@@ -30,12 +30,15 @@
(HAVE_ ## cpuext ## suffix && ((flags) & AV_CPU_FLAG_ ## cpuext) && \
!((flags) & AV_CPU_FLAG_ ## slow_cpuext ## SLOW))
+#define CPUEXT_SUFFIX_SLOW(flags, suffix, cpuext) \
+ (HAVE_ ## cpuext ## suffix && \
+ ((flags) & (AV_CPU_FLAG_ ## cpuext | AV_CPU_FLAG_ ## cpuext ## SLOW)))
+
#define CPUEXT_SUFFIX_SLOW2(flags, suffix, cpuext, slow_cpuext) \
(HAVE_ ## cpuext ## suffix && ((flags) & AV_CPU_FLAG_ ## cpuext) && \
- ((flags) & AV_CPU_FLAG_ ## slow_cpuext ## SLOW))
+ ((flags) & (AV_CPU_FLAG_ ## slow_cpuext | AV_CPU_FLAG_ ## slow_cpuext ## SLOW)))
#define CPUEXT_SUFFIX_FAST(flags, suffix, cpuext) CPUEXT_SUFFIX_FAST2(flags, suffix, cpuext, cpuext)
-#define CPUEXT_SUFFIX_SLOW(flags, suffix, cpuext) CPUEXT_SUFFIX_SLOW2(flags, suffix, cpuext, cpuext)
#define CPUEXT(flags, cpuext) CPUEXT_SUFFIX(flags, , cpuext)
#define CPUEXT_FAST(flags, cpuext) CPUEXT_SUFFIX_FAST(flags, , cpuext)
For SSE2 and SSE3, there are four states that the two flags involved (AV_CPU_FLAG_SSE[23] and AV_CPU_FLAG_SSE[23]SLOW) can convey. When ordered from worst to best they are: 1. both flags unset (SSE[23] unavailable) 2. the slow flag set, the ordinary flag unset (this is designed for cases where SSE2 is available, but so slow that MMX(EXT)/SSE code is usually faster) 3. both flags set (SSE2 is available, but there might be scenarios where MMX(EXT)/SSE code is faster) 4. the ordinary flag set, the slow flag unset (this is the normal case) The ordinary macros for checking cpuflags return true in the latter two cases; the fast macros only return true for the latter case. Yet the macros to check for slow currently only return true in case three. This seems unintended. In fact, the only uses of the slow macros are all of the form if (EXTERNAL_SSE2(cpu_flags) || EXTERNAL_SSE2_SLOW(cpu_flags)) where the check for EXTERNAL_SSE2_SLOW is completely redundant. Even more importantly, it is not what was intended. Before 6369ba3c9cc74becfaad2a8882dff3dd3e7ae3c0, the checks passed in cases 2 to 4. Said commit changed this to something that only passes for the third case. Commits 7fb758cd8ed08e4a37f10e25003953d13c68b8cd and c1913064e38cb338039f29c280a0dacc3fd1e451 restored the old behaviour, yet merging 4efab89332ea39a77145e8b15562b981d9dbde68 (in commit ac774cfa571734c49c26e2d3387adccff8957ff8) broke this again by changing it to what it is now.* This commit changes the macros to make the slow macros check whether a specific instruction is supported, even if slow. This restores the intended meaning to all uses of the SLOW macros and is generally more natural. *: Libav only checks for EXTERNAL_SSE2_SLOW, i.e. for the third case only. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com> --- libavutil/cpu_internal.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)