Description: fix WTF::StringImpl::copyChars segfault when built with GCC 7
Origin: upstream, https://github.com/annulen/webkit/commit/0caec8a593cd872e
Last-Update: 2017-10-27

--- a/Source/WTF/wtf/text/StringImpl.h
+++ b/Source/WTF/wtf/text/StringImpl.h
@@ -619,25 +619,7 @@
             *destination = *source;
             return;
         }
-
-        if (numCharacters <= s_copyCharsInlineCutOff) {
-            unsigned i = 0;
-#if (CPU(X86) || CPU(X86_64))
-            const unsigned charsPerInt = sizeof(uint32_t) / sizeof(T);
-
-            if (numCharacters > charsPerInt) {
-                unsigned stopCount = numCharacters & ~(charsPerInt - 1);
-
-                const uint32_t* srcCharacters = reinterpret_cast<const uint32_t*>(source);
-                uint32_t* destCharacters = reinterpret_cast<uint32_t*>(destination);
-                for (unsigned j = 0; i < stopCount; i += charsPerInt, ++j)
-                    destCharacters[j] = srcCharacters[j];
-            }
-#endif
-            for (; i < numCharacters; ++i)
-                destination[i] = source[i];
-        } else
-            memcpy(destination, source, numCharacters * sizeof(T));
+        memcpy(destination, source, numCharacters * sizeof(T));
     }
 
     ALWAYS_INLINE static void copyChars(UChar* destination, const LChar* source, unsigned numCharacters)
@@ -855,9 +837,6 @@
         return *tailPointer<StringImpl*>();
     }
 
-    // This number must be at least 2 to avoid sharing empty, null as well as 1 character strings from SmallStrings.
-    static const unsigned s_copyCharsInlineCutOff = 20;
-
     enum class CaseConvertType { Upper, Lower };
     template<CaseConvertType type, typename CharacterType> static Ref<StringImpl> convertASCIICase(StringImpl&, const CharacterType*, unsigned);