Many changes, most related to creating entry point information on a per-objfile

basis.  See comments in objfiles.h and details in ChangeLog.  Also remove
redundant definitions of FRAME_CHAIN_VALID from most of the tm-* files and
use a default definition in frame.h.

1 files changed, 313 insertions, 0 deletions

diff --git a/gdb/objfiles.h b/gdb/objfiles.h
new file mode 100644
index 0000000000..8efaa93e11
--- /dev/null
+++ b/gdb/objfiles.h
@@ -0,0 +1,313 @@
+/* Definitions for symbol file management in GDB.
+   Copyright (C) 1992 Free Software Foundation, Inc.
+
+This file is part of GDB.
+
+This program 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 of the License, or
+(at your option) any later version.
+
+This program 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 this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#if !defined (OBJFILES_H)
+#define OBJFILES_H
+
+/* This structure maintains information on a per-objfile basis about the
+   "entry point" of the objfile, and the scope within which the entry point
+   exists.  It is possible that gdb will see more than one objfile that is
+   executable, each with it's own entry point.
+
+   For example, for dynamically linked executables in SVR4, the dynamic linker
+   code is contained within the shared C library, which is actually executable
+   and is run by the kernel first when an exec is done of a user executable
+   that is dynamically linked.  The dynamic linker within the shared C library
+   then maps in the various program segments in the user executable and jumps
+   to the user executable's recorded entry point, as if the call had been made
+   directly by the kernel.
+
+   The traditional gdb method of using this info is to use the recorded entry
+   point to set the variables entry_file_lowpc and entry_file_highpc from
+   the debugging information, where these values are the starting address
+   (inclusive) and ending address (exclusive) of the instruction space in the
+   executable which correspond to the "startup file", I.E. crt0.o in most
+   cases.  This file is assumed to be a startup file and frames with pc's
+   inside it are treated as nonexistent.  Setting these variables is necessary
+   so that backtraces do not fly off the bottom of the stack (or top, depending
+   upon your stack orientation).
+
+   Gdb also supports an alternate method to avoid running off the top/bottom
+   of the stack.
+
+   There are two frames that are "special", the frame for the function
+   containing the process entry point, since it has no predecessor frame,
+   and the frame for the function containing the user code entry point
+   (the main() function), since all the predecessor frames are for the
+   process startup code.  Since we have no guarantee that the linked
+   in startup modules have any debugging information that gdb can use,
+   we need to avoid following frame pointers back into frames that might
+   have been built in the startup code, as we might get hopelessly 
+   confused.  However, we almost always have debugging information
+   available for main().
+
+   These variables are used to save the range of PC values which are valid
+   within the main() function and within the function containing the process
+   entry point.  If we always consider the frame for main() as the outermost
+   frame when debugging user code, and the frame for the process entry
+   point function as the outermost frame when debugging startup code, then
+   all we have to do is have FRAME_CHAIN_VALID return false whenever a
+   frame's current PC is within the range specified by these variables.
+   In essence, we set "ceilings" in the frame chain beyond which we will
+   not proceed when following the frame chain back up the stack.
+
+   A nice side effect is that we can still debug startup code without
+   running off the end of the frame chain, assuming that we have usable
+   debugging information in the startup modules, and if we choose to not
+   use the block at main, or can't find it for some reason, everything
+   still works as before.  And if we have no startup code debugging
+   information but we do have usable information for main(), backtraces
+   from user code don't go wandering off into the startup code.
+
+   To use this method, define your FRAME_CHAIN_VALID macro like:
+
+	#define FRAME_CHAIN_VALID(chain, thisframe)     \
+	  (chain != 0                                   \
+	   && !(inside_main_func ((thisframe)->pc))     \
+	   && !(inside_entry_func ((thisframe)->pc)))
+
+   and add initializations of the four scope controlling variables inside
+   the object file / debugging information processing modules.  */
+
+struct entry_info
+{
+  
+  /* The value we should use for this objects entry point.
+     The illegal/unknown value needs to be something other than 0, ~0
+     for instance, which is much less likely than 0. */
+
+  CORE_ADDR entry_point;
+
+  /* Start (inclusive) and end (exclusive) of function containing the
+     entry point. */
+
+  CORE_ADDR entry_func_lowpc;
+  CORE_ADDR entry_func_highpc;
+
+  /* Start (inclusive) and end (exclusive) of object file containing the
+     entry point. */
+  
+  CORE_ADDR entry_file_lowpc;
+  CORE_ADDR entry_file_highpc;
+
+  /* Start (inclusive) and end (exclusive) of the user code main() function. */
+
+  CORE_ADDR main_func_lowpc;
+  CORE_ADDR main_func_highpc;
+
+};
+
+
+/* Master structure for keeping track of each input file from which
+   gdb reads symbols.  One of these is allocated for each such file we
+   access, e.g. the exec_file, symbol_file, and any shared library object
+   files. */
+
+struct objfile
+{
+
+  /* All struct objfile's are chained together by their next pointers.
+     The global variable "object_files" points to the first link in this
+     chain. */
+
+  struct objfile *next;
+
+  /* The object file's name.  Malloc'd; free it if you free this struct.  */
+
+  char *name;
+
+  /* Some flag bits for this objfile. */
+
+  unsigned short flags;
+
+  /* Each objfile points to a linked list of symtabs derived from this file,
+     one symtab structure for each compilation unit (source file).  Each link
+     in the symtab list contains a backpointer to this objfile. */
+
+  struct symtab *symtabs;
+
+  /* Each objfile points to a linked list of partial symtabs derived from
+     this file, one partial symtab structure for each compilation unit
+     (source file). */
+
+  struct partial_symtab *psymtabs;
+
+  /* List of freed partial symtabs, available for re-use */
+
+  struct partial_symtab *free_psymtabs;
+
+  /* The object file's BFD.  Can be null, in which case bfd_open (name) and
+     put the result here.  */
+
+  bfd *obfd;
+
+  /* The modification timestamp of the object file, as of the last time
+     we read its symbols.  */
+
+  long mtime;
+
+  /* Obstacks to hold objects that should be freed when we load a new symbol
+     table from this object file. */
+
+  struct obstack psymbol_obstack;	/* Partial symbols */
+  struct obstack symbol_obstack;	/* Full symbols */
+  struct obstack type_obstack;		/* Types */
+
+  /* Vectors of all partial symbols read in from file.  The actual data
+     is stored in the psymbol_obstack. */
+
+  struct psymbol_allocation_list global_psymbols;
+  struct psymbol_allocation_list static_psymbols;
+
+  /* Each file contains a pointer to an array of minimal symbols for all
+     global symbols that are defined within the file.  The array is terminated
+     by a "null symbol", one that has a NULL pointer for the name and a zero
+     value for the address.  This makes it easy to walk through the array
+     when passed a pointer to somewhere in the middle of it.  There is also
+     a count of the number of symbols, which does include the terminating
+     null symbol.  The array itself, as well as all the data that it points
+     to, should be allocated on the symbol_obstack for this file. */
+
+  struct minimal_symbol *msymbols;
+  int minimal_symbol_count;
+
+  /* For object file formats which don't specify fundamental types, gdb
+     can create such types.  For now, it maintains a vector of pointers
+     to these internally created fundamental types on a per objfile basis,
+     however it really should ultimately keep them on a per-compilation-unit
+     basis, to account for linkage-units that consist of a number of
+     compilation units that may have different fundamental types, such as
+     linking C modules with ADA modules, or linking C modules that are
+     compiled with 32-bit ints with C modules that are compiled with 64-bit
+     ints (not inherently evil with a smarter linker). */
+
+  struct type **fundamental_types;
+
+  /* The mmalloc() malloc-descriptor for this objfile if we are using
+     the memory mapped malloc() package to manage storage for this objfile's
+     data.  NULL if we are not. */
+
+  PTR md;
+
+  /* Structure which keeps track of functions that manipulate objfile's
+     of the same type as this objfile.  I.E. the function to read partial
+     symbols for example.  Note that this structure is in statically
+     allocated memory, and is shared by all objfiles that use the
+     object module reader of this type. */
+
+  struct sym_fns *sf;
+
+  /* The per-objfile information about the entry point, the scope (file/func)
+     containing the entry point, and the scope of the user's main() func. */
+
+  struct entry_info ei;
+
+  /* Hook for information which is shared by sym_init and sym_read for
+     this objfile.  It is typically a pointer to malloc'd memory.  */
+
+  PTR sym_private;
+
+};
+
+/* Defines for the objfile flag word. */
+
+/* Gdb can arrange to allocate storage for all objects related to a
+   particular objfile in a designated section of it's address space,
+   managed at a low level by mmap() and using a special version of
+   malloc that handles malloc/free/realloc on top of the mmap() interface.
+   This allows the "internal gdb state" for a particular objfile to be
+   dumped to a gdb state file and subsequently reloaded at a later time. */
+
+#define OBJF_MAPPED	(1 << 0)	/* Objfile data is mmap'd */
+
+/* The object file that the main symbol table was loaded from (e.g. the
+   argument to the "symbol-file" or "file" command).  */
+
+extern struct objfile *symfile_objfile;
+
+/* When we need to allocate a new type, we need to know which type_obstack
+   to allocate the type on, since there is one for each objfile.  The places
+   where types are allocated are deeply buried in function call hierarchies
+   which know nothing about objfiles, so rather than trying to pass a
+   particular objfile down to them, we just do an end run around them and
+   set current_objfile to be whatever objfile we expect to be using at the
+   time types are being allocated.  For instance, when we start reading
+   symbols for a particular objfile, we set current_objfile to point to that
+   objfile, and when we are done, we set it back to NULL, to ensure that we
+   never put a type someplace other than where we are expecting to put it.
+   FIXME:  Maybe we should review the entire type handling system and
+   see if there is a better way to avoid this problem. */
+
+extern struct objfile *current_objfile;
+
+/* All known objfiles are kept in a linked list.  This points to the
+   root of this list. */
+
+extern struct objfile *object_files;
+
+/* Declarations for functions defined in objfiles.c */
+
+extern struct objfile *
+allocate_objfile PARAMS ((bfd *, int));
+
+extern void
+free_objfile PARAMS ((struct objfile *));
+
+extern void
+free_all_objfiles PARAMS ((void));
+
+extern int
+have_partial_symbols PARAMS ((void));
+
+extern int
+have_full_symbols PARAMS ((void));
+
+/* Functions for dealing with the minimal symbol table, really a misc
+   address<->symbol mapping for things we don't have debug symbols for.  */
+
+extern int
+have_minimal_symbols PARAMS ((void));
+
+extern PTR
+iterate_over_objfiles PARAMS ((PTR (*func) (struct objfile *,
+					    PTR arg1, PTR arg2, PTR arg3),
+			       PTR arg1, PTR arg2, PTR arg3));
+
+extern PTR
+iterate_over_symtabs PARAMS ((PTR (*func) (struct objfile *, struct symtab *,
+					   PTR arg1, PTR arg2, PTR arg3),
+			      PTR arg1, PTR arg2, PTR arg3));
+
+extern PTR 
+iterate_over_psymtabs PARAMS ((PTR (*func) (struct objfile *,
+					    struct partial_symtab *,
+					    PTR arg1, PTR arg2, PTR arg3),
+			       PTR arg1, PTR arg2, PTR arg3));
+
+
+/* Traverse all object files.  ALL_OBJFILES_SAFE works even if you delete
+   the objfile during the traversal.  */
+
+#define	ALL_OBJFILES(obj) \
+  for ((obj)=object_files; (obj)!=NULL; (obj)=(obj)->next)
+
+#define	ALL_OBJFILES_SAFE(obj,nxt) \
+  for ((obj)=object_files; (obj)!=NULL?((nxt)=(obj)->next,1):0; (obj)=(nxt))
+
+#endif	/* !defined (OBJFILES_H) */