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bitmap memory allocation

Bitmaps have four different creation mechanisms,
1) GC allocated head, GC allocated elements
2) malloc'd head, bitmap obstack'd elements
3) stack-frame head, bitmap obstack'd elements
4) obstack'd head, bitmap obstack'd elements

This is confusing and unnecessary.  Note that #2 and #4 allocate the head
from a different pool than the elements -- lifetime issues anyone? tree-cse
uses #4 to allocate the heads from one bitmap, but it doesn't do
a bitmap-clear, so the elements are lost on the bitmap obstack itself.

In addition to this, we have regsets, which are merely aliases for
bitmap entry points.  Regsets can be allocated off the flow obstack.
The naming of some of these routines is confusing, for instance a malloced
bitmap or regset is freed with XFREE_BITMAP, not with FREE_BITMAP
(yet of course xmalloc itself is freed by free, not xfree).

This can be rationalized by allowing the heads and the elements to
be allocated from the same obstack, with appropriate free-lists added.
Doing so we can remove #2 and ensure the lifetime of the heads is the
same as that of the elements.  This patch is a move in that direction.

The patch implements a new bitmap_obstack, which is merely a regular
obstack with element and head freelists.  Unfortunately this has to
be exposed in bitmap.h so that other modules can create bitmap obstacks.
This exposure leads to more header file inclusion, but I took the
opportunity of rationalizing that, because regs.h already include

I've added separate bitmap allocators for gc'd, malloc'd and obstack'd
bitmaps.  I've added a separate reg_obstack to allocate regsets from.
The bitmap obstacks are initialized and freed within tree-optimize.  Both
those obstacks have the same lifetime.  I suspect the register obstack need
only exists for the rtl optimizations though.

I intend to remove the XMALLOC entry points after this patch has gone in.
Such a patch will clean up the naming scheme of the various bitmap
creation entry points. I have already tested a compiler where the xmalloc
entry points forwarded to the obstack ones, so am confident it can be done.
I did measure a 0.5% bootstrap time improvement for c & c++ on i86 and
powerpc.  I did not measure any change for _unoptimized_ qt building (I
did not expect to).

booted & tested on i686-pc-linux-gnu, ok?


Nathan Sidwell    ::   ::     CodeSourcery LLC    ::

2004-11-12  Nathan Sidwell  <>

	* bitmap.h (struct bitmap_obstack): New obstack type.
	(struct bitmap_head_def): Replace using_obstack with obstack
	(bitmap_default_obstack): New.
	(bitmap_initialize): Make inline, does not do allocation.
	(bitmap_release_memory): Remove.
	(bitmap_obstack_initialize, bitmap_obstack_release): Declare.
	(bitmap_obstack_alloc, bitmap_malloc_alloc, bitmap_gc_alloc,
	bitmap_obstack_free, bitmap_malloc_free): Declare.
	(BITMAP_FREE): Replace with ...
	(BITMAP_XFREE): Adjust.
	* bitmap.c (bitmap_obstack, bitmap_obstack_init, bitmap_free: Remove.
	(bitmap_default_obstack): New.
	(bitmap_elem_to_freelist): Adjust.
	(bitmap_element_allocate): Adjust. Break initialization into ...
	(bitmap_obstack_initialize): ... here.
	(bitmap_release_memory): Replace with ...
	(bitmap_obstack_release): ... this.
	(bitmap_obstack_alloc, bitmap_malloc_alloc, bitmap_gc_alloc,
	bitmap_obstack_free, bitmap_malloc_free): New.
	(bitmap_ior_and_compl, bitmap_ior_and_compl_into): Use
	(bitmap_initialize): Move to bitmap.h.
	* gengtype.c (open_base_files): Add obstack.h to ifiles.
	* (BASIC_BLOCK_H, REGS_H): Add obstack.h.
	* basic-block.h (INIT_REG_SET): Allocate from reg_obstack.
	(flow_obstack): Do not declare.
	(reg_obstack): Declare.
	* regs.h: Include obstack.h.
	* tree-optimize.c (tree_rest_of_compilation): Initialize and
	release bitmap obstack here.
	* bb-reorder.c: #include regs, not basic-block.
	(fix_crossing_conditional_branches): Allocate regsets from
	* bt-load.c: Do not inlude bitmap.h, sbitmap.h, basic-block.h or
	* caller-save.c: Include regs.h earlier.
	* cfg.c: Do not include basic-block.h or obstack.h.
	(reg_obstack): Define.
	* cfganal.c: Include obstack.h
	* cfgcleanyp.c: Do not include basic-block.h. Include regs.h
	* cfglayout.c: Do not include obstack.h.
	(flow_obstack): Remove declaration.
	(cfg_layout_duplicate_bb): Use reg_obstack.
	* cfgloop.c, cfgloopanal.c, cfgloopmanip.c: Include obstack.h.
	* cfgrtl.c (rtl_split_block): Use reg_obstack.
	(force_nonfallthru_and_redirect, rtl_split_edge): Likewise.
	(safe_insert_insn_on_edge): Use OBSTACK_ALLOC_REG_SET, adjust.
	(cfg_layout_split_edge): Use reg_obstack.
	* cse.c: Include regs.h earlier.
	* ddg.c: Do not include basic-block.h.
	* dominance.c: Inlude obstack.h.
	* flow.c (update_life_info): Use OBSTACK_ALLOC_REG_SET, adjust.
	(calculate_global_regs_live): Likewise.
	(allocate_bb_life_data): Use reg_obstack.
	(init_propagate_block_info): Use OBSTACK_ALLOC_REGSET.
	* global.c: Do not include basic-block.h.
	(build_insn_chain): Use OBSTACK_ALLOC_REG_SET, adjust.
	* graph.c: Include obstack.h.
	* haifa-sched.c: Do not include basic-block.h.
	* ifcvt.c: Use OBSTACK_ALLOC_REG_SET, adjust.
	* local-alloc.c: Do not include basic-block.h.
	* loop-init.c, loop-invariant.c: Include obstack.h.
	* loop-iv.c: Likewise.
	(simplify_using_initial_values): Use OBSTACK_ALLOC_REG_SET,
	* loop-unroll.c, loop-unswitch.c: Inlude obstack.h.
	* modulo-sched.c: Do not include basic-block.h.
	* passes.c (rest_of_handle_final): Do not call
	* ra-debug.c: Include regs.h earlier. Do not include
	* recog.c (peephole2_optimize): Use OBSTACK_ALLOC_REG_SET, adjust.
	* regclass.c (init_reg_sets): Do not call INIT_ONCE_REG_SET.
	(allocate_reg_info): Do not call MAX_REGNO_REG_SET.
	(regset_release_memory): Remove.
	* resource.c: Do not include basic-block.h.
	* rtlanal.c: Do not include basic-block.h.
	* sbitmap.c: Include obstack.h.
	* sched-deps.c: Do not include basic-block.h.
	(reg_pending_sets_head, reg_pending_clobbers_head,
	reg_pending_uses_head): Remove.
	(init_deps_global): Use OBSTACK_ALLOC_REG_SET.
	* sched-ebb.c: Do not include basic-block.h.
	* sched-rgn.c: Likewise.
	* tree-if-conv.c (get_loop_body_in_if_conv_order): Use
	* tree-outof-ssa.c (perform_edge_inserts): Use BITMAP_XFREE.
	* tree-sra.c (decide_instantiations): Adjust bitmap
	* tree-ssa-dce.c: Include obstack.h.
	* tree-ssa-pre.c (grand_bitmap_obstack): Make a bitmap_obstack.
	(value_insert_into_set_bitmap): Remove useless bitmap_clear.
	(bitmap_set_new): Likewise.
	(init_pre): Initialize bitmap obstack.
	(fini_pre): Release bitmap obstack.
	* tree-ssanames.c (ssa_names_to_rewrite): Make static.
	(marked_for_rewrite_p): ssa_names_to_rewrite is never NULL.
	(mark_for_rewrite, unmark_for_rewrite): Likewise.
	(marked_ssa_names): Likewise.
	(init_ssanames): Use BITMAP_XMALLOC.
	(fini_ssanames): Use BITMAP_XFREE.
	* web.c: Include obstack.h

Attachment: bitmap-memory-1a.patch.gz
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