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w6c+selfhost: float globals — DATAW + LEAQ-indirect MOVSS/MOVSD

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f32 → 4B slot, f64 → 8B. C cgen bakes the FLOATLIT bit pattern into
DATAW directly; selfhost emits zero-init only (its parser doesn't
lex N_FLOATLIT yet). Read/write goes LEAQ name(SB),CX + MOVSS/MOVSD
since w6a has no D_EXTERN operand form for SSE moves.
This commit is contained in:
Hojun-Cho
2026-05-12 13:23:45 +09:00
parent 1ac9980f7e
commit 6f04713601
5 changed files with 284 additions and 16 deletions
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61
cmd/w6c/cgen.c
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@@ -398,8 +398,8 @@ struct LetVar {
static LetVar *letvars;
/* Slot size for a top-level `let` of type t, or 0 if the type isn't
* supported as a writable global yet. Floats (MOVSS/SD) and tagged
* unions are deferred. enums route through their storage type.
* supported as a writable global yet. Tagged unions are deferred.
* enums route through their storage type.
* Keep this tight — extending it requires the matching load/store
* code below. */
static int
@@ -415,6 +415,10 @@ let_emit_size(Type *t)
case TY_INT: case TY_UINT: case TY_UINTPTR:
case TY_PTR:
return 8;
case TY_F32:
return 4; /* MOVSS loads/stores 4B via LEAQ+indir. */
case TY_F64:
return 8; /* MOVSD loads/stores 8B via LEAQ+indir. */
case TY_STR:
return 16; /* {ptr, len}; literal-strlit init NYI. */
case TY_SLICE:
@@ -459,6 +463,17 @@ let_isstruct(Type *t)
return u && u->kind == TY_STRUCT;
}
/* Is the unwrapped type a float (f32 or f64)? Float globals flow
* through X0 — load/store goes LEAQ name(SB),CX → MOVSS/MOVSD via the
* indirect, since the asm has no D_EXTERN form for SSE moves yet. */
static int
let_isfloat(Type *t)
{
if (t == NULL) return 0;
Type *u = (t->kind == TY_NAMED) ? t->under : t;
return u && (u->kind == TY_F32 || u->kind == TY_F64);
}
/* Returns the unwrapped Type — handy when we need to walk struct
* fields. NULL if t is NULL or unresolved. */
static Type *
@@ -815,6 +830,15 @@ cgexpr(Cg *c, Node *n, Local *locals)
ins2(c, A_MOVQ, amem(D_CX, 16), areg(D_CX));
goto ident_done;
}
if (let_islet(n->str) && let_isfloat(n->type)) {
/* Top-level float global: same LEAQ-indirect
* shape as str/slice, since MOVSS/MOVSD have
* no D_EXTERN operand form in w6a. */
int op = type_isf32(n->type) ? A_MOVSS : A_MOVSD;
ins2(c, A_LEAQ, masym(c, n->str), areg(D_CX));
ins2(c, op, amem(D_CX, 0), areg(D_X0));
goto ident_done;
}
ins2(c, A_MOVQ, masym(c, n->str), areg(D_AX));
}
ident_done:
@@ -1363,13 +1387,17 @@ cgexpr(Cg *c, Node *n, Local *locals)
}
}
}
/* float assignment to a local */
/* float assignment to a local or top-level global. Globals
* route through LEAQ+indirect (no D_EXTERN SSE in w6a). */
if (n->lhs && n->lhs->kind == N_IDENT && node_isfloat(n)) {
cgexpr(c, n->rhs, locals); /* X0 */
int op = op_for(n, A_MOVSD, A_MOVSS);
int off = localfind(locals, n->lhs->str);
if (off != 0) {
int op = op_for(n, A_MOVSD, A_MOVSS);
ins2(c, op, areg(D_X0), amem(D_BP, off));
} else if (let_islet(n->lhs->str)) {
ins2(c, A_LEAQ, masym(c, n->lhs->str), areg(D_CX));
ins2(c, op, areg(D_X0), amem(D_CX, 0));
}
break;
}
@@ -3745,6 +3773,31 @@ emit_lets(Cg *c, FILE *out, Node *file)
if (d->str == NULL || d->str[0] == '\0') continue;
int sz = let_emit_size(d->type);
if (sz == 0) continue;
if (let_isfloat(d->type)) {
/* sz is 4 (f32) or 8 (f64). FLOATLIT init or zero. */
int isf32 = type_isf32(d->type);
u64 v = 0;
if (d->rhs != NULL) {
Node *r = d->rhs;
while (r != NULL && r->kind == N_CAST) r = r->lhs;
if (r == NULL) continue;
if (r->kind != N_FLOATLIT) continue;
if (isf32) {
union { float f; u32 u; } x;
x.f = (float)r->fval;
v = (u64)x.u;
} else {
union { double d; u64 u; } x;
x.d = r->fval;
v = x.u;
}
}
fprintf(out, "DATAW %s(SB),\"", mod_mangle(c, d->str));
for (int i = 0; i < sz; i++)
emit_data_byte(out, (u8)((v >> (i * 8)) & 0xff));
fputs("\"\n", out);
continue;
}
if (sz == 8) {
u64 v = 0;
if (d->rhs != NULL) {