coolguy
dacf1e1b1b
?T 의 페이로드가 null 이 될 수 없으면 태그를 따로 두지 않고 그 불가능한 값을 null 로 쓴다. ?^T 와 ?&T 가 그렇다. 그런데 if let 이 그것을 풀 때 두 경우를 한 갈래로 처리하고 있었다. 바인딩이 참조인 이유가 둘이다. 페이로드가 값이면 바인딩은 그것이 래퍼 안에 앉은 자리를 가리켜야 하고(주소), 페이로드가 이미 포인터면 바인딩은 그 포인터여야 한다(값). 후자에 주소를 쓰면 포인터의 포인터가 되고, 프로그램은 값이 있어야 할 자리에서 주소를 읽는다. 컴파일도 되고 실행도 됐다. ?i32 5 (맞았음 -- 태그가 있어서 다른 길로 갔다) ?^i32 6125480 → 5 ?&i32 6125496 → 5 그리고 옵셔널을 null 과 비교하는 것이 lowering 되지 않았다 -- 래퍼 전체를 값으로 읽으려 해서 'cannot lower an aggregate as a value' 였다. 태그만 보면 되는 질문이다. optional/oknull.fe 가 검사만 하는 fixture 라 드러나지 않았다. exec/optref.fe 가 세 모양을 전부 고정한다: if let, orelse, .?, == null, 그리고 R7 관용구인 mem.replace(&mut box, null).? 로 소유자를 꺼내 놓는 것까지. 229/229, 33/33.
554 lines
24 KiB
C
554 lines
24 KiB
C
#include "lowerpri.h"
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Slot lower_expr_core(Lower *L, FeNode *n)
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{
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FeType *t;
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FeIrType it;
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if (!n || L->failed) return slot_void();
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t = n->sem_type;
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it = ir_type(t);
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switch (n->kind) {
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case FE_N_LITERAL:
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if (n->text && n->text[0] == '"') {
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/* The bytes live in the image; the value is a pointer to them and
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how many there are. The lexer keeps the quotes and the escapes,
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so this is where `
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` becomes one byte. */
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char text[1024];
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unsigned long raw = strlen(n->text);
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unsigned long len = 0;
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unsigned long i;
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const char *label;
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unsigned local;
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unsigned p;
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unsigned c;
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if (raw >= 2) raw -= 2;
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for (i = 0; i < raw && len + 1 < sizeof text; ++i) {
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char ch = n->text[1 + i];
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if (ch == 92 && i + 1 < raw) { /* a backslash */
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++i;
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switch (n->text[1 + i]) {
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case 'n': ch = 10; break;
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case 't': ch = 9; break;
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case 'r': ch = 13; break;
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case '0': ch = 0; break;
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default: ch = n->text[1 + i]; break;
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}
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}
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text[len++] = ch;
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}
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label = fe_ir_string(L->m, text, len);
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if (!label) { fail(L, "a string literal", n); return slot_void(); }
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local = scratch(L, t, "text");
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p = fe_ir_addr(L->m, L->b, fe_ir_at_global(label, 0));
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fe_ir_store(L->m, L->b, fe_ir_at_local(local, SLICE_PTR_OFFSET), p,
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FE_IR_PTR);
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c = fe_ir_const(L->m, L->b, FE_IR_I32, (long)len);
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fe_ir_store(L->m, L->b, fe_ir_at_local(local, SLICE_LEN_OFFSET), c,
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FE_IR_I32);
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return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(t));
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}
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return slot_value(fe_ir_const(L->m, L->b,
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it == FE_IR_VOID ? FE_IR_I32 : it,
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literal_value(n)),
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it == FE_IR_VOID ? FE_IR_I32 : it);
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case FE_N_IDENT: {
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LowerVar *var = find_var(L, n->cname);
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if (var) {
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if (var->by_address) {
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unsigned p = fe_ir_load(L->m, L->b, FE_IR_PTR,
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fe_ir_at_local(var->local, 0));
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return slot_place(fe_ir_at_temp(p, 0), it, ir_size(t));
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}
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return slot_place(fe_ir_at_local(var->local, 0), it, ir_size(t));
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}
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if (n->cname)
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return slot_place(fe_ir_at_global(n->cname, 0), it, ir_size(t));
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fail(L, "an unresolved name", n);
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return slot_void();
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}
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case FE_N_BINARY: {
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int is_cmp = 0;
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FeIrOp op;
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unsigned a;
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unsigned b;
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FeIrType operand;
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if (n->text && !strcmp(n->text, "orelse")) return lower_lazy(L, n, 0);
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if (n->text && !strcmp(n->text, "catch")) return lower_lazy(L, n, 1);
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if (n->text && (!strcmp(n->text, "and") || !strcmp(n->text, "or")))
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return lower_logical(L, n, !strcmp(n->text, "and"));
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op = binary_op(n->text, &is_cmp);
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/* Comparing an optional with `null` asks about its tag, not about the
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bytes of the whole wrapper -- which has no value form at all. */
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if ((op == FE_IR_EQ || op == FE_IR_NE) && n->a && n->b) {
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FeNode *w = fe_m7_is_null(n->b) ? n->a :
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(fe_m7_is_null(n->a) ? n->b : 0);
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FeType *wt = w ? w->sem_type : 0;
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if (wt && wt->kind == FE_TYPE_OPTIONAL) {
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Slot s = lower_expr(L, w);
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unsigned t0;
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unsigned z;
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if (!s.is_place) {
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fail(L, "an optional with no place", w);
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return slot_void();
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}
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t0 = wrapper_tag(L, s, wt, w);
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z = fe_ir_const(L->m, L->b,
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uses_niche(wt) ? FE_IR_PTR : FE_IR_I8, 0);
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return slot_value(fe_ir_binary(L->m, L->b, op,
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uses_niche(wt) ? FE_IR_PTR : FE_IR_I8, t0, z, 1),
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FE_IR_I8);
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}
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}
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operand = ir_type(n->a ? n->a->sem_type : 0);
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if (operand == FE_IR_VOID || operand == FE_IR_MEM) operand = FE_IR_I32;
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a = as_value(L, lower_expr(L, n->a), n->a);
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b = as_value(L, lower_expr(L, n->b), n->b);
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return slot_value(fe_ir_binary(L->m, L->b, op, operand, a, b,
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type_is_unsigned(n->a ? n->a->sem_type
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: 0)),
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is_cmp ? FE_IR_I8 : operand);
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}
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case FE_N_UNARY:
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if (n->text && !strcmp(n->text, "try")) return lower_try(L, n);
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if (n->text && !strcmp(n->text, "-")) {
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unsigned zero = fe_ir_const(L->m, L->b, it, 0);
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unsigned v = as_value(L, lower_expr(L, n->a), n->a);
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return slot_value(fe_ir_binary(L->m, L->b, FE_IR_SUB, it, zero, v,
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0), it);
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}
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if (n->text && !strcmp(n->text, "not")) {
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unsigned zero = fe_ir_const(L->m, L->b, FE_IR_I8, 0);
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unsigned v = as_value(L, lower_expr(L, n->a), n->a);
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return slot_value(fe_ir_binary(L->m, L->b, FE_IR_EQ, FE_IR_I8, v,
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zero, 0), FE_IR_I8);
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}
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if (n->text && (!strcmp(n->text, "&") || !strcmp(n->text, "&mut"))) {
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Slot inner = lower_expr(L, n->a);
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return slot_value(as_address(L, inner, n->a), FE_IR_PTR);
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}
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fail(L, "this unary operator", n);
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return slot_void();
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case FE_N_MEMBER:
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/* A variant used as a value carries nothing but its tag. When no
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variant of the enum carries anything the whole value is that tag;
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otherwise it is a tag sitting in front of an unused payload. */
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if (t && t->kind == FE_TYPE_ENUM && n->b && n->b->text) {
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FeVariantType *v = fe_type_variant(t, n->b->text);
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if (v && !enum_has_payload(t))
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return slot_value(fe_ir_const(L->m, L->b, ir_type(t),
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(long)v->tag), ir_type(t));
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if (v && !v->field_count) {
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unsigned local = scratch(L, t, "variant");
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unsigned tag = fe_ir_const(L->m, L->b, tag_type_of(t),
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(long)v->tag);
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fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), tag,
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tag_type_of(t));
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return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM,
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ir_size(t));
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}
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}
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/* `error.Name` is a member of the open default set: a code, and
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nothing to look up. */
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if (n->a && n->a->kind == FE_N_IDENT && n->a->text &&
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!strcmp(n->a->text, "error") && n->b && n->b->text)
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return slot_value(fe_ir_const(L->m, L->b, FE_IR_I16,
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error_code(L, n->b->text)),
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FE_IR_I16);
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/* `.?` is the payload of an optional the checker already proved is
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there. */
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if (n->text && !strcmp(n->text, ".?")) {
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FeType *bt = n->a ? n->a->sem_type : 0;
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return wrapper_payload(L, lower_expr(L, n->a), bt);
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}
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/* `p.^` reads through a pointer -- except for an owned slice, whose
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pointer and length are the value itself, so there is nothing to
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step through. */
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if (n->text && !strcmp(n->text, ".^")) {
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Slot base = lower_expr(L, n->a);
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unsigned p;
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if (base.type == FE_IR_MEM)
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return slot_place(base.place, it, ir_size(t));
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p = as_value(L, base, n->a);
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return slot_place(fe_ir_at_temp(p, 0), it, ir_size(t));
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}
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/* `.n` is how many elements there are, which an array knows at
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compile time and a slice carries beside its pointer. Only for those:
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a struct is free to have a field called `n`, and reading it as a
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length would quietly hand back the wrong four bytes. */
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if (n->b && n->b->text && !strcmp(n->b->text, "n") &&
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n->a && n->a->sem_type &&
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(n->a->sem_type->kind == FE_TYPE_ARRAY ||
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n->a->sem_type->kind == FE_TYPE_SLICE ||
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n->a->sem_type->kind == FE_TYPE_STR)) {
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FeType *bt = n->a->sem_type;
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Slot base;
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if (bt && bt->kind == FE_TYPE_ARRAY)
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return slot_value(fe_ir_const(L->m, L->b, FE_IR_I32,
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(long)bt->length), FE_IR_I32);
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base = lower_expr(L, n->a);
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if (!base.is_place) { fail(L, "a length of a temporary", n); return slot_void(); }
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base.place.offset += SLICE_LEN_OFFSET;
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return slot_place(base.place, FE_IR_I32, 4);
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}
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/* A field is a constant offset from the base. */
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{
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FeType *base = n->a ? n->a->sem_type : 0;
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FeFieldType *field;
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Slot b;
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if (base && (base->kind == FE_TYPE_REF ||
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base->kind == FE_TYPE_OWNED)) base = base->elem;
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field = fe_type_field(base, n->b && n->b->text ? n->b->text : "");
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/* `binding.name` is not a field of anything: it is a constant or a
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global in another unit, and the checker already turned it into a
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link name. */
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if (!field && n->cname)
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return slot_place(fe_ir_at_global(n->cname, 0), it,
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ir_size(t));
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if (!field) { fail(L, "an unresolved field", n); return slot_void(); }
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b = lower_expr(L, n->a);
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if (n->a->sem_type && (n->a->sem_type->kind == FE_TYPE_REF ||
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n->a->sem_type->kind == FE_TYPE_OWNED)) {
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unsigned p = as_value(L, b, n->a);
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return slot_place(fe_ir_at_temp(p, (long)field->offset), it,
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ir_size(t));
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}
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if (!b.is_place) { fail(L, "a field of a temporary", n); return slot_void(); }
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b.place.offset += (long)field->offset;
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return slot_place(b.place, it, ir_size(t));
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}
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case FE_N_INDEX: {
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FeType *bt = n->a ? n->a->sem_type : 0;
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FeType *elem = bt ? bt->elem : 0;
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Slot base;
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unsigned data;
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unsigned length;
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unsigned index;
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unsigned scale;
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unsigned offset;
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unsigned addr;
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if (n->flags & FE_NODE_SLICE) return lower_slice(L, n);
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base = lower_expr(L, n->a);
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indexable_parts(L, base, bt, &data, &length, n);
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index = as_value(L, lower_expr(L, n->b), n->b);
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if (!L->c->no_checks) {
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unsigned ok = fe_ir_binary(L->m, L->b, FE_IR_LT, FE_IR_I32,
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index, length, 1);
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guard(L, ok, FE_TRAP_BOUNDS, n->loc.line);
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}
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scale = fe_ir_const(L->m, L->b, FE_IR_I32, (long)ir_size(elem));
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offset = fe_ir_binary(L->m, L->b, FE_IR_MUL, FE_IR_I32, index, scale, 1);
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addr = fe_ir_binary(L->m, L->b, FE_IR_ADD, FE_IR_PTR, data, offset, 1);
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return slot_place(fe_ir_at_temp(addr, 0), ir_type(elem), ir_size(elem));
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}
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case FE_N_ARRAY_INIT: {
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unsigned local = scratch(L, t, "array");
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FeType *elem = t ? t->elem : 0;
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unsigned long step = ir_size(elem);
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long at = 0;
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FeNode *x;
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for (x = n->children; x; x = x->next) {
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Slot v = lower_expr(L, x);
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store_into(L, fe_ir_at_local(local, at), v, x, step);
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at += (long)step;
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}
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return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(t));
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}
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case FE_N_STRUCT_INIT: {
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unsigned local;
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FeNode *f;
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/* `Enum.Variant{ .. }` builds a variant, not a struct: the tag first,
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then the named fields inside the payload area. */
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if (t && t->kind == FE_TYPE_ENUM && n->a && n->a->kind == FE_N_MEMBER) {
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const FeVariantType *v = fe_type_variant(t,
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n->a->b && n->a->b->text ? n->a->b->text : "");
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long base = (long)fe_type_payload_offset(t);
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unsigned tag;
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if (!v) { fail(L, "an unknown variant", n); return slot_void(); }
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local = scratch(L, t, "variant");
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tag = fe_ir_const(L->m, L->b, tag_type_of(t), (long)v->tag);
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fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), tag,
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tag_type_of(t));
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for (f = n->children; f; f = f->next) {
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unsigned i;
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if (f->kind != FE_N_FIELD) continue;
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for (i = 0; i < v->field_count; ++i)
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if (f->text && v->fields[i].name &&
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!strcmp(v->fields[i].name, f->text)) break;
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if (i == v->field_count) {
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fail(L, "an unknown variant field", f);
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return slot_void();
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}
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store_into(L, fe_ir_at_local(local,
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base + (long)v->fields[i].offset),
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lower_expr(L, f->a), f, ir_size(v->fields[i].type));
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}
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return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(t));
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}
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local = scratch(L, t, "struct");
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for (f = n->children; f; f = f->next) {
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FeFieldType *field;
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Slot v;
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if (f->kind != FE_N_FIELD) continue;
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field = fe_type_field(t, f->text);
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if (!field) { fail(L, "an unresolved field", f); return slot_void(); }
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v = lower_expr(L, f->a);
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store_into(L, fe_ir_at_local(local, (long)field->offset), v, f,
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ir_size(field->type));
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}
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return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(t));
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}
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case FE_N_CALL:
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return lower_call(L, n);
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case FE_N_TYPE:
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/* `x as T`: the operand is `a` and the target type is the node's own.
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Between integers this only changes how wide the value is and whether
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the top bits repeat the sign. */
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if (n->a) {
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FeType *from = n->a->sem_type;
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unsigned v = as_value(L, lower_expr(L, n->a), n->a);
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if (ir_type(from) == it) return slot_value(v, it);
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return slot_value(fe_ir_cast(L->m, L->b, ir_type(from), it, v,
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type_is_unsigned(from)), it);
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}
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fail(L, "this type expression", n);
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return slot_void();
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case FE_N_EXPR:
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return lower_expr(L, n->a);
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default:
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fail(L, "this expression", n);
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return slot_void();
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}
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}
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/* The link name of the `drop` method for this type, found through the instance
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the checker recorded. */
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const char *drop_name(Lower *L, const FeType *t)
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{
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unsigned i;
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FeNode *method = 0;
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if (!t || !t->decl_node) return 0;
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for (method = t->decl_node->children; method; method = method->next)
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if (method->kind == FE_N_FN && method->text &&
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!strcmp(method->text, "drop")) break;
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if (!method) return 0;
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for (i = 0; i < L->c->instance_count; ++i)
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if (L->c->instances[i].decl == method &&
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L->c->instances[i].owner == t)
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return L->c->instances[i].cname;
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return method->cname;
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}
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/* Let go of one value sitting at `at`. A type that says how to let go of
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itself is asked first; then whatever it holds is let go of in turn, so a
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struct that owns a struct that owns a buffer settles all three without
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anyone writing a `drop` (SPEC 5 R1). */
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void release_at(Lower *L, const FeType *t, FeIrPlace at)
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{
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unsigned args[1];
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unsigned i;
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if (!t) return;
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if (t->has_drop) {
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const char *how = drop_name(L, t);
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args[0] = fe_ir_addr(L->m, L->b, at);
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if (how) fe_ir_call(L->m, L->b, FE_IR_VOID, how, args, 1);
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}
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if (t->kind == FE_TYPE_OWNED) {
|
|
FeIrPlace p = at;
|
|
if (t->elem && t->elem->kind == FE_TYPE_SLICE)
|
|
p.offset += SLICE_PTR_OFFSET;
|
|
args[0] = fe_ir_load(L->m, L->b, FE_IR_PTR, p);
|
|
fe_ir_call(L->m, L->b, FE_IR_VOID, "fe_rt_free", args, 1);
|
|
return;
|
|
}
|
|
if (t->kind == FE_TYPE_STRUCT)
|
|
for (i = 0; i < t->field_count; ++i) {
|
|
FeIrPlace p = at;
|
|
if (!needs_release(t->fields[i].type)) continue;
|
|
p.offset += (long)t->fields[i].offset;
|
|
release_at(L, t->fields[i].type, p);
|
|
}
|
|
}
|
|
|
|
/* Settle what a scope owes, most recent first. A `return` in the middle of a
|
|
function still owes everything, so every exit path calls this. */
|
|
void run_deferred(Lower *L, unsigned from)
|
|
{
|
|
unsigned i;
|
|
for (i = L->owed_count; i > from; --i) {
|
|
if (L->owed[i - 1].block) {
|
|
lower_stmt(L, L->owed[i - 1].block);
|
|
continue;
|
|
}
|
|
{
|
|
/* Release only where the value is still here. */
|
|
unsigned live = fe_ir_load(L->m, L->b, FE_IR_I8,
|
|
fe_ir_at_local(L->owed[i - 1].flag, 0));
|
|
FeIrBlock *doit = new_block(L);
|
|
FeIrBlock *skip = new_block(L);
|
|
FeType *t = L->owed[i - 1].type;
|
|
fe_ir_br(L->b, live, doit->id, skip->id);
|
|
L->b = doit;
|
|
release_at(L, t, fe_ir_at_local(L->owed[i - 1].local, 0));
|
|
fe_ir_jmp(L->b, skip->id);
|
|
L->b = skip;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ------------------------------------------------------- wrappers -------- *
|
|
* An optional is a tag and a payload; an error union is an error code and a
|
|
* payload, where a code of zero means there is no error. Both are memory, and
|
|
* both are built the same way: write the tag, then write the value after it.
|
|
* -------------------------------------------------------------------------- */
|
|
|
|
Slot wrap_context(Lower *L, Slot v, FeNode *n)
|
|
{
|
|
FeType *want = n->sem_context;
|
|
unsigned local;
|
|
long payload_at;
|
|
if (!want) return v;
|
|
local = scratch(L, want, "wrapped");
|
|
payload_at = (long)fe_type_payload_offset(want);
|
|
if (want->kind == FE_TYPE_OPTIONAL) {
|
|
if (fe_m7_is_null(n)) {
|
|
/* A payload with a spare representation uses it for "nothing"
|
|
instead of carrying a separate tag. */
|
|
unsigned z = fe_ir_const(L->m, L->b,
|
|
uses_niche(want) ? FE_IR_PTR : FE_IR_I8, 0);
|
|
fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), z,
|
|
uses_niche(want) ? FE_IR_PTR : FE_IR_I8);
|
|
return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(want));
|
|
}
|
|
if (!uses_niche(want)) {
|
|
unsigned one = fe_ir_const(L->m, L->b, FE_IR_I8, 1);
|
|
fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), one, FE_IR_I8);
|
|
}
|
|
store_into(L, fe_ir_at_local(local, payload_at), v, n,
|
|
ir_size(want->elem));
|
|
return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(want));
|
|
}
|
|
if (want->kind == FE_TYPE_ERROR_UNION) {
|
|
FeType *value_type = want->error_value;
|
|
if (n->sem_type && n->sem_type->is_error) {
|
|
fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0),
|
|
as_value(L, v, n), FE_IR_I16);
|
|
} else {
|
|
unsigned zero = fe_ir_const(L->m, L->b, FE_IR_I16, 0);
|
|
fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), zero, FE_IR_I16);
|
|
if (value_type && value_type->kind != FE_TYPE_VOID)
|
|
store_into(L, fe_ir_at_local(local, payload_at), v, n,
|
|
ir_size(value_type));
|
|
}
|
|
return slot_place(fe_ir_at_local(local, 0), FE_IR_MEM, ir_size(want));
|
|
}
|
|
return v;
|
|
}
|
|
|
|
/* The tag of a wrapper that is already in memory. */
|
|
unsigned wrapper_tag(Lower *L, Slot w, const FeType *t, FeNode *n)
|
|
{
|
|
FeIrPlace p;
|
|
if (!w.is_place) { fail(L, "a wrapper with no place", n); return 0; }
|
|
p = w.place;
|
|
if (uses_niche(t)) return fe_ir_load(L->m, L->b, FE_IR_PTR, p);
|
|
return fe_ir_load(L->m, L->b, tag_type(t), p);
|
|
}
|
|
|
|
Slot wrapper_payload(Lower *L, Slot w, const FeType *t)
|
|
{
|
|
FeType *payload = t ? (t->kind == FE_TYPE_ERROR_UNION ? t->error_value
|
|
: t->elem) : 0;
|
|
FeIrPlace p = w.place;
|
|
(void)L;
|
|
p.offset += (long)fe_type_payload_offset(t);
|
|
return slot_place(p, ir_type(payload), ir_size(payload));
|
|
}
|
|
|
|
/* Leave the function with this error code, after the deferred blocks. */
|
|
void return_error(Lower *L, unsigned err, FeNode *n)
|
|
{
|
|
FeType *ret = L->ret_type;
|
|
unsigned local = scratch(L, ret, "failure");
|
|
fe_ir_store(L->m, L->b, fe_ir_at_local(local, 0), err, FE_IR_I16);
|
|
run_deferred(L, 0);
|
|
if (L->fn->returns_by_address) {
|
|
unsigned dst = fe_ir_load(L->m, L->b, FE_IR_PTR,
|
|
fe_ir_at_local(L->ret_local, 0));
|
|
fe_ir_copy(L->m, L->b, fe_ir_at_temp(dst, 0), fe_ir_at_local(local, 0),
|
|
ir_size(ret));
|
|
fe_ir_ret(L->b, 0, 0);
|
|
return;
|
|
}
|
|
fe_ir_ret(L->b, fe_ir_load(L->m, L->b, ir_type(ret),
|
|
fe_ir_at_local(local, 0)), 1);
|
|
(void)n;
|
|
}
|
|
|
|
/* `try e` -- if e failed, leave with its error; otherwise the value. */
|
|
Slot lower_try(Lower *L, FeNode *n)
|
|
{
|
|
FeType *t = n->a ? n->a->sem_type : 0;
|
|
Slot e = lower_expr(L, n->a);
|
|
unsigned err = wrapper_tag(L, e, t, n);
|
|
unsigned zero = fe_ir_const(L->m, L->b, FE_IR_I16, 0);
|
|
unsigned ok = fe_ir_binary(L->m, L->b, FE_IR_EQ, FE_IR_I16, err, zero, 1);
|
|
FeIrBlock *bad = new_block(L);
|
|
FeIrBlock *good = new_block(L);
|
|
fe_ir_br(L->b, ok, good->id, bad->id);
|
|
L->b = bad;
|
|
return_error(L, err, n);
|
|
L->b = good;
|
|
return wrapper_payload(L, e, t);
|
|
}
|
|
|
|
/* `e orelse d` and `e catch d` both mean "the value, or that instead". The
|
|
right-hand side is only evaluated when it is needed, so it is a branch. */
|
|
Slot lower_lazy(Lower *L, FeNode *n, int is_catch)
|
|
{
|
|
FeType *t = n->a ? n->a->sem_type : 0;
|
|
FeType *payload = t ? (is_catch ? t->error_value : t->elem) : 0;
|
|
Slot e;
|
|
unsigned tag;
|
|
unsigned zero;
|
|
unsigned ok;
|
|
unsigned result;
|
|
FeIrBlock *other;
|
|
FeIrBlock *join;
|
|
FeIrBlock *have;
|
|
e = lower_expr(L, n->a);
|
|
tag = wrapper_tag(L, e, t, n);
|
|
zero = fe_ir_const(L->m, L->b, is_catch || uses_niche(t) ? FE_IR_PTR
|
|
: FE_IR_I8, 0);
|
|
/* An error union is fine when its code is zero; an optional is fine when
|
|
its tag is not. */
|
|
ok = fe_ir_binary(L->m, L->b, is_catch ? FE_IR_EQ : FE_IR_NE,
|
|
is_catch ? FE_IR_I16 : (uses_niche(t) ? FE_IR_PTR
|
|
: FE_IR_I8),
|
|
tag, zero, 1);
|
|
result = scratch(L, payload, "result");
|
|
have = new_block(L);
|
|
other = new_block(L);
|
|
join = new_block(L);
|
|
fe_ir_br(L->b, ok, have->id, other->id);
|
|
L->b = have;
|
|
store_into(L, fe_ir_at_local(result, 0), wrapper_payload(L, e, t), n,
|
|
ir_size(payload));
|
|
fe_ir_jmp(L->b, join->id);
|
|
L->b = other;
|
|
if (is_catch && n->c) {
|
|
/* The block form handles the error and must not fall through with a
|
|
value, so whatever it leaves behind is what the checker allowed. */
|
|
lower_stmt(L, n->c);
|
|
} else {
|
|
Slot d = lower_expr(L, n->b);
|
|
store_into(L, fe_ir_at_local(result, 0), d, n->b, ir_size(payload));
|
|
}
|
|
fe_ir_jmp(L->b, join->id);
|
|
L->b = join;
|
|
return slot_place(fe_ir_at_local(result, 0), ir_type(payload),
|
|
ir_size(payload));
|
|
}
|
|
|
|
/* ----------------------------------------------------------- statements --- */
|