All three JNode compilers (l1a, l1b, l2) PASS astore_2 spec compliance.

[opencode-agent]

Spec compliance report

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

---

Details

l1a Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:1297, core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:4375 (wstore), core/src/core/org/jnode/vm/x86/compiler/l1a/X86StackFrame.java:322 (getEbpOffset), core/src/core/org/jnode/vm/bytecode/BytecodeParser.java:422 (parser dispatch)
• Issues: None

Analysis:

• BytecodeParser correctly decodes opcode 0x4D (astore_2) at line 422, calling handler.visit_astore(2) with implicit index 2.
• X86BytecodeVisitor.visit_astore (line 1297) delegates to wstore(JvmType.REFERENCE, index).
• wstore (line 4375) correctly handles category-1 reference values: pops WordItem from virtual stack, pins aliases via vstack.loadLocal, computes frame offset via stackFrame.getEbpOffset, emits MOV to [EBP+disp].
• X86StackFrame.getEbpOffset (line 322) correctly calculates local offsets: for index >= argSlotCount, offset = (index - argSlotCount + 1) * -slotSize.
• Wide prefix (0xC4) correctly handled at parser lines 827-872: reads 16-bit index for astore (0x3A); not applicable to astore_2 which has implicit index.
• Stack effect: pops 1 category-1 item (REFERENCE), matching JVM spec "..., objectref → ...".

l1b Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:1471, core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:5368 (wstore), core/src/core/org/jnode/vm/x86/compiler/l1b/X86StackFrame.java:314 (getEbpOffset), core/src/core/org/jnode/vm/bytecode/BytecodeParser.java:422 (parser dispatch)
• Issues: None

Analysis:

• Identical parser dispatch as l1a (shared BytecodeParser).
• visit_astore (line 1471) delegates to wstore(JvmType.REFERENCE, index).
• wstore (line 5368) similar logic: pops WordItem, handles constant tracking via constLocals, pins aliases, computes offset, emits MOV to [EBP+disp].
• X86StackFrame.getEbpOffset (line 314) identical offset calculation.
• Stack effect and type handling identical to l1a, spec-compliant.

l2 Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/compiler/ir/IRGenerator.java:415 (visit_astore), core/src/core/org/jnode/vm/x86/compiler/l2/GenericX86CodeGenerator.java:278 (generateCodeFor VariableRefAssignQuad), core/src/core/org/jnode/vm/x86/compiler/l2/X86StackFrame.java:322 (getEbpOffset), core/src/core/org/jnode/vm/x86/compiler/l2/L2ByteCodeSupportChecker.java (no override = supported)
• Issues: None

Analysis:

• IRGenerator.visit_astore (line 415): stackOffset -= 1, sets Operand.REFERENCE for local[index] and stack[stackOffset], emits VariableRefAssignQuad(index, stackOffset).
• GenericX86CodeGenerator.generateCodeFor(VariableRefAssignQuad) (line 278) handles STACK→STACK, REGISTER→STACK, CONSTANT→STACK, TOPS→STACK for LHS=STACK (local), emitting MOV/POP to [EBP+disp].
• X86StackFrame.getEbpOffset (line 322) identical offset calculation.
• L2ByteCodeSupportChecker does NOT override visit_astore → instruction supported.
• Wide prefix: IRGenerator.visit_astore(int index) accepts any index; parser handles wide by calling with 16-bit index.
• Stack effect: pops 1 category-1 item (Operand.REFERENCE = 1 slot), matching spec.
• Note: returnAddress type (for jsr/ret) not modeled; L2ByteCodeSupportChecker marks jsr/ret as unsupported — known L2 limitation, not an astore_2 issue.

---

JVM Spec References (astore_2)

Spec Page: https://docs.oracle.com/javase/specs/jvms/se6/html/Instructions2.doc.html

• Opcode: 0x4D (77)
• Format: astore_2
• Operand Stack: ..., objectref → ...
• Description: Index 2 into local variable array. objectref (type returnAddress or reference) popped and stored at local[2].

Verified Compliance Points:

1. ✅ Implicit index 2 correctly decoded (BytecodeParser.java:422)
2. ✅ 8-bit index normal; 16-bit after wide (parser lines 827-872)
3. ✅ Category-1 local slot (single slot for reference)
4. ✅ Stack pop of 1 reference (category 1)
5. ✅ Local offset calculation matches verifier frame model (all three X86StackFrame.getEbpOffset)
6. ✅ Type propagation: REFERENCE/Operand.REFERENCE throughout
7. ⚠️ returnAddress not handled (jsr/ret unsupported in L2) — acceptable deviation

Closes #218

opencode session  |  github run