rs6000 -fdata-sections

[Alan Modra <amodra at bigpond dot net dot au>]

This simple testcase illustrates a problem with current powerpc-linux-gcc
on both mainline and branch.

$ cat static.c
const int a[10000] = {1, 2, };
$ powerpc-linux-gcc -O2 -ffunction-sections -fdata-sections -S static.c
$ cat static.s
        .file   "static.c"
        .globl  a
        .section        .sdata.a,"a",@progbits
        .align 2
        .type   a,@object
        .size   a,40000
a:
        .long   1
        .long   2
        .space  39992
        .ident  "GCC: (GNU) 3.0.3 20011127 (prerelease)"

'a' certainly shouldn't go into .sdata

The nub of the problem is that this expression

  sec = ((TREE_CODE (decl) == FUNCTION_DECL ? 0 : 1)
	 + (readonly ? 0 : 2) 
	 + (needs_sdata ? 1 : 0)
	 + (DECL_INITIAL (decl) == 0
	    || DECL_INITIAL (decl) == error_mark_node) ? 4 : 0);

is missing parentheses around the last term, but I didn't find that until
I'd simplified things as in the following patch.  At least in my opinion
it's simpler and gcc seems to agree, generating smaller and likely faster
code.

	* config/rs6000/rs6000.c (rs6000_unique_section): Simplify and
	correct code selecting section.

OK for mainline and branch?  Or should I just fix the missing parens on
the branch?

Oh yeah, bootstrapping powerpc-linux at the moment.

-- 
Alan Modra

*** gcc/config/rs6000/rs6000.c~	Tue Dec  4 07:49:51 2001
--- gcc/config/rs6000/rs6000.c	Tue Dec  4 15:03:53 2001
*************** rs6000_unique_section (decl, reloc)
*** 9451,9504 ****
       tree decl;
       int reloc;
  {
!   int size = int_size_in_bytes (TREE_TYPE (decl));
!   int needs_sdata;
!   int readonly;
    int len;
    int sec;
    const char *name;
    char *string;
    const char *prefix;
  
!   static const char *const prefixes[7][2] =
    {
!     { ".text.",   ".gnu.linkonce.t." },
!     { ".rodata.", ".gnu.linkonce.r." },
!     { ".sdata2.", ".gnu.linkonce.s2." },
!     { ".data.",   ".gnu.linkonce.d." },
!     { ".sdata.",  ".gnu.linkonce.s." },
!     { ".bss.",    ".gnu.linkonce.b." },
!     { ".sbss.",   ".gnu.linkonce.sb." }
    };
-   
-   needs_sdata = (TREE_CODE (decl) != FUNCTION_DECL
- 		 && size > 0 
- 		 && size <= g_switch_value
- 		 && rs6000_sdata != SDATA_NONE
- 		 && (rs6000_sdata != SDATA_DATA || TREE_PUBLIC (decl)));
  
!   if (TREE_CODE (decl) == STRING_CST)
!     readonly = ! flag_writable_strings;
!   else if (TREE_CODE (decl) == VAR_DECL)
!     readonly = (! (flag_pic && reloc)
! 		&& TREE_READONLY (decl)
! 		&& ! TREE_SIDE_EFFECTS (decl)
! 		&& DECL_INITIAL (decl)
! 		&& DECL_INITIAL (decl) != error_mark_node
! 		&& TREE_CONSTANT (DECL_INITIAL (decl)));
    else
!     readonly = 1;
!   if (needs_sdata && rs6000_sdata != SDATA_EABI)
!     readonly = 0;
  
!   sec = ((TREE_CODE (decl) == FUNCTION_DECL ? 0 : 1)
! 	 + (readonly ? 0 : 2) 
! 	 + (needs_sdata ? 1 : 0)
! 	 + (DECL_INITIAL (decl) == 0
! 	    || DECL_INITIAL (decl) == error_mark_node) ? 4 : 0);
  
    STRIP_NAME_ENCODING (name, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
!   prefix = prefixes[sec][DECL_ONE_ONLY (decl)];
    len    = strlen (name) + strlen (prefix);
    string = alloca (len + 1);
    
--- 9451,9509 ----
       tree decl;
       int reloc;
  {
!   int size;
    int len;
    int sec;
    const char *name;
    char *string;
    const char *prefix;
  
!   static const char *const prefixes[14] =
    {
!     ".rodata.", ".gnu.linkonce.r.",
!     ".sdata2.", ".gnu.linkonce.s2.",
!     ".data.",   ".gnu.linkonce.d.",
!     ".sdata.",  ".gnu.linkonce.s.",
!     ".bss.",    ".gnu.linkonce.b.",
!     ".sbss.",   ".gnu.linkonce.sb.",
!     ".text.",   ".gnu.linkonce.t."
    };
  
!   if (TREE_CODE (decl) == FUNCTION_DECL)
!     sec = 12;
    else
!     {
!       if (DECL_INITIAL (decl) == 0
! 	  || DECL_INITIAL (decl) == error_mark_node)
! 	sec = 8;
!       else if ((TREE_CODE (decl) == STRING_CST
! 		&& flag_writable_strings)
! 	       || (TREE_CODE (decl) == VAR_DECL
! 		   && ((flag_pic && reloc)
! 		       || ! TREE_READONLY (decl)
! 		       || TREE_SIDE_EFFECTS (decl)
! 		       || ! TREE_CONSTANT (DECL_INITIAL (decl)))))
! 	sec = 4;
!       else
! 	sec = 0;
  
!       size = int_size_in_bytes (TREE_TYPE (decl));
!       if (size > 0 
! 	  && size <= g_switch_value
! 	  && rs6000_sdata != SDATA_NONE
! 	  && (rs6000_sdata != SDATA_DATA || TREE_PUBLIC (decl)))
! 	{
! 	  if (sec == 0 && rs6000_sdata != SDATA_EABI)
! 	    sec = 4;
! 	  sec += 2;
! 	}
!     }
! 
!   if (DECL_ONE_ONLY (decl))
!     sec += 1;
  
    STRIP_NAME_ENCODING (name, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
!   prefix = prefixes[sec];
    len    = strlen (name) + strlen (prefix);
    string = alloca (len + 1);