Reserve space for strings. (#3546)

runtime/src/main/cpp/Console.cpp

@@ -33,6 +33,7 @@ void Kotlin_io_Console_print(KString message) {
   // TODO: system stdout must be aware about UTF-8.
   const KChar* utf16 = CharArrayAddressOfElementAt(message, 0);
   KStdString utf8;
+  utf8.reserve(message->count_);
   // Replace incorrect sequences with a default codepoint (see utf8::with_replacement::default_replacement)
   utf8::with_replacement::utf16to8(utf16, utf16 + message->count_, back_inserter(utf8));
   konan::consoleWriteUtf8(utf8.c_str(), utf8.size());

runtime/src/main/cpp/KString.cpp

@@ -53,6 +53,7 @@ OBJ_GETTER(unsafeUtf16ToUtf8Impl, KString thiz, KInt start, KInt size) {
   RuntimeAssert(thiz->type_info() == theStringTypeInfo, "Must use String");
   const KChar* utf16 = CharArrayAddressOfElementAt(thiz, start);
   KStdString utf8;
+  utf8.reserve(size);
   conversion(utf16, utf16 + size, back_inserter(utf8));
   ArrayHeader* result = AllocArrayInstance(theByteArrayTypeInfo, utf8.size(), OBJ_RESULT)->array();
   ::memcpy(ByteArrayAddressOfElementAt(result, 0), utf8.c_str(), utf8.size());
@@ -714,6 +715,7 @@ char* CreateCStringFromString(KConstRef kref) {
   KString kstring = kref->array();
   const KChar* utf16 = CharArrayAddressOfElementAt(kstring, 0);
   KStdString utf8;
+  utf8.reserve(kstring->count_);
   utf8::unchecked::utf16to8(utf16, utf16 + kstring->count_, back_inserter(utf8));
   char* result = reinterpret_cast<char*>(konan::calloc(1, utf8.size() + 1));
   ::memcpy(result, utf8.c_str(), utf8.size());

runtime/src/main/cpp/dtoa/dblparse.cpp

@@ -642,6 +642,7 @@ KDouble Kotlin_native_FloatingPointParser_parseDoubleImpl (KString s, KInt e)
 {
   const KChar* utf16 = CharArrayAddressOfElementAt(s, 0);
   KStdString utf8;
+  utf8.reserve(s->count_);
   TRY_CATCH(utf8::utf16to8(utf16, utf16 + s->count_, back_inserter(utf8)),
             utf8::unchecked::utf16to8(utf16, utf16 + s->count_, back_inserter(utf8)),
             /* Illegal UTF-16 string. */ ThrowNumberFormatException());

runtime/src/main/cpp/dtoa/fltparse.cpp

@@ -542,6 +542,7 @@ Kotlin_native_FloatingPointParser_parseFloatImpl(KString s, KInt e)
 {
   const KChar* utf16 = CharArrayAddressOfElementAt(s, 0);
   KStdString utf8;
+  utf8.reserve(s->count_);
   TRY_CATCH(utf8::utf16to8(utf16, utf16 + s->count_, back_inserter(utf8)),
             utf8::unchecked::utf16to8(utf16, utf16 + s->count_, back_inserter(utf8)),
             /* Illegal UTF-16 string. */ ThrowNumberFormatException());