codegen: perry_method_<Class>__<name> emission order is HashMap-nondeterministic when a method name is shared across classes (#7038/#7039 family) #7172

Found during PR #7171's IR-neutrality verification (macOS arm64, same-compiler control runs): emitted LLVM IR is nondeterministic when a method name is shared across classes — perry_method_<Class>__<name> symbols are emitted in HashMap iteration order, so two runs of the same compiler on the same source produce differently-ordered IR.

Observed on real dependency files: vite's module-runner.js and rollup's shared/index.js (the two corpus files excluded as control-failed in #7171's 47/0/2 IR comparison — reported honestly as control failures, not counted as passing).

Class

Same family as #7038/#7039 (closure-source HashMap iteration made @.str.N numbering a per-process permutation on macOS — fixed by sorting) and #7131 (Linux temp names — fixed). This is the method-emission sibling: cross-class shared method names iterate an unordered map.

Why it matters

• Any object-hash or IR-diff A/B silently excludes affected files (or worse, reads phantom diffs) — two agents have now had to build control-run machinery to detect it.
• Fix shape is the fix(codegen): sort closure-source emission so the same input compiles to the same IR (#7038) #7039 precedent: sort the emission order by a stable key (class id, then name).

Repro

Compile vite/dist/node/module-runner.js (or rollup shared/index.js) twice with the same compiler, --trace llvm or --no-link, diff the IR: method-symbol ordering differs run-to-run.