EXPcalibur guide

A source call uses three kinds of state.

Three different pieces of state during a function callThree different pieces of state during a function callInstruction pointerWhere is the next opcode?A call changes theinstruction address. Areturn restores a savedcontinuation.Operand stackWhich values are beingcomputed?Expressions push operands;ALU instructions pop inputsand push a result.Compiler frameWhich locals belong to thiscall?FP + 0: saved returnFP + 4: first slotFP + 8: second slotAll guest storage shares one byte array. These are software roles, not separate protected memories.

The instruction pointer answers where execution continues. The operand stack holds intermediate computations. The compiler frame holds named values belonging to this activation.