All 3 compilers ✅ PASS — no issues

[opencode-agent]

Spec compliance report

Compiler	Status	Issues
l1a	✅ PASS	None
l1b	✅ PASS	None
l2	✅ PASS	None

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Details

l1a Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:2292-2341
• Issues: None

Analysis:

• Stack effect: Correctly pops two IntItem values from virtual stack (vstack.popInt() ×2) — matches JVM spec "..., value1, value2 → ..."
• Signed comparison: Uses X86Constants.JGE (0x8D, "Jump if Greater or Equal" signed) — matches JVM spec "ge succeeds if and only if value1 ≥ value2 (signed)"
• Branch target: Parser computes address + gets2() where gets2() reads signed 16-bit offset — matches JVM spec "(branchbyte1 << 8) | branchbyte2" as signed 16-bit
• Basic block barrier: Flushes virtual stack via vstack.push(eContext) before emitting jump — correct for control-flow boundaries
• Operand handling: prepareForOperation ensures value1 (v1) is in a register; value2 (v2) can be register, local, or constant — correct for x86 CMP dest, src
• Commutativity handling: Only swaps for JE/JNE (equality); correctly does NOT swap for JGE/JG/JL/JLE — x86 CMP is dest−src, so operand order matters for signed relational ops
• Yield point: Not emitted for forward branches; backward branches handled at caller level — acceptable

l1b Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:2809-2884
• Issues: None

Analysis:

• Identical logic to l1a for visit_if_icmp helper and visit_if_icmpge dispatch
• Adds bytecode counters (countBytecode, countConstOps) for metrics — no functional impact
• Same constant-folding TODO comments as l1a — not a spec violation, optimization opportunity only

l2 Implementation

• Status: ✅ PASS
• Files:
  • core/src/core/org/jnode/vm/x86/compiler/l2/GenericX86CodeGenerator.java:3787-3824 (codegen)
  • core/src/core/org/jnode/vm/compiler/ir/quad/BranchCondition.java:30-31 (IR enum)
  • core/src/core/org/jnode/vm/compiler/ir/IRGenerator.java:917 (IR generation)
  • core/src/core/org/jnode/vm/bytecode/BasicBlockFinder.java:218-223 (stack simulation)
• Issues: None

Analysis:

• IR representation: BranchCondition.IF_ICMPGE(">=", true) — binary=true correctly indicates two stack operands
• IR generation: IRGenerator.visitBranchCondition creates ConditionalBranchQuad with two stack slots (s1, s2) of type Operand.INT — matches stack effect
• Basic block finder: Pops two JvmType.INT from type stack, calls addBranch(address, true) and condYieldPoint — correct control-flow construction
• Code generation: generateJumpForBinaryCondition switches on IF_ICMPGE → emits os.writeJCC(target, X86Constants.JGE) — correct signed ≥
• Support checker: L2ByteCodeSupportChecker does NOT override visit_if_icmpge — inherits empty impl from BytecodeVisitorSupport, meaning instruction is supported (unsupported ops explicitly throw)
• Branch offset: Uses same parser (BytecodeParser.gets2()) for signed 16-bit target — correct

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JVM Spec References (Java SE 6)

• Opcode: if_icmpge = 162 (0xA2)
• Operand Stack: ..., value1, value2 → ... (both int, both popped)
• Comparison: Signed integer comparison; branch taken iff value1 ≥ value2
• Branch Offset: Signed 16-bit constructed from branchbyte1, branchbyte2; target = address + offset
• Target Constraint: Must be an opcode within the same method

All three JNode compiler tiers implement the above faithfully. No spec violations found.

Closes #400

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