The InstructionKey::InstructionKeyInfo had getEmptyKey() and getTombstoneKey()
both returning InstructionKey(nullptr, nullptr). LLVM DenseMap requires these
to be distinct sentinel values. This violated the DenseMap contract, causing
bucket corruption during copy/iteration (the old FIXME about 'last item
corrupted').
Fix: use reinterpret_cast sentinel pointers -1 and -2, matching LLVM convention.
Also cleaned up the non-const copy constructor (removed dead local copy and
stale FIXME comment).
Also adds:
- switch_sparse.asm test (non-consecutive case values: 10, 50, 200, 1000)
- calc_cout.cpp test (skipped - documents inline policy limitation with STL)
- C++ compilation support in build_samples.cmd
- Skip mechanism for manifest entries (skip: true + skip_reason)
- Fix test.py update-golden to not run determinism check before updating
68 pattern checks, 40 golden hashes, 108 handler microtests — all green.
yusufcanislek