An asm result can be STORED through a place (a local / struct field) instead of
returned; the place output does not join the result tuple.
- parser.zig: `-> @place` parses `@place` as an ordinary address-of expression
→ an out_place operand (the in-function form; reuses the existing `@` prefix).
- inst.zig: AsmOperand gains out_ty (the output slot's value type) so emit can
build the combined return struct without re-deriving from Inst.ty.
- lower/expr.zig: out_place operand = the lowered @place address, out_ty = the
pointee. Read-write (`+`) and indirect-memory (`*`) constraints rejected loudly
(not yet implemented) rather than miscompiled.
- ops.zig emitInlineAsm: the LLVM return type is built from ALL outputs
(out_value + out_place); after the call, out_place slots are stored through
their address and out_value slots rebuild the sx result. Fast path when there
are no place outputs (the struct return IS the result — pure-value asm IR
unchanged).
Verified: write-to-local (42), struct field, mixed value+place (v=10 b=20), `+`
rejected. Locked with 1649-platform-asm-place-output (mixed, runs on aarch64).
zig build test green (657 corpus, 446 unit).
967005621a