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AstGen: implement comptime struct fields

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This commit is contained in:
Andrew Kelley 2021-04-29 16:57:13 -07:00
parent fb4cb430e0
commit 55e86b724a
5 changed files with 50 additions and 19 deletions
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4
BRANCH_TODO
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@ -52,6 +52,10 @@
- not sure why this happened, it's stage1 code??
- search the behavior test diff for "TODO"
* memory efficiency: add another representation for structs which use
natural alignment for fields and do not have any comptime fields. this
will save 16 bytes per struct field in the compilation.
fn getAnonTypeName(mod: *Module, scope: *Scope, base_token: std.zig.ast.TokenIndex) ![]u8 {
// TODO add namespaces, generic function signatrues
const tree = scope.tree();

27
src/AstGen.zig
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@ -3220,7 +3220,9 @@ fn structDeclInner(
var fields_data = ArrayListUnmanaged(u32){};
defer fields_data.deinit(gpa);
// We only need this if there are greater than 16 fields.
const bits_per_field = 4;
const fields_per_u32 = 32 / bits_per_field;
// We only need this if there are greater than fields_per_u32 fields.
var bit_bag = ArrayListUnmanaged(u32){};
defer bit_bag.deinit(gpa);
@ -3307,13 +3309,10 @@ fn structDeclInner(
},
else => unreachable,
};
if (field_index % 16 == 0 and field_index != 0) {
if (field_index % fields_per_u32 == 0 and field_index != 0) {
try bit_bag.append(gpa, cur_bit_bag);
cur_bit_bag = 0;
}
if (member.comptime_token) |comptime_token| {
return astgen.failTok(comptime_token, "TODO implement comptime struct fields", .{});
}
try fields_data.ensureUnusedCapacity(gpa, 4);
const field_name = try gz.identAsString(member.ast.name_token);
@ -3324,9 +3323,13 @@ fn structDeclInner(
const have_align = member.ast.align_expr != 0;
const have_value = member.ast.value_expr != 0;
cur_bit_bag = (cur_bit_bag >> 2) |
(@as(u32, @boolToInt(have_align)) << 30) |
(@as(u32, @boolToInt(have_value)) << 31);
const is_comptime = member.comptime_token != null;
const unused = false;
cur_bit_bag = (cur_bit_bag >> bits_per_field) |
(@as(u32, @boolToInt(have_align)) << 28) |
(@as(u32, @boolToInt(have_value)) << 29) |
(@as(u32, @boolToInt(is_comptime)) << 30) |
(@as(u32, @boolToInt(unused)) << 31);
if (have_align) {
const align_inst = try expr(&block_scope, &block_scope.base, align_rl, member.ast.align_expr);
@ -3335,14 +3338,16 @@ fn structDeclInner(
if (have_value) {
const default_inst = try expr(&block_scope, &block_scope.base, .{ .ty = field_type }, member.ast.value_expr);
fields_data.appendAssumeCapacity(@enumToInt(default_inst));
} else if (member.comptime_token) |comptime_token| {
return astgen.failTok(comptime_token, "comptime field without default initialization value", .{});
}
field_index += 1;
}
{
const empty_slot_count = 16 - (field_index % 16);
if (empty_slot_count < 16) {
cur_bit_bag >>= @intCast(u5, empty_slot_count * 2);
const empty_slot_count = fields_per_u32 - (field_index % fields_per_u32);
if (empty_slot_count < fields_per_u32) {
cur_bit_bag >>= @intCast(u5, empty_slot_count * bits_per_field);
}
}
{

1
src/Module.zig
View File

@ -471,6 +471,7 @@ pub const Struct = struct {
abi_align: Value,
/// Uses `unreachable_value` to indicate no default.
default_val: Value,
is_comptime: bool,
};
pub fn getFullyQualifiedName(s: *Struct, gpa: *Allocator) ![]u8 {

13
src/Sema.zig
View File

@ -719,14 +719,16 @@ pub fn zirStructDecl(
sema.branch_count = struct_sema.branch_count;
sema.branch_quota = struct_sema.branch_quota;
}
const bit_bags_count = std.math.divCeil(usize, fields_len, 16) catch unreachable;
const bits_per_field = 4;
const fields_per_u32 = 32 / bits_per_field;
const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
const body_end = extra_index + body.len;
extra_index += bit_bags_count;
var bit_bag_index: usize = body_end;
var cur_bit_bag: u32 = undefined;
var field_i: u32 = 0;
while (field_i < fields_len) : (field_i += 1) {
if (field_i % 16 == 0) {
if (field_i % fields_per_u32 == 0) {
cur_bit_bag = sema.code.extra[bit_bag_index];
bit_bag_index += 1;
}
@ -734,6 +736,12 @@ pub fn zirStructDecl(
cur_bit_bag >>= 1;
const has_default = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
const is_comptime = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
const unused = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
_ = unused;
const field_name_zir = sema.code.nullTerminatedString(sema.code.extra[extra_index]);
extra_index += 1;
@ -753,6 +761,7 @@ pub fn zirStructDecl(
.ty = field_ty,
.abi_align = Value.initTag(.abi_align_default),
.default_val = Value.initTag(.unreachable_value),
.is_comptime = is_comptime,
};
if (has_align) {

24
src/Zir.zig
View File

@ -2387,13 +2387,16 @@ pub const Inst = struct {
/// link_section: Ref, // if corresponding bit is set
/// }
/// 2. inst: Index // for every body_len
/// 3. has_bits: u32 // for every 16 fields
/// - sets of 2 bits:
/// 0b0X: whether corresponding field has an align expression
/// 0bX0: whether corresponding field has a default expression
/// 3. flags: u32 // for every 8 fields
/// - sets of 4 bits:
/// 0b000X: whether corresponding field has an align expression
/// 0b00X0: whether corresponding field has a default expression
/// 0b0X00: whether corresponding field is comptime
/// 0bX000: unused
/// 4. fields: { // for every fields_len
/// field_name: u32,
/// field_type: Ref,
/// - if none, means `anytype`.
/// align: Ref, // if corresponding bit is set
/// default_value: Ref, // if corresponding bit is set
/// }
@ -3394,14 +3397,16 @@ const Writer = struct {
try stream.writeAll("}, {\n");
}
const bit_bags_count = std.math.divCeil(usize, fields_len, 16) catch unreachable;
const bits_per_field = 4;
const fields_per_u32 = 32 / bits_per_field;
const bit_bags_count = std.math.divCeil(usize, fields_len, fields_per_u32) catch unreachable;
const body_end = extra_index;
extra_index += bit_bags_count;
var bit_bag_index: usize = body_end;
var cur_bit_bag: u32 = undefined;
var field_i: u32 = 0;
while (field_i < fields_len) : (field_i += 1) {
if (field_i % 16 == 0) {
if (field_i % fields_per_u32 == 0) {
cur_bit_bag = self.code.extra[bit_bag_index];
bit_bag_index += 1;
}
@ -3409,6 +3414,12 @@ const Writer = struct {
cur_bit_bag >>= 1;
const has_default = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
const is_comptime = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
const unused = @truncate(u1, cur_bit_bag) != 0;
cur_bit_bag >>= 1;
_ = unused;
const field_name = self.code.nullTerminatedString(self.code.extra[extra_index]);
extra_index += 1;
@ -3416,6 +3427,7 @@ const Writer = struct {
extra_index += 1;
try stream.writeByteNTimes(' ', self.indent);
try self.writeFlag(stream, "comptime ", is_comptime);
try stream.print("{}: ", .{std.zig.fmtId(field_name)});
try self.writeInstRef(stream, field_type);