Spec compliance report

Details

l1a Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:1344 (visit_castore), core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:4143 (wastore), core/src/core/org/jnode/vm/x86/compiler/l1a/X86BytecodeVisitor.java:330 (checkBounds)
• Issues: None

Analysis:

• Operand stack order: Correctly pops in reverse order: val (value), idx (index), ref (arrayref) at lines 4181-4183. Matches JVM spec ..., arrayref, index, value → ....
• Null check: checkBounds() at line 330 emits CMP against arrayLengthOffset after loading ref. If ref is null, the memory access faults or the comparison fails, and invokeJavaMethod(context.getThrowArrayOutOfBounds()) is called. The ThrowArrayOutOfBounds method throws NullPointerException for null refs and ArrayIndexOutOfBoundsException for invalid indices.
• Bounds check: checkBounds() compares array length with index using JNA (Jump if Not Above, i.e., unsigned ≤), correctly throwing ArrayIndexOutOfBoundsException on failure.
• Truncation: For JvmType.CHAR, valSize = BITS16 (line 4157) and scale = 2 (line 4158), so only lower 16 bits are stored — matches spec "The int value is truncated to a char".
• ArrayStoreException: The TODO at line 4201 ("add type compatibility check... throw ArrayStoreException") is not applicable to castore. Per JVM spec, ArrayStoreException only applies to reference array stores (aastore). Primitive array stores (castore, bastore, sastore, etc.) do not throw ArrayStoreException.

l1b Implementation

• Status: ✅ PASS
• Files: core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:1534 (visit_castore), core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:5127 (wastore), core/src/core/org/jnode/vm/x86/compiler/l1b/X86BytecodeVisitor.java:322 (checkBounds)
• Issues: None

Analysis: Identical implementation to l1a. Same correct operand stack handling, null/bounds checks via checkBounds(), and 16-bit truncation for char arrays. Same TODO comment at line 5185 is not applicable to castore.

l2 Implementation

• Status: ❌ FAIL
• Files: core/src/core/org/jnode/vm/x86/compiler/l2/L2ByteCodeSupportChecker.java:99 (visit_castore)
• Issues: castore is explicitly marked as not supported. The L2 compiler will fall back to L1 compilation for methods containing this instruction. No code generation exists in GenericX86CodeGenerator or X86CodeGenerator for castore (or any array store instruction: aastore, bastore, sastore, castore, fastore, dastore, lastore, iastore).

JVM Spec References

• castore spec: https://docs.oracle.com/javase/specs/jvms/se6/html/Instructions2.doc2.html
• Operand Stack: ..., arrayref, index, value → ...
• Runtime Exceptions: NullPointerException, ArrayIndexOutOfBoundsException
• No ArrayStoreException for primitive arrays (only for aastore on reference arrays)
• Truncation: "The int value is truncated to a char"

Closes #225

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