run_examples.sh now supports an optional `tests/expected/<name>.ir`
sibling to `.txt`/`.exit`. When present, the runner also captures
`sx ir <file>` output, normalizes target-/host-specific noise
(module ID, target triple/datalayout, attribute groups, LLVM's
auto-suffixed %temp numbering), and diffs against the snapshot.
`--update` regenerates it alongside the runtime output.
Catches lowering changes that don't affect what the program prints
— exactly the shape Phase 1.5's selector interning will produce
(same runtime output, very different IR).
First snapshot: `ffi-objc-call-03-selector-sharing.ir`. Today the
test emits four `call ptr @sel_registerName(ptr @str.N)` lines for
its four call sites; after 1.5 we expect two static
`@OBJC_SELECTOR_REFERENCES_<sel>` globals + loads at each call
site. The diff between the two snapshots will be the visible
artifact of the optimization.
101/101 regression tests pass (+ffi-objc-call-03-selector-sharing).
Test exercises four call sites — three sharing "init" and one
"release" — to pin the multi-site / multi-selector lowering before
1.5 changes how SEL lookups are cached.
Runtime behavior: identical before and after 1.5 (all call sites
hit nil receivers; libobjc returns 0 for void). The improvement is
visible only in the emitted IR — today:
$ ./zig-out/bin/sx ir examples/ffi-objc-call-03-selector-sharing.sx \\
| grep -c "call ptr @sel_registerName"
4
After 1.5 (planned): 2 — one `sel_registerName` per unique selector
string, materialized into a static `OBJC_SELECTOR_REFERENCES_<sel>`
global at module init, then loaded at each call site. Matches the
shape clang produces for `@selector(...)`. Worth re-running the
above grep after 1.5 lands as a manual sanity check.
The IR-shape snapshot harness (auto-diff of `sx ir` output) is
deferred; for now we verify by eye.
