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[subset/cff] Allocate more memory for retain-gids

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To avoid serializing twice.

20% speedup in:
BM_subset/subset_glyphs/SourceSansPro-Regular.otf/retaingids/10
This commit is contained in:
Behdad Esfahbod 2023-06-25 22:25:24 -06:00
parent 30f1ab86ea
commit e7ad017ca6
1 changed files with 26 additions and 11 deletions
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37
src/hb-subset.cc
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@ -213,15 +213,36 @@ _get_table_tags (const hb_subset_plan_t* plan,
static unsigned
_plan_estimate_subset_table_size (hb_subset_plan_t *plan,
unsigned table_len,
bool same_size)
hb_tag_t table_tag)
{
unsigned src_glyphs = plan->source->get_num_glyphs ();
unsigned dst_glyphs = plan->glyphset ()->get_population ();
if (unlikely (!src_glyphs) || same_size)
return 8192 + table_len;
unsigned bulk = 8192;
/* Tables that we want to allocate same space as the source table. For GSUB/GPOS it's
* because those are expensive to subset, so giving them more room is fine. */
bool same_size = table_tag == HB_OT_TAG_GSUB ||
table_tag == HB_OT_TAG_GPOS ||
table_tag == HB_OT_TAG_name;
return 8192 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
if (plan->flags & HB_SUBSET_FLAGS_RETAIN_GIDS)
{
if (table_tag == HB_OT_TAG_CFF1)
{
/* Add some extra room for the CFF charset. */
bulk += src_glyphs * 16;
}
else if (table_tag == HB_OT_TAG_CFF2)
{
/* Just extra CharString offsets. */
bulk += src_glyphs * 4;
}
}
if (unlikely (!src_glyphs) || same_size)
return bulk + table_len;
return bulk + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
}
/*
@ -306,13 +327,7 @@ _subset (hb_subset_plan_t *plan, hb_vector_t<char> &buf)
return false;
}
/* Tables that we want to allocate same space as the source table. For GSUB/GPOS it's
* because those are expensive to subset, so giving them more room is fine. */
bool same_size_table = TableType::tableTag == HB_OT_TAG_GSUB ||
TableType::tableTag == HB_OT_TAG_GPOS ||
TableType::tableTag == HB_OT_TAG_name;
unsigned buf_size = _plan_estimate_subset_table_size (plan, blob->length, same_size_table);
unsigned buf_size = _plan_estimate_subset_table_size (plan, blob->length, TableType::tableTag);
DEBUG_MSG (SUBSET, nullptr,
"OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);
if (unlikely (!buf.alloc (buf_size)))