Daniel Jacobowitz wrote:
> 
> Maybe there's some way we can avoid needing psymbols for types at all.
> But I think we need to have a real design and some documentation for
> it instead of just accidentally omitting them.
> 
Here is a revised patch I am suggesting. It does not completely eliminate the
need for psymbols for types, but does significantly reduce number of global type
symbols. I tried to explain in detail why is it possible and safe. Here is the 
explanation:

First the facts about the partial symbols:

1. add_partial_symbol
This function gets called during reading the partial symbol information to add a
partial_symbol to either global_list or static_list declared in struct objfile.
The following table lists partial symbol types and scope.

DW_TAG_		 Lang		Scope (DOMAIN,LOC)
subprogram	 Ada		global (VAR,BLOCK)
		 All other	global if ext or static	(VAR,BLOCK)
variable	 All		global if ext or static (VAR,STATIC)
typedef
base_type
subrange_type	 All		static (VAR,TYPEDEF)
namespace	 All		global (VAR,TYPEDEF)
class_type
interface_type
union_type
enumeration_type cplus,java	global (STRUCT,TYPEDEF)
		 cplus,java,ada	again to global (VAR,TYPEDEF)
enumerator	 cplus,java	global (VAR,CONST)
		 All other	static (VAR,CONST)

Note that psymbol types namespace, class_type, interface_type, union_type,
enumeration_type and enumerator, for c++ and java, always go to global list and
will always have address 0 (anything else wouldn't make sense).

2. add_psymbol_to_list
This function adds partial symbol first to bcache (objfile->psymbol_cache) and
then to objfile->global_psymbols or objfile->static_psymbols list, depending on
which one was passed in.
It gets called by add_partial_symbol function.

In this function we will add partial symbol to one of the lists; the partial
symbols will always have exactly the same order in which they were added. This
fact will be used when building partial symbol table which will use this list
and with offset and number of symbols determine which partial symbols "belong"
to it. The reason why partial symbol table needs to know about a symbol is to be
able to eventually load full symbols.

3. lookup_partial_symbol
Function looks up global or static list of objfile, but only subset of it
determined by partial symtab's offset and number of symbols. Returns partial
symbol found. This function is always called from a loop through all partial
symtabs (this fact is important).


When is a partial symbol really matched:

Now let's look at the partial symbols which are added only to global partial
symbol list: namespace, class_type, interface_type, union_type,
enumeration_type, enumerator. The partial symbol will contain names and no
address (it will be 0). Therefore, lookup_partial_symbol will always return the
first partial symbol table where the psymbol was found. Once the psymbol was
found, most probably full symbols will be loaded; once full symbols are loaded,
all subsequent lookups for a symbol will first find it in full symtab and will
never look for it in the partial symtab again. As a result, all but the first
addition of such partial symbol will never be found and are therefore redundant
and only take up time to qsort partial symbols within a partial symbol table.


The patch:

This revised patch adds global symbols only once to first partial symbol table 
where the symbol was encountered, but only for namespace,
class_type, interface_type, union_type, enumeration_type and enumerator partial
symbol types (for the last two, only for java and cplus).


2008-02-12  Aleksandar Ristovski  <aristovski@qnx.com>

	* bcache.c (bcache_data): Call bcache_added function.
	(bcache_added): New function name. Body of function bcache_data
	is used here with the addition of 'added' argument. The argument
	is optional and if specified, bcache_added returns 1 if the data
	was added and 0 if it was found in the hash.
	* bcache.h (bcache_added): New function.
	* dwarf2read.c (add_partial_symbol): Make call to
	new function add_psymbol_to_global_list for namespace, class_type,
	interface_type, union_type, enumeration_type and enumerator partial
	symbol types.
	* symfile.c (add_psymbol_to_bcache): New helper function, takes part of
	work from add_psymbol_to_list - initialises partial symbol and stashes
	it in objfile's cache.
	(append_psymbol_to_list): New helper function, takes other part of
	work from add_psymbol_to_list - adds partial symbol to the given list.
	(add_psymbol_to_list): Call helper functions instead of doing work
	here. Functionally, the function hasn't changed.
	(add_psymbol_to_global_list): New function, adds partial symbol to
	global list and does it only once per objfile.
	* symfile.h (add_psymbol_to_global_list): New function.