Implement Conservative Garbage Collection

Scan Stacks Without Exact Maps

Conservative GC treats stack and register words as possible pointers. If a word points into the heap, keep the object. Boehm-Demers-Weiser GC powers some C/C++ runtimes where precise roots are unavailable.

Conservative Root Scan

Walk stack slots; if value looks like heap address and aligns to object boundary, treat as reference. No relocation possible because any word might be a disguised pointer.

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• Cannot compact or move objects
• False retention causes memory leaks of a sort
• Works with uncooperative C code
• Used when precise stack maps are too costly

Connecting to real compilers

Production compilers embed this step inside a longer pipeline. GCC flows through cpp, cc1, assembly, and ld; Clang uses the driver, Sema, LLVM IR passes, and a target backend. LLVM bitcode, JVM bytecode, and WASM are other familiar IRs at the same layer. The exercise isolates one pass so you can test it alone before chaining it to the next stage.

Why for this exercise

You will implement conservative garbage collection root scanning. This exercise requires walking stack words, testing heap likelihood, and marking objects without exact pointer maps.