arm: Check the build time constants in av_clip_*intp2

This fixes building for arm targets with optimizations disabled.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavutil/arm/intmath.h

@@ -65,17 +65,29 @@ static av_always_inline av_const int av_clip_int16_arm(int a)
 #define av_clip_intp2 av_clip_intp2_arm
 static av_always_inline av_const int av_clip_intp2_arm(int a, int p)
 {
-    unsigned x;
-    __asm__ ("ssat %0, %2, %1" : "=r"(x) : "r"(a), "i"(p+1));
-    return x;
+    if (av_builtin_constant_p(p)) {
+        unsigned x;
+        __asm__ ("ssat %0, %2, %1" : "=r"(x) : "r"(a), "i"(p+1));
+        return x;
+    } else {
+        if (((unsigned)a + (1 << p)) & ~((2 << p) - 1))
+            return (a >> 31) ^ ((1 << p) - 1);
+        else
+            return a;
+    }
 }
 
 #define av_clip_uintp2 av_clip_uintp2_arm
 static av_always_inline av_const unsigned av_clip_uintp2_arm(int a, int p)
 {
-    unsigned x;
-    __asm__ ("usat %0, %2, %1" : "=r"(x) : "r"(a), "i"(p));
-    return x;
+    if (av_builtin_constant_p(p)) {
+        unsigned x;
+        __asm__ ("usat %0, %2, %1" : "=r"(x) : "r"(a), "i"(p));
+        return x;
+    } else {
+        if (a & ~((1<<p) - 1)) return (~a) >> 31 & ((1<<p) - 1);
+        else                   return  a;
+    }
 }
 
 #define av_sat_add32 av_sat_add32_arm