Bug 177372 – Consider a throwExceptionIf bytecode.

• Status: NEW
• Component: JavaScriptCore

[Keith Miller]

There are several places in BytecodeGenerator.cpp where we emit roughly the following bytecodes:

Ref<Label> typeIsObject = newLabel();
emitJumpIfTrue(emitIsObject(newTemporary(), dst), typeIsObject.get());
emitThrowTypeError(ASCIILiteral("Expected Object"));
emitLabel(typeIsObject.get());

This will get split into a basic block in the DFG, which might slow down compile times or prevent some optimizations.

I'm not exactly sure on the semantics we want. Do we want to do toBoolean on the condition or do we want to assume it's a boolean already? We should also figure out if we want to allow this bytecode to throw different types of exceptions. I think we really only throw type errors however.