-06-11  Stan Shebs  <shebs@apple.com>

	* darwin.c (darwin_encode_section_info):  Rewrite to simplify
	and fix coding mistakes.

Index: config/darwin.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/darwin.c,v
retrieving revision 1.2
diff -c -3 -p -r1.2 darwin.c
*** darwin.c	2001/06/08 02:28:04	1.2
--- darwin.c	2001/06/11 18:51:18
*************** darwin_encode_section_info (decl)
*** 1001,1006 ****
--- 1001,1009 ----
  {
    char code = '\0';
    int defined = 0;
+   rtx sym_ref;
+   char *orig_str, *new_str;
+   size_t len, new_len;
  
    if ((TREE_CODE (decl) == FUNCTION_DECL
         || TREE_CODE (decl) == VAR_DECL)
*************** darwin_encode_section_info (decl)
*** 1014,1043 ****
    else if (TREE_CODE (decl) == VAR_DECL)
      code = (defined ? 'D' : 'd');
  
!   if (code != '\0')
!     {
!       rtx sym_ref = XEXP (DECL_RTL (decl), 0);
! 
!       if (*(XSTR (sym_ref, 0)) == '!')
! 	{
! 	  (XSTR(sym_ref, 0))[1] = code;
! 	  update_non_lazy_ptrs (XSTR (sym_ref, 0));
! 	  return;
! 	}
! 
!       {
! 	size_t len = strlen (XSTR (sym_ref, 0));
! 	size_t newlen = len + 4;
! 	char *str = alloca (newlen);
  
! 	str[0] = '!';
! 	str[1] = code;
! 	str[2] = '_';
! 	str[3] = '_';
! 	memcpy (str + 4, XSTR (sym_ref, 0), len + 1);
  
! 	XSTR (sym_ref, 0) = ggc_alloc_string (str, newlen);
!       }
      }
  }
  
--- 1017,1054 ----
    else if (TREE_CODE (decl) == VAR_DECL)
      code = (defined ? 'D' : 'd');
  
!   if (code == '\0')
!     return;
  
!   sym_ref = XEXP (DECL_RTL (decl), 0);
!   orig_str = XSTR (sym_ref, 0);
!   len = strlen (orig_str) + 1;
  
!   if (orig_str[0] == '!')
!     {
!       /* Already encoded; see if we need to change it.  */
!       if (code == orig_str[1])
! 	return;
!       /* Yes, tweak a copy of the name and put it in a new string.  */
!       new_str = alloca (len);
!       memcpy (new_str, orig_str, len);
!       new_str[1] = code;
!       XSTR (sym_ref, 0) = ggc_alloc_string (new_str, len);
!       /* The non-lazy pointer list may have captured references to the
! 	 old encoded name, change them.  */
!       update_non_lazy_ptrs (XSTR (sym_ref, 0));
!     }
!   else
!     {
!       /* Add the encoding.  */
!       new_len = len + 4;
!       new_str = alloca (new_len);
!       new_str[0] = '!';
!       new_str[1] = code;
!       new_str[2] = '_';
!       new_str[3] = '_';
!       memcpy (new_str + 4, orig_str, len);
!       XSTR (sym_ref, 0) = ggc_alloc_string (new_str, new_len);
      }
  }