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(WIP) translate-c: handle bitfield #14068

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(WIP) translate-c: handle bitfield #14068

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69 changes: 54 additions & 15 deletions src/translate_c.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -1071,6 +1071,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
if (!toplevel) name = try bs.makeMangledName(c, name);
try c.decl_table.putNoClobber(c.gpa, @ptrToInt(record_decl.getCanonicalDecl()), name);

var record_layout: ast.Payload.RecordLayout = .@"extern";
const is_pub = toplevel and !is_unnamed;
const init_node = blk: {
const record_def = record_decl.getDefinition() orelse {
Expand All @@ -1096,12 +1097,6 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
const field_loc = field_decl.getLocation();
const field_qt = field_decl.getType();

if (field_decl.isBitField()) {
try c.opaque_demotes.put(c.gpa, @ptrToInt(record_decl.getCanonicalDecl()), {});
try warn(c, scope, field_loc, "{s} demoted to opaque type - has bitfield", .{container_kind_name});
break :blk Tag.opaque_literal.init();
}

var is_anon = false;
var field_name = try c.str(@ptrCast(*const clang.NamedDecl, field_decl).getName_bytes_begin());
if (field_decl.isAnonymousStructOrUnion() or field_name.len == 0) {
Expand All @@ -1122,14 +1117,26 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
try functions.append(flexible_array_fn);
continue;
}
const field_type = transQualType(c, scope, field_qt, field_loc) catch |err| switch (err) {
error.UnsupportedType => {
try c.opaque_demotes.put(c.gpa, @ptrToInt(record_decl.getCanonicalDecl()), {});
try warn(c, scope, record_loc, "{s} demoted to opaque type - unable to translate type of field {s}", .{ container_kind_name, field_name });
break :blk Tag.opaque_literal.init();
},
else => |e| return e,
};

if (field_decl.isBitField()) record_layout = .@"packed";
const field_type = if (field_decl.isBitField())
transQualTypeBitField(c, scope, field_qt, field_loc) catch |err| switch (err) {
error.UnsupportedType => {
try c.opaque_demotes.put(c.gpa, @ptrToInt(record_decl.getCanonicalDecl()), {});
try warn(c, scope, field_loc, "{s} demoted to opaque type - has bitfield '{s}'' with invalid type", .{container_kind_name, field_name});
break :blk Tag.opaque_literal.init();
},
else => |e| return e,
}
else
transQualType(c, scope, field_qt, field_loc) catch |err| switch (err) {
error.UnsupportedType => {
try c.opaque_demotes.put(c.gpa, @ptrToInt(record_decl.getCanonicalDecl()), {});
try warn(c, scope, record_loc, "{s} demoted to opaque type - unable to translate type of field {s}", .{ container_kind_name, field_name });
break :blk Tag.opaque_literal.init();
},
else => |e| return e,
};

const alignment = if (has_flexible_array and field_decl.getFieldIndex() == 0)
@intCast(c_uint, record_alignment)
Expand All @@ -1151,7 +1158,7 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
record_payload.* = .{
.base = .{ .tag = ([2]Tag{ .@"struct", .@"union" })[@boolToInt(is_union)] },
.data = .{
.layout = .@"extern",
.layout = record_layout,
.fields = try c.arena.dupe(ast.Payload.Record.Field, fields.items),
.functions = try c.arena.dupe(Node, functions.items),
.variables = &.{},
Expand Down Expand Up @@ -4202,6 +4209,38 @@ fn transQualType(c: *Context, scope: *Scope, qt: clang.QualType, source_loc: cla
return transType(c, scope, qt.getTypePtr(), source_loc);
}

/// get the size of bitfield in BITS
fn bitFieldSize(qt: clang.QualType) usize {
return std.debug.panic("TODO: hook up clang to get bitsize of field: {}", .{qt});
}

/// (according to C99 https://en.cppreference.com/w/c/language/bit_field)
/// implementation-defined detail:
/// `int` is treated as `signed int`
fn transQualTypeBitField(c: *Context, scope: *Scope, qt: clang.QualType, source_loc: clang.SourceLocation) TypeError!Node {
_ = scope;
const ty = qt.getTypePtr();
switch (ty.getTypeClass()) {
.Builtin => {
const builtin_ty = @ptrCast(*const clang.BuiltinType, ty);
return Tag.type.create(c.arena, switch (builtin_ty.getKind()) {
.Bool => "bool",
.UInt => blk: {
break :blk try std.fmt.allocPrint("u{}", .{bitFieldSize(qt)});
},
.Int => blk: {
break :blk try std.fmt.allocPrint("i{}", .{bitFieldSize(qt)});
},
else => return fail(c, error.UnsupportedType, source_loc, "unsupported builtin type", .{}),
});
},
else => {
const type_name = try c.str(ty.getTypeClassName());
return fail(c, error.UnsupportedType, source_loc, "unsupported type: '{s}'", .{type_name});
},
}
}

/// Produces a Zig AST node by translating a Clang QualType, respecting the width, but modifying the signed-ness.
/// Asserts the type is an integer.
fn transQualTypeIntWidthOf(c: *Context, ty: clang.QualType, is_signed: bool) TypeError!Node {
Expand Down
4 changes: 3 additions & 1 deletion src/translate_c/ast.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -562,10 +562,12 @@ pub const Payload = struct {
type: Node,
};

pub const RecordLayout = enum { @"packed", @"extern", none };

pub const Record = struct {
base: Payload,
data: struct {
layout: enum { @"packed", @"extern", none },
layout: RecordLayout,
fields: []Field,
functions: []Node,
variables: []Node,
Expand Down