Hojun-Cho
d9345555c0
rt_malloc was a bare mmap-per-call wrapper: every allocation, even a 32-72B AST/symbol node, consumed a page-rounded 4KB region and was never freed. w6a/w6c emit ~4 such nodes per .s line, so assembling a 145K-line file burned ~625K pages (~2.5GB); test 995's 5 concurrent self-rebuilds then OOM'd. The defect is linear and str-independent -- the str->24B codegen merely enlarged .s files past the cliff. Replace it with the no-free SUBSET of Hare's allocator (ref/hare/rt/malloc.ha): 2MiB chunk-bump (CHUNKSZ malloc.ha:24, ALIGN malloc.ha:14), oversized (>CHUNKSZ) requests direct-mmap'd. The bin/freelist/META machinery exists only to support free, which ww does not have, so it is omitted. Policy lives in rt/malloc.ww; the raw mmap primitive stays in rt/alloc.s as rt_segmalloc -- Hare's malloc/segmalloc split. rt_free becomes a documented no-op (os.free re-exports it for the public API, so the symbol must stay); rt/ensure.ww drops its now-impossible reclaim. Zero-init is preserved: the bump never reuses memory, so every byte is fresh MAP_ANONYMOUS-zeroed. w6a_ww on a 145K-line .s: 2165MB -> 28MB (~glibc parity, C w6a 24MB). .o output byte-identical; both stages emit identical asm. make test 134/134.
37 lines
1.4 KiB
ArmAsm
37 lines
1.4 KiB
ArmAsm
// rt/alloc.s — raw page primitive via the mmap syscall.
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//
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// rt_segmalloc(n: u64) returns a *void aligned at a page boundary, sized
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// to the next page multiple. It is the primitive under rt/malloc.ww's
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// bump allocator (renamed from rt_malloc, task #8) — callers use the
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// bump rt_malloc, not this directly.
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//
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// We pin to PROT_READ|PROT_WRITE and MAP_PRIVATE|MAP_ANONYMOUS so
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// callers never have to plumb file descriptors through.
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//
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// On mmap failure the raw syscall returns -errno (negative); we map
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// that to 0 so the bump allocator's null-check (and the alloc builtin's
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// `!`/`?` lowering, task #30) sees a clean nil.
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TEXT rt_segmalloc,$0
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MOVQ DI, SI // arg 1: length = caller's n
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MOVQ $0, DI // arg 0: addr = NULL (kernel chooses)
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MOVQ $3, DX // arg 2: prot = R|W
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MOVQ $34, R10 // arg 3: flags = MAP_PRIVATE|MAP_ANON
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MOVQ $-1, R8 // arg 4: fd = -1
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MOVQ $0, R9 // arg 5: offset = 0
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MOVQ $9, AX // syscall: mmap
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SYSCALL
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CMPQ $0, AX
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JGE rt_segmalloc_ok
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XORQ AX, AX
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rt_segmalloc_ok:
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RET
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// rt_free is a no-op: ww is a no-free runtime. rt/malloc.ww bumps over
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// shared 2MiB chunks, so a mid-chunk pointer cannot be unmapped without
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// corrupting its neighbours; all memory is reclaimed at process exit.
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// Kept as a symbol because os.free re-exports it (lib/os/os.ww) for the
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// public API — callers' frees become harmless leaks. (task #8)
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TEXT rt_free,$0
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RET
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