On Wed, Jan 16, 2019 at 08:00:22PM +0100, Marton Balint wrote: > > > On Tue, 15 Jan 2019, Michael Niedermayer wrote: > > >On Sun, Dec 30, 2018 at 07:15:49PM +0100, Marton Balint wrote: > >> > >> > >>On Fri, 28 Dec 2018, Michael Niedermayer wrote: > >> > >>>On Wed, Dec 26, 2018 at 10:16:47PM +0100, Marton Balint wrote: > >>>> > >>>> > >>>>On Wed, 26 Dec 2018, Paul B Mahol wrote: > >>>> > >>>>>On 12/26/18, Michael Niedermayer <mich...@niedermayer.cc> wrote: > >>>>>>On Wed, Dec 26, 2018 at 04:32:17PM +0100, Paul B Mahol wrote: > >>>>>>>On 12/25/18, Michael Niedermayer <mich...@niedermayer.cc> wrote: > >>>>>>>>Fixes: Timeout > >>>>>>>>Fixes: > >>>>>>>>11502/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920 > >>>>>>>>Before: Executed > >>>>>>>>clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920 > >>>>>>>>in 11294 ms > >>>>>>>>After : Executed > >>>>>>>>clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920 > >>>>>>>>in 4249 ms > >>>>>>>> > >>>>>>>>Found-by: continuous fuzzing process > >>>>>>>>https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >>>>>>>>Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >>>>>>>>--- > >>>>>>>>libavutil/imgutils.c | 6 ++++++ > >>>>>>>>1 file changed, 6 insertions(+) > >>>>>>>> > >>>>>>>>diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c > >>>>>>>>index 4938a7ef67..cc38f1e878 100644 > >>>>>>>>--- a/libavutil/imgutils.c > >>>>>>>>+++ b/libavutil/imgutils.c > >>>>>>>>@@ -529,6 +529,12 @@ static void memset_bytes(uint8_t *dst, size_t > >>>>>>>>dst_size, > >>>>>>>>uint8_t *clear, > >>>>>>>> } > >>>>>>>> } else if (clear_size == 4) { > >>>>>>>> uint32_t val = AV_RN32(clear); > >>>>>>>>+ uint64_t val8 = val * 0x100000001ULL; > >>>>>>>>+ for (; dst_size >= 32; dst_size -= 32) { > >>>>>>>>+ AV_WN64(dst , val8); AV_WN64(dst+ 8, val8); > >>>>>>>>+ AV_WN64(dst+16, val8); AV_WN64(dst+24, val8); > >>>>>>>>+ dst += 32; > >>>>>>>>+ } > >>>>>>>> for (; dst_size >= 4; dst_size -= 4) { > >>>>>>>> AV_WN32(dst, val); > >>>>>>>> dst += 4; > >>>>>>>>-- > >>>>>>>>2.20.1 > >>>>>>>> > >>>>>>> > >>>>>>>NAK, implement special memset function instead. > >>>>>> > >>>>>>I can move the added loop into a seperate function, if thats what you > >>>>>>suggest ? > >>>>> > >>>>>No, don't do that. > >>>>> > >>>>>>All the code is already in a "special" memset though, this is > >>>>>>memset_bytes() > >>>>>> > >>>>> > >>>>>I guess function is less useful if its static. So any duplicate should > >>>>>be avoided in codebase. > >>>> > >>>>Isn't av_memcpy_backptr does almost exactly what is needed here? That can > >>>>also be optimized further if needed. > >>> > >>>av_memcpy_backptr() copies data with overlap, its more like a recursive > >>>memmove(). > >> > >>So? As far as I see the memset_bytes function in imgutils.c can be replaced > >>with this: > >> > >> if (clear_size > dst_size) > >> clear_size = dst_size; > >> memcpy(dst, clear, clear_size); > >> av_memcpy_backptr(dst + clear_size, clear_size, dst_size - clear_size); > >> > >>I am not against an av_memset_bytes API addition, but I believe it should > >>share code with av_memcpy_backptr to avoid duplication. > > > >ive implemented this, it does not seem to be really faster in the testcase > > I guess it is not faster because you have not applied your original > optimalization to fill32 in libavutil/mem.c. Could you compare speed after > optimizing that the same way your original patch did it with imgutils > memset_bytes?
sure, that makes it faster:
From f5660e4025bb8161ebdb55cda03b656cbf685b1a Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <mich...@niedermayer.cc>
Date: Thu, 17 Jan 2019 22:35:10 +0100
Subject: [PATCH 1/2] avutil/mem: Optimize fill32() by unrolling and using
64bit
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavutil/mem.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/libavutil/mem.c b/libavutil/mem.c
index 6149755a6b..88fe09b179 100644
--- a/libavutil/mem.c
+++ b/libavutil/mem.c
@@ -399,6 +399,18 @@ static void fill32(uint8_t *dst, int len)
{
uint32_t v = AV_RN32(dst - 4);
+#if HAVE_FAST_64BIT
+ uint64_t v2= v + ((uint64_t)v<<32);
+ while (len >= 32) {
+ AV_WN64(dst , v2);
+ AV_WN64(dst+ 8, v2);
+ AV_WN64(dst+16, v2);
+ AV_WN64(dst+24, v2);
+ dst += 32;
+ len -= 32;
+ }
+#endif
+
while (len >= 4) {
AV_WN32(dst, v);
dst += 4;
--
2.20.1
From 9b5573f91a043a818fe1fd6b93d0d36c4830cd9c Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <mich...@niedermayer.cc>
Date: Tue, 25 Dec 2018 23:15:20 +0100
Subject: [PATCH 2/2] avutil/imgutils: Optimize memset_bytes() by using
av_memcpy_backptr()
This is strongly based on code by Marton Balint
Fixes: Timeout
Fixes:
11502/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
Before: Executed
clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
in 11209 ms
After: Executed
clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WCMV_fuzzer-5664893810769920
in 4104 ms
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavutil/imgutils.c | 26 +++++---------------------
1 file changed, 5 insertions(+), 21 deletions(-)
diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c
index 4938a7ef67..cf06afde3f 100644
--- a/libavutil/imgutils.c
+++ b/libavutil/imgutils.c
@@ -521,28 +521,12 @@ static void memset_bytes(uint8_t *dst, size_t dst_size,
uint8_t *clear,
if (clear_size == 1) {
memset(dst, clear[0], dst_size);
dst_size = 0;
- } else if (clear_size == 2) {
- uint16_t val = AV_RN16(clear);
- for (; dst_size >= 2; dst_size -= 2) {
- AV_WN16(dst, val);
- dst += 2;
- }
- } else if (clear_size == 4) {
- uint32_t val = AV_RN32(clear);
- for (; dst_size >= 4; dst_size -= 4) {
- AV_WN32(dst, val);
- dst += 4;
- }
- } else if (clear_size == 8) {
- uint32_t val = AV_RN64(clear);
- for (; dst_size >= 8; dst_size -= 8) {
- AV_WN64(dst, val);
- dst += 8;
- }
+ } else {
+ if (clear_size > dst_size)
+ clear_size = dst_size;
+ memcpy(dst, clear, clear_size);
+ av_memcpy_backptr(dst + clear_size, clear_size, dst_size - clear_size);
}
-
- for (; dst_size; dst_size--)
- *dst++ = clear[pos++ % clear_size];
}
// Maximum size in bytes of a plane element (usually a pixel, or multiple
pixels
--
2.20.1
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Dictatorship: All citizens are under surveillance, all their steps and
actions recorded, for the politicians to enforce control.
Democracy: All politicians are under surveillance, all their steps and
actions recorded, for the citizens to enforce control.
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
