From 55fc2c5a892c50feb1b9a8f55b74ec6594755ddb Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Sat, 11 Jun 2022 23:25:14 +0200 Subject: swresample/resample: Properly empty MMX state There is a x86-32 MMXEXT implementation for resampling planar 16bit data. multiple_resample() therefore calls emms_c() if it thinks that this needed. And this is bad: 1. It is a maintenance nightmare because changes to the x86 resample DSP code would necessitate changes to the check whether to call emms_c(). 2. The return value of av_get_cpu_flags() does not tell whether the MMX DSP functions are in use, as they could have been overridden by av_force_cpu_flags(). 3. The MMX DSP functions will never be overridden in case of an x86-32 build with --disable-sse2. In this scenario lots of resampling tests (like swr-resample_exact_lin_async-s16p-8000-48000) fail because the cpuflags indicate that SSE2 is available (presuming that the test is run on a CPU with SSE2). 4. The check includes a call to av_get_cpu_flags(). This is not optimized away for arches other than x86-32. 5. The check takes about as much time as emms_c() itself, making it pointless. This commit therefore removes the check and calls emms_c() unconditionally (it is a no-op for non-x86). Signed-off-by: Andreas Rheinhardt --- libswresample/resample.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'libswresample') diff --git a/libswresample/resample.c b/libswresample/resample.c index f1ec77f54b..9c5b7fee72 100644 --- a/libswresample/resample.c +++ b/libswresample/resample.c @@ -452,9 +452,6 @@ static int set_compensation(ResampleContext *c, int sample_delta, int compensati static int multiple_resample(ResampleContext *c, AudioData *dst, int dst_size, AudioData *src, int src_size, int *consumed){ int i; - int av_unused mm_flags = av_get_cpu_flags(); - int need_emms = c->format == AV_SAMPLE_FMT_S16P && ARCH_X86_32 && - (mm_flags & (AV_CPU_FLAG_MMX2 | AV_CPU_FLAG_SSE2)) == AV_CPU_FLAG_MMX2; int64_t max_src_size = (INT64_MAX/2 / c->phase_count) / c->src_incr; if (c->compensation_distance) @@ -500,8 +497,7 @@ static int multiple_resample(ResampleContext *c, AudioData *dst, int dst_size, A } } - if(need_emms) - emms_c(); + emms_c(); if (c->compensation_distance) { c->compensation_distance -= dst_size; -- cgit v1.2.3