Kotlin ir documentation

Kotlin IR Documentation

Kotlin IR is virtually undocumented, so here are some notes

IrFunction

Represents a function, either declared in your code - in which case it has a body of declarations - or declared externally.

In either case, what you do know about it is the input and output types.

IrDeclaration

A 'line of code' - can be a function call, setting a variable, an if statement, etc.

IrExpression

This is 'anything that returns a value'. Some prime examples are:

• IrCall - a function call
• IrConst - a hardcoded const value - e.g. 1, "hi", false
• IrGetValue - a local variable

IrCall

An IrExpression representing a function call - x() or a.x().

irCall.symbol.owner gets you to the IrFunction.

When the function is part of a class (a.x()), irCall.dispatchReceiver lets you retrieve the IrExpression to the left of the dot - in this case a.

When it's an extension function, the same applies to irCall.extensionReceiver.

IrGetValue

An IrExpression that retrieves the value of a local variable, which can be val or var.

To find out about the actual val/var being referenced, you need to check irGetValue.symbol.owner which is a IrValueDeclaration.

For example, irValueDeclaration.isVar indicates mutability.

IrProperty

Unlike local variables, all class properties are represented by IrProperty, which generates behind the scenes:

• An IrField for the backing field
• a getter IrFunction
• a setter IrFunction (for var properties)

This means all access to properties is through the getter/setter functions (IrCall) and not through IrGetValue