PATCH: Darwin pragmas and pragma doc, rev 2

[Stan Shebs <shebs at apple dot com>]

OK, this version incorporates all suggestions (I think), bootstraps
with powerpc-apple-darwin1.3, etc.  I've tested the manual addition
with "make info" but not "make dvi" because I don't have the right
bits here right now, but I won't commit it until it's been checked.

As a special bonus :-), I added a subsection for the ARM pragmas,
but there are six other architectures with target-specific pragmas
that somebody needs to describe.  Probably worthwhile to have
an additional subsection for #pragma weak and #pragma pack, they're
hinted at in several places but not formally described anywhere.

Stan

2001-06-27  Stan Shebs  <shebs@apple.com>

        * config/darwin.h (REGISTER_TARGET_PRAGMAS): Define.
        * config/darwin-c.c: New file.
        * config/darwin-protos.h: Declare new functions.
        * config/rs6000/t-darwin (darwin-c.o): New rule.
        * config.gcc (powerpc-*-darwin*): Define c_target_objs and
        cxx_target_objs.
        * doc/extend.texi (Pragmas): New section.


2001-06-27  Stan Shebs  <shebs@apple.com>

        * gcc.dg/pragma-darwin.c: New test.

Index: config.gcc
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config.gcc,v
retrieving revision 1.69
diff -c -3 -p -r1.69 config.gcc
*** config.gcc	2001/06/26 03:50:47	1.69
--- config.gcc	2001/06/27 20:56:16
*************** powerpc-*-darwin*)
*** 2569,2574 ****
--- 2569,2576 ----
  	# fixed and we can get rid of this silliness.
  	xm_defines="HAVE_DESIGNATED_INITIALIZERS=0"
  	extra_objs="darwin.o"
+ 	c_target_objs="darwin-c.o"
+ 	cxx_target_objs="darwin-c.o"
  	# Darwin linker does collect2 functionality
  	use_collect2=no
  	;;
Index: doc/extend.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/extend.texi,v
retrieving revision 1.12
diff -c -3 -p -r1.12 extend.texi
*** extend.texi	2001/06/27 15:04:15	1.12
--- extend.texi	2001/06/27 20:56:17
*************** extensions, accepted by GCC in C89 mode 
*** 73,78 ****
--- 73,79 ----
  			 function.
  * Return Address::      Getting the return or frame address of a function.
  * Other Builtins::      Other built-in functions.
+ * Pragmas::             Pragmas accepted by GCC.
  @end menu
  @end ifset
  @ifclear INTERNALS
*************** extensions, accepted by GCC in C89 mode 
*** 125,130 ****
--- 126,132 ----
  			 function.
  * Return Address::      Getting the return or frame address of a function.
  * Other Builtins::      Other built-in functions.
+ * Pragmas::             Pragmas accepted by GCC.
  @end menu
  @end ifclear
  
*************** if (__builtin_expect (ptr != NULL, 1))
*** 3908,3913 ****
--- 3910,3992 ----
  @noindent
  when testing pointer or floating-point values.
  @end deftypefn
+ 
+ @node Pragmas
+ @section Pragmas Accepted by GCC
+ @cindex pragmas
+ @cindex #pragma
+ 
+ GCC supports several types of pragmas, primarily in order to compile
+ code originally written for other compilers.  Note that in general
+ we do not recommend the use of pragmas; @xref{Function Attributes},
+ for further explanation.
+ 
+ @menu
+ * ARM Pragmas::
+ * Darwin Pragmas::
+ @end menu
+ 
+ @node ARM Pragmas
+ @subsection ARM Pragmas
+ 
+ The ARM target defines pragmas for controlling the default addition of
+ @code{long_call} and @code{short_call} attributes to functions.
+ @xref{Function Attributes}, for information about the effects of these
+ attributes.
+ 
+ @table @code
+ @item long_calls
+ @cindex pragma, long_calls
+ Set all subsequent functions to have the @code{long_call} attribute.
+ 
+ @item no_long_calls
+ @cindex pragma, no_long_calls
+ Set all subsequent functions to have the @code{short_call} attribute.
+ 
+ @item long_calls_off
+ @cindex pragma, long_calls_off
+ Do not affect the @code{long_call} or @code{short_call} attributes of
+ subsequent functions.
+ @end table
+ 
+ @c Describe c4x pragmas here.
+ @c Describe h8300 pragmas here.
+ @c Describe i370 pragmas here.
+ @c Describe i960 pragmas here.
+ @c Describe sh pragmas here.
+ @c Describe v850 pragmas here.
+ 
+ @node Darwin Pragmas
+ @subsection Darwin Pragmas
+ 
+ The following pragmas are available for all architectures running the
+ Darwin operating system.  These are useful for compatibility with other
+ MacOS compilers.
+ 
+ @table @code
+ @item mark @var{tokens}@dots{}
+ @cindex pragma, mark
+ This pragma is accepted, but has no effect.
+ 
+ @item options align=@var{alignment}
+ @cindex pragma, options align
+ This pragma sets the alignment of fields in structures.  The values of
+ @var{alignment} may be @code{mac68k}, to emulate m68k alignment, or
+ @code{power}, to emulate PowerPC alignment.  Uses of this pragma nest
+ properly; to restore the previous setting, use @code{reset} for the
+ @var{alignment}.
+ 
+ @item segment @var{tokens}@dots{}
+ @cindex pragma, segment
+ This pragma is accepted, but has no effect.
+ 
+ @item unused (@var{var} [, @var{var}]@dots{})
+ @cindex pragma, unused
+ This pragma declares a variable to be possibly unused.  GCC will not
+ produce a warning for this variable.  The effect is similar to that
+ of the unused attribute, except that this pragma may appear anywhere
+ within the variable's scope.
+ @end table
  
  @node C++ Extensions
  @chapter Extensions to the C++ Language
Index: config/darwin-c.c
===================================================================
RCS file: darwin-c.c
diff -N darwin-c.c
*** /dev/null	Tue May  5 13:32:27 1998
--- darwin-c.c	Wed Jun 27 13:56:17 2001
***************
*** 0 ****
--- 1,153 ----
+ /* Darwin support needed only by C/C++ frontends.
+    Copyright (C) 2001
+    Free Software Foundation, Inc.
+    Contributed by Apple Computer Inc.
+ 
+ This file is part of GNU CC.
+ 
+ GNU CC is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+ 
+ GNU CC is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+ 
+ You should have received a copy of the GNU General Public License
+ along with GNU CC; see the file COPYING.  If not, write to
+ the Free Software Foundation, 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.  */
+ 
+ #include "config.h"
+ #include "system.h"
+ #include "cpplib.h"
+ #include "tree.h"
+ #include "c-pragma.h"
+ #include "c-lex.h"
+ #include "c-tree.h"
+ #include "toplev.h"
+ #include "tm_p.h"
+ 
+ /* Pragmas.  */
+ 
+ #define BAD(msgid) do { warning (msgid); return; } while (0)
+ 
+ /* Maintain a small stack of alignments.  This is similar to pragma
+    pack's stack, but simpler.  */
+ 
+ static void push_field_alignment PARAMS ((int));
+ static void pop_field_alignment PARAMS ((void));
+ 
+ typedef struct align_stack
+ {
+   int alignment;
+   struct align_stack * prev;
+ } align_stack;
+ 
+ static struct align_stack * field_align_stack = NULL;
+ 
+ static void
+ push_field_alignment (bit_alignment)
+      int bit_alignment;
+ {
+   align_stack *entry = (align_stack *) xmalloc (sizeof (align_stack));
+ 
+   entry->alignment = maximum_field_alignment;
+   entry->prev = field_align_stack;
+   field_align_stack = entry;
+ 
+   maximum_field_alignment = bit_alignment;
+ }
+ 
+ static void
+ pop_field_alignment ()
+ {
+   if (field_align_stack)
+     {
+       align_stack *entry = field_align_stack;
+ 
+       maximum_field_alignment = entry->alignment;
+       field_align_stack = entry->prev;
+       free (entry);
+     }
+   else
+     error ("too many #pragma options align=reset");
+ }
+ 
+ /* Handlers for Darwin-specific pragmas.  */
+ 
+ void
+ darwin_pragma_ignore (pfile)
+      cpp_reader *pfile ATTRIBUTE_UNUSED;
+ {
+   /* Do nothing.  */
+ }
+ 
+ /* #pragma options align={mac68k|power|reset} */
+ 
+ void
+ darwin_pragma_options (pfile)
+      cpp_reader *pfile ATTRIBUTE_UNUSED;
+ {
+   char *arg;
+   tree t, x;
+ 
+   if (c_lex (&t) != CPP_NAME)
+     BAD ("malformed '#pragma options', ignoring");
+   arg = IDENTIFIER_POINTER (t);
+   if (strcmp (arg, "align"))
+     BAD ("malformed '#pragma options', ignoring");
+   if (c_lex (&t) != CPP_EQ)
+     BAD ("malformed '#pragma options', ignoring");
+   if (c_lex (&t) != CPP_NAME)
+     BAD ("malformed '#pragma options', ignoring");
+ 
+   if (c_lex (&x) != CPP_EOF)
+     warning ("junk at end of '#pragma options'");
+ 
+   arg = IDENTIFIER_POINTER (t);
+   if (!strcmp (arg, "mac68k"))
+     push_field_alignment (16);
+   else if (!strcmp (arg, "power"))
+     push_field_alignment (0);
+   else if (!strcmp (arg, "reset"))
+     pop_field_alignment ();
+   else
+     warning ("malformed '#pragma options align={mac68k|power|reset}', ignoring");
+ }
+ 
+ /* #pragma unused ([var {, var}*]) */
+ 
+ void
+ darwin_pragma_unused (pfile)
+      cpp_reader *pfile ATTRIBUTE_UNUSED;
+ {
+   tree decl, x;
+   int tok;
+ 
+   if (c_lex (&x) != CPP_OPEN_PAREN)
+     BAD ("missing '(' after '#pragma unused', ignoring");
+ 
+   while (1)
+     {
+       tok = c_lex (&decl);
+       if (tok == CPP_NAME && decl)
+ 	{
+ 	  tree local = IDENTIFIER_LOCAL_VALUE (decl);
+ 	  if (local && (TREE_CODE (local) == PARM_DECL
+ 			|| TREE_CODE (local) == VAR_DECL))
+ 	    TREE_USED (local) = 1;
+ 	  tok = c_lex (&x);
+ 	  if (tok != CPP_COMMA)
+ 	    break;
+ 	}
+     }
+ 
+   if (tok != CPP_CLOSE_PAREN)
+     BAD ("missing ')' after '#pragma unused', ignoring");
+ 
+   if (c_lex (&x) != CPP_EOF)
+     warning ("junk at end of '#pragma unused'");
+ }
Index: config/darwin-protos.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/darwin-protos.h,v
retrieving revision 1.2
diff -c -3 -p -r1.2 darwin-protos.h
*** darwin-protos.h	2001/06/08 02:28:04	1.2
--- darwin-protos.h	2001/06/27 20:56:17
*************** extern void darwin_encode_section_info P
*** 56,58 ****
--- 56,65 ----
  #endif /* TREE_CODE */
  
  extern void machopic_finish PARAMS ((FILE *));
+ 
+ #ifdef GCC_C_PRAGMA_H
+ extern void darwin_init_pragma PARAMS ((int (*) (tree *)));
+ extern void darwin_pragma_ignore PARAMS ((cpp_reader *));
+ extern void darwin_pragma_options PARAMS ((cpp_reader *));
+ extern void darwin_pragma_unused PARAMS ((cpp_reader *));
+ #endif
Index: config/darwin.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/darwin.h,v
retrieving revision 1.6
diff -c -3 -p -r1.6 darwin.h
*** darwin.h	2001/06/12 00:27:31	1.6
--- darwin.h	2001/06/27 20:56:17
*************** enum machopic_addr_class {
*** 780,782 ****
--- 780,789 ----
        }								\
    } while (0)
  
+ #define REGISTER_TARGET_PRAGMAS(PFILE)                          \
+   do {                                                          \
+     cpp_register_pragma (PFILE, 0, "mark", darwin_pragma_ignore);  \
+     cpp_register_pragma (PFILE, 0, "options", darwin_pragma_options);  \
+     cpp_register_pragma (PFILE, 0, "segment", darwin_pragma_ignore);  \
+     cpp_register_pragma (PFILE, 0, "unused", darwin_pragma_unused);  \
+   } while (0)
Index: config/rs6000/t-darwin
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/t-darwin,v
retrieving revision 1.3
diff -c -3 -p -r1.3 t-darwin
*** t-darwin	2001/05/25 19:50:50	1.3
--- t-darwin	2001/06/27 20:56:18
*************** fp-bit.c: $(srcdir)/config/fp-bit.c
*** 12,20 ****
  
  darwin.o: $(srcdir)/config/darwin.c $(CONFIG_H) $(SYSTEM_H) $(RTL_BASE_H) \
            $(REGS_H) hard-reg-set.h insn-config.h conditions.h output.h \
!           insn-attr.h flags.h $(TREE_H) $(EXPR_H) reload.h $(C_TREE_H) \
            function.h $(GGC_H) $(TM_P_H)
! 	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $(srcdir)/config/darwin.c
  
  # Build the libraries for both hard and soft floating point
  
--- 12,25 ----
  
  darwin.o: $(srcdir)/config/darwin.c $(CONFIG_H) $(SYSTEM_H) $(RTL_BASE_H) \
            $(REGS_H) hard-reg-set.h insn-config.h conditions.h output.h \
!           insn-attr.h flags.h $(TREE_H) $(EXPR_H) reload.h \
            function.h $(GGC_H) $(TM_P_H)
! 	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<
! 
! darwin-c.o: $(srcdir)/config/darwin-c.c $(CONFIG_H) $(SYSTEM_H) \
! 	    $(TREE_H) $(C_TREE_H) c-lex.h c-pragma.h toplev.h cpplib.h \
! 	    $(TM_P_H)
! 	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<
  
  # Build the libraries for both hard and soft floating point
  
Index: testsuite/gcc.dg/pragma-darwin.c
===================================================================
RCS file: pragma-darwin.c
diff -N pragma-darwin.c
*** /dev/null	Tue May  5 13:32:27 1998
--- pragma-darwin.c	Wed Jun 27 13:56:19 2001
***************
*** 0 ****
--- 1,59 ----
+ /* Darwin (Mac OS X) pragma exercises.  */
+ 
+ /* { dg-do run { target powerpc-*-darwin* } } */
+ /* { dg-options "-O -Wunused" } */
+ 
+ /* The mark pragma is to help decorate IDEs.  */
+ 
+ #pragma mark hey hey ho
+ 
+ /* The options pragma used to do a lot, now it's only for emulating
+    m68k alignment rules in structs.  */
+ 
+ #pragma options 23  /* { dg-error "malformed '#pragma options'" } */
+ #pragma options align  /* { dg-error "malformed '#pragma options'" } */
+ #pragma options align mac68k /* { dg-error "malformed '#pragma options'" } */
+ #pragma options align=45 /* { dg-error "malformed '#pragma options'" } */
+ #pragma options align=foo /* { dg-error "malformed '#pragma options align" } */
+ 
+ #pragma options align=mac68k
+ struct s1 { short f1; int f2; };
+ #pragma options align=power
+ struct s2 { short f1; int f2; };
+ #pragma options align=mac68k
+ struct s3 { short f1; int f2; };
+ #pragma options align=reset
+ struct s4 { short f1; int f2; };
+ 
+ #pragma options align=mac68k foo /* { dg-warning "junk at end of '#pragma options'" } */
+ 
+ /* Segment pragmas don't do anything anymore.  */
+ 
+ #pragma segment foo
+ 
+ int
+ main ()
+ {
+   int x, z;  /* { dg-warning "unused variable" } */
+   #pragma unused (x, y)
+ 
+   if (sizeof (struct s1) != 6)
+     abort ();
+   if (sizeof (struct s2) != 8)
+     abort ();
+   if (sizeof (struct s3) != 6)
+     abort ();
+   if (sizeof (struct s4) != 8)
+     abort ();
+   return 0;
+ }
+ 
+ void
+ unused_err_test ()
+ {
+   int a, b;
+   /* Trying to match on '(' or ')' gives regexp headaches, use . instead.  */
+ #pragma unused  /* { dg-error "missing '.' after '#pragma unused" } */
+ #pragma unused (a  /* { dg-error "missing '.' after '#pragma unused" } */
+ #pragma unused (b) foo /* { dg-warning "junk at end of '#pragma unused'" } */
+ }