ARM64: Faster immediate check and fix corner cases

src/arm64/utils-arm64.h

Index: src/arm64/utils-arm64.h
diff --git a/src/arm64/utils-arm64.h b/src/arm64/utils-arm64.h
index 3c040c6be455d48e197204a04bab346f7b3ebcef..0f8ba935e2ba00989cf6a89fbe9851265d5abeba 100644
--- a/src/arm64/utils-arm64.h
+++ b/src/arm64/utils-arm64.h
@@ -57,6 +57,7 @@ int CountLeadingZeros(uint64_t value, int width);
 int CountLeadingSignBits(int64_t value, int width);
 int CountTrailingZeros(uint64_t value, int width);
 int CountSetBits(uint64_t value, int width);
+uint64_t LowestSetBit(uint64_t value);

[ulan, 2014/06/30 12:50:08]

The name suggests that the function returns a bit position instead of 2^(bit
position). Could you please either add a comment or rename it to something like
LargestPowerOf2Divisor.

 int MaskToBit(uint64_t mask);