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Allow transmute to be constant for integers of the same internal endianness

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gingerBill
2022-10-19 16:59:38 +01:00
parent 765969e6a3
commit 098f51aa80
2 changed files with 52 additions and 11 deletions
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61
src/check_expr.cpp
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@@ -2916,7 +2916,12 @@ bool check_transmute(CheckerContext *c, Ast *node, Operand *o, Type *t) {
// return false;
// }
if (is_type_untyped(o->type)) {
Type *src_t = o->type;
Type *dst_t = t;
Type *src_bt = base_type(src_t);
Type *dst_bt = base_type(dst_t);
if (is_type_untyped(src_t)) {
gbString expr_str = expr_to_string(o->expr);
error(o->expr, "Cannot transmute untyped expression: '%s'", expr_str);
gb_string_free(expr_str);
@@ -2925,7 +2930,6 @@ bool check_transmute(CheckerContext *c, Ast *node, Operand *o, Type *t) {
return false;
}
Type *dst_bt = base_type(t);
if (dst_bt == nullptr || dst_bt == t_invalid) {
GB_ASSERT(global_error_collector.count != 0);
@@ -2934,21 +2938,21 @@ bool check_transmute(CheckerContext *c, Ast *node, Operand *o, Type *t) {
return false;
}
Type *src_bt = base_type(o->type);
if (src_bt == nullptr || src_bt == t_invalid) {
// NOTE(bill): this should be an error
GB_ASSERT(global_error_collector.count != 0);
o->mode = Addressing_Value;
o->expr = node;
o->type = t;
o->type = dst_t;
return true;
}
i64 srcz = type_size_of(o->type);
i64 dstz = type_size_of(t);
i64 srcz = type_size_of(src_t);
i64 dstz = type_size_of(dst_t);
if (srcz != dstz) {
gbString expr_str = expr_to_string(o->expr);
gbString type_str = type_to_string(t);
gbString type_str = type_to_string(dst_t);
error(o->expr, "Cannot transmute '%s' to '%s', %lld vs %lld bytes", expr_str, type_str, srcz, dstz);
gb_string_free(type_str);
gb_string_free(expr_str);
@@ -2958,16 +2962,53 @@ bool check_transmute(CheckerContext *c, Ast *node, Operand *o, Type *t) {
}
if (build_context.vet_extra) {
if (are_types_identical(o->type, t)) {
gbString str = type_to_string(t);
if (are_types_identical(o->type, dst_t)) {
gbString str = type_to_string(dst_t);
warning(o->expr, "Unneeded transmute to the same type '%s'", str);
gb_string_free(str);
}
}
o->expr = node;
o->type = dst_t;
if (o->mode == Addressing_Constant) {
if (are_types_identical(src_bt, dst_bt)) {
return true;
}
if (is_type_integer(src_t) && is_type_integer(dst_t)) {
if (types_have_same_internal_endian(src_t, dst_t)) {
ExactValue src_v = exact_value_to_integer(o->value);
GB_ASSERT(src_v.kind == ExactValue_Integer);
BigInt v = src_v.value_integer;
BigInt smax = {};
BigInt umax = {};
big_int_from_u64(&smax, 0);
big_int_not(&smax, &smax, cast(i32)(srcz*8 - 1), false);
big_int_from_u64(&umax, 1);
BigInt sz_in_bits = big_int_make_i64(srcz*8);
big_int_shl_eq(&umax, &sz_in_bits);
if (is_type_unsigned(src_t) && !is_type_unsigned(dst_t)) {
if (big_int_cmp(&v, &smax) >= 0) {
big_int_sub_eq(&v, &umax);
}
} else if (!is_type_unsigned(src_t) && is_type_unsigned(dst_t)) {
if (big_int_is_neg(&v)) {
big_int_add_eq(&v, &umax);
}
}
o->value.kind = ExactValue_Integer;
o->value.value_integer = v;
return true;
}
}
}
o->mode = Addressing_Value;
o->type = t;
o->value = {};
return true;
}