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cgen: route aggregate field-to-field assignment through the aggregate copier

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The direct-field assignment arms enumerate CALL, STRUCTLIT, and local
IDENT producers; an addressable N_DOT/N_INDEX/deref rhs fell through to
the scalar tail, so a 16-byte struct field copied only its first word.
Resolve both places through the existing address funnels and use the
tail-aware aggregate copier. Both stages.
This commit is contained in:
Hojun-Cho
2026-08-07 22:59:52 +09:00
parent c654e97db1
commit 078708770b
3 changed files with 148 additions and 0 deletions
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33
cmd/w6c/cgen.c
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@@ -5257,6 +5257,39 @@ cgexpr(Cg *c, Node *n, Local *locals)
fatal("array-literal store at assignment "
"unwired (task #32)");
}
/* A plain aggregate field-to-field assignment is a memory copy,
* not a scalar expression/store. The legacy direct-field arms
* below enumerate CALL, STRUCTLIT, and local IDENT producers; an
* addressable N_DOT/N_INDEX/deref rhs fell through, so a 16-byte
* time.instant copied only its first word. Resolve both places
* through the existing generic address funnels and use the single
* tail-aware aggregate copier. Calls/literals/unwraps stay on their
* specialized ABI paths, and tagged/str/slice fields are excluded by
* the destination type gate. */
if (n->op == TK_ASSIGN && n->lhs
&& n->lhs->kind == N_DOT && n->lhs->lhs
&& (n->lhs->lhs->kind == N_IDENT
|| n->lhs->lhs->kind == N_DOT
|| (n->lhs->lhs->kind == N_UN
&& n->lhs->lhs->op == TK_STAR))
&& n->rhs) {
Type *au = type_chase_named(n->lhs->type);
int memrhs = n->rhs->kind == N_IDENT
|| n->rhs->kind == N_DOT
|| n->rhs->kind == N_INDEX
|| (n->rhs->kind == N_UN && n->rhs->op == TK_STAR);
if (au && (au->kind == TY_STRUCT || au->kind == TY_ARRAY
|| au->kind == TY_TUPLE) && memrhs) {
if (!cgplaceaddr(c, n->lhs, D_BX, locals))
fatal("aggregate field destination unresolved");
ins1(c, A_PUSHQ, areg(D_BX));
if (!aggarg_srcaddr(c, n->rhs, D_SI, locals))
fatal("aggregate field source unresolved");
ins1(c, A_POPQ, areg(D_BX));
cg_aggcopy(c, (int)au->size);
break;
}
}
/* #16: a single-dot aggregate-field unwrap store whose base
* is a module-GLOBAL value-struct (`g.f = mk()!`) or a
* CHAINED struct field (`o.m.f = mk()!`). The #12 single-dot