arm64: clang assembler compatability

dl/sp/api/armSP.h

Index: dl/sp/api/armSP.h
diff --git a/dl/sp/api/armSP.h b/dl/sp/api/armSP.h
index 2592679c759c2149120f83ec2668c04ede212a2b..54ae05bf14393e525c5fc42f66ebafbc6bf94ee9 100644
--- a/dl/sp/api/armSP.h
+++ b/dl/sp/api/armSP.h
@@ -93,11 +93,11 @@ typedef struct ARMsFFTSpec_FC32_Tag
 /*
  * Compute log2(x), where x must be a power of 2.
  */
-static inline OMX_U32 fastlog2(long x) {
+static inline OMX_U32 fastlog2(OMX_U32 x) {

[Raymond Toy (Google), 2015/10/30 22:38:46]

Why the change from long to OMX_U32?

[Riku Voipio, 2015/11/02 12:24:12]

clang throws a warning:
../../third_party/openmax_dl/dl/sp/api/armSP.h:101:14: warning: value size does
not match register size specified by
 the constraint and modifier [-Wasm-operand-widths]
      : "=r"(out)

The only users of this fastlog2 call it with OMX_U32 value (spec->N). So instead
of changing the just the out value to long, I changed the whole function to
32bit. 

I'll update the patch to only change the return type.

   OMX_U32 out;
-  asm("clz %0,%1\n\t"
-      "sub %0, %0, #63\n\t"
-      "neg %0, %0\n\t"
+  asm("clz %w0,%w1\n\t"
+      "sub %w0, %w0, #63\n\t"

[Raymond Toy (Google), 2015/10/30 22:38:46]

If %w0 means a 32-bit register than clz is probably only returning a max value
of 32, so subtracting 63 is probably wrong.

[Riku Voipio, 2015/11/02 12:24:12]

Will be fixed in the next iteration by keeping the function 64bit.

+      "neg %w0, %w0\n\t"
       : "=r"(out)
       : "r"(x)
       :);