simon/jolt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Recover TCO-elided frames in uncaught-error stack traces

Browse source 
On the eval path nothing registers a source map, so jolt-backtrace-string
dropped every walkable frame and printed no trace at all. Keep any named,
non-plumbing continuation frame (rendered as a bare name when unmapped) so a
runtime error shows the surviving non-tail spine — "print what is available".

Add an opt-in tail-frame history behind JOLT_TRACE for the frames TCO erases.
Each compiled fn records itself on entry into a bounded ring-of-rings, MIT
Scheme's "history" shape: the outer ring holds one rib per non-tail subproblem,
each rib a small inner ring of the tail-calls made at that level. A tight tail
loop churns one rib instead of flushing the spine, so the non-tail caller
context survives and total space stays bounded. The reporter prefers this
history over the continuation when it's present, and resets it per top-level
form so an error's trace isn't padded with earlier REPL frames.

The emitter marks a tail call with (jolt-trace-mark! #t) so the runtime routes
the callee into the current rib vs a fresh one; a *tail?* dynamic var tracks
tail position (cleared by default, passed through if/do/let/loop/fn-body). It's
all gated on trace-frames?, which compile-eval turns on for JOLT_TRACE and
emit-image/`jolt build` force off — so non-trace emitted output is byte-identical
(prelude unchanged, seed re-minted), and a built binary carries no per-call cost.
This commit is contained in:
Yogthos 2026-07-04 15:00:52 -04:00
parent 773e647b4a
commit a3e2365217
8 changed files with 511 additions and 170 deletions
Download patch file Download diff file Expand all files Collapse all files

4
host/chez/emit-image.ss
View file

@ -46,6 +46,10 @@
;; after it). Guarded for the first re-mint pass off an older seed.
(let ((scv (var-deref "jolt.backend-scheme" "set-var-cache!")))
(when (procedure? scv) (scv #f)))
;; Tail-frame tracing off for the mint + `jolt build`: the seed must stay a
;; byte-fixpoint, and a built app should carry no per-call trace overhead.
(let ((stf (var-deref "jolt.backend-scheme" "set-trace-frames!")))
(when (procedure? stf) (stf #f)))
(define (ei-compile-form ctx f optimize?)
(let ((ir (jolt-ce-analyze ctx f)))
(jolt-ce-emit-top (if optimize? (jolt-ce-run-passes ir ctx) ir))))