Six bottom-up IR rewrites (const-fold, inline-node, subst, flatten-lets,
subst-lookup, scalar-replace) each hand-listed every op's child positions —
~250 lines of identical "recurse children, rebuild" arms that had to be kept in
sync whenever an op was added. Extract one map-ir-children into ir.clj that
knows each op's child layout; each walk keeps only its genuine specials
(const-fold's invoke/if, inline-node's invoke, subst's local/let alpha-rename,
scalar-replace's invoke/let folds) and delegates the rest.
The combinator is total over the op set, so the walks are now total too: a
couple soundly gain coverage they previously skipped (const-fold now folds
inside :try; subst-lookup now recurses :def inits, which fixes a latent dangling
ref where a dropped const-key-map binding was referenced inside a def). These
are sound — all six are result-preserving optimizations — and 3-mode conformance
+ fixpoint confirm identical program behavior.
map-ir-children is shape-preserving for :try (recurses :catch-body/:finally only
when present, never assoc's nil) so it can't turn a struct node into a phm.
Written with cond/get only, matching the passes' tier, so no new load-order dep.
Predicates (body-closed?/pure?/local-escapes?), the type-threading infer, and the
Janet backend emit stay as-is: their conservative :else defaults / [type node]
threading / host language don't fit a node-rebuilding combinator.
Adds ir-passes-test coverage for folding reaching fn/loop/try bodies. Full gate
green (conformance x3, suite >=4695/88, fixpoint stage1==2==3, inline-sra + devirt).
A typo'd symbol used to auto-intern an unbound var and die later as
'Cannot call nil as a function' with no hint which symbol. Now:
$ jolt -e '(undefined-fn 1)'
Error: Unable to resolve symbol: undefined-fn in this context
The analyzer's :unresolved fallthrough now punts to the interpreter
(whose resolver raises the message above when the form runs) instead of
emitting a var-ref that interned the var. A punt rather than a hard
throw because runtime-interning forms (defmulti's setup) legitimately
reference the var they're about to create from a nested do.
Pulling that thread surfaced three real bugs the leniency was masking:
- h-resolve-global resolved unqualified symbols against ctx-current-ns,
which during analysis is jolt.analyzer — so user-ns vars NEVER
resolved through it; the lenient arm happened to emit the right ns.
Now resolves against the compile ns like the qualified branch.
- Top-level (do ...) wasn't split: Clojure compiles and EVALS each
child in sequence so earlier children's runtime effects (defmulti's
intern) are visible while later children compile. eval-toplevel now
splits.
- The stdlib itself had forward references the auto-intern hid:
10-seq's transducers used vreset!/vswap! from 20-coll (moved to
10-seq); in 20-coll qualified-ident?/realized?/list*/underive
referenced defs declared later in the file (reordered); sorted? and
partition-all are genuinely later-tier and got (declare ...).
Test rows updated where they encoded the old leniency: ir-passes'
dead-branch row (unresolved in a dead branch is an error, as in
Clojure), compile-mode's ctx-isolation row (other ctx now errors
instead of reading nil), cli rows assert the new message. Gate green,
conformance 335/335 x3, suite 4718 steady, bench within noise.
jolt.passes is the new portable pipeline stage between the analyzer and the
back end: pure IR -> IR rewrites, total over node :ops (unknown ops pass
through with folded children), loaded with the compiler namespaces and
resolved lazily by analyze-form (JOLT_NO_IR_PASSES=1 disables — the same
escape-hatch pattern as the macro oracle). The shape is flatiron's opt.clj
applied to the jolt IR, which is what jolt-2om asked for.
The first pass is constant folding: a call of a foldable numeric SEED fn
(the later tiers don't exist when the compiler loads) whose args are all
constant numbers becomes a constant, and an if with a constant test becomes
the taken branch (dead-branch elimination — the untaken side never even
resolves). Folding computes with the ACTUAL jolt fns, so results match
runtime semantics by construction; a fold that would throw (mod 5 0) is
left for runtime.
Two walk lessons paid for in debugging: let/loop bindings are
[name init-ir] PAIRS, not maps (assoc'ing :init into a pair corrupts it);
and a throw inside the interpreted pass unwinds past the interpreter's ns
restores, so analyze-form restores the compile ns after the (protected)
pass call — without that, one pass error left current-ns in jolt.passes and
the rest of the tier compile resolved against the wrong namespace (sort-by
landed on the 2-arg JANET builtin).
ir-passes-test pins folds, conservatism (free vars, throwing folds), and
end-to-end eval. Gate exit 0.
