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authorAndreas Rheinhardt <andreas.rheinhardt@outlook.com>2023-11-01 10:01:09 +0100
committerAndreas Rheinhardt <andreas.rheinhardt@outlook.com>2023-11-04 01:26:03 +0100
commit5b85ca5317f28a73eadf10d604d2a7421b84bed8 (patch)
treed678474b9d9ed6a1a5bf30d615c188b8f0db7a1c /libavcodec/intrax8.c
parent8661b5e8f9e63d2775978f2aa3ee6fae4d515c53 (diff)
downloadffmpeg-5b85ca5317f28a73eadf10d604d2a7421b84bed8.tar.gz
avutil/x86/pixelutils: Empty MMX state in ff_pixelutils_sad_8x8_mmxext
We currently mostly do not empty the MMX state in our MMX DSP functions; instead we only do so before code that might be using x87 code. This is a violation of the System V i386 ABI (and maybe of other ABIs, too): "The CPU shall be in x87 mode upon entry to a function. Therefore, every function that uses the MMX registers is required to issue an emms or femms instruction after using MMX registers, before returning or calling another function." (See 2.2.1 in [1]) This patch does not intend to change all these functions to abide by the ABI; it only does so for ff_pixelutils_sad_8x8_mmxext, as this function can by called by external users, because it is exported via the pixelutils API. Without this, the following fragment will assert (on x86/x64): uint8_t src1[8 * 8], src2[8 * 8]; av_pixelutils_sad_fn fn = av_pixelutils_get_sad_fn(3, 3, 0, NULL); fn(src1, 8, src2, 8); av_assert0_fpu(); [1]: https://raw.githubusercontent.com/wiki/hjl-tools/x86-psABI/intel386-psABI-1.1.pdf Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Diffstat (limited to 'libavcodec/intrax8.c')
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