Class DoWhileLoopAsmGenerator

java.lang.Object

org.ek9lang.compiler.backend.jvm.AbstractAsmGenerator

org.ek9lang.compiler.backend.jvm.AbstractControlFlowAsmGenerator

org.ek9lang.compiler.backend.jvm.DoWhileLoopAsmGenerator

final class DoWhileLoopAsmGenerator
extends AbstractControlFlowAsmGenerator

Specialized generator for EK9 do-while loops. Handles CONTROL_FLOW_CHAIN with chain_type: "DO_WHILE_LOOP".

JVM Bytecode Pattern (different from while loop):

loop_start:
  [body instructions]         ; Execute body FIRST
  [condition evaluation]      ; Then evaluate condition
  iload primitive_condition
  ifne loop_start             ; If TRUE (non-zero), jump BACK
loop_end:                     ; Fall through if false

Key Differences from While Loop:

• Body executes BEFORE condition (guaranteed at least once)
• Uses IFNE (jump if NON-ZERO/true) instead of IFEQ
• No need for forward branch before body
• Loop always executes at least once

Stack Frame Invariant: Stack is empty before loop, after body, after condition, and after loop exit.

Nested Class Summary

Nested classes/interfaces inherited from class AbstractAsmGenerator

AbstractAsmGenerator.LocalVariableInfo, AbstractAsmGenerator.MethodContext, AbstractAsmGenerator.ScopeInfo, AbstractAsmGenerator.TempVariableSource

Field Summary

Fields inherited from class AbstractControlFlowAsmGenerator

context

Fields inherited from class AbstractAsmGenerator

classWriter, constructTargetTuple, outputVisitor

Constructor Summary

Constructors

Constructor	Description
DoWhileLoopAsmGenerator(ConstructTargetTuple constructTargetTuple, OutputVisitor outputVisitor, org.objectweb.asm.ClassWriter classWriter, BytecodeGenerationContext context)

Method Summary

Modifier and Type	Method	Description
void	generate(ControlFlowChainInstr instr)	Generate bytecode for do-while loop.

Methods inherited from class AbstractControlFlowAsmGenerator

branchIfFalse, branchIfTrue, copyResultVariable, createControlFlowLabel, jumpTo, placeLabel, processBodyEvaluation, processConditionCase, processConditionCaseWithoutLabelPlacement, processConditionEvaluation, processInstructions

Methods inherited from class AbstractAsmGenerator

convertBooleanToInt, convertToJvmDescriptor, convertToJvmName, generateBooleanLiteral, generateCharacterLiteral, generateDebugInfo, generateFloatLiteral, generateIntegerLiteral, generateLoadVariable, generateLocalVariableTable, generateMethodDescriptor, generateObjectLiteral, generateStackOperation, generateStoreVariable, generateStringLiteral, getCurrentMethodVisitor, getMethodContext, getOrCreateLabel, getVariableIndex, isVariableAllocated, setCurrentMethodVisitor, setSharedMethodContext, trackTempVariableFromLiteral, trackTempVariableFromLoad

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

DoWhileLoopAsmGenerator

DoWhileLoopAsmGenerator(ConstructTargetTuple constructTargetTuple,
 OutputVisitor outputVisitor,
 org.objectweb.asm.ClassWriter classWriter,
 BytecodeGenerationContext context)

Method Details

generate

public void generate(ControlFlowChainInstr instr)

Generate bytecode for do-while loop.

Control Flow:

1. Place loop start label
2. Execute body (leaves stack empty)
3. Evaluate condition (leaves stack empty)
4. Branch BACK to loop start if condition is TRUE
5. Fall through to loop end if condition is FALSE

Stack Frame Invariant: Pre-condition: stack is empty Post-condition: stack is empty

Parameters:

instr - CONTROL_FLOW_CHAIN instruction with DO_WHILE_LOOP type