Enable cyclic control flow support in block tree construction

[River41]

Refs #29

[River41]

I've refined the logic to ensure the partitioning correctly handles nested control flow structures. To verify this, I tested the CFG construction against matmul.o, which contains nested loops. I also integrated Mermaid into the output to visualize the resulting graph.

---

While verifying the partitioning logic, I noticed some unreachable instructions in the test files. For example, in kalman.o, instruction 47 (79 a1 a8 ff...) appears to be dead code:

• Line 46 is 05 00 17 00 00 00 00 00 (ja +23), which jumps to Line 70 ($46 + 23 + 1$).
• Line 13 is 05 00 22 00 00 00 00 00 (ja +34), which jumps to Line 48.
• No other lines jump to line 47.

Is this kind of unreachable code common?

[h313]

Yes, we can safely ignore unreachable code. This seems to be more of an issue with the Clang output making things weird and forgetting to remove unused code.

[River41]

Additionally, here are the reasons why this algorithm can handle nested loops.

• Leader Identification: During the pre-scan phase, the algorithm marks all jump targets as Leaders. In the case of nested loops, both inner and outer loop entry points are identified, ensuring each loop starts as a distinct Basic Block.
• Recursive Exploration: The recursive structure allows the algorithm to follow Jump Edges deep into the control flow. When encountering nested loops, it fully processes all inner loop paths before returning to resolve the remaining execution paths of the outer loop.