da1063f1bb
Building on the Option 3 lvalue-borrow rule, the long-lived allocators
in `library/modules/allocators.sx` (GPA, Arena, TrackingAllocator) now
return their state by value instead of via a heap-allocated `*T`. The
caller binds the result to a local; the local IS the allocator state.
`xx local` borrows that storage under Option 3, so the `Allocator`
protocol value's `ctx` points at the local — no heap allocation for
the state struct, no `free` of the state needed.
```sx
gpa := GPA.init(); // GPA (value)
arena := Arena.init(xx gpa, 4096); // Arena (value)
tracker := TrackingAllocator.init(xx gpa); // TrackingAllocator (value)
push Context.{ allocator = xx tracker, data = null } { ... }
```
Why by-value:
- One fewer `libc_malloc` per allocator instance.
- No state-struct leak. The local is reclaimed at scope exit; `deinit`
only handles downstream resources (chunks, etc.) — not its own struct.
- Owning structs can embed allocators as value fields directly.
Callsite changes:
- `library/modules/ui/pipeline.sx`: `arena_a: Arena;` / `arena_b:
Arena;` (was `*Arena;`). The `build_arena: *Arena` local takes
`@self.arena_a` / `@self.arena_b`.
- `examples/126-xx-recover-then-dispatch.sx`: `recovered == @gpa`
instead of `recovered == gpa` (gpa is a value now).
- `examples/135-xx-lvalue-borrows.sx`: drop the `tracker_ptr.*`
deref — `init` already returns the value.
- `examples/50-smoke.sx`: Arena alloc counts dropped by 1 (no
state-struct allocation). Comments + snapshot updated.
`Arena.deinit` drops the trailing `parent.dealloc(xx a)` — the
caller's local owns the storage.
FFI IR snapshots regenerated to reflect the new signatures:
`@GPA.init` returns `i64` (was `ptr`); `@Arena.init` and
`@TrackingAllocator.init` use sret returns (was `ptr`).
CLAUDE.md "Allocator construction" rule rewritten around the
by-value convention. The forbidden caller-provides-storage and
redundant-pointer-rename patterns are still forbidden but for the
right reasons now (verbose, fragile) rather than as a workaround
for the old `init() -> *T` shape.
157/157 example tests pass; chess clean on macOS, iOS sim, and
Android via `tools/verify-step.sh`.
27 lines
806 B
Plaintext
27 lines
806 B
Plaintext
// `xx allocator` recovers the typed concrete pointer (ctx) from a
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// protocol value. The recovery is read-only and must not perturb
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// subsequent dispatch through the protocol value, regardless of
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// whether the recovery happens BEFORE or AFTER the first dispatch.
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#import "modules/std.sx";
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main :: () -> s32 {
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gpa := GPA.init();
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a : Allocator = xx gpa;
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// Recover BEFORE first dispatch.
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recovered : *GPA = xx a;
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print("recovered == gpa? {}\n", recovered == @gpa);
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p := a.alloc(64);
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print("alloc count after first alloc: {}\n", gpa.alloc_count);
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// Recover AFTER dispatch — still works.
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recovered2 : *GPA = xx a;
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print("recovered2 == gpa? {}\n", recovered2 == @gpa);
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a.dealloc(p);
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print("alloc count after dealloc: {}\n", gpa.alloc_count);
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0;
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}
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