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reachability scan (25.5b) and exit accounting; free() and print release what they are handed

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Mem.scan() and R3D_ALLOC_SCAN=<frame> (at that frame's mark, when no function is running) walk
every heap block reachable from the program's globals - the states among them - conservatively: each
word that is a heap block's start (malloc_size says so) is followed, blocks made before tracking too.
A tracked block nothing reaches is a leak whatever a frame's totals say; they are summed by site and
printed ('alloc-scan: frame 39 - 32 bytes in 2 blocks ... reachable from no global or state', then
the sites). R3D_ALLOC_EXIT=1 runs the same scan as the program quits. A test: two records dropped in
frame 20 are the two found, the one pushed into a state is not.

The escape analysis now takes free(x) as giving x back (ES_FREED, flowing to what reached x) and a
print's argument as used up, so ludic deps --births lists only what is never given back.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Orkun ÇAKILKAYA 2026-09-28 16:48:35 +03:00
parent 3205408290
commit 39af9cabc0
7 changed files with 74517 additions and 71904 deletions
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15
selfhost/backend/emit_escape.ludic
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@ -16,6 +16,7 @@
const ES_SCRATCH: int = 77 # Node.uns on an allocating expression: scratch
const ES_ESC: int = 1
const ES_HEAP: int = 2
const ES_FREED: int = 4 # given back with free(): not a leak at birth
var g_es_flag: []int = new []int
var g_es_why: []Node = new []Node # per class: the statement that made it escape
@ -190,7 +191,18 @@ function es_call(e: Node) -> int {
es_args_walk(e)
return es_site(e)
}
if (nm == "print") or (nm == "len") or (nm == "free") { es_args_walk(e); return -1 }
if (nm == "free") and len(e.kids) == 1 { # given back: what flows into it is not kept by nothing
let v = es_val(e.kids[0])
if v >= 0 { g_es_flag[v] = g_es_flag[v] | ES_FREED }
return -1
}
if (nm == "print") { # print frees a fresh text it is handed
es_args_walk(e)
var i = 0
while i < len(e.kids) { push(g_es_consumed, e.kids[i]); i += 1 }
return -1
}
if (nm == "len") { es_args_walk(e); return -1 }
let f = es_fn(nm)
if f >= 0 {
push(g_es_calls_f, g_es_cur)
@ -327,6 +339,7 @@ function es_solve() -> void {
let a = g_es_ff[i]
let b = g_es_ft[i]
if (g_es_flag[a] & ES_HEAP) != 0 and (g_es_flag[b] & ES_HEAP) == 0 { g_es_flag[b] = g_es_flag[b] | ES_HEAP; changed = true }
if (g_es_flag[b] & ES_FREED) != 0 and (g_es_flag[a] & ES_FREED) == 0 { g_es_flag[a] = g_es_flag[a] | ES_FREED; changed = true }
if (g_es_flag[b] & ES_ESC) != 0 and (g_es_flag[a] & ES_ESC) == 0 {
g_es_flag[a] = g_es_flag[a] | ES_ESC
g_es_why[a] = g_es_why[b]