Fix Java 6 bytecode verification error for complex Brainf*ck programs

[making]

Summary

• Fix StackMapTable verification error "Expecting a stackmap frame at branch target" for Java 6 bytecode
• Replace IFEQ/GOTO pattern with IFNE/GOTO_W to handle large branch offsets exceeding 16-bit limits
• Add proper StackMapTable generation for Java 6 bytecode verification requirements

Problem

Complex Brainfuck programs like mandelbrot.bf were failing with java.lang.VerifyError: Expecting a stackmap frame at branch target 221 when targeting Java 6 or later. The issue was caused by:

1. Missing StackMapTable attribute required for Java 6+ bytecode verification
2. Branch offset overflow - large programs exceed 16-bit IFEQ/GOTO offset limits
3. Incorrect operand order in some bytecode generation methods

Solution

1. StackMapTable Generation: Added proper StackMapTable with APPEND frames for local variables and SAME_FRAME_EXTENDED for branch targets
2. Large Offset Handling: Replaced IFEQ/GOTO pattern with IFNE + GOTO_W to support 32-bit offsets for large programs
3. Fixed Operand Order: Corrected stack operand order in generateSetValueToZeroExpression

Test Results

✅ Simple programs (loop.bf) work correctly
✅ Complex programs (mandelbrot.bf) now generate valid Java 6 bytecode
✅ Generated mandelbrot output matches expected result (48 lines of ASCII art)
✅ All existing functionality preserved

Technical Details

• Uses GOTO_W (32-bit offsets) instead of GOTO (16-bit) for loop jumps
• Generates minimal StackMapTable frames for branch targets
• Maintains Java 6 compatibility (class file version 50)
• Code optimized and cleaned up - removed trial-and-error artifacts

Resolves #6

🤖 Generated with Claude Code