[patch] Provide a target macro that allows unmodified LIBGCC_SPEC

[Matt Austern <austern at apple dot com>]

As I pointed out in an earlier message: at present, if 
ENABLE_SHARED_LIBGCC is defined, the compiler unconditionally mungs 
whatever LIBGCC_SPEC the target provides.  I find this very 
unfortunate: a target that defines a nondefault LIBGCC_SPEC probably 
has a good reason for it, and the complicated modifications we get 
init_gcc_specs and init_spec are likely to conflict with special target 
needs.  (Conjecture: this is already causing bugs, but nobody has 
noticed because the bugs only come up in unusual combinations of 
flags.)

This is somewhere between a workaround and a fix.  I don't know what 
LIBGCC_SPEC should be like on every target out there, and I don't know 
which targets should and shouldn't use the init_gcc_specs munging.  So 
instead all I'm doing is providing a mechanism that allows a target to 
provide a version of LIBGCC_SPEC.  I admit that this isn't a very clean 
solution, but I think it's the best we can do given where we are now.

Testing: bootstrapped on OS X, verified that this didn't interfere with 
the default libgcc spec.

OK to commit to mainline?

			--Matt

Index: gcc/gcc.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/gcc.c,v
retrieving revision 1.405
diff -p -r1.405 gcc.c
*** gcc/gcc.c	24 Jan 2004 10:09:48 -0000	1.405
--- gcc/gcc.c	15 Feb 2004 17:19:34 -0000
*************** static int execute (void);
*** 345,351 ****
  static void alloc_args (void);
  static void clear_args (void);
  static void fatal_error (int);
! #ifdef ENABLE_SHARED_LIBGCC
  static void init_gcc_specs (struct obstack *, const char *, const 
char *,
  			    const char *);
  #endif
--- 345,351 ----
  static void alloc_args (void);
  static void clear_args (void);
  static void fatal_error (int);
! #if defined(ENABLE_SHARED_LIBGCC) && !defined(REAL_LIBGCC_SPEC)
  static void init_gcc_specs (struct obstack *, const char *, const 
char *,
  			    const char *);
  #endif
*************** proper position among the other output f
*** 598,604 ****
  /* config.h can define LIBGCC_SPEC to override how and when libgcc.a 
is
     included.  */
  #ifndef LIBGCC_SPEC
! #if defined(LINK_LIBGCC_SPECIAL) || defined(LINK_LIBGCC_SPECIAL_1)
  /* Have gcc do the search for libgcc.a.  */
  #define LIBGCC_SPEC "libgcc.a%s"
  #else
--- 598,606 ----
  /* config.h can define LIBGCC_SPEC to override how and when libgcc.a 
is
     included.  */
  #ifndef LIBGCC_SPEC
! #if defined(REAL_LIBGCC_SPEC)
! #define LIBGCC_SPEC REAL_LIBGCC_SPEC
! #elif defined(LINK_LIBGCC_SPECIAL) || defined(LINK_LIBGCC_SPECIAL_1)
  /* Have gcc do the search for libgcc.a.  */
  #define LIBGCC_SPEC "libgcc.a%s"
  #else
*************** static int processing_spec_function;
*** 1522,1528 ****
  /* Add appropriate libgcc specs to OBSTACK, taking into account
     various permutations of -shared-libgcc, -shared, and such.  */

! #ifdef ENABLE_SHARED_LIBGCC
  static void
  init_gcc_specs (struct obstack *obstack, const char *shared_name,
  		const char *static_name, const char *eh_name)
--- 1524,1530 ----
  /* Add appropriate libgcc specs to OBSTACK, taking into account
     various permutations of -shared-libgcc, -shared, and such.  */

! #if defined(ENABLE_SHARED_LIBGCC) && !defined(REAL_LIBGCC_SPEC)
  static void
  init_gcc_specs (struct obstack *obstack, const char *shared_name,
  		const char *static_name, const char *eh_name)
*************** init_spec (void)
*** 1589,1595 ****
        next = sl;
      }

! #ifdef ENABLE_SHARED_LIBGCC
    /* ??? If neither -shared-libgcc nor --static-libgcc was
       seen, then we should be making an educated guess.  Some proposed
       heuristics for ELF include:
--- 1591,1597 ----
        next = sl;
      }

! #if defined(ENABLE_SHARED_LIBGCC) && !defined(REAL_LIBGCC_SPEC)
    /* ??? If neither -shared-libgcc nor --static-libgcc was
       seen, then we should be making an educated guess.  Some proposed
       heuristics for ELF include:
Index: gcc/doc/tm.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/tm.texi,v
retrieving revision 1.297
diff -p -r1.297 tm.texi
*** gcc/doc/tm.texi	8 Feb 2004 23:08:48 -0000	1.297
--- gcc/doc/tm.texi	15 Feb 2004 17:20:11 -0000
*************** If this macro is not defined, the GCC dr
*** 293,298 ****
--- 293,310 ----
  passes the string @option{-lgcc} to the linker.
  @end defmac

+ @defmac REAL_LIBGCC_SPEC
+ By default, if @code{ENABLE_SHARED_LIBGCC} is defined, the
+ @code{LIBGCC_SPEC} is not directly used by the driver program but is
+ instead modified to refer to different versions of @file{libgcc.a}
+ depending on the values of the command line flags @code{-static},
+ @code{-shared}, @code{-static-libgcc}, and @code{-shared-libgcc}.  On
+ targets where these modifications are inappropriate, define
+ @code{REAL_LIBGCC_SPEC} instead.  @code{REAL_LIBGCC_SPEC} tells the
+ driver how to place a reference to @file{libgcc} on the link command
+ line, but, unlike @code{LIBGCC_SPEC}, it is used unmodified.
+ @end defmac
+
  @defmac STARTFILE_SPEC
  Another C string constant used much like @code{LINK_SPEC}.  The
  difference between the two is that @code{STARTFILE_SPEC} is used at