l1a/l1b: PASS; l2: FAIL (unsupported)

[opencode-agent]

Spec compliance report

Compiler	Status	Issues
l1a	✅ PASS	None
l1b	✅ PASS	None
l2	❌ FAIL	L2ByteCodeSupportChecker marks i2l as unsupported; register-to-register codegen throws "Unknown operation"

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Details

l1a Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:2078-2111, core/src/core/org/jnode/vm/x86/compiler/l1a/VirtualStack.java:178-180
• Issues: None
• Analysis: Correctly implements JVM spec for i2l. Pops IntItem from virtual stack. For constants, creates LongItem with sign-extended value. For register values, ensures input is in EAX, then uses CDQ (32-bit) or CDQE (64-bit) to sign-extend to 64-bit result in EDX:EAX or RAX respectively. Creates LongItem (category-2) with proper register pairing. Pushes result to virtual stack. Operand stack effect (int → long) correctly handled.

l1b Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:2504-2540, core/src/core/org/jnode/vm/x86/compiler/l1b/VirtualStack.java:177-179
• Issues: None
• Analysis: Nearly identical to l1a. Correctly handles sign-extension via CDQ/CDQE, constant folding, and category-2 LongItem creation. Operand stack effect matches spec.

l2 Implementation

• Status: ❌ FAIL
• Files: core/src/core/org/jnode/vm/x86/compiler/l2/L2ByteCodeSupportChecker.java:260-262, core/src/core/org/jnode/vm/x86/compiler/l2/GenericX86CodeGenerator.java:414,491,568,648
• Issues:
  1. L2ByteCodeSupportChecker.visit_i2l() explicitly calls notSupported() (line 261), causing any method containing i2l to be rejected from L2 compilation and fall back to L1.
  2. GenericX86CodeGenerator has partial implementation: register-to-register variants (lines 414, 491) throw IllegalArgumentException("Unknown operation: I2L"), while memory-operand variants (lines 568-577, 648-657) correctly implement sign-extension via CDQ and proper 64-bit stack slot storage (high word at lhsDisp, low word at lhsDisp - SLOTSIZE).
  3. The L2 IR defines UnaryOperation.I2L but the support checker prevents its use.

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JVM Spec Reference (Java SE 6):

• i2l (0x85): "The value on the top of the operand stack must be of type int. It is popped from the operand stack and sign-extended to a long result. That result is pushed onto the operand stack."
• "The i2l instruction performs a widening primitive conversion. Because all values of type int are exactly representable by type long, the conversion is exact."
• Operand stack: ..., value → ..., result (category-1 → category-2)

Closes #295

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