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re PR tree-optimization/64058 (Performance degradation after r216304)

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PR tree-optimization/64058
	* tree-ssa-coalesce.c (struct coalesce_pair): Add new field
	CONFLICT_COUNT.
	(struct ssa_conflicts): Move up earlier in the file.
	(conflicts_, var_map_): New static variables.
	(initialize_conflict_count): New function to initialize the
	CONFLICT_COUNT field for each conflict pair.
	(compare_pairs): Lazily initialize the conflict count and use it
	as the first tie-breaker.
	(sort_coalesce_list): Add new arguments conflicts, map.  Initialize
	and wipe conflicts_ and map_ around the call to qsort.  Remove
	special case for 2 coalesce pairs.
	* bitmap.c (bitmap_count_unique_bits): New function.
	(bitmap_count_bits_in_word): New function, extracted from
	bitmap_count_bits.
	(bitmap_count_bits): Use bitmap_count_bits_in_word.
	* bitmap.h (bitmap_count_unique_bits): Declare it.

From-SVN: r234425
This commit is contained in:
Jeff Law 2016-03-23 07:20:16 -06:00 committed by Jeff Law
parent b01e88e56b
commit 478baf913e
4 changed files with 168 additions and 41 deletions
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20
gcc/ChangeLog
View File

@ -1,3 +1,23 @@
2016-03-23 Jeff Law <law@redhat.com>
PR tree-optimization/64058
* tree-ssa-coalesce.c (struct coalesce_pair): Add new field
CONFLICT_COUNT.
(struct ssa_conflicts): Move up earlier in the file.
(conflicts_, var_map_): New static variables.
(initialize_conflict_count): New function to initialize the
CONFLICT_COUNT field for each conflict pair.
(compare_pairs): Lazily initialize the conflict count and use it
as the first tie-breaker.
(sort_coalesce_list): Add new arguments conflicts, map. Initialize
and wipe conflicts_ and map_ around the call to qsort. Remove
special case for 2 coalesce pairs.
* bitmap.c (bitmap_count_unique_bits): New function.
(bitmap_count_bits_in_word): New function, extracted from
bitmap_count_bits.
(bitmap_count_bits): Use bitmap_count_bits_in_word.
* bitmap.h (bitmap_count_unique_bits): Declare it.
2016-03-23 Ilya Enkovich <enkovich.gnu@gmail.com>
PR target/69917

63
gcc/bitmap.c
View File

@ -662,6 +662,26 @@ bitmap_popcount (BITMAP_WORD a)
return ret;
}
#endif
/* Count and return the number of bits set in the bitmap word BITS. */
static unsigned long
bitmap_count_bits_in_word (const BITMAP_WORD *bits)
{
unsigned long count = 0;
for (unsigned ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
{
#if GCC_VERSION >= 3400
/* Note that popcountl matches BITMAP_WORD in type, so the actual size
of BITMAP_WORD is not material. */
count += __builtin_popcountl (bits[ix]);
#else
count += bitmap_popcount (bits[ix]);
#endif
}
return count;
}
/* Count the number of bits set in the bitmap, and return it. */
unsigned long
@ -669,19 +689,44 @@ bitmap_count_bits (const_bitmap a)
{
unsigned long count = 0;
const bitmap_element *elt;
unsigned ix;
for (elt = a->first; elt; elt = elt->next)
count += bitmap_count_bits_in_word (elt->bits);
return count;
}
/* Count the number of unique bits set in A and B and return it. */
unsigned long
bitmap_count_unique_bits (const_bitmap a, const_bitmap b)
{
unsigned long count = 0;
const bitmap_element *elt_a, *elt_b;
for (elt_a = a->first, elt_b = b->first; elt_a && elt_b; )
{
for (ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
/* If we're at different indices, then count all the bits
in the lower element. If we're at the same index, then
count the bits in the IOR of the two elements. */
if (elt_a->indx < elt_b->indx)
{
#if GCC_VERSION >= 3400
/* Note that popcountl matches BITMAP_WORD in type, so the actual size
of BITMAP_WORD is not material. */
count += __builtin_popcountl (elt->bits[ix]);
#else
count += bitmap_popcount (elt->bits[ix]);
#endif
count += bitmap_count_bits_in_word (elt_a->bits);
elt_a = elt_a->next;
}
else if (elt_b->indx < elt_a->indx)
{
count += bitmap_count_bits_in_word (elt_b->bits);
elt_b = elt_b->next;
}
else
{
BITMAP_WORD bits[BITMAP_ELEMENT_WORDS];
for (unsigned ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
bits[ix] = elt_a->bits[ix] | elt_b->bits[ix];
count += bitmap_count_bits_in_word (bits);
elt_a = elt_a->next;
elt_b = elt_b->next;
}
}
return count;

3
gcc/bitmap.h
View File

@ -280,6 +280,9 @@ extern bool bitmap_single_bit_set_p (const_bitmap);
/* Count the number of bits set in the bitmap. */
extern unsigned long bitmap_count_bits (const_bitmap);
/* Count the number of unique bits set across the two bitmaps. */
extern unsigned long bitmap_count_unique_bits (const_bitmap, const_bitmap);
/* Boolean operations on bitmaps. The _into variants are two operand
versions that modify the first source operand. The other variants
are three operand versions that to not destroy the source bitmaps.

123
gcc/tree-ssa-coalesce.c
View File

@ -51,12 +51,40 @@ struct coalesce_pair
int second_element;
int cost;
/* A count of the number of unique partitions this pair would conflict
with if coalescing was successful. This is the secondary sort key,
given two pairs with equal costs, we will prefer the pair with a smaller
conflict set.
This is lazily initialized when we discover two coalescing pairs have
the same primary cost.
Note this is not updated and propagated as pairs are coalesced. */
int conflict_count;
/* The order in which coalescing pairs are discovered is recorded in this
field, which is used as the final tie breaker when sorting coalesce
pairs. */
int index;
};
/* This represents a conflict graph. Implemented as an array of bitmaps.
A full matrix is used for conflicts rather than just upper triangular form.
this make sit much simpler and faster to perform conflict merges. */
struct ssa_conflicts
{
bitmap_obstack obstack; /* A place to allocate our bitmaps. */
vec<bitmap> conflicts;
};
/* The narrow API of the qsort comparison function doesn't allow easy
access to additional arguments. So we have two globals (ick) to hold
the data we need. They're initialized before the call to qsort and
wiped immediately after. */
static ssa_conflicts *conflicts_;
static var_map map_;
/* Coalesce pair hashtable helpers. */
struct coalesce_pair_hasher : nofree_ptr_hash <coalesce_pair>
@ -303,6 +331,7 @@ find_coalesce_pair (coalesce_list *cl, int p1, int p2, bool create)
pair->second_element = p.second_element;
pair->cost = 0;
pair->index = num_coalesce_pairs (cl);
pair->conflict_count = 0;
*slot = pair;
}
@ -345,21 +374,66 @@ add_coalesce (coalesce_list *cl, int p1, int p2, int value)
}
}
/* Compute and record how many unique conflicts would exist for the
representative partition for each coalesce pair in CL.
CONFLICTS is the conflict graph and MAP is the current partition view. */
static void
initialize_conflict_count (coalesce_pair *p,
ssa_conflicts *conflicts,
var_map map)
{
int p1 = var_to_partition (map, ssa_name (p->first_element));
int p2 = var_to_partition (map, ssa_name (p->second_element));
/* 4 cases. If both P1 and P2 have conflicts, then build their
union and count the members. Else handle the degenerate cases
in the obvious ways. */
if (conflicts->conflicts[p1] && conflicts->conflicts[p2])
p->conflict_count = bitmap_count_unique_bits (conflicts->conflicts[p1],
conflicts->conflicts[p2]);
else if (conflicts->conflicts[p1])
p->conflict_count = bitmap_count_bits (conflicts->conflicts[p1]);
else if (conflicts->conflicts[p2])
p->conflict_count = bitmap_count_bits (conflicts->conflicts[p2]);
else
p->conflict_count = 0;
}
/* Comparison function to allow qsort to sort P1 and P2 in Ascending order. */
static int
compare_pairs (const void *p1, const void *p2)
{
const coalesce_pair *const *const pp1 = (const coalesce_pair *const *) p1;
const coalesce_pair *const *const pp2 = (const coalesce_pair *const *) p2;
coalesce_pair *const *const pp1 = (coalesce_pair *const *) p1;
coalesce_pair *const *const pp2 = (coalesce_pair *const *) p2;
int result;
result = (* pp1)->cost - (* pp2)->cost;
/* And if everything else is equal, then sort based on which
coalesce pair was found first. */
/* We use the size of the resulting conflict set as the secondary sort key.
Given two equal costing coalesce pairs, we want to prefer the pair that
has the smaller conflict set. */
if (result == 0)
result = (*pp2)->index - (*pp1)->index;
{
if (flag_expensive_optimizations)
{
/* Lazily initialize the conflict counts as it's fairly expensive
to compute. */
if ((*pp2)->conflict_count == 0)
initialize_conflict_count (*pp2, conflicts_, map_);
if ((*pp1)->conflict_count == 0)
initialize_conflict_count (*pp1, conflicts_, map_);
result = (*pp2)->conflict_count - (*pp1)->conflict_count;
}
/* And if everything else is equal, then sort based on which
coalesce pair was found first. */
if (result == 0)
result = (*pp2)->index - (*pp1)->index;
}
return result;
}
@ -374,7 +448,7 @@ compare_pairs (const void *p1, const void *p2)
in order from most important coalesce to least important. */
static void
sort_coalesce_list (coalesce_list *cl)
sort_coalesce_list (coalesce_list *cl, ssa_conflicts *conflicts, var_map map)
{
unsigned x, num;
coalesce_pair *p;
@ -400,19 +474,14 @@ sort_coalesce_list (coalesce_list *cl)
if (num == 1)
return;
/* If there are only 2, just pick swap them if the order isn't correct. */
if (num == 2)
{
if (cl->sorted[0]->cost > cl->sorted[1]->cost)
std::swap (cl->sorted[0], cl->sorted[1]);
return;
}
/* Only call qsort if there are more than 2 items.
??? Maybe std::sort will do better, provided that compare_pairs
can be inlined. */
if (num > 2)
qsort (cl->sorted, num, sizeof (coalesce_pair *), compare_pairs);
/* We don't want to depend on qsort_r, so we have to stuff away
additional data into globals so it can be referenced in
compare_pairs. */
conflicts_ = conflicts;
map_ = map;
qsort (cl->sorted, num, sizeof (coalesce_pair *), compare_pairs);
conflicts_ = NULL;
map_ = NULL;
}
@ -437,7 +506,7 @@ dump_coalesce_list (FILE *f, coalesce_list *cl)
print_generic_expr (f, var1, TDF_SLIM);
fprintf (f, " <-> ");
print_generic_expr (f, var2, TDF_SLIM);
fprintf (f, " (%1d), ", node->cost);
fprintf (f, " (%1d, %1d), ", node->cost, node->conflict_count);
fprintf (f, "\n");
}
}
@ -447,7 +516,7 @@ dump_coalesce_list (FILE *f, coalesce_list *cl)
for (x = cl->num_sorted - 1 ; x >=0; x--)
{
node = cl->sorted[x];
fprintf (f, "(%d) ", node->cost);
fprintf (f, "(%d, %d) ", node->cost, node->conflict_count);
var = ssa_name (node->first_element);
print_generic_expr (f, var, TDF_SLIM);
fprintf (f, " <-> ");
@ -459,16 +528,6 @@ dump_coalesce_list (FILE *f, coalesce_list *cl)
}
/* This represents a conflict graph. Implemented as an array of bitmaps.
A full matrix is used for conflicts rather than just upper triangular form.
this make sit much simpler and faster to perform conflict merges. */
struct ssa_conflicts
{
bitmap_obstack obstack; /* A place to allocate our bitmaps. */
vec<bitmap> conflicts;
};
/* Return an empty new conflict graph for SIZE elements. */
static inline ssa_conflicts *
@ -1800,7 +1859,7 @@ coalesce_ssa_name (void)
if (dump_file && (dump_flags & TDF_DETAILS))
ssa_conflicts_dump (dump_file, graph);
sort_coalesce_list (cl);
sort_coalesce_list (cl, graph, map);
if (dump_file && (dump_flags & TDF_DETAILS))
{