1 files changed, 29 insertions, 7 deletions
diff --git a/deps/v8/src/base/bits.cc b/deps/v8/src/base/bits.cc
index 909f9deb8c..049dc4a1b1 100644
--- a/deps/v8/src/base/bits.cc
+++ b/deps/v8/src/base/bits.cc
@@ -14,14 +14,36 @@ namespace base {
 namespace bits {
 
 uint32_t RoundUpToPowerOfTwo32(uint32_t value) {
-  DCHECK_LE(value, 0x80000000u);
-  value = value - 1;
-  value = value | (value >> 1);
-  value = value | (value >> 2);
-  value = value | (value >> 4);
-  value = value | (value >> 8);
-  value = value | (value >> 16);
+  DCHECK_LE(value, uint32_t{1} << 31);
+  if (value) --value;
+// Use computation based on leading zeros if we have compiler support for that.
+#if V8_HAS_BUILTIN_CLZ || V8_CC_MSVC
+  return 1u << (32 - CountLeadingZeros32(value));
+#else
+  value |= value >> 1;
+  value |= value >> 2;
+  value |= value >> 4;
+  value |= value >> 8;
+  value |= value >> 16;
   return value + 1;
+#endif
+}
+
+uint64_t RoundUpToPowerOfTwo64(uint64_t value) {
+  DCHECK_LE(value, uint64_t{1} << 63);
+  if (value) --value;
+// Use computation based on leading zeros if we have compiler support for that.
+#if V8_HAS_BUILTIN_CLZ
+  return uint64_t{1} << (64 - CountLeadingZeros64(value));
+#else
+  value |= value >> 1;
+  value |= value >> 2;
+  value |= value >> 4;
+  value |= value >> 8;
+  value |= value >> 16;
+  value |= value >> 32;
+  return value + 1;
+#endif
 }