Re: demand_empty_rest_of_line and ignore_rest_of_line

[Ian Lance Taylor <ian at wasabisystems dot com>]

Zack Weinberg <zack@codesourcery.com> writes:

> I'm going to take this as "put up or shut up", and indeed I would not
> have blathered on about this for so long if it weren't that I expect
> to get a chance to do some performance work on GAS fairly soon (by
> which I mean "sometime this year").  I'm going to drop the thread now,
> and come back when I have actual code to show people.

I'm glad that you will have some time to work on this.

For what it's worth, I think the thing which most needs fixing in gas
is the relocation handling, which is completely and horribly broken.
However, that is not a performance issue.

For performance issues, I'll note that assembler relaxation currently
walks the entire frag chain at least three times.  I'm sure a more
clever algorithm is possible.  I wouldn't be surprised if some more
code is quietly walking long lists somewhere.

It might be beneficial to change the hash table to use
libiberty/hashtab.c; I don't know.

The last time I did serious performance hacking on gas, I did the
following.  I uncovered this mostly by using profiling and examing
memory usage.

Ian

http://sources.redhat.com/ml/binutils/1999-q2/msg00108.html

1999-06-03  Ian Lance Taylor  <ian@zembu.com>

	Add support for storing local symbols in a small structure to save
	memory when assembling large files.
	* as.h: Don't include struc-symbol.h.
	(symbolS): Add typedef.
	* symbols.c: Include struc-symbol.h.
	(local_hash): New static variable.
	(save_symbol_name): New static function, from symbol_create.
	(symbol_create): Call save_symbol_name.
	(local_symbol_count): New static variable.
	(local_symbol_conversion_count): Likewise.
	(LOCAL_SYMBOL_CHECK): Define.
	(local_symbol_make): New static function.
	(local_symbol_convert): New static function.
	(colon): Handle local symbols.  Create local symbol for local
	label name.
	(symbol_table_insert): Handle local symbols.
	(symbol_find_or_make): Create local symbol for local label name.
	(symbol_find_base): Check for local symbol.
	(symbol_append, symbol_insert): Check for local symbols.
	(symbol_clear_list_pointers, symbol_remove): Likewise.
	(verify_symbol_chain): Likewise.
	(copy_symbol_attributes): Likewise.
	(resolve_symbol_value): Handle local symbols.
	(resolve_local_symbol): New static function.
	(resolve_local_symbol_values): New function.
	(S_GET_VALUE, S_SET_VALUE): Handle local symbols.
	(S_IS_FUNCTION, S_IS_EXTERNAL, S_IS_WEAK, S_IS_COMMON): Likewise.
	(S_IS_DEFINED, S_IS_DEBUG, S_IS_LOCAL, S_GET_NAME): Likewise.
	(S_GET_SEGMENT, S_SET_SEGMENT, S_SET_EXTERNAL): Likewise.
	(S_CLEAR_EXTERNAL, S_SET_WEAK, S_SET_NAME): Likewise.
	(symbol_previous, symbol_next): New functions.
	(symbol_get_value_expression): Likewise.
	(symbol_set_value_expression): Likewise.
	(symbol_set_frag, symbol_get_frag): Likewise.
	(symbol_mark_used, symbol_clear_used, symbol_used_p): Likewise.
	(symbol_mark_used_in_reloc): Likewise.
	(symbol_clear_used_in_reloc, symbol_used_in_reloc_p): Likewise.
	(symbol_mark_mri_common, symbol_clear_mri_common): Likewise.
	(symbol_mri_common_p): Likewise.
	(symbol_mark_written, symbol_clear_written): Likewise.
	(symbol_written_p): Likewise.
	(symbol_mark_resolved, symbol_resolved_p): Likewise.
	(symbol_section_p, symbol_equated_p): Likewise.
	(symbol_constant_p): Likewise.
	(symbol_get_bfdsym, symbol_set_bfdsym): Likewise.
	(symbol_get_obj, symbol_set_obj): Likewise.
	(symbol_get_tc, symbol_set_tc): Likewise.
	(symbol_begin): Initialize local_hash.
	(print_symbol_value_1): Handle local symbols.
	(symbol_print_statistics): Print local symbol statistics.
	* symbols.h: Include "struc-symbol.h" if not BFD_ASSEMBLER.
	Declare new symbols.c functions.  Move many declarations here from
	struc-symbol.h.
	(SYMBOLS_NEED_BACKPOINTERS): Define if needed.
	* struc-symbol.h (SYMBOLS_NEED_BACKPOINTERS): Don't set.
	(struct symbol): Move bsym to make it clearly the first field.
	Remove TARGET_SYMBOL_FIELDS.
	(symbolS): Don't typedef.
	(struct broken_word): Remove.
	(N_TYPE_seg, seg_N_TYPE): Move to symbol.h.
	(SEGMENT_TO_SYMBOL_TYPE, N_REGISTER): Likewise.
	(symbol_clear_list_pointers): Likewise.
	(symbol_insert, symbol_remove): Likewise.
	(symbol_previous, symbol_append): Likewise.
	(verify_symbol_chain, verify_symbol_chain_2): Likewise.
	(struct local_symbol): Define.
	(local_symbol_converted_p, local_symbol_mark_converted): Define.
	(local_symbol_resolved_p, local_symbol_mark_resolved): Define.
	(local_symbol_get_frag, local_symbol_set_frag): Define.
	(local_symbol_get_real_symbol): Define.
	(local_symbol_set_real_symbol): Define.
	Define.
	* write.c (write_object_file): Call resolve_local_symbol_values.
	* config/obj-ecoff.h (OBJ_SYMFIELD_TYPE): Define.
	(TARGET_SYMBOL_FIELDS): Don't define.
	* config/obj-elf.h (OBJ_SYMFIELD_TYPE): Add local field.  If
	ECOFF_DEBUGGING, add ECOFF fields.
	(ELF_TARGET_SYMBOL_FIELDS, TARGET_SYMBOL_FIELDS): Don't define.
	* config/obj-multi.h (struct elf_obj_sy): Add local field.  If
	ECOFF_DEBUGGING, add ECOFF fields.
	(ELF_TARGET_SYMBOL_FIELDS, TARGET_SYMBOL_FIELDS): Don't define.
	(ECOFF_DEBUG_TARGET_SYMBOL_FIELDS): Don't define.
	* config/tc-mcore.h: Don't include struc-symbol.h.
	(TARGET_SYMBOL_FIELDS): Don't define.
	(struct mcore_tc_sy): Define.
	(TC_SYMFIELD_TYPE): Define.
	* Many files: Use symbolS instead of struct symbol.  Use new
	accessor functions rather than referring to symbolS fields
	directly.

	* read.c (s_mri_common): Don't add in value of line_label.

	* config/tc-mips.c (md_apply_fix): Correct parenthesization when
	checking for SEC_LINK_ONCE.

	* config/tc-sh.h (sh_fix_adjustable): Declare.

	* app.c (input_buffer): New static variable.
	(app_push): Save saved_input in allocated buffer.
	(app_pop): Restored saved_input.
	(do_scrub_chars): Change get parameter to take char * and int as
	arguments.  Change GET macro to pass input_buffer to get
	function.  Don't save input into allocated buffer.
	* as.h (do_scrub_chars): Update declaration.
	* input-file.c (input_file_get): Change to take char * and int.
	Read data into passed in buffer.  Remove static buffer.
	* read.c (scrub_from_string): Change to take char * and int.  Copy
	data into passed in buffer.

	* hash.h: Neaten.  Declare hash_traverse.
	* hash.c: Complete rewrite based on BFD hashing code.
	* gasp.c (chunksize): New variable.
	* macro.c (macro_expand_body): Call hash_jam with NULL rather than
	hash_delete.