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Merge pull request #11429 from ziglang/stage2-alive-decls

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stage2: fix (recursively) marking decls as alive, and improve DWARF for local vars
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Andrew Kelley 2022-04-14 02:01:16 -04:00 committed by GitHub
commit 59fa548be8
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5 changed files with 218 additions and 46 deletions
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124
src/arch/x86_64/CodeGen.zig
View File

@ -3903,17 +3903,17 @@ fn airDbgVar(self: *Self, inst: Air.Inst.Index) !void {
const pl_op = self.air.instructions.items(.data)[inst].pl_op;
const operand = pl_op.operand;
const ty = self.air.typeOf(operand);
const mcv = try self.resolveInst(operand);
if (!self.liveness.operandDies(inst, 0)) {
const mcv = try self.resolveInst(operand);
const name = self.air.nullTerminatedString(pl_op.payload);
log.debug("airDbgVar: %{d}: {}, {}", .{ inst, ty.fmtDebug(), mcv });
const tag = self.air.instructions.items(.tag)[inst];
switch (tag) {
.dbg_var_ptr => try self.genVarDbgInfo(ty.childType(), mcv, name),
.dbg_var_val => try self.genVarDbgInfo(ty, mcv, name),
else => unreachable,
}
const name = self.air.nullTerminatedString(pl_op.payload);
const tag = self.air.instructions.items(.tag)[inst];
switch (tag) {
.dbg_var_ptr => try self.genVarDbgInfo(tag, ty.childType(), mcv, name),
.dbg_var_val => try self.genVarDbgInfo(tag, ty, mcv, name),
else => unreachable,
}
return self.finishAir(inst, .dead, .{ operand, .none, .none });
@ -3921,36 +3921,27 @@ fn airDbgVar(self: *Self, inst: Air.Inst.Index) !void {
fn genVarDbgInfo(
self: *Self,
tag: Air.Inst.Tag,
ty: Type,
mcv: MCValue,
name: [:0]const u8,
) !void {
const name_with_null = name.ptr[0 .. name.len + 1];
switch (mcv) {
.register => |reg| {
switch (self.debug_output) {
.dwarf => |dw| {
const dbg_info = &dw.dbg_info;
try dbg_info.ensureUnusedCapacity(3);
dbg_info.appendAssumeCapacity(@enumToInt(link.File.Dwarf.AbbrevKind.variable));
switch (self.debug_output) {
.dwarf => |dw| {
const dbg_info = &dw.dbg_info;
try dbg_info.append(@enumToInt(link.File.Dwarf.AbbrevKind.variable));
switch (mcv) {
.register => |reg| {
try dbg_info.ensureUnusedCapacity(2);
dbg_info.appendSliceAssumeCapacity(&[2]u8{ // DW.AT.location, DW.FORM.exprloc
1, // ULEB128 dwarf expression length
reg.dwarfLocOp(),
});
try dbg_info.ensureUnusedCapacity(5 + name_with_null.len);
try self.addDbgInfoTypeReloc(ty); // DW.AT.type, DW.FORM.ref4
dbg_info.appendSliceAssumeCapacity(name_with_null); // DW.AT.name, DW.FORM.string
},
.plan9 => {},
.none => {},
}
},
.ptr_stack_offset, .stack_offset => |off| {
switch (self.debug_output) {
.dwarf => |dw| {
const dbg_info = &dw.dbg_info;
try dbg_info.ensureUnusedCapacity(8);
dbg_info.appendAssumeCapacity(@enumToInt(link.File.Dwarf.AbbrevKind.variable));
.ptr_stack_offset, .stack_offset => |off| {
try dbg_info.ensureUnusedCapacity(7);
const fixup = dbg_info.items.len;
dbg_info.appendSliceAssumeCapacity(&[2]u8{ // DW.AT.location, DW.FORM.exprloc
1, // we will backpatch it after we encode the displacement in LEB128
@ -3958,18 +3949,54 @@ fn genVarDbgInfo(
});
leb128.writeILEB128(dbg_info.writer(), -off) catch unreachable;
dbg_info.items[fixup] += @intCast(u8, dbg_info.items.len - fixup - 2);
try dbg_info.ensureUnusedCapacity(5 + name_with_null.len);
try self.addDbgInfoTypeReloc(ty); // DW.AT.type, DW.FORM.ref4
dbg_info.appendSliceAssumeCapacity(name_with_null); // DW.AT.name, DW.FORM.string
},
.plan9 => {},
.none => {},
.memory, .got_load, .direct_load => {
const endian = self.target.cpu.arch.endian();
const ptr_width = @intCast(u8, @divExact(self.target.cpu.arch.ptrBitWidth(), 8));
const is_ptr = switch (tag) {
.dbg_var_ptr => true,
.dbg_var_val => false,
else => unreachable,
};
try dbg_info.ensureUnusedCapacity(2 + ptr_width);
dbg_info.appendSliceAssumeCapacity(&[2]u8{ // DW.AT.location, DW.FORM.exprloc
1 + ptr_width + @boolToInt(is_ptr),
DW.OP.addr, // literal address
});
const offset = @intCast(u32, dbg_info.items.len);
const addr = switch (mcv) {
.memory => |addr| addr,
else => 0,
};
switch (ptr_width) {
0...4 => {
try dbg_info.writer().writeInt(u32, @intCast(u32, addr), endian);
},
5...8 => {
try dbg_info.writer().writeInt(u64, addr, endian);
},
else => unreachable,
}
if (is_ptr) {
// We need deref the address as we point to the value via GOT entry.
try dbg_info.append(DW.OP.deref);
}
switch (mcv) {
.got_load, .direct_load => |index| try dw.addExprlocReloc(index, offset, is_ptr),
else => {},
}
},
else => {
log.debug("TODO generate debug info for {}", .{mcv});
},
}
try dbg_info.ensureUnusedCapacity(5 + name_with_null.len);
try self.addDbgInfoTypeReloc(ty); // DW.AT.type, DW.FORM.ref4
dbg_info.appendSliceAssumeCapacity(name_with_null); // DW.AT.name, DW.FORM.string
},
else => {
log.debug("TODO generate debug info for {}", .{mcv});
},
.plan9 => {},
.none => {},
}
}
@ -6089,6 +6116,7 @@ fn limitImmediateType(self: *Self, operand: Air.Inst.Ref, comptime T: type) !MCV
}
fn lowerDeclRef(self: *Self, tv: TypedValue, decl: *Module.Decl) InnerError!MCValue {
log.debug("lowerDeclRef: ty = {}, val = {}", .{ tv.ty.fmtDebug(), tv.val.fmtDebug() });
const ptr_bits = self.target.cpu.arch.ptrBitWidth();
const ptr_bytes: u64 = @divExact(ptr_bits, 8);
@ -6100,7 +6128,8 @@ fn lowerDeclRef(self: *Self, tv: TypedValue, decl: *Module.Decl) InnerError!MCVa
}
}
decl.alive = true;
decl.markAlive();
if (self.bin_file.cast(link.File.Elf)) |elf_file| {
const got = &elf_file.program_headers.items[elf_file.phdr_got_index.?];
const got_addr = got.p_vaddr + decl.link.elf.offset_table_index * ptr_bytes;
@ -6120,8 +6149,6 @@ fn lowerDeclRef(self: *Self, tv: TypedValue, decl: *Module.Decl) InnerError!MCVa
} else {
return self.fail("TODO codegen non-ELF const Decl pointer", .{});
}
_ = tv;
}
fn lowerUnnamedConst(self: *Self, tv: TypedValue) InnerError!MCValue {
@ -6144,6 +6171,7 @@ fn lowerUnnamedConst(self: *Self, tv: TypedValue) InnerError!MCValue {
}
fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
log.debug("genTypedValue: ty = {}, val = {}", .{ typed_value.ty.fmtDebug(), typed_value.val.fmtDebug() });
if (typed_value.val.isUndef())
return MCValue{ .undef = {} };
const ptr_bits = self.target.cpu.arch.ptrBitWidth();
@ -6181,8 +6209,6 @@ fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
.Bool => {
return MCValue{ .immediate = @boolToInt(typed_value.val.toBool()) };
},
.ComptimeInt => unreachable, // semantic analysis prevents this
.ComptimeFloat => unreachable, // semantic analysis prevents this
.Optional => {
if (typed_value.ty.isPtrLikeOptional()) {
if (typed_value.val.isNull())
@ -6243,6 +6269,18 @@ fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
}
}
},
.ComptimeInt => unreachable,
.ComptimeFloat => unreachable,
.Type => unreachable,
.EnumLiteral => unreachable,
.Void => unreachable,
.NoReturn => unreachable,
.Undefined => unreachable,
.Null => unreachable,
.BoundFn => unreachable,
.Opaque => unreachable,
else => {},
}

2
src/codegen.zig
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@ -203,7 +203,6 @@ pub fn generateSymbol(
},
.Array => switch (typed_value.val.tag()) {
.bytes => {
// TODO populate .debug_info for the array
const payload = typed_value.val.castTag(.bytes).?;
const len = @intCast(usize, typed_value.ty.arrayLenIncludingSentinel());
// The bytes payload already includes the sentinel, if any
@ -212,7 +211,6 @@ pub fn generateSymbol(
return Result{ .appended = {} };
},
.aggregate => {
// TODO populate .debug_info for the array
const elem_vals = typed_value.val.castTag(.aggregate).?.data;
const elem_ty = typed_value.ty.elemType();
const len = @intCast(usize, typed_value.ty.arrayLenIncludingSentinel());

78
src/link/Dwarf.zig
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@ -79,6 +79,7 @@ pub const DeclState = struct {
std.hash_map.default_max_load_percentage,
) = .{},
abbrev_relocs: std.ArrayListUnmanaged(AbbrevRelocation) = .{},
exprloc_relocs: std.ArrayListUnmanaged(ExprlocRelocation) = .{},
fn init(gpa: Allocator, target: std.Target) DeclState {
return .{
@ -97,6 +98,16 @@ pub const DeclState = struct {
self.abbrev_table.deinit(self.gpa);
self.abbrev_resolver.deinit(self.gpa);
self.abbrev_relocs.deinit(self.gpa);
self.exprloc_relocs.deinit(self.gpa);
}
pub fn addExprlocReloc(self: *DeclState, target: u32, offset: u32, is_ptr: bool) !void {
log.debug("{x}: target sym @{d}, via GOT {}", .{ offset, target, is_ptr });
try self.exprloc_relocs.append(self.gpa, .{
.@"type" = if (is_ptr) .got_load else .direct_load,
.target = target,
.offset = offset,
});
}
pub fn addTypeReloc(
@ -270,6 +281,27 @@ pub const DeclState = struct {
try self.addTypeReloc(atom, ty.childType(), @intCast(u32, index), null);
}
},
.Array => {
// DW.AT.array_type
try dbg_info_buffer.append(@enumToInt(AbbrevKind.array_type));
// DW.AT.name, DW.FORM.string
try dbg_info_buffer.writer().print("{}\x00", .{ty.fmt(target)});
// DW.AT.type, DW.FORM.ref4
var index = dbg_info_buffer.items.len;
try dbg_info_buffer.resize(index + 4);
try self.addTypeReloc(atom, ty.childType(), @intCast(u32, index), null);
// DW.AT.subrange_type
try dbg_info_buffer.append(@enumToInt(AbbrevKind.array_dim));
// DW.AT.type, DW.FORM.ref4
index = dbg_info_buffer.items.len;
try dbg_info_buffer.resize(index + 4);
try self.addTypeReloc(atom, Type.usize, @intCast(u32, index), null);
// DW.AT.count, DW.FORM.udata
const len = ty.arrayLenIncludingSentinel();
try leb128.writeULEB128(dbg_info_buffer.writer(), len);
// DW.AT.array_type delimit children
try dbg_info_buffer.append(0);
},
.Struct => blk: {
// DW.AT.structure_type
try dbg_info_buffer.append(@enumToInt(AbbrevKind.struct_type));
@ -528,6 +560,18 @@ pub const AbbrevRelocation = struct {
addend: u32,
};
pub const ExprlocRelocation = struct {
/// Type of the relocation: direct load ref, or GOT load ref (via GOT table)
@"type": enum {
direct_load,
got_load,
},
/// Index of the target in the linker's locals symbol table.
target: u32,
/// Offset within the debug info buffer where to patch up the address value.
offset: u32,
};
pub const SrcFn = struct {
/// Offset from the beginning of the Debug Line Program header that contains this function.
off: u32,
@ -564,6 +608,8 @@ pub const AbbrevKind = enum(u8) {
pad1,
parameter,
variable,
array_type,
array_dim,
};
/// The reloc offset for the virtual address of a function in its Line Number Program.
@ -986,6 +1032,26 @@ pub fn commitDeclState(
}
}
while (decl_state.exprloc_relocs.popOrNull()) |reloc| {
switch (self.tag) {
.macho => {
const macho_file = file.cast(File.MachO).?;
const d_sym = &macho_file.d_sym.?;
try d_sym.relocs.append(d_sym.base.base.allocator, .{
.@"type" = switch (reloc.@"type") {
.direct_load => .direct_load,
.got_load => .got_load,
},
.target = reloc.target,
.offset = reloc.offset + atom.off,
.addend = 0,
.prev_vaddr = 0,
});
},
else => unreachable,
}
}
try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
}
@ -1357,6 +1423,18 @@ pub fn writeDbgAbbrev(self: *Dwarf, file: *File) !void {
DW.AT.name, DW.FORM.string,
0,
0, // table sentinel
@enumToInt(AbbrevKind.array_type),
DW.TAG.array_type, DW.CHILDREN.yes, // header
DW.AT.name, DW.FORM.string,
DW.AT.type, DW.FORM.ref4,
0,
0, // table sentinel
@enumToInt(AbbrevKind.array_dim),
DW.TAG.subrange_type, DW.CHILDREN.no, // header
DW.AT.type, DW.FORM.ref4,
DW.AT.count, DW.FORM.udata,
0,
0, // table sentinel
0,
0,
0, // section sentinel

8
src/link/MachO.zig
View File

@ -3472,6 +3472,9 @@ pub fn closeFiles(self: MachO) void {
for (self.dylibs.items) |dylib| {
dylib.file.close();
}
if (self.d_sym) |ds| {
ds.file.close();
}
}
fn freeAtom(self: *MachO, atom: *Atom, match: MatchingSection, owns_atom: bool) void {
@ -4274,6 +4277,11 @@ pub fn freeDecl(self: *MachO, decl: *Module.Decl) void {
self.got_entries_free_list.append(self.base.allocator, @intCast(u32, got_index)) catch {};
self.got_entries.items[got_index] = .{ .target = .{ .local = 0 }, .atom = undefined };
_ = self.got_entries_table.swapRemove(.{ .local = decl.link.macho.local_sym_index });
if (self.d_sym) |*d_sym| {
d_sym.swapRemoveRelocs(decl.link.macho.local_sym_index);
}
log.debug(" adding GOT index {d} to free list (target local@{d})", .{
got_index,
decl.link.macho.local_sym_index,

52
src/link/MachO/DebugSymbols.zig
View File

@ -59,6 +59,19 @@ debug_aranges_section_dirty: bool = false,
debug_info_header_dirty: bool = false,
debug_line_header_dirty: bool = false,
relocs: std.ArrayListUnmanaged(Reloc) = .{},
pub const Reloc = struct {
@"type": enum {
direct_load,
got_load,
},
target: u32,
offset: u64,
addend: u32,
prev_vaddr: u64,
};
/// You must call this function *after* `MachO.populateMissingMetadata()`
/// has been called to get a viable debug symbols output.
pub fn populateMissingMetadata(self: *DebugSymbols, allocator: Allocator) !void {
@ -254,6 +267,30 @@ pub fn flushModule(self: *DebugSymbols, allocator: Allocator, options: link.Opti
// Zig source code.
const module = options.module orelse return error.LinkingWithoutZigSourceUnimplemented;
for (self.relocs.items) |*reloc| {
const sym = switch (reloc.@"type") {
.direct_load => self.base.locals.items[reloc.target],
.got_load => blk: {
const got_index = self.base.got_entries_table.get(.{ .local = reloc.target }).?;
const got_entry = self.base.got_entries.items[got_index];
break :blk self.base.locals.items[got_entry.atom.local_sym_index];
},
};
if (sym.n_value == reloc.prev_vaddr) continue;
const seg = &self.load_commands.items[self.dwarf_segment_cmd_index.?].segment;
const sect = &seg.sections.items[self.debug_info_section_index.?];
const file_offset = sect.offset + reloc.offset;
log.debug("resolving relocation: {d}@{x} ('{s}') at offset {x}", .{
reloc.target,
sym.n_value,
self.base.getString(sym.n_strx),
file_offset,
});
try self.file.pwriteAll(mem.asBytes(&sym.n_value), file_offset);
reloc.prev_vaddr = sym.n_value;
}
if (self.debug_abbrev_section_dirty) {
try self.dwarf.writeDbgAbbrev(&self.base.base);
self.load_commands_dirty = true;
@ -330,7 +367,20 @@ pub fn deinit(self: *DebugSymbols, allocator: Allocator) void {
}
self.load_commands.deinit(allocator);
self.dwarf.deinit();
self.file.close();
self.relocs.deinit(allocator);
}
pub fn swapRemoveRelocs(self: *DebugSymbols, target: u32) void {
// TODO re-implement using a hashmap with free lists
var last_index: usize = 0;
while (last_index < self.relocs.items.len) {
const reloc = self.relocs.items[last_index];
if (reloc.target == target) {
_ = self.relocs.swapRemove(last_index);
} else {
last_index += 1;
}
}
}
fn copySegmentCommand(