2 files changed, 14 insertions, 0 deletions
diff --git a/src/support/bits.cpp b/src/support/bits.cpp
index 992b97955..e60f2365b 100644
--- a/src/support/bits.cpp
+++ b/src/support/bits.cpp
@@ -152,6 +152,14 @@ template<> int CountLeadingZeroes<uint64_t>(uint64_t v) {
 #endif
 }
 
+template<> int CeilLog2<uint32_t>(uint32_t v) {
+  return 32 - CountLeadingZeroes(v - 1);
+}
+
+template<> int CeilLog2<uint64_t>(uint64_t v) {
+  return 64 - CountLeadingZeroes(v - 1);
+}
+
 uint32_t Log2(uint32_t v) {
   switch (v) {
     default:
diff --git a/src/support/bits.h b/src/support/bits.h
index bd91fdec6..a927a2832 100644
--- a/src/support/bits.h
+++ b/src/support/bits.h
@@ -40,6 +40,7 @@ template<typename T> int PopCount(T);
 template<typename T> uint32_t BitReverse(T);
 template<typename T> int CountTrailingZeroes(T);
 template<typename T> int CountLeadingZeroes(T);
+template<typename T> int CeilLog2(T);
 
 #ifndef wasm_support_bits_definitions
 // The template specializations are provided elsewhere.
@@ -52,6 +53,8 @@ extern template int CountTrailingZeroes(uint32_t);
 extern template int CountTrailingZeroes(uint64_t);
 extern template int CountLeadingZeroes(uint32_t);
 extern template int CountLeadingZeroes(uint64_t);
+extern template int CeilLog2(uint32_t);
+extern template int CeilLog2(uint64_t);
 #endif
 
 // Convenience signed -> unsigned. It usually doesn't make much sense to use bit
@@ -65,6 +68,9 @@ template<typename T> int CountTrailingZeroes(T v) {
 template<typename T> int CountLeadingZeroes(T v) {
   return CountLeadingZeroes(typename std::make_unsigned<T>::type(v));
 }
+template<typename T> int CeilLog2(T v) {
+  return CeilLog2(typename std::make_unsigned<T>::type(v));
+}
 template<typename T> bool IsPowerOf2(T v) {
   return v != 0 && (v & (v - 1)) == 0;
 }