Hojun-Cho
1657bdeda3
C bootstrap (phases 0-9):
cmd/wwc, cmd/6c, cmd/6a, cmd/6l, cmd/ww, rt, lib/*.
ww-side self-host (phase 10):
selfhost/cmd/wwc — ww-cgen frontend; bootstrap fixed point.
selfhost/cmd/6a — assembler; byte-identical to C 6a (test 991).
selfhost/cmd/6l — linker w/ archive (.a) support; byte-identical
to C 6l (test 992).
selfhost/cmd/ww — driver (build/run/version); byte-identical to
C ww (test 993).
make test: 15/15. make bootstrap: ww2.s == ww3.s, ww2.o == ww3.o,
ww2 == ww3 byte-identical, with the full ww-tooled chain.
107 lines
2.6 KiB
Plaintext
107 lines
2.6 KiB
Plaintext
// selfhost/cmd/wwc/mem.ww — port of cmd/wwc/mem.c.
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//
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// Bump arena allocator. Backed by the runtime page allocator
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// (rt_alloc / rt_free), no libc. Each chunk is mmap'd; when the
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// current chunk runs out we link a fresh one. Freeing the arena
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// unmaps the chain.
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//
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// Memory handed out is 16-byte aligned. The C version under
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// cmd/wwc/ is retained until the three-stage bootstrap diffs clean.
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use os;
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def ALIGN: u64 = 16u64;
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def INIT_CHUNK: u64 = 65536u64;
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def MAX_CHUNK: u64 = 4194304u64;
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def ARENA_SZ: u64 = 48u64; // sizeof(arena), kept in sync below
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type arena = struct {
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buf: *u8,
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off: u64,
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cap: u64,
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next: *arena,
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total: u64,
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};
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fn roundup(n: u64, a: u64) u64 = {
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return (n + a - 1u64) & ~(a - 1u64);
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};
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export fn newarena() *arena = {
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let a: *arena = os.alloc(ARENA_SZ): *arena;
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a.buf = os.alloc(INIT_CHUNK): *u8;
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a.off = 0u64;
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a.cap = INIT_CHUNK;
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a.next = nil;
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a.total = 0u64;
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return a;
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};
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// Grow: link a fresh chunk in front of the head. We push the old
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// chunk into `next` so the head always describes the current bump
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// region. Chunk size doubles up to MAX_CHUNK.
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fn grow(a: *arena, need: u64) bool = {
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let want: u64 = a.cap * 2u64;
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if (want < need) { want = need; };
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if (want > MAX_CHUNK) { want = MAX_CHUNK; };
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if (want < need) { return false; }; // single allocation too big
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let old: *arena = os.alloc(ARENA_SZ): *arena;
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old.buf = a.buf;
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old.off = a.off;
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old.cap = a.cap;
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old.next = a.next;
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old.total = 0u64;
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a.buf = os.alloc(want): *u8;
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a.off = 0u64;
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a.cap = want;
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a.next = old;
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return true;
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};
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export fn amalloc(a: *arena, n: u64) *void = {
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let need: u64 = roundup(n, ALIGN);
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if (need > a.cap - a.off) {
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if (!grow(a, need)) { return nil; };
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};
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let p: *u8 = a.buf + a.off;
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a.off += need;
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a.total += need;
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// Zero the region. Plan 9 amalloc zeroes; we mirror that here so
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// the checker can assume freshly allocated nodes start at 0.
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let i: u64 = 0u64;
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for (i < need) {
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p[i] = 0u8;
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i += 1u64;
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};
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return p: *void;
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};
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// astrndup — copy `n` bytes into the arena and produce a NUL-terminated
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// view. Returns a `str` whose ptr is arena-owned and whose len is `n`
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// (the trailing NUL is past `len`, so callers reading exactly n bytes
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// see no padding). Used by the lexer to capture token text.
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export fn astrndup(a: *arena, src: *u8, n: u64) str = {
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let p: *u8 = amalloc(a, n + 1u64): *u8;
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let i: u64 = 0u64;
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for (i < n) {
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p[i] = src[i];
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i += 1u64;
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};
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p[n] = 0u8;
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let r: str;
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r.ptr = p;
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r.len = n: i32;
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return r;
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};
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export fn freearena(a: *arena) void = {
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for (a != nil) {
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let next: *arena = a.next;
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os.free(a.buf: *void, a.cap);
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os.free(a: *void, ARENA_SZ);
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a = next;
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};
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};
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