russell@unturf.com
5ec9eff5fe
Replaces header format from [size:63 | mark:1] with [size:48 | type:8 | flags:8 (mark in bit 0)]. Every heap_alloc call site in the GC build now sets its type byte via one extra `orq $(HT_X << 8), -8(%rax)` after return. Ten types defined: HT_PAIR, HT_CLOSURE, HT_STRING, HT_SYMBOL, HT_VECTOR, HT_HASHTABLE, HT_HASHSET, HT_ENVNODE, HT_CHAINNODE, HT_PADDING. The mark / sweep / arena-escape walkers now dispatch on the type byte instead of heuristically guessing from block size. Deletes the special-case "negative sentinel at offset 0" branch in gc_mark_drain (hash-table vs hash-set vs vector discrimination was encoded there), the "size == 24 and TAG_SYM at offset 0" check in gc_mark_env, and the "length fits block" sanity check in the vector walker. All that logic collapses into a single compare on the type byte. Also routed the remaining direct-%r15-bump allocators (bi_strref, bi_vector, bi_makevec, bi_listtovec, bi_substr) through heap_alloc so they get proper headers + type bytes. These had been silently broken under the GC build because they bypassed the header-emitting path entirely; any direct-bump'd data appeared to the sweep walker as garbage headers. §6.6.4 cell 4 (asm GC + no snapshot) was crashing at first GC before this change. After: serves 5,000 HTTP requests at ~410 req/s, peak RSS 1,088 KB (one chunk), growth 972 KB — the collector hit its natural steady state. First time we've validated "naive GC as replacement for snapshot discipline" under real traffic. New §6.6.5 "Precise Block Typing" in the whitepaper documents the old heuristic bugs, the new header format, and the cost (one orq per alloc, 16 header bits) vs benefit (class of bugs eliminated). Updated §6.6.4 to reflect cell 4 passing. Remaining known issue: the hash-set bench on the GC build under very heavy sustained allocation still surfaces an occasional unbound-variable error. The precise-type fix addressed the observed HTTP crash; a deeper root-scan edge case remains. Tracked for Fix 2 work. 137 asm no-GC + 137 asm GC + 189 shared functional tests all pass.
58 KiB
Executable file
58 KiB
Executable file