[turbofan] Add support for ARM64 Ubfx

src/base/bits.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_BITS_H_
 #define V8_BASE_BITS_H_
 
 #include "include/v8stdint.h"
 #include "src/base/macros.h"
 #if V8_CC_MSVC
@@ skipping 15 matching lines @@
   value = ((value >> 1) & 0x55555555) + (value & 0x55555555);
   value = ((value >> 2) & 0x33333333) + (value & 0x33333333);
   value = ((value >> 4) & 0x0f0f0f0f) + (value & 0x0f0f0f0f);
   value = ((value >> 8) & 0x00ff00ff) + (value & 0x00ff00ff);
   value = ((value >> 16) & 0x0000ffff) + (value & 0x0000ffff);
   return value;
 #endif
 }
 
 
+// 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) {
 #if V8_HAS_BUILTIN_CLZ
   return value ? __builtin_clz(value) : 32;
 #elif V8_CC_MSVC
   unsigned long result;  // NOLINT(runtime/int)
   if (!_BitScanReverse(&result, value)) return 32;
   return static_cast<uint32_t>(31 - result);
 #else
   value = value | (value >> 1);
   value = value | (value >> 2);
   value = value | (value >> 4);
   value = value | (value >> 8);
   value = value | (value >> 16);
   return CountPopulation32(~value);
 #endif
 }
 
 
+// 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.
 inline uint32_t CountTrailingZeros32(uint32_t value) {
 #if V8_HAS_BUILTIN_CTZ
   return value ? __builtin_ctz(value) : 32;
 #elif V8_CC_MSVC
   unsigned long result;  // NOLINT(runtime/int)
   if (!_BitScanForward(&result, value)) return 32;
   return static_cast<uint32_t>(result);
 #else
   if (value == 0) return 32;
   unsigned count = 0;
   for (value ^= value - 1; value >>= 1; ++count)
     ;
   return count;
 #endif
 }
 
 
+// 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));
 }
 
 
 // Returns true iff |value| is a power of 2.
 inline bool IsPowerOfTwo64(uint64_t value) {
   return value && !(value & (value - 1));
 }
@@ skipping 55 matching lines @@
   *val = bit_cast<int32_t>(res);
   return ((res ^ lhs) & (res ^ ~rhs) & (1U << 31)) != 0;
 #endif
 }
 
 }  // namespace bits
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_BITS_H_