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Generate default constructors at compile time.

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Also re-ordered a few of the cases in the interpret loop. 
Removing a bit of code from CODE_CLASS and CODE_CALL triggered
some branch alignment issues which had a negative perf impact.
The new ordering seems to cancel that out.
This commit is contained in:
Bob Nystrom
2013-12-12 07:34:16 -08:00
parent e191424a70
commit 4ba5c38bbf
4 changed files with 232 additions and 237 deletions
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src/wren_compiler.c
+29 -9
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@@ -1604,6 +1604,24 @@ void block(Compiler* compiler)
emit(compiler, CODE_POP);
}
// Defines a default constructor method with an empty body.
static void defaultConstructor(Compiler* compiler)
{
Compiler ctorCompiler;
int constant = initCompiler(&ctorCompiler, compiler->parser, compiler, 1);
// Just return the receiver which is in the first local slot.
emit(&ctorCompiler, CODE_LOAD_LOCAL);
emit(&ctorCompiler, 0);
emit(&ctorCompiler, CODE_RETURN);
endCompiler(&ctorCompiler, constant);
// Define the constructor method.
emit(compiler, CODE_METHOD_CTOR);
emit(compiler, ensureSymbol(&compiler->parser->vm->methods, "new", 3));
}
// Compiles a statement. These can only appear at the top-level or within
// curly blocks. Unlike expressions, these do not leave a value on the stack.
void statement(Compiler* compiler)
@@ -1630,21 +1648,20 @@ void statement(Compiler* compiler)
// used.
int numFieldsInstruction = emit(compiler, 255);
// Compile the method definitions.
consume(compiler, TOKEN_LEFT_BRACE, "Expect '}' after class body.");
// Set up a symbol table for the class's fields.
// Set up a symbol table for the class's fields. We'll initially compile
// them to slots starting at zero. When the method is bound to the close
// the bytecode will be adjusted by [wrenBindMethod] to take inherited
// fields into account.
SymbolTable* previousFields = compiler->fields;
SymbolTable fields;
initSymbolTable(&fields);
compiler->fields = &fields;
// TODO(bob): Need to handle inherited fields. Ideally, a subclass's fields
// would be statically compiled to slot indexes right after the superclass
// ones, but we don't know the superclass statically. Instead, will
// probably have to determine the field offset at class creation time in
// the VM and then adjust by that every time a field is accessed/modified.
// Classes with no explicitly defined constructor get a default one.
int hasConstructor = 0;
// Compile the method definitions.
consume(compiler, TOKEN_LEFT_BRACE, "Expect '}' after class body.");
while (!match(compiler, TOKEN_RIGHT_BRACE))
{
Code instruction = CODE_METHOD_INSTANCE;
@@ -1659,6 +1676,7 @@ void statement(Compiler* compiler)
{
// If the method name is prefixed with "this", it's a constructor.
instruction = CODE_METHOD_CTOR;
hasConstructor = 1;
}
SignatureFn signature = rules[compiler->parser->current.type].method;
@@ -1675,6 +1693,8 @@ void statement(Compiler* compiler)
"Expect newline after definition in class.");
}
if (!hasConstructor) defaultConstructor(compiler);
// Update the class with the number of fields.
compiler->fn->bytecode[numFieldsInstruction] = fields.count;