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w6c+selfhost: cgen N_ASSIGN TY_STRUCT field branch (closes #25)

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Parallel to TY_STR/TY_SLICE branches at cgen.c:1939/1962. Word-copy
from src slot to field+k*8 via AX, MOVL/MOVB ragged tail. N_IDENT
rhs only — struct-call-result and struct-literal rhs are different
code paths, filed as task #27. Symmetric in N_ASSIGN field case AND
spine-walker terminal; mirrored in wwstage cgassign four sub-shapes
(*struct base, direct local, global, spine terminal).
This commit is contained in:
Hojun-Cho
2026-05-14 18:16:51 +09:00
parent eb0602d070
commit 1726bcef18
5 changed files with 843 additions and 0 deletions
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84
cmd/w6c/cgen.c
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@@ -1978,6 +1978,43 @@ cgexpr(Cg *c, Node *n, Local *locals)
}
break;
}
/* struct-typed field, struct-ident rhs: cgexpr cannot
* materialise a whole struct value in registers, so
* word-copy from the rhs slot directly to the dest
* field. Other rhs shapes (struct-returning call,
* struct literal) stay broken at the cgexpr level —
* tracked as #27. */
if (n->op == TK_ASSIGN && str_fu
&& str_fu->kind == TY_STRUCT
&& n->rhs && n->rhs->kind == N_IDENT
&& localfind(locals, n->rhs->str) != 0) {
int soff = localfind(locals, n->rhs->str);
int ssz = (int)str_fu->size;
if (via_ptr)
ins2(c, A_MOVQ, amem(D_BP, boff), areg(D_BX));
else if (is_global)
ins2(c, A_LEAQ, masym(c, base->str), areg(D_BX));
int k = 0;
while (k + 8 <= ssz) {
ins2(c, A_MOVQ, amem(D_BP, soff + k), areg(D_AX));
if (via_ptr || is_global)
ins2(c, A_MOVQ, areg(D_AX), amem(D_BX, foff + k));
else
ins2(c, A_MOVQ, areg(D_AX), amem(D_BP, boff + foff + k));
k += 8;
}
if (k < ssz) {
int tail = ssz - k;
int lop = (tail == 4) ? A_MOVL
: (tail == 1 ? A_MOVB : A_MOVQ);
ins2(c, lop, amem(D_BP, soff + k), areg(D_AX));
if (via_ptr || is_global)
ins2(c, lop, areg(D_AX), amem(D_BX, foff + k));
else
ins2(c, lop, areg(D_AX), amem(D_BP, boff + foff + k));
}
break;
}
/* compound: load current value into BX */
if (n->op != TK_ASSIGN) {
if (via_ptr) {
@@ -2557,6 +2594,53 @@ cgexpr(Cg *c, Node *n, Local *locals)
}
break;
}
/* TY_STRUCT terminal: word-copy the rhs slot onto
* base+total_off. Only N_IDENT rhs is wired —
* other shapes route through #27. */
if (fu && fu->kind == TY_STRUCT
&& n->rhs && n->rhs->kind == N_IDENT
&& localfind(locals, n->rhs->str) != 0) {
int soff = localfind(locals, n->rhs->str);
int ssz = fsz;
if (via_cx) {
if (ptr_root)
ins2(c, A_MOVQ,
amem(D_BP, base_disp),
areg(D_CX));
else
ins2(c, A_LEAQ,
masym(c, cur->str),
areg(D_CX));
}
int k = 0;
while (k + 8 <= ssz) {
ins2(c, A_MOVQ,
amem(D_BP, soff + k),
areg(D_AX));
if (via_cx)
ins2(c, A_MOVQ, areg(D_AX),
amem(D_CX, total_off + k));
else
ins2(c, A_MOVQ, areg(D_AX),
amem(D_BP, base_disp + total_off + k));
k += 8;
}
if (k < ssz) {
int tail = ssz - k;
int lop = (tail == 4) ? A_MOVL
: (tail == 1 ? A_MOVB : A_MOVQ);
ins2(c, lop,
amem(D_BP, soff + k),
areg(D_AX));
if (via_cx)
ins2(c, lop, areg(D_AX),
amem(D_CX, total_off + k));
else
ins2(c, lop, areg(D_AX),
amem(D_BP, base_disp + total_off + k));
}
break;
}
int sf32 = 0;
if (fld_isfloat(leaf_type, &sf32)) {
int mov = sf32 ? A_MOVSS : A_MOVSD;