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[SimpleGlyph] Avoid branches in read_points

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Calculate total bytes in read_flags and bounds-check once.

This slows things down apparently, so going to revert.
This commit is contained in:
Behdad Esfahbod 2023-06-28 13:24:37 -06:00
parent 62f5ed461e
commit ba062c713e
1 changed files with 17 additions and 4 deletions
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21
src/OT/glyf/SimpleGlyph.hh
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@ -123,20 +123,32 @@ struct SimpleGlyph
first_flag = (uint8_t) first_flag | FLAG_OVERLAP_SIMPLE;
}
__attribute__((noinline))
static bool read_flags (const HBUINT8 *&p /* IN/OUT */,
hb_array_t<contour_point_t> points_ /* IN/OUT */,
const HBUINT8 *end)
const HBUINT8 *end,
unsigned &x_points_len,
unsigned &y_points_len)
{
unsigned count = points_.length;
x_points_len = y_points_len = 0;
for (unsigned int i = 0; i < count;)
{
if (unlikely (p + 1 > end)) return false;
uint8_t flag = *p++;
x_points_len += bool (flag & FLAG_X_SHORT);
x_points_len += 2 * bool ((flag & (FLAG_X_SHORT | FLAG_X_SAME)) == 0);
y_points_len += bool (flag & FLAG_Y_SHORT);
y_points_len += 2 * bool ((flag & (FLAG_Y_SHORT | FLAG_Y_SAME)) == 0);
points_.arrayZ[i++].flag = flag;
if (flag & FLAG_REPEAT)
{
if (unlikely (p + 1 > end)) return false;
unsigned int repeat_count = *p++;
x_points_len += repeat_count * bool (flag & FLAG_X_SHORT);
x_points_len += repeat_count * 2 * bool ((flag & (FLAG_X_SHORT | FLAG_X_SAME)) == 0);
y_points_len += repeat_count * bool (flag & FLAG_Y_SHORT);
y_points_len += repeat_count * 2 * bool ((flag & (FLAG_Y_SHORT | FLAG_Y_SAME)) == 0);
unsigned stop = hb_min (i + repeat_count, count);
for (; i < stop; i++)
points_.arrayZ[i].flag = flag;
@ -145,6 +157,7 @@ struct SimpleGlyph
return true;
}
__attribute__((noinline))
static bool read_points (const HBUINT8 *&p /* IN/OUT */,
hb_array_t<contour_point_t> points_ /* IN/OUT */,
const HBUINT8 *end,
@ -160,7 +173,6 @@ struct SimpleGlyph
unsigned flag = points_.arrayZ[i].flag;
if (flag & short_flag)
{
if (unlikely (p + 1 > end)) return false;
if (flag & same_flag)
v += *p++;
else
@ -170,7 +182,6 @@ struct SimpleGlyph
{
if (!(flag & same_flag))
{
if (unlikely (p + HBINT16::static_size > end)) return false;
v += *(const HBINT16 *) p;
p += HBINT16::static_size;
}
@ -209,7 +220,9 @@ struct SimpleGlyph
if (unlikely (p >= end)) return false;
/* Read x & y coordinates */
return read_flags (p, points_, end)
unsigned x_points_len, y_points_len;
return read_flags (p, points_, end, x_points_len, y_points_len)
&& end - p >= (int) (x_points_len + y_points_len)
&& read_points (p, points_, end, &contour_point_t::x,
FLAG_X_SHORT, FLAG_X_SAME)
&& read_points (p, points_, end, &contour_point_t::y,