Merge pull request #2522 from dneto0/intlog2

Add IntLog2 and use it

glslang/Include/Common.h

@@ -286,6 +286,18 @@ template <class T> bool IsMultipleOfPow2(T number, int powerOf2)
     return ! (number & (powerOf2 - 1));
 }
 
+// Returns log2 of an integer power of 2.
+// T should be integral.
+template <class T> int IntLog2(T n)
+{
+    assert(IsPow2(n));
+    int result = 0;
+    while ((T(1) << result) != n) {
+      result++;
+    }
+    return result;
+}
+
 } // end namespace glslang
 
 #endif // _COMMON_INCLUDED_

glslang/MachineIndependent/ParseHelper.cpp

@@ -5602,14 +5602,7 @@ void TParseContext::setLayoutQualifier(const TSourceLoc& loc, TPublicType& publi
         if (! IsPow2(value))
             error(loc, "must be a power of 2", "buffer_reference_align", "");
         else
-#ifdef __ANDROID__
-            // Android NDK r15c tageting ABI 15 doesn't have full support for C++11
-            // (no std::exp2/log2). ::exp2 is available from C99 but ::log2 isn't
-            // available up until ABI 18 so we use the mathematical equivalent form
-            publicType.qualifier.layoutBufferReferenceAlign = (unsigned int)(std::log(value) / std::log(2.0));
-#else
-            publicType.qualifier.layoutBufferReferenceAlign = (unsigned int)std::log2(value);
-#endif
+            publicType.qualifier.layoutBufferReferenceAlign = IntLog2(value);
         if (nonLiteral)
             error(loc, "needs a literal integer", "buffer_reference_align", "");
         return;