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dwarf: add debug info for unions

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This commit is contained in:
Jakub Konka 2022-03-24 23:01:46 +01:00
parent 0d5d353197
commit 1c33ea2c35
1 changed files with 126 additions and 5 deletions
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131
src/link/Dwarf.zig
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@ -83,8 +83,9 @@ pub const abbrev_struct_type = 6;
pub const abbrev_struct_member = 7;
pub const abbrev_enum_type = 8;
pub const abbrev_enum_variant = 9;
pub const abbrev_pad1 = 10;
pub const abbrev_parameter = 11;
pub const abbrev_union_type = 10;
pub const abbrev_pad1 = 11;
pub const abbrev_parameter = 12;
/// The reloc offset for the virtual address of a function in its Line Number Program.
/// Size is a virtual address integer.
@ -452,6 +453,8 @@ pub fn commitDeclDebugInfo(
var dbg_type_arena = std.heap.ArenaAllocator.init(gpa);
defer dbg_type_arena.deinit();
var nested_ref4_relocs = std.ArrayList(u32).init(gpa);
defer nested_ref4_relocs.deinit();
{
// Now we emit the .debug_info types of the Decl. These will count towards the size of
// the buffer, so we have to do it before computing the offset, and we can't perform the actual
@ -463,7 +466,13 @@ pub fn commitDeclDebugInfo(
.target = self.target,
}).?;
value_ptr.off = @intCast(u32, dbg_info_buffer.items.len);
try self.addDbgInfoType(dbg_type_arena.allocator(), ty, dbg_info_buffer, dbg_info_type_relocs);
try self.addDbgInfoType(
dbg_type_arena.allocator(),
ty,
dbg_info_buffer,
dbg_info_type_relocs,
&nested_ref4_relocs,
);
}
}
@ -478,13 +487,27 @@ pub fn commitDeclDebugInfo(
// Now that we have the offset assigned we can finally perform type relocations.
for (dbg_info_type_relocs.values()) |value| {
for (value.relocs.items) |off| {
mem.writeIntLittle(
mem.writeInt(
u32,
dbg_info_buffer.items[off..][0..4],
atom.off + value.off,
target_endian,
);
}
}
// Offsets to positions with known a priori relative displacement values.
// Here, we just need to add the offset of the atom to the read value in the
// relocated cell.
// TODO Should probably generalise this with type relocs.
for (nested_ref4_relocs.items) |off| {
const addend = mem.readInt(u32, dbg_info_buffer.items[off..][0..4], target_endian);
mem.writeInt(
u32,
dbg_info_buffer.items[off..][0..4],
atom.off + addend,
target_endian,
);
}
}
try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
@ -751,8 +774,10 @@ fn addDbgInfoType(
ty: Type,
dbg_info_buffer: *std.ArrayList(u8),
dbg_info_type_relocs: *File.DbgInfoTypeRelocsTable,
nested_ref4_relocs: *std.ArrayList(u32),
) error{OutOfMemory}!void {
const target = self.target;
const target_endian = self.target.cpu.arch.endian();
var relocs = std.ArrayList(struct { ty: Type, reloc: u32 }).init(arena);
switch (ty.zigTypeTag()) {
@ -962,7 +987,6 @@ fn addDbgInfoType(
.enum_numbered => ty.castTag(.enum_numbered).?.data.values,
else => unreachable,
};
const target_endian = self.target.cpu.arch.endian();
for (fields.keys()) |field_name, field_i| {
// DW.AT.enumerator
try dbg_info_buffer.ensureUnusedCapacity(field_name.len + 2 + @sizeOf(u64));
@ -983,6 +1007,94 @@ fn addDbgInfoType(
// DW.AT.enumeration_type delimit children
try dbg_info_buffer.append(0);
},
.Union => {
const layout = ty.unionGetLayout(target);
const union_obj = ty.cast(Type.Payload.Union).?.data;
const payload_offset = if (layout.tag_align >= layout.payload_align) layout.tag_size else 0;
const tag_offset = if (layout.tag_align >= layout.payload_align) 0 else layout.payload_size;
const is_tagged = layout.tag_size > 0;
const union_name = try ty.nameAllocArena(arena, target);
// TODO this is temporary to match current state of unions in Zig - we don't yet have
// safety checks implemented meaning the implicit tag is not yet stored and generated
// for untagged unions.
if (is_tagged) {
// DW.AT.structure_type
try dbg_info_buffer.append(abbrev_struct_type);
// DW.AT.byte_size, DW.FORM.sdata
try leb128.writeULEB128(dbg_info_buffer.writer(), layout.abi_size);
// DW.AT.name, DW.FORM.string
try dbg_info_buffer.ensureUnusedCapacity(union_name.len + 1);
dbg_info_buffer.appendSliceAssumeCapacity(union_name);
dbg_info_buffer.appendAssumeCapacity(0);
// DW.AT.member
try dbg_info_buffer.ensureUnusedCapacity(9);
dbg_info_buffer.appendAssumeCapacity(abbrev_struct_member);
// DW.AT.name, DW.FORM.string
dbg_info_buffer.appendSliceAssumeCapacity("payload");
dbg_info_buffer.appendAssumeCapacity(0);
// DW.AT.type, DW.FORM.ref4
const inner_union_index = dbg_info_buffer.items.len;
try dbg_info_buffer.ensureUnusedCapacity(4);
mem.writeInt(
u32,
dbg_info_buffer.addManyAsArrayAssumeCapacity(4),
@intCast(u32, inner_union_index + 5),
target_endian,
);
try nested_ref4_relocs.append(@intCast(u32, inner_union_index));
// DW.AT.data_member_location, DW.FORM.sdata
try leb128.writeULEB128(dbg_info_buffer.writer(), payload_offset);
}
// DW.AT.union_type
try dbg_info_buffer.append(abbrev_union_type);
// DW.AT.byte_size, DW.FORM.sdata,
try leb128.writeULEB128(dbg_info_buffer.writer(), layout.payload_size);
// DW.AT.name, DW.FORM.string
if (is_tagged) {
try dbg_info_buffer.writer().print("AnonUnion\x00", .{});
} else {
try dbg_info_buffer.writer().print("{s}\x00", .{union_name});
}
const fields = ty.unionFields();
for (fields.keys()) |field_name| {
const field = fields.get(field_name).?;
if (!field.ty.hasRuntimeBits()) continue;
// DW.AT.member
try dbg_info_buffer.append(abbrev_struct_member);
// DW.AT.name, DW.FORM.string
try dbg_info_buffer.writer().print("{s}\x00", .{field_name});
// DW.AT.type, DW.FORM.ref4
const index = dbg_info_buffer.items.len;
try dbg_info_buffer.resize(index + 4);
try relocs.append(.{ .ty = field.ty, .reloc = @intCast(u32, index) });
// DW.AT.data_member_location, DW.FORM.sdata
try dbg_info_buffer.append(0);
}
// DW.AT.union_type delimit children
try dbg_info_buffer.append(0);
if (is_tagged) {
// DW.AT.member
try dbg_info_buffer.ensureUnusedCapacity(5);
dbg_info_buffer.appendAssumeCapacity(abbrev_struct_member);
// DW.AT.name, DW.FORM.string
dbg_info_buffer.appendSliceAssumeCapacity("tag");
dbg_info_buffer.appendAssumeCapacity(0);
// DW.AT.type, DW.FORM.ref4
const index = dbg_info_buffer.items.len;
try dbg_info_buffer.resize(index + 4);
try relocs.append(.{ .ty = union_obj.tag_ty, .reloc = @intCast(u32, index) });
// DW.AT.data_member_location, DW.FORM.sdata
try leb128.writeULEB128(dbg_info_buffer.writer(), tag_offset);
// DW.AT.structure_type delimit children
try dbg_info_buffer.append(0);
}
},
else => {
log.debug("TODO implement .debug_info for type '{}'", .{ty.fmtDebug()});
try dbg_info_buffer.append(abbrev_pad1);
@ -1089,6 +1201,15 @@ pub fn writeDbgAbbrev(self: *Dwarf, file: *File) !void {
DW.FORM.data8,
0,
0, // table sentinel
abbrev_union_type,
DW.TAG.union_type,
DW.CHILDREN.yes, // header
DW.AT.byte_size,
DW.FORM.sdata,
DW.AT.name,
DW.FORM.string,
0,
0, // table sentinel
abbrev_pad1,
DW.TAG.unspecified_type,
DW.CHILDREN.no, // header