Summary

Fixes LayerInfo initialization failure on Peano/Strix designs when the model path name contains the substring "ret", causing automated L2/L3 debug (-auto / -l3) to exit immediately after the Peano compiler autodetect warning.

Problem

• On Peano builds, MLDebugger disassembles ELFs via llvm-objdump and parses the output in _parse_lst_llvm() which uses a substring check ("ret" in line) to detect ret instructions.
• The first line of llvm-objdump output is a file header that includes the model's name. For designs containing ret in their name, the substring "ret" matches before any function is parsed.
• The code then executed flist[-1] on an empty list → IndexError → LayerInfo init failure.
• A similar substring risk existed for "rel" substring.

Fix

• Add _is_llvm_insn_line() to restrict ret / rel parsing to real disassembly rows ( :), skipping objdump headers, section banners, and function/local labels.
• Match ret and rel as whole instruction tokens (\bret\b, \brel\b) instead of substrings.
• Guard flist[-1] with if flist: when handling ret outside an active function.

Testing

• Reproduced on pretrained_deep_ocr_recognition_fixed_int8 Work tree: failed before fix, passes after.
• LayerInfo init completes: 91 layers, 6 PM-reload ELFs parsed, all layers assigned start PCs.
• Verified llvm-objdump output line types: only instruction rows contain real ret/rel opcodes.
• Verified design runs successfully using the automated_debug workflow.

Impact

• Peano autodetect behavior unchanged (warning still expected when .lst is absent).
• No change to Chess LST parsing path.
• Fixes false init failures for any design whose path contains "pretrained" (or similar ret/rel substrings).
• Fixes AIESW-37123.