Fix implementation of bit count functions.

include/v8config.h

 // Copyright 2013 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 V8CONFIG_H_
 #define V8CONFIG_H_
 
 // Platform headers for feature detection below.
 #if defined(__ANDROID__)
 # include <sys/cdefs.h>
@@ skipping 157 matching lines @@
 //  V8_HAS___ALIGNOF__                  - __alignof__(type) operator supported
 //  V8_HAS_ATTRIBUTE_ALIGNED            - __attribute__((aligned(n))) supported
 //  V8_HAS_ATTRIBUTE_ALWAYS_INLINE      - __attribute__((always_inline))
 //                                        supported
 //  V8_HAS_ATTRIBUTE_DEPRECATED         - __attribute__((deprecated)) supported
 //  V8_HAS_ATTRIBUTE_NOINLINE           - __attribute__((noinline)) supported
 //  V8_HAS_ATTRIBUTE_UNUSED             - __attribute__((unused)) supported
 //  V8_HAS_ATTRIBUTE_VISIBILITY         - __attribute__((visibility)) supported
 //  V8_HAS_ATTRIBUTE_WARN_UNUSED_RESULT - __attribute__((warn_unused_result))
 //                                        supported
+//  V8_HAS_BUILTIN_CLZ                  - __builtin_clz() supported
+//  V8_HAS_BUILTIN_CTZ                  - __builtin_ctz() supported
 //  V8_HAS_BUILTIN_EXPECT               - __builtin_expect() supported
+//  V8_HAS_BUILTIN_POPCOUNT             - __builtin_popcount() supported
 //  V8_HAS_DECLSPEC_ALIGN               - __declspec(align(n)) supported
 //  V8_HAS_DECLSPEC_DEPRECATED          - __declspec(deprecated) supported
 //  V8_HAS_DECLSPEC_NOINLINE            - __declspec(noinline) supported
 //  V8_HAS___FINAL                      - __final supported in non-C++11 mode
 //  V8_HAS___FORCEINLINE                - __forceinline supported
 //  V8_HAS_SEALED                       - MSVC style sealed marker supported
 //
 // Note that testing for compilers and/or features must be done using #if
 // not #ifdef. For example, to test for Intel C++ Compiler, use:
 //  #if V8_CC_INTEL
@@ skipping 10 matching lines @@
 
 # define V8_HAS_ATTRIBUTE_ALIGNED (__has_attribute(aligned))
 # define V8_HAS_ATTRIBUTE_ALWAYS_INLINE (__has_attribute(always_inline))
 # define V8_HAS_ATTRIBUTE_DEPRECATED (__has_attribute(deprecated))
 # define V8_HAS_ATTRIBUTE_NOINLINE (__has_attribute(noinline))
 # define V8_HAS_ATTRIBUTE_UNUSED (__has_attribute(unused))
 # define V8_HAS_ATTRIBUTE_VISIBILITY (__has_attribute(visibility))
 # define V8_HAS_ATTRIBUTE_WARN_UNUSED_RESULT \
     (__has_attribute(warn_unused_result))
 
+# define V8_HAS_BUILTIN_CLZ (__has_builtin(__builtin_clz))
+# define V8_HAS_BUILTIN_CTZ (__has_builtin(__builtin_ctz))
 # define V8_HAS_BUILTIN_EXPECT (__has_builtin(__builtin_expect))
+# define V8_HAS_BUILTIN_POPCOUNT (__has_builtin(__builtin_popcount))
 
 # define V8_HAS_CXX11_ALIGNAS (__has_feature(cxx_alignas))
 # define V8_HAS_CXX11_STATIC_ASSERT (__has_feature(cxx_static_assert))
 # define V8_HAS_CXX11_DELETE (__has_feature(cxx_deleted_functions))
 # define V8_HAS_CXX11_FINAL (__has_feature(cxx_override_control))
 # define V8_HAS_CXX11_OVERRIDE (__has_feature(cxx_override_control))
 
 #elif defined(__GNUC__)
 
 # define V8_CC_GNU 1
@@ skipping 11 matching lines @@
 // older compilers.
 # define V8_HAS_ATTRIBUTE_ALWAYS_INLINE (V8_GNUC_PREREQ(4, 4, 0))
 # define V8_HAS_ATTRIBUTE_DEPRECATED (V8_GNUC_PREREQ(3, 4, 0))
 # define V8_HAS_ATTRIBUTE_DEPRECATED_MESSAGE (V8_GNUC_PREREQ(4, 5, 0))
 # define V8_HAS_ATTRIBUTE_NOINLINE (V8_GNUC_PREREQ(3, 4, 0))
 # define V8_HAS_ATTRIBUTE_UNUSED (V8_GNUC_PREREQ(2, 95, 0))
 # define V8_HAS_ATTRIBUTE_VISIBILITY (V8_GNUC_PREREQ(4, 3, 0))
 # define V8_HAS_ATTRIBUTE_WARN_UNUSED_RESULT \
     (!V8_CC_INTEL && V8_GNUC_PREREQ(4, 1, 0))
 
+# define V8_HAS_BUILTIN_CLZ (V8_GNUC_PREREQ(3, 4, 0))
+# define V8_HAS_BUILTIN_CTZ (V8_GNUC_PREREQ(3, 4, 0))
 # define V8_HAS_BUILTIN_EXPECT (V8_GNUC_PREREQ(2, 96, 0))
+# define V8_HAS_BUILTIN_POPCOUNT (V8_GNUC_PREREQ(3, 4, 0))
 
 // g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
 // without warnings (functionality used by the macros below).  These modes
 // are detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or,
 // more standardly, by checking whether __cplusplus has a C++11 or greater
 // value. Current versions of g++ do not correctly set __cplusplus, so we check
 // both for forward compatibility.
 # if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
 #  define V8_HAS_CXX11_ALIGNAS (V8_GNUC_PREREQ(4, 8, 0))
 #  define V8_HAS_CXX11_ALIGNOF (V8_GNUC_PREREQ(4, 8, 0))
@@ skipping 190 matching lines @@
 # define V8_ALIGNOF(type) __alignof__(type)
 #else
 // Note that alignment of a type within a struct can be less than the
 // alignment of the type stand-alone (because of ancient ABIs), so this
 // should only be used as a last resort.
 namespace v8 { template <typename T> class AlignOfHelper { char c; T t; }; }
 # define V8_ALIGNOF(type) (sizeof(::v8::AlignOfHelper<type>) - sizeof(type))
 #endif
 
 #endif  // V8CONFIG_H_