On 2019-07-23 08:51, ckerchne wrote:
A bug exist with the gcc compilers for Power in versions 6.x and 7.x
(verified with 6.3 and 7.4). It was fixed in version 8.x (verified
with 8.3). I was using a Power 9 ppc64le machine for building and
testing.
It appears the compiler is generating the wrong code for little endian
machines for the vec_lvsl/vec_perm instruction combos in some cases.
If these instructions are replaced with vec_xl, the problem goes away
for all versions of the compilers.
---
libswscale/ppc/yuv2rgb_altivec.c | 24 ++++--------------------
1 file changed, 4 insertions(+), 20 deletions(-)
diff --git a/libswscale/ppc/yuv2rgb_altivec.c
b/libswscale/ppc/yuv2rgb_altivec.c
index c1e2852adb..536545293d 100644
--- a/libswscale/ppc/yuv2rgb_altivec.c
+++ b/libswscale/ppc/yuv2rgb_altivec.c
@@ -305,9 +305,6 @@ static int altivec_ ## name(SwsContext *c, const
unsigned char **in, \
vector signed short R1, G1, B1;
\
vector unsigned char R, G, B;
\
\
- const vector unsigned char *y1ivP, *y2ivP, *uivP, *vivP;
\
- vector unsigned char align_perm;
\
-
\
vector signed short lCY = c->CY;
\
vector signed short lOY = c->OY;
\
vector signed short lCRV = c->CRV;
\
@@ -338,26 +335,13 @@ static int altivec_ ## name(SwsContext *c, const
unsigned char **in, \
vec_dstst(oute, (0x02000002 | (((w * 3 + 32) / 32) << 16)),
1); \
\
for (j = 0; j < w / 16; j++) {
\
- y1ivP = (const vector unsigned char *) y1i;
\
- y2ivP = (const vector unsigned char *) y2i;
\
- uivP = (const vector unsigned char *) ui;
\
- vivP = (const vector unsigned char *) vi;
\
-
\
- align_perm = vec_lvsl(0, y1i);
\
- y0 = (vector unsigned char)
\
- vec_perm(y1ivP[0], y1ivP[1], align_perm);
\
+ y0 = vec_xl(0, y1i);
\
\
- align_perm = vec_lvsl(0, y2i);
\
- y1 = (vector unsigned char)
\
- vec_perm(y2ivP[0], y2ivP[1], align_perm);
\
+ y1 = vec_xl(0, y2i);
\
\
- align_perm = vec_lvsl(0, ui);
\
- u = (vector signed char)
\
- vec_perm(uivP[0], uivP[1], align_perm);
\
+ u = (vector signed char) vec_xl(0, ui);
\
\
- align_perm = vec_lvsl(0, vi);
\
- v = (vector signed char)
\
- vec_perm(vivP[0], vivP[1], align_perm);
\
+ v = (vector signed char) vec_xl(0, vi);
\
\
u = (vector signed char)
\
vec_sub(u,
\
--
2.17.1
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Could someone please engage on this issue? It's been almost 10 days.
Chip Kerchner
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