avutil: turn arm setend into a cpuflag

this allows disabling and enabling it
it also prevents crashes if vfpv3 and neon are disabled which previously
would have enabled the flag

And last but not least one can enable setend on cpus like cortex-a8 where
its fast but disabled by default

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -1525,6 +1525,7 @@ ARCH_EXT_LIST_ARM="
     neon
     vfp
     vfpv3
+    setend
 "
 
 ARCH_EXT_LIST_MIPS="
@@ -1951,6 +1952,7 @@ neon_deps_any="aarch64 arm"
 intrinsics_neon_deps="neon"
 vfp_deps_any="aarch64 arm"
 vfpv3_deps="vfp"
+setend_deps="arm"
 
 map 'eval ${v}_inline_deps=inline_asm' $ARCH_EXT_LIST_ARM
 
@@ -4447,6 +4449,7 @@ EOF
     enabled neon    && check_insn neon    'vadd.i16 q0, q0, q0'
     enabled vfp     && check_insn vfp     'fadds s0, s0, s0'
     enabled vfpv3   && check_insn vfpv3   'vmov.f32 s0, #1.0'
+    enabled setend  && check_insn setend  'setend be'
 
     [ $target_os = linux ] || [ $target_os = android ] ||
         map 'enabled_any ${v}_external ${v}_inline || disable $v' \

libavutil/arm/cpu.c

@@ -128,6 +128,12 @@ int ff_get_cpu_flags_arm(void)
        trickle down. */
     if (flags & (AV_CPU_FLAG_VFPV3 | AV_CPU_FLAG_NEON))
         flags |= AV_CPU_FLAG_ARMV6T2;
+    else
+    /* Some functions use the 'setend' instruction which is deprecated on ARMv8
+     * and serializing on some ARMv7 cores. This ensures such functions
+     * are only enabled on ARMv6. */
+        flags |= AV_CPU_FLAG_SETEND;
+
     if (flags & AV_CPU_FLAG_ARMV6T2)
         flags |= AV_CPU_FLAG_ARMV6;
 
@@ -143,7 +149,8 @@ int ff_get_cpu_flags_arm(void)
            AV_CPU_FLAG_ARMV6T2 * HAVE_ARMV6T2 |
            AV_CPU_FLAG_VFP     * HAVE_VFP     |
            AV_CPU_FLAG_VFPV3   * HAVE_VFPV3   |
-           AV_CPU_FLAG_NEON    * HAVE_NEON;
+           AV_CPU_FLAG_NEON    * HAVE_NEON    |
+           AV_CPU_FLAG_SETEND  * !(HAVE_NEON | HAVE_VFPV3);
 }
 
 #endif

libavutil/arm/cpu.h

@@ -29,11 +29,6 @@
 #define have_vfp(flags)     CPUEXT(flags, VFP)
 #define have_vfpv3(flags)   CPUEXT(flags, VFPV3)
 #define have_neon(flags)    CPUEXT(flags, NEON)
-
-/* Some functions use the 'setend' instruction which is deprecated on ARMv8
- * and serializing on some ARMv7 cores. This macro ensures such functions
- * are only enabled on ARMv6. */
-#define have_setend(flags)                                              \
-    (have_armv6(flags) && !(have_vfpv3(flags) || have_neon(flags)))
+#define have_setend(flags)  CPUEXT(flags, SETEND)
 
 #endif /* AVUTIL_ARM_CPU_H */

libavutil/cpu.c

@@ -225,6 +225,7 @@ int av_parse_cpu_caps(unsigned *flags, const char *s)
         { "vfp",      NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_VFP      },    .unit = "flags" },
         { "vfpv3",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_VFPV3    },    .unit = "flags" },
         { "neon",     NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_NEON     },    .unit = "flags" },
+        { "setend",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_SETEND   },    .unit = "flags" },
 #elif ARCH_AARCH64
         { "armv8",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_ARMV8    },    .unit = "flags" },
         { "neon",     NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_CPU_FLAG_NEON     },    .unit = "flags" },
@@ -303,6 +304,7 @@ static const struct {
     { AV_CPU_FLAG_VFP,       "vfp"        },
     { AV_CPU_FLAG_VFPV3,     "vfpv3"      },
     { AV_CPU_FLAG_NEON,      "neon"       },
+    { AV_CPU_FLAG_SETEND,    "setend"     },
 #elif ARCH_PPC
     { AV_CPU_FLAG_ALTIVEC,   "altivec"    },
 #elif ARCH_X86

libavutil/cpu.h

@@ -64,6 +64,7 @@
 #define AV_CPU_FLAG_VFPV3        (1 << 4)
 #define AV_CPU_FLAG_NEON         (1 << 5)
 #define AV_CPU_FLAG_ARMV8        (1 << 6)
+#define AV_CPU_FLAG_SETEND       (1 <<16)
 
 /**
  * Return the flags which specify extensions supported by the CPU.