mirror/opencv
1
0
Fork 0
mirror of https://github.com/opencv/opencv.git synced 2025-07-30 17:37:05 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

imgproc(resize): improve 8u3 HResize vector exit calc

Browse Source 
Actually, we can do this in constant time. xofs always
contains same or increasing offset values. We can instead
find the most extreme value used and never attempt to load it.

Similarly, we can note for all dx >= 0 and dx < (dwidth - cn)
where xofs[dx] + cn < xofs[dwidth-cn] implies dx < (dwidth - cn).

Thus, we can use this to control our loop termination optimally.

This fixes #16137 with little or no performance impact. I have
also added a debug check as a sanity check.
This commit is contained in:
Paul E. Murphy 2019-12-12 10:33:08 -06:00
parent 40ac72a8f1
commit c1cdb2416a
1 changed files with 10 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
modules/imgproc/src/resize.cpp
View File

@ -1526,7 +1526,7 @@ struct HResizeLinearVec_X4
struct HResizeLinearVecU8_X4
{
int operator()(const uchar** src, int** dst, int count, const int* xofs,
const short* alpha/*[xmax]*/, int smax, int /*dmax*/, int cn, int /*xmin*/, int xmax) const
const short* alpha/*[xmax]*/, int /*smax*/, int dmax, int cn, int /*xmin*/, int xmax) const
{
int dx = 0, k = 0;
@ -1612,17 +1612,11 @@ struct HResizeLinearVecU8_X4
}
else if(cn == 3)
{
int len0 = xmax - cn;
/* This may need to trim 1 or more extra units depending on the amount of
scaling. Test until we find the first value which we know cannot overrun. */
while (len0 >= cn &&
xofs[len0 - cn] + cn >= smax - cn // check access: v_load_expand_q(S+xofs[dx]+cn)
)
{
len0 -= cn;
}
CV_DbgAssert(len0 <= 0 || len0 >= cn);
/* Peek at the last x offset to find the maximal s offset. We know the loop
will terminate prior to value which may be 1 or more elements prior to the
final valid offset. xofs[] is constucted to be an array of increasingly
large offsets (i.e xofs[x] <= xofs[x+1] for x < xmax). */
int smax = xofs[dmax-cn];
for( ; k <= (count - 2); k+=2 )
{
@ -1631,7 +1625,7 @@ struct HResizeLinearVecU8_X4
const uchar *S1 = src[k+1];
int *D1 = dst[k+1];
for( dx = 0; dx < len0; dx += cn )
for( dx = 0; (xofs[dx] + cn) < smax; dx += cn )
{
v_int16x8 a = v_load(alpha+dx*2);
v_store(&D0[dx], v_dotprod(v_reinterpret_as_s16(v_load_expand_q(S0+xofs[dx]) | (v_load_expand_q(S0+xofs[dx]+cn)<<16)), a));
@ -1642,12 +1636,14 @@ struct HResizeLinearVecU8_X4
{
const uchar *S = src[k];
int *D = dst[k];
for( dx = 0; dx < len0; dx += cn )
for( dx = 0; (xofs[dx] + cn) < smax; dx += cn )
{
v_int16x8 a = v_load(alpha+dx*2);
v_store(&D[dx], v_dotprod(v_reinterpret_as_s16(v_load_expand_q(S+xofs[dx]) | (v_load_expand_q(S+xofs[dx]+cn)<<16)), a));
}
}
/* Debug check to ensure truthiness that we never vector the final value. */
CV_DbgAssert(dx < dmax);
}
else if(cn == 4)
{