From 433fb8cb71e98bbfd579fb43dbc0eac0a60bae73 Mon Sep 17 00:00:00 2001 From: zinc Date: Wed, 14 Oct 2026 18:35:03 +0330 Subject: rt: exact-size heap bounds; n, the words new asked for, lives in bits 32..62 of p[-4] the bnd recipe and paylen read n instead of the power-of-two block: bnd: r6 = sub p 3; r6 = ld r6; r7 = xor p 0x2B7E1516; r6 = eq r6 r7; r7 = sub p 4; r7 = ld r7; r7 = shr r7 32; r7 = mul r7 q; r8 = mul i m; r8 = ltu r8 r7; r8 = xor r8 1; r0 = and r6 r8 paylen: return p[-4] >> 32 two loads instead of three; osize, bchk, release, recycle and the memdebug leak report all read n (rt.new(4) has length 4, rt.new(0) has 0). writers: new_raw and new_k set n; stack.h line 87 and tinyvm.ts (BigInt) set it on stack segments. release clears n when a block goes into quarantine (len 0, indexing traps; under memdebug bchk reports a use after free); every free-list path (fpush, mkblock, bdrop, recycle_leaf, balloc hold) rewrites the word as k << 16, and an array that grows gets a fresh block. a request over 2^31-1-HDR words stops in new_raw (oom), and the compiler only takes the new_k fast path for constant sizes that fit, so n is never truncated. bit users checked (all mask or preserve bits 32..62; none compares or copies the whole word): gc mark and sweep; release, free, recycle, recycle_leaf; share and own; isobj, quar, checkptr, obj_base; bclass and the bfree buddy merge; balloc, mkblock, fpush, funlink, heap_grow; frame_grow; stack_allocate in src/core/stack.h and src/js/tinyvm.ts; micro.c and core.c (check word only); the compiler's two p[-4] | F_INTERNAL writes (base.zc, builtins.zc). 32-bit ports: none (baremetal, wasm and micro use int64 Cell). tests: tests/programs/exactsize.zc (n-1/n for non-power-of-two sizes, new(0), packed bytes, recycle, grow, stack growth); 8-runtime: exact_size_bounds, pointer_index_n_minus_1, pointer_index_n_traps, pointer_index_n_traps_memdebug, new_zero_index_traps, new_too_big_traps, stale_index_after_free_traps, stale_index_after_free_memdebug. expectations changed: leak report shows n (tests/test.sh line 169, examples/learn/13-memdebug.out, docs/LEARN.md, 4-statements/memdebug_report_line.zc). programs adjusted to keep test.sh expectations: quarantine.zc (unbounded), bounds_heap.zc (rt.new(11)). spec 3.7.4 and 4.11 updated. fixpoint 402204 words (main 402197). --- tests/conformance/8-runtime/exact_size_bounds.zc | 45 ++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 tests/conformance/8-runtime/exact_size_bounds.zc (limited to 'tests/conformance/8-runtime/exact_size_bounds.zc') diff --git a/tests/conformance/8-runtime/exact_size_bounds.zc b/tests/conformance/8-runtime/exact_size_bounds.zc new file mode 100644 index 0000000..7a8c440 --- /dev/null +++ b/tests/conformance/8-runtime/exact_size_bounds.zc @@ -0,0 +1,45 @@ +// expect: 11 11 11 11 11 11 11 11/10 1/1101/1601/200000 11 11/ +// spec 8.4: exact heap lengths at n-1 and n, new(0), packed bytes, a recycled block, a grown array, after the stacks grow (copy of tests/programs/exactsize.zc) +include rt; +// exact-size bounds: a heap block knows the n words new asked for (bits 32..62 of +// p[-4]), not just its power-of-two block. rt.bnd(p, i, 1, 1) is 1 when p[i] is +// outside: the same recipe every backend inlines in front of p[i]. +struct P { int a; int b; int c; } +struct Q { int a; } +// n-1 inside, n outside, osize is n, and p[n-1] is usable +int edge(int n) { + word* p = rt.new(n); + p[n - 1] = n; + return rt.bnd(p, n - 1, 1, 1) * 100 + rt.bnd(p, n, 1, 1) * 10 + (rt.osize(p) == n) + (p[n - 1] == n) - 1; +} +int zero() { word* p = rt.new(0); return rt.bnd(p, 0, 1, 1) * 10 + rt.osize(p); } +int bytes() { word* p = rt.new(3); return rt.bnd(p, 23, 1, 8) * 10 + rt.bnd(p, 24, 1, 8); } // 3 words are 24 bytes +int where; +int leaf() { P* a = rt.new(P); a.c = 3; where = (&a.a) as int; return a.c; } // a is recycled at the function's end +// recycle: the next 1-word object reuses the 3-word block, with n = 1 +int reuse() { + Q* q = rt.new(Q); int same = where == ((&q.a) as int); + return same * 1000 + rt.osize(q) * 100 + rt.bnd(q, 0, 1, 1) * 10 + rt.bnd(q, 1, 1, 1); +} +// grow: the items block is replaced by one with its own exact n (16 words for 9 ints) +int grow() { + int[?] d = rt.new(int[?], 0); int i = 0; word* h; word* p; + while (i < 9) { d.push(i); i++; } + h = &d[0]; p = h; + return rt.osize(p) * 100 + rt.bnd(p, 15, 1, 1) * 10 + rt.bnd(p, 16, 1, 1); +} +// deep enough to grow the stacks: their segments are heap blocks the core allocates +// (src/core/stack.h, src/js/tinyvm.ts) with n set too. after they go back, blocks reused +// from them carry their own n. +int deep(int k) { if (k == 0) return 0; return deep(k - 1) + 1; } +fn main() { + rt.put_n(edge(1)); rt.put_c(32); rt.put_n(edge(3)); rt.put_c(32); rt.put_n(edge(5)); rt.put_c(32); + rt.put_n(edge(6)); rt.put_c(32); rt.put_n(edge(7)); rt.put_c(32); rt.put_n(edge(11)); rt.put_c(32); + rt.put_n(edge(13)); rt.put_c(32); rt.put_n(edge(100)); rt.put_c(10); + rt.put_n(zero()); rt.put_c(32); rt.put_n(bytes()); rt.put_c(10); + leaf(); rt.put_n(reuse()); rt.put_c(10); + rt.put_n(grow()); rt.put_c(10); + rt.put_n(deep(200000)); rt.put_c(32); rt.put_n(edge(9)); rt.put_c(32); rt.put_n(edge(21)); rt.put_c(10); + return 0; +} +// zc0: skip -- cgit v1.2.3