diff options
Diffstat (limited to 'gdb/symtab.h')
| -rw-r--r-- | gdb/symtab.h | 139 |
1 files changed, 87 insertions, 52 deletions
diff --git a/gdb/symtab.h b/gdb/symtab.h index cc30975..54d9731 100644 --- a/gdb/symtab.h +++ b/gdb/symtab.h @@ -35,24 +35,55 @@ struct blockvector; struct axs_value; struct agent_expr; -/* Don't do this; it means that if some .o's are compiled with GNU C - and some are not (easy to do accidentally the way we configure - things; also it is a pain to have to "make clean" every time you - want to switch compilers), then GDB dies a horrible death. */ -/* GNU C supports enums that are bitfields. Some compilers don't. */ -#if 0 && defined(__GNUC__) && !defined(BYTE_BITFIELD) -#define BYTE_BITFIELD :8; -#else -#define BYTE_BITFIELD /*nothing */ -#endif +/* Some of the structures in this file are space critical. + The space-critical structures are: + + struct general_symbol_info + struct symbol + struct partial_symbol + + These structures are layed out to encourage good packing. + They use ENUM_BITFIELD and short int fields, and they order the + structure members so that fields less than a word are next + to each other so they can be packed together. */ + +/* Rearranged: used ENUM_BITFIELD and rearranged field order in + all the space critical structures (plus struct minimal_symbol). + Memory usage dropped from 99360768 bytes to 90001408 bytes. + I measured this with before-and-after tests of + "HEAD-old-gdb -readnow HEAD-old-gdb" and + "HEAD-new-gdb -readnow HEAD-old-gdb" on native i686-pc-linux-gnu, + red hat linux 8, with LD_LIBRARY_PATH=/usr/lib/debug, + typing "maint space 1" at the first command prompt. + + Here is another measurement (from andrew c): + # no /usr/lib/debug, just plain glibc, like a normal user + gdb HEAD-old-gdb + (gdb) break internal_error + (gdb) run + (gdb) maint internal-error + (gdb) backtrace + (gdb) maint space 1 + + gdb gdb_6_0_branch 2003-08-19 space used: 8896512 + gdb HEAD 2003-08-19 space used: 8904704 + gdb HEAD 2003-08-21 space used: 8396800 (+symtab.h) + gdb HEAD 2003-08-21 space used: 8265728 (+gdbtypes.h) + + The third line shows the savings from the optimizations in symtab.h. + The fourth line shows the savings from the optimizations in + gdbtypes.h. Both optimizations are in gdb HEAD now. + + --chastain 2003-08-21 */ + + /* Define a structure for the information that is common to all symbol types, including minimal symbols, partial symbols, and full symbols. In a multilanguage environment, some language specific information may need to - be recorded along with each symbol. + be recorded along with each symbol. */ - These fields are ordered to encourage good packing, since we frequently - have tens or hundreds of thousands of these. */ +/* This structure is space critical. See space comments at the top. */ struct general_symbol_info { @@ -107,7 +138,7 @@ struct general_symbol_info This is used to select one of the fields from the language specific union above. */ - enum language language BYTE_BITFIELD; + ENUM_BITFIELD(language) language : 8; /* Which section is this symbol in? This is an index into section_offsets for this objfile. Negative means that the symbol @@ -228,6 +259,37 @@ extern const char *symbol_demangled_name (const struct general_symbol_info #define SYMBOL_MATCHES_NATURAL_NAME(symbol, name) \ (strcmp_iw (SYMBOL_NATURAL_NAME (symbol), (name)) == 0) +/* Classification types for a minimal symbol. These should be taken as + "advisory only", since if gdb can't easily figure out a + classification it simply selects mst_unknown. It may also have to + guess when it can't figure out which is a better match between two + types (mst_data versus mst_bss) for example. Since the minimal + symbol info is sometimes derived from the BFD library's view of a + file, we need to live with what information bfd supplies. */ + +enum minimal_symbol_type +{ + mst_unknown = 0, /* Unknown type, the default */ + mst_text, /* Generally executable instructions */ + mst_data, /* Generally initialized data */ + mst_bss, /* Generally uninitialized data */ + mst_abs, /* Generally absolute (nonrelocatable) */ + /* GDB uses mst_solib_trampoline for the start address of a shared + library trampoline entry. Breakpoints for shared library functions + are put there if the shared library is not yet loaded. + After the shared library is loaded, lookup_minimal_symbol will + prefer the minimal symbol from the shared library (usually + a mst_text symbol) over the mst_solib_trampoline symbol, and the + breakpoints will be moved to their true address in the shared + library via breakpoint_re_set. */ + mst_solib_trampoline, /* Shared library trampoline code */ + /* For the mst_file* types, the names are only guaranteed to be unique + within a given .o file. */ + mst_file_text, /* Static version of mst_text */ + mst_file_data, /* Static version of mst_data */ + mst_file_bss /* Static version of mst_bss */ +}; + /* Define a simple structure used to hold some very basic information about all defined global symbols (text, data, bss, abs, etc). The only required information is the general_symbol_info. @@ -269,37 +331,9 @@ struct minimal_symbol char *filename; #endif - /* Classification types for this symbol. These should be taken as "advisory - only", since if gdb can't easily figure out a classification it simply - selects mst_unknown. It may also have to guess when it can't figure out - which is a better match between two types (mst_data versus mst_bss) for - example. Since the minimal symbol info is sometimes derived from the - BFD library's view of a file, we need to live with what information bfd - supplies. */ + /* Classification type for this minimal symbol. */ - enum minimal_symbol_type - { - mst_unknown = 0, /* Unknown type, the default */ - mst_text, /* Generally executable instructions */ - mst_data, /* Generally initialized data */ - mst_bss, /* Generally uninitialized data */ - mst_abs, /* Generally absolute (nonrelocatable) */ - /* GDB uses mst_solib_trampoline for the start address of a shared - library trampoline entry. Breakpoints for shared library functions - are put there if the shared library is not yet loaded. - After the shared library is loaded, lookup_minimal_symbol will - prefer the minimal symbol from the shared library (usually - a mst_text symbol) over the mst_solib_trampoline symbol, and the - breakpoints will be moved to their true address in the shared - library via breakpoint_re_set. */ - mst_solib_trampoline, /* Shared library trampoline code */ - /* For the mst_file* types, the names are only guaranteed to be unique - within a given .o file. */ - mst_file_text, /* Static version of mst_text */ - mst_file_data, /* Static version of mst_data */ - mst_file_bss /* Static version of mst_bss */ - } - type BYTE_BITFIELD; + ENUM_BITFIELD(minimal_symbol_type) type : 8; /* Minimal symbols with the same hash key are kept on a linked list. This is the link. */ @@ -322,10 +356,7 @@ struct minimal_symbol /* Different name domains for symbols. Looking up a symbol specifies a domain and ignores symbol definitions in other name domains. */ -/* FIXME: carlton/2002-11-22: This name me crazy when doing C++ - namespace stuff. Maybe name_space_enum and XXX_NAME_SPACE? */ - -typedef enum +typedef enum domain_enum_tag { /* UNDEF_DOMAIN is used when a domain has not been discovered or none of the following apply. This usually indicates an error either @@ -571,6 +602,8 @@ struct alias_list struct alias_list *next; }; +/* This structure is space critical. See space comments at the top. */ + struct symbol { @@ -584,11 +617,11 @@ struct symbol /* Domain code. */ - domain_enum domain BYTE_BITFIELD; + ENUM_BITFIELD(domain_enum_tag) domain : 6; /* Address class */ - enum address_class aclass BYTE_BITFIELD; + ENUM_BITFIELD(address_class) aclass : 6; /* Line number of definition. FIXME: Should we really make the assumption that nobody will try to debug files longer than 64K lines? What about @@ -652,6 +685,8 @@ struct symbol on a partial symtab list and which points to the corresponding normal symtab once the partial_symtab has been referenced. */ +/* This structure is space critical. See space comments at the top. */ + struct partial_symbol { @@ -661,11 +696,11 @@ struct partial_symbol /* Name space code. */ - domain_enum domain BYTE_BITFIELD; + ENUM_BITFIELD(domain_enum_tag) domain : 6; /* Address class (for info_symbols) */ - enum address_class aclass BYTE_BITFIELD; + ENUM_BITFIELD(address_class) aclass : 6; }; |