Introduce StringImpl::createPreallocatedStatic

third_party/WebKit/Source/build/scripts/templates/MakeNames.cpp.tmpl

 {% from "macros.tmpl" import license %}
 {{ license() }}
 
 #include "config.h"
 
 #include "{{namespace}}{{suffix}}Names.h"
 
 #include "wtf/StdLibExtras.h"
 
 // Generated from:
 {% for entry in in_files|sort %}
 // - {{entry}}
 {% endfor %}
 
 namespace blink {
 namespace {{namespace}}Names {
 
 using namespace WTF;
 
 void* {{suffix}}NamesStorage[{{namespace}}{{suffix}}NamesCount * ((sizeof(AtomicString) + sizeof(void *) - 1) / sizeof(void *))];
 
 {% for entry in entries|sort(attribute='name', case_sensitive=True) %}
 {% filter enable_conditional(entry.Conditional) %}
 const AtomicString& {{entry|symbol}} = reinterpret_cast<AtomicString*>(&{{suffix}}NamesStorage)[{{loop.index0}}];
 {% endfilter %}
 {% endfor %}
 
 void init{{suffix}}()
 {
+    const int kMaxNameLength = {{entries|map(attribute='name')|map('length')|max}} + 1;
     struct NameEntry {
-        const char* name;
+        // StringImpl instances are created at |stringImplStorage| in-place.
+        // |name| must be placed soon after |stringImplStorage| to match the memory layout requirement of StringImpl.
+        char stringImplStorage[sizeof(StringImpl)];
+        char name[kMaxNameLength];
         unsigned hash;
         unsigned char length;
     };
 
-    static const NameEntry kNames[] = {
+    static NameEntry kNames[] = {
     {% for entry in entries|sort(attribute='name', case_sensitive=True) %}
-        { "{{entry|cpp_name}}", {{entry|cpp_name|hash}}, {{entry|cpp_name|length}} },
+        { "", "{{entry|cpp_name}}", {{entry|cpp_name|hash}}, {{entry|cpp_name|length}} },
     {% endfor %}
     };
 
     for (size_t i = 0; i < WTF_ARRAY_LENGTH(kNames); i++) {
-        StringImpl* stringImpl = StringImpl::createStatic(kNames[i].name, kNames[i].length, kNames[i].hash);
+        StringImpl* stringImpl = StringImpl::createPreallocatedStatic(kNames[i].stringImplStorage, kNames[i].length, kNames[i].hash);
+        ASSERT(reinterpret_cast<char*>(stringImpl + 1) == kNames[i].name);
         void* address = reinterpret_cast<AtomicString*>(&{{suffix}}NamesStorage) + i;
         new (address) AtomicString(stringImpl);
     }
 }
 
 } // {{namespace}}Names
 } // namespace blink