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Optimize tvb_ensure_bytes_exist through manual inlining and removal of redundant 

checks and computations. Should contain no behavioural changes at *all*, I hope.

svn path=/trunk/; revision=52768
This commit is contained in:
Evan Huus 2013-10-22 16:29:10 +00:00
parent a3a15ff90b
commit 7aee8b2dcf
1 changed files with 51 additions and 2 deletions
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53
epan/tvbuff.c
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@ -467,7 +467,7 @@ tvb_bytes_exist(const tvbuff_t *tvb, const gint offset, const gint length)
void
tvb_ensure_bytes_exist(const tvbuff_t *tvb, const gint offset, const gint length)
{
guint abs_offset, abs_length;
guint real_offset, end_offset;
DISSECTOR_ASSERT(tvb && tvb->initialized);
@ -484,7 +484,56 @@ tvb_ensure_bytes_exist(const tvbuff_t *tvb, const gint offset, const gint length
if (length < 0) {
THROW(ReportedBoundsError);
}
check_offset_length(tvb, offset, length, &abs_offset, &abs_length);
/* XXX: Below this point could be replaced with a call to
* check_offset_length with no functional change, however this is a
* *very* hot path and check_offset_length is not well-optimized for
* this case, so we eat some code duplication for a lot of speedup. */
if (offset >= 0) {
/* Positive offset - relative to the beginning of the packet. */
if ((guint) offset <= tvb->length) {
real_offset = offset;
} else if ((guint) offset <= tvb->reported_length) {
THROW(BoundsError);
} else if (tvb->flags & TVBUFF_FRAGMENT) {
THROW(FragmentBoundsError);
} else {
THROW(ReportedBoundsError);
}
}
else {
/* Negative offset - relative to the end of the packet. */
if ((guint) -offset <= tvb->length) {
real_offset = tvb->length + offset;
} else if ((guint) -offset <= tvb->reported_length) {
THROW(BoundsError);
} else if (tvb->flags & TVBUFF_FRAGMENT) {
THROW(FragmentBoundsError);
} else {
THROW(ReportedBoundsError);
}
}
/*
* Compute the offset of the first byte past the length.
*/
end_offset = real_offset + length;
/*
* Check for an overflow
*/
if (end_offset < real_offset)
THROW(BoundsError);
if (G_LIKELY(end_offset <= tvb->length))
return;
else if (end_offset <= tvb->reported_length)
THROW(BoundsError);
else if (tvb->flags & TVBUFF_FRAGMENT)
THROW(FragmentBoundsError);
else
THROW(ReportedBoundsError);
}
gboolean