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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-07 11:13:41 +02:00
FFmpeg/tests
Rémi Denis-Courmont 378d1b06c3 riscv: probe for Zbb extension at load time
Due to hysterical raisins, most RISC-V Linux distributions target a
RV64GC baseline excluding the Bit-manipulation ISA extensions, most
notably:
- Zba: address generation extension and
- Zbb: basic bit manipulation extension.
Most CPUs that would make sense to run FFmpeg on support Zba and Zbb
(including the current FATE runner), so it makes sense to optimise for
them. In fact a large chunk of existing assembler optimisations relies
on Zba and/or Zbb.

Since we cannot patch shared library code, the next best thing is to
carry a flag initialised at load-time and check it on need basis.
This results in 3 instructions overhead on isolated use, e.g.:
1:  AUIPC rd, %pcrel_hi(ff_rv_zbb_supported)
    LBU   rd, %pcrel_lo(1b)(rd)
    BEQZ  rd, non_Zbb_fallback_code
    // Zbb code here

The C compiler will typically load the flag ahead of time to reducing
latency, and can also keep it around if Zbb is used multiple times in a
single optimisation scope. For this to work, the flag symbol must be
hidden; otherwise the optimisation degrades with a GOT look-up to
support interposition:
1:  AUIPC rd, GOT_OFFSET_HI
    LD    rd, GOT_OFFSET_LO(rd)
    LBU   rd, (rd)
    BEQZ  rd, non_Zbb_fallback_code
    // Zbb code here

This patch adds code to provision the flag in libraries using bit
manipulation functions from libavutil: byte-swap, bit-weight and
counting leading or trailing zeroes.
2024-06-11 20:12:37 +03:00
..
api avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
checkasm checkasm/lls: adjust buffer sizes and alignments 2024-06-11 20:07:55 +03:00
fate fate: add tests for xHE-AAC 2024-06-02 18:34:46 +02:00
filtergraphs fate/scale2ref_keep_aspect: switch to vf_scale ref_* 2024-05-03 14:23:23 +02:00
maps
ref riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
streamgroups
.gitignore
audiogen.c
audiomatch.c
base64.c
copycooker.sh
extended.ffconcat
fate-run.sh configure, etc: switch to shebang without space 2024-04-09 16:01:24 +02:00
fate-valgrind.supp
fate.sh fate: allow https for git URLs 2024-04-27 23:24:58 +02:00
Makefile fate/ffprobe: Fix test requirements 2024-04-03 19:10:24 +02:00
md5.sh
refcmp-metadata.awk
reference.pnm
rotozoom.c
simple1.ffconcat
simple2.ffconcat
test.ffmeta
tiny_psnr.c
tiny_ssim.c
utils.c
videogen.c