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ggc-page.c: Avoid division in ggc_set_mark.

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* ggc-page.c: Avoid division in ggc_set_mark.
	(DIV_MULT, DIV_SHIFT, OFFSET_TO_BIT, inverse_table,
	compute_inverse): New.
	(ggc_set_mark, ggc_marked_p): Use OFFSET_TO_BIT.
	(init_ggc): Initialize inverse_table.

From-SVN: r56512
This commit is contained in:
Zack Weinberg 2002-08-22 19:17:04 +00:00
parent 8567c70f72
commit 8537ed688c
2 changed files with 76 additions and 17 deletions
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34
gcc/ChangeLog
View File

@ -1,3 +1,11 @@
2002-08-22 Zack Weinberg <zack@codesourcery.com>
* ggc-page.c: Avoid division in ggc_set_mark.
(DIV_MULT, DIV_SHIFT, OFFSET_TO_BIT, inverse_table,
compute_inverse): New.
(ggc_set_mark, ggc_marked_p): Use OFFSET_TO_BIT.
(init_ggc): Initialize inverse_table.
2002-08-22 Tom Tromey <tromey@redhat.com>
* doc/install.texi (Configuration): Document --datadir.
@ -46,7 +54,7 @@
* config/rs6000/rs6000.c: Ditto.
* config/stormy16/stormy16.h: Ditto.
* doc/md.texi: Ditto.
2002-08-21 John David Anglin <dave@hiauly1.hia.nrc.ca>
* cppinit.c (remove_dup_nonsys_dirs): Fix warning and return value.
@ -59,11 +67,11 @@
errors.
2002-08-21 Andrew Pinski <pinskia@physics.uc.edu>
Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* doc/tm.texi (TARGET_ASM_GLOBALIZE_LABEL): Move '@end deftypefn'
to the actual end. Add '@end table' and '@table @code'.
2002-08-20 Geoffrey Keating <geoffk@redhat.com>
* doc/tm.texi (Label Output): Add missing '@end deftypefn'.
@ -157,7 +165,7 @@
2002-08-20 Devang Patel <dpatel@apple.com>
* tree.c (get_qualified_type): Add TYPE_CONTEXT check.
2002-08-20 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* arc.c (output_shift): Use stdio instead of asm_fprintf.
@ -205,7 +213,7 @@
(mips_use_dfa_pipeline_interface): Use.
2002-08-15 Eric Christopher <echristo@redhat.com>
Richard Sandiford <rsandifo@redhat.com>
Richard Sandiford <rsandifo@redhat.com>
Aldy Hernandez <aldyh@redhat.com>
Graham Stott <grahams@redhat.com>
Michael Meissner <meissner@redhat.com>
@ -249,8 +257,8 @@
quote and bracket include chains when they duplicate equivalent system
directories.
* doc/cpp.texi (-I): Update.
* doc/cppopts.texi (-I): Update.
* doc/install.texi (--with-local-prefix): Further document usage of
* doc/cppopts.texi (-I): Update.
* doc/install.texi (--with-local-prefix): Further document usage of
this option.
* doc/invoke.texi (-I): Update.
@ -558,7 +566,7 @@
2002-08-14 Dale Johannesen <dalej@apple.com>
* explow.c (emit_stack_restore): Emit memory clobbers
* explow.c (emit_stack_restore): Emit memory clobbers
preceding the stack pop, to prevent the scheduler from
moving refs to variable arrays below this pop.
* reload1.c (reload): Preserve these clobbers for sched2.
@ -794,7 +802,7 @@ Tue Aug 13 17:40:25 2002 J"orn Rennecke <joern.rennecke@superh.com>
2002-08-13 Denis Chertykov <denisc@overta.ru>
* config/avr/avr.md: Call CC_STATUS_INIT in all peepnoles
which can change CC0.
which can change CC0.
Tue Aug 13 14:49:20 2002 J"orn Rennecke <joern.rennecke@superh.com>
@ -1357,10 +1365,10 @@ Sat Aug 10 19:59:43 CEST 2002 Jan Hubicka <jh@suse.cz>
2002-08-06 Aldy Hernandez <aldyh@redhat.com>
* c-decl.c (duplicate_decls): Error out for incompatible TLS
declarations.
* c-decl.c (duplicate_decls): Error out for incompatible TLS
declarations.
* testsuite/gcc.dg/tls/diag-3.c: New.
* testsuite/gcc.dg/tls/diag-3.c: New.
2002-08-06 Jason Merrill <jason@redhat.com>
@ -1369,7 +1377,7 @@ Sat Aug 10 19:59:43 CEST 2002 Jan Hubicka <jh@suse.cz>
2002-08-06 Dale Johannesen <dalej@apple.com>
* c-common.c (fname_decl): Use line number 0 for
__func__, to avoid confusing debuggers.
__func__, to avoid confusing debuggers.
2002-08-06 Nathan Sidwell <nathan@codesourcery.com>

59
gcc/ggc-page.c
View File

@ -158,6 +158,15 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
/* The size of an object on a page of the indicated ORDER. */
#define OBJECT_SIZE(ORDER) object_size_table[ORDER]
/* For speed, we avoid doing a general integer divide to locate the
offset in the allocation bitmap, by precalculating numbers M, S
such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
within the page which is evenly divisible by the object size Z. */
#define DIV_MULT(ORDER) inverse_table[ORDER].mult
#define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
#define OFFSET_TO_BIT(OFFSET, ORDER) \
(((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
/* The number of extra orders, not corresponding to power-of-two sized
objects. */
@ -209,6 +218,17 @@ static unsigned objects_per_page_table[NUM_ORDERS];
static size_t object_size_table[NUM_ORDERS];
/* The Ith entry is a pair of numbers (mult, shift) such that
((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
for all k evenly divisible by OBJECT_SIZE(I). */
static struct
{
unsigned int mult;
unsigned int shift;
}
inverse_table[NUM_ORDERS];
/* A page_entry records the status of an allocation page. This
structure is dynamically sized to fit the bitmap in_use_p. */
typedef struct page_entry
@ -377,6 +397,7 @@ static void release_pages PARAMS ((void));
static void clear_marks PARAMS ((void));
static void sweep_pages PARAMS ((void));
static void ggc_recalculate_in_use_p PARAMS ((page_entry *));
static void compute_inverse PARAMS ((unsigned));
#ifdef GGC_POISON
static void poison_pages PARAMS ((void));
@ -988,7 +1009,7 @@ ggc_set_mark (p)
/* Calculate the index of the object on the page; this is its bit
position in the in_use_p bitmap. */
bit = (((const char *) p) - entry->page) / OBJECT_SIZE (entry->order);
bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
word = bit / HOST_BITS_PER_LONG;
mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
@ -1028,7 +1049,7 @@ ggc_marked_p (p)
/* Calculate the index of the object on the page; this is its bit
position in the in_use_p bitmap. */
bit = (((const char *) p) - entry->page) / OBJECT_SIZE (entry->order);
bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
word = bit / HOST_BITS_PER_LONG;
mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
@ -1045,8 +1066,37 @@ ggc_get_size (p)
return OBJECT_SIZE (pe->order);
}
/* Initialize the ggc-mmap allocator. */
/* Subroutine of init_ggc which computes the pair of numbers used to
perform division by OBJECT_SIZE (order) and fills in inverse_table[].
This algorithm is taken from Granlund and Montgomery's paper
"Division by Invariant Integers using Multiplication"
(Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
constants). */
static void
compute_inverse (order)
unsigned order;
{
unsigned size, inv, e;
size = OBJECT_SIZE (order);
e = 0;
while (size % 2 == 0)
{
e++;
size >>= 1;
}
inv = size;
while (inv * size != 1)
inv = inv * (2 - inv*size);
DIV_MULT (order) = inv;
DIV_SHIFT (order) = e;
}
/* Initialize the ggc-mmap allocator. */
void
init_ggc ()
{
@ -1109,12 +1159,13 @@ init_ggc ()
object_size_table[order] = s;
}
/* Initialize the objects-per-page table. */
/* Initialize the objects-per-page and inverse tables. */
for (order = 0; order < NUM_ORDERS; ++order)
{
objects_per_page_table[order] = G.pagesize / OBJECT_SIZE (order);
if (objects_per_page_table[order] == 0)
objects_per_page_table[order] = 1;
compute_inverse (order);
}
/* Reset the size_lookup array to put appropriately sized objects in