[turbofan] Add support for ARM64 Ubfx

src/base/bits.h

Index: src/base/bits.h
diff --git a/src/base/bits.h b/src/base/bits.h
index e6a733a45dbb24ce4c95a30a817b2de2b4ee2354..38a7c57d98c453de6ba2c417f5a4c2c8f7ae64a8 100644
--- a/src/base/bits.h
+++ b/src/base/bits.h
@@ -33,6 +33,17 @@ inline uint32_t CountPopulation32(uint32_t value) {
 }
 
 
+// CountPopulation64(value) returns the number of bits set in |value|.
+inline uint32_t CountPopulation64(uint64_t value) {
+#if V8_HAS_BUILTIN_POPCOUNT
+  return __builtin_popcountll(value);
+#else
+  return CountPopulation32(static_cast<uint32_t>(value)) +
+         CountPopulation32(static_cast<uint32_t>(value >> 32));
+#endif
+}
+
+
 // CountLeadingZeros32(value) returns the number of zero bits following the most
 // significant 1 bit in |value| if |value| is non-zero, otherwise it returns 32.
 inline uint32_t CountLeadingZeros32(uint32_t value) {
@@ -53,6 +64,23 @@ inline uint32_t CountLeadingZeros32(uint32_t value) {
 }
 
 
+// CountLeadingZeros64(value) returns the number of zero bits following the most
+// significant 1 bit in |value| if |value| is non-zero, otherwise it returns 64.
+inline uint32_t CountLeadingZeros64(uint64_t value) {
+#if V8_HAS_BUILTIN_CLZ
+  return value ? __builtin_clzll(value) : 64;
+#else
+  value = value | (value >> 1);
+  value = value | (value >> 2);
+  value = value | (value >> 4);
+  value = value | (value >> 8);
+  value = value | (value >> 16);
+  value = value | (value >> 32);
+  return CountPopulation64(~value);
+#endif
+}
+
+
 // CountTrailingZeros32(value) returns the number of zero bits preceding the
 // least significant 1 bit in |value| if |value| is non-zero, otherwise it
 // returns 32.
@@ -73,6 +101,22 @@ inline uint32_t CountTrailingZeros32(uint32_t value) {
 }
 
 
+// CountTrailingZeros64(value) returns the number of zero bits preceding the
+// least significant 1 bit in |value| if |value| is non-zero, otherwise it
+// returns 64.
+inline uint64_t CountTrailingZeros64(uint64_t value) {

[Benedikt Meurer, 2014/10/08 11:40:12]

I think the result type of all these Count* functions should be unsigned. Can
you fix that for the 32-bit versions as well?

[m.m.capewell, 2014/10/08 17:35:01]

Done.

+#if V8_HAS_BUILTIN_CTZ
+  return value ? __builtin_ctzll(value) : 64;
+#else
+  if (value == 0) return 64;
+  unsigned count = 0;
+  for (value ^= value - 1; value >>= 1; ++count)
+    ;
+  return count;
+#endif
+}
+
+
 // Returns true iff |value| is a power of 2.
 inline bool IsPowerOfTwo32(uint32_t value) {
   return value && !(value & (value - 1));