Files
zig/src/link/MachO/DebugSymbols.zig
Andrew Kelley 61b868f9a5 stage2: simplify Decl src_node field
Also fix "previous definition here" error notes to be correct.
2021-04-08 20:37:19 -07:00

1543 lines
66 KiB
Zig

const DebugSymbols = @This();
const std = @import("std");
const assert = std.debug.assert;
const fs = std.fs;
const log = std.log.scoped(.link);
const macho = std.macho;
const mem = std.mem;
const DW = std.dwarf;
const leb = std.leb;
const Allocator = mem.Allocator;
const build_options = @import("build_options");
const trace = @import("../../tracy.zig").trace;
const Module = @import("../../Module.zig");
const Type = @import("../../type.zig").Type;
const link = @import("../../link.zig");
const MachO = @import("../MachO.zig");
const SrcFn = MachO.SrcFn;
const TextBlock = MachO.TextBlock;
const padToIdeal = MachO.padToIdeal;
const makeStaticString = MachO.makeStaticString;
usingnamespace @import("commands.zig");
const page_size: u16 = 0x1000;
base: *MachO,
file: fs.File,
/// Mach header
header: ?macho.mach_header_64 = null,
/// Table of all load commands
load_commands: std.ArrayListUnmanaged(LoadCommand) = .{},
/// __PAGEZERO segment
pagezero_segment_cmd_index: ?u16 = null,
/// __TEXT segment
text_segment_cmd_index: ?u16 = null,
/// __DATA_CONST segment
data_const_segment_cmd_index: ?u16 = null,
/// __DATA segment
data_segment_cmd_index: ?u16 = null,
/// __LINKEDIT segment
linkedit_segment_cmd_index: ?u16 = null,
/// __DWARF segment
dwarf_segment_cmd_index: ?u16 = null,
/// Symbol table
symtab_cmd_index: ?u16 = null,
/// UUID load command
uuid_cmd_index: ?u16 = null,
/// Index into __TEXT,__text section.
text_section_index: ?u16 = null,
linkedit_off: u16 = page_size,
linkedit_size: u16 = page_size,
debug_info_section_index: ?u16 = null,
debug_abbrev_section_index: ?u16 = null,
debug_str_section_index: ?u16 = null,
debug_aranges_section_index: ?u16 = null,
debug_line_section_index: ?u16 = null,
debug_abbrev_table_offset: ?u64 = null,
/// A list of `SrcFn` whose Line Number Programs have surplus capacity.
/// This is the same concept as `text_block_free_list`; see those doc comments.
dbg_line_fn_free_list: std.AutoHashMapUnmanaged(*SrcFn, void) = .{},
dbg_line_fn_first: ?*SrcFn = null,
dbg_line_fn_last: ?*SrcFn = null,
/// A list of `TextBlock` whose corresponding .debug_info tags have surplus capacity.
/// This is the same concept as `text_block_free_list`; see those doc comments.
dbg_info_decl_free_list: std.AutoHashMapUnmanaged(*TextBlock, void) = .{},
dbg_info_decl_first: ?*TextBlock = null,
dbg_info_decl_last: ?*TextBlock = null,
/// Table of debug symbol names aka the debug string table.
debug_string_table: std.ArrayListUnmanaged(u8) = .{},
header_dirty: bool = false,
load_commands_dirty: bool = false,
string_table_dirty: bool = false,
debug_string_table_dirty: bool = false,
debug_abbrev_section_dirty: bool = false,
debug_aranges_section_dirty: bool = false,
debug_info_header_dirty: bool = false,
debug_line_header_dirty: bool = false,
const abbrev_compile_unit = 1;
const abbrev_subprogram = 2;
const abbrev_subprogram_retvoid = 3;
const abbrev_base_type = 4;
const abbrev_pad1 = 5;
const abbrev_parameter = 6;
/// The reloc offset for the virtual address of a function in its Line Number Program.
/// Size is a virtual address integer.
const dbg_line_vaddr_reloc_index = 3;
/// The reloc offset for the virtual address of a function in its .debug_info TAG_subprogram.
/// Size is a virtual address integer.
const dbg_info_low_pc_reloc_index = 1;
const min_nop_size = 2;
/// 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 {
if (self.header == null) {
const base_header = self.base.header.?;
var header: macho.mach_header_64 = undefined;
header.magic = macho.MH_MAGIC_64;
header.cputype = base_header.cputype;
header.cpusubtype = base_header.cpusubtype;
header.filetype = macho.MH_DSYM;
// These will get populated at the end of flushing the results to file.
header.ncmds = 0;
header.sizeofcmds = 0;
header.flags = 0;
header.reserved = 0;
self.header = header;
self.header_dirty = true;
}
if (self.uuid_cmd_index == null) {
const base_cmd = self.base.load_commands.items[self.base.uuid_cmd_index.?];
self.uuid_cmd_index = @intCast(u16, self.load_commands.items.len);
try self.load_commands.append(allocator, base_cmd);
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.symtab_cmd_index == null) {
self.symtab_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.symtab_cmd_index.?].Symtab;
const symtab_size = base_cmd.nsyms * @sizeOf(macho.nlist_64);
const symtab_off = self.findFreeSpaceLinkedit(symtab_size, @sizeOf(macho.nlist_64));
log.debug("found dSym symbol table free space 0x{x} to 0x{x}", .{ symtab_off, symtab_off + symtab_size });
const strtab_off = self.findFreeSpaceLinkedit(base_cmd.strsize, 1);
log.debug("found dSym string table free space 0x{x} to 0x{x}", .{ strtab_off, strtab_off + base_cmd.strsize });
try self.load_commands.append(allocator, .{
.Symtab = .{
.cmd = macho.LC_SYMTAB,
.cmdsize = @sizeOf(macho.symtab_command),
.symoff = @intCast(u32, symtab_off),
.nsyms = base_cmd.nsyms,
.stroff = @intCast(u32, strtab_off),
.strsize = base_cmd.strsize,
},
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.string_table_dirty = true;
}
if (self.pagezero_segment_cmd_index == null) {
self.pagezero_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.pagezero_segment_cmd_index.?].Segment;
const cmd = try self.copySegmentCommand(allocator, base_cmd);
try self.load_commands.append(allocator, .{ .Segment = cmd });
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.text_segment_cmd_index == null) {
self.text_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.text_segment_cmd_index.?].Segment;
const cmd = try self.copySegmentCommand(allocator, base_cmd);
try self.load_commands.append(allocator, .{ .Segment = cmd });
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.data_const_segment_cmd_index == null) outer: {
if (self.base.data_const_segment_cmd_index == null) break :outer; // __DATA_CONST is optional
self.data_const_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.data_const_segment_cmd_index.?].Segment;
const cmd = try self.copySegmentCommand(allocator, base_cmd);
try self.load_commands.append(allocator, .{ .Segment = cmd });
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.data_segment_cmd_index == null) outer: {
if (self.base.data_segment_cmd_index == null) break :outer; // __DATA is optional
self.data_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.data_segment_cmd_index.?].Segment;
const cmd = try self.copySegmentCommand(allocator, base_cmd);
try self.load_commands.append(allocator, .{ .Segment = cmd });
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.linkedit_segment_cmd_index == null) {
self.linkedit_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const base_cmd = self.base.load_commands.items[self.base.linkedit_segment_cmd_index.?].Segment;
var cmd = try self.copySegmentCommand(allocator, base_cmd);
cmd.inner.vmsize = self.linkedit_size;
cmd.inner.fileoff = self.linkedit_off;
cmd.inner.filesize = self.linkedit_size;
try self.load_commands.append(allocator, .{ .Segment = cmd });
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.dwarf_segment_cmd_index == null) {
self.dwarf_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const linkedit = self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const ideal_size: u16 = 200 + 128 + 160 + 250;
const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), page_size);
const off = linkedit.inner.fileoff + linkedit.inner.filesize;
const vmaddr = linkedit.inner.vmaddr + linkedit.inner.vmsize;
log.debug("found dSym __DWARF segment free space 0x{x} to 0x{x}", .{ off, off + needed_size });
try self.load_commands.append(allocator, .{
.Segment = SegmentCommand.empty(.{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__DWARF"),
.vmaddr = vmaddr,
.vmsize = needed_size,
.fileoff = off,
.filesize = needed_size,
.maxprot = 0,
.initprot = 0,
.nsects = 0,
.flags = 0,
}),
});
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.debug_str_section_index == null) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
self.debug_str_section_index = @intCast(u16, dwarf_segment.sections.items.len);
assert(self.debug_string_table.items.len == 0);
try dwarf_segment.addSection(allocator, .{
.sectname = makeStaticString("__debug_str"),
.segname = makeStaticString("__DWARF"),
.addr = dwarf_segment.inner.vmaddr,
.size = @intCast(u32, self.debug_string_table.items.len),
.offset = @intCast(u32, dwarf_segment.inner.fileoff),
.@"align" = 1,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.debug_string_table_dirty = true;
}
if (self.debug_info_section_index == null) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
self.debug_info_section_index = @intCast(u16, dwarf_segment.sections.items.len);
const file_size_hint = 200;
const p_align = 1;
const off = dwarf_segment.findFreeSpace(file_size_hint, p_align, null);
log.debug("found dSym __debug_info free space 0x{x} to 0x{x}", .{ off, off + file_size_hint });
try dwarf_segment.addSection(allocator, .{
.sectname = makeStaticString("__debug_info"),
.segname = makeStaticString("__DWARF"),
.addr = dwarf_segment.inner.vmaddr + off - dwarf_segment.inner.fileoff,
.size = file_size_hint,
.offset = @intCast(u32, off),
.@"align" = p_align,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.debug_info_header_dirty = true;
}
if (self.debug_abbrev_section_index == null) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
self.debug_abbrev_section_index = @intCast(u16, dwarf_segment.sections.items.len);
const file_size_hint = 128;
const p_align = 1;
const off = dwarf_segment.findFreeSpace(file_size_hint, p_align, null);
log.debug("found dSym __debug_abbrev free space 0x{x} to 0x{x}", .{ off, off + file_size_hint });
try dwarf_segment.addSection(allocator, .{
.sectname = makeStaticString("__debug_abbrev"),
.segname = makeStaticString("__DWARF"),
.addr = dwarf_segment.inner.vmaddr + off - dwarf_segment.inner.fileoff,
.size = file_size_hint,
.offset = @intCast(u32, off),
.@"align" = p_align,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.debug_abbrev_section_dirty = true;
}
if (self.debug_aranges_section_index == null) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
self.debug_aranges_section_index = @intCast(u16, dwarf_segment.sections.items.len);
const file_size_hint = 160;
const p_align = 16;
const off = dwarf_segment.findFreeSpace(file_size_hint, p_align, null);
log.debug("found dSym __debug_aranges free space 0x{x} to 0x{x}", .{ off, off + file_size_hint });
try dwarf_segment.addSection(allocator, .{
.sectname = makeStaticString("__debug_aranges"),
.segname = makeStaticString("__DWARF"),
.addr = dwarf_segment.inner.vmaddr + off - dwarf_segment.inner.fileoff,
.size = file_size_hint,
.offset = @intCast(u32, off),
.@"align" = p_align,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.debug_aranges_section_dirty = true;
}
if (self.debug_line_section_index == null) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
self.debug_line_section_index = @intCast(u16, dwarf_segment.sections.items.len);
const file_size_hint = 250;
const p_align = 1;
const off = dwarf_segment.findFreeSpace(file_size_hint, p_align, null);
log.debug("found dSym __debug_line free space 0x{x} to 0x{x}", .{ off, off + file_size_hint });
try dwarf_segment.addSection(allocator, .{
.sectname = makeStaticString("__debug_line"),
.segname = makeStaticString("__DWARF"),
.addr = dwarf_segment.inner.vmaddr + off - dwarf_segment.inner.fileoff,
.size = file_size_hint,
.offset = @intCast(u32, off),
.@"align" = p_align,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.header_dirty = true;
self.load_commands_dirty = true;
self.debug_line_header_dirty = true;
}
}
pub fn flushModule(self: *DebugSymbols, allocator: *Allocator, options: link.Options) !void {
// TODO This linker code currently assumes there is only 1 compilation unit and it corresponds to the
// Zig source code.
const module = options.module orelse return error.LinkingWithoutZigSourceUnimplemented;
const init_len_size: usize = 4;
if (self.debug_abbrev_section_dirty) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_abbrev_sect = &dwarf_segment.sections.items[self.debug_abbrev_section_index.?];
// These are LEB encoded but since the values are all less than 127
// we can simply append these bytes.
const abbrev_buf = [_]u8{
abbrev_compile_unit, DW.TAG_compile_unit, DW.CHILDREN_yes, // header
DW.AT_stmt_list, DW.FORM_sec_offset, // offset
DW.AT_low_pc, DW.FORM_addr,
DW.AT_high_pc, DW.FORM_addr,
DW.AT_name, DW.FORM_strp,
DW.AT_comp_dir, DW.FORM_strp,
DW.AT_producer, DW.FORM_strp,
DW.AT_language, DW.FORM_data2,
0, 0, // table sentinel
abbrev_subprogram, DW.TAG_subprogram, DW.CHILDREN_yes, // header
DW.AT_low_pc, DW.FORM_addr, // start VM address
DW.AT_high_pc, DW.FORM_data4,
DW.AT_type, DW.FORM_ref4,
DW.AT_name, DW.FORM_string,
DW.AT_decl_line, DW.FORM_data4,
DW.AT_decl_file, DW.FORM_data1,
0, 0, // table sentinel
abbrev_subprogram_retvoid,
DW.TAG_subprogram, DW.CHILDREN_yes, // header
DW.AT_low_pc, DW.FORM_addr,
DW.AT_high_pc, DW.FORM_data4,
DW.AT_name, DW.FORM_string,
DW.AT_decl_line, DW.FORM_data4,
DW.AT_decl_file, DW.FORM_data1,
0, 0, // table sentinel
abbrev_base_type, DW.TAG_base_type, DW.CHILDREN_no, // header
DW.AT_encoding, DW.FORM_data1, DW.AT_byte_size,
DW.FORM_data1, DW.AT_name, DW.FORM_string,
0, 0, // table sentinel
abbrev_pad1, DW.TAG_unspecified_type, DW.CHILDREN_no, // header
0, 0, // table sentinel
abbrev_parameter, DW.TAG_formal_parameter, DW.CHILDREN_no, // header
DW.AT_location, DW.FORM_exprloc, DW.AT_type,
DW.FORM_ref4, DW.AT_name, DW.FORM_string,
0, 0, // table sentinel
0, 0, 0, // section sentinel
};
const needed_size = abbrev_buf.len;
const allocated_size = dwarf_segment.allocatedSize(debug_abbrev_sect.offset);
if (needed_size > allocated_size) {
debug_abbrev_sect.size = 0; // free the space
const offset = dwarf_segment.findFreeSpace(needed_size, 1, null);
debug_abbrev_sect.offset = @intCast(u32, offset);
debug_abbrev_sect.addr = dwarf_segment.inner.vmaddr + offset - dwarf_segment.inner.fileoff;
}
debug_abbrev_sect.size = needed_size;
log.debug("__debug_abbrev start=0x{x} end=0x{x}", .{
debug_abbrev_sect.offset,
debug_abbrev_sect.offset + needed_size,
});
const abbrev_offset = 0;
self.debug_abbrev_table_offset = abbrev_offset;
try self.file.pwriteAll(&abbrev_buf, debug_abbrev_sect.offset + abbrev_offset);
self.load_commands_dirty = true;
self.debug_abbrev_section_dirty = false;
}
if (self.debug_info_header_dirty) debug_info: {
// If this value is null it means there is an error in the module;
// leave debug_info_header_dirty=true.
const first_dbg_info_decl = self.dbg_info_decl_first orelse break :debug_info;
const last_dbg_info_decl = self.dbg_info_decl_last.?;
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_info_sect = &dwarf_segment.sections.items[self.debug_info_section_index.?];
var di_buf = std.ArrayList(u8).init(allocator);
defer di_buf.deinit();
// We have a function to compute the upper bound size, because it's needed
// for determining where to put the offset of the first `LinkBlock`.
try di_buf.ensureCapacity(self.dbgInfoNeededHeaderBytes());
// initial length - length of the .debug_info contribution for this compilation unit,
// not including the initial length itself.
// We have to come back and write it later after we know the size.
const after_init_len = di_buf.items.len + init_len_size;
// +1 for the final 0 that ends the compilation unit children.
const dbg_info_end = last_dbg_info_decl.dbg_info_off + last_dbg_info_decl.dbg_info_len + 1;
const init_len = dbg_info_end - after_init_len;
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, init_len));
mem.writeIntLittle(u16, di_buf.addManyAsArrayAssumeCapacity(2), 4); // DWARF version
const abbrev_offset = self.debug_abbrev_table_offset.?;
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, abbrev_offset));
di_buf.appendAssumeCapacity(8); // address size
// Write the form for the compile unit, which must match the abbrev table above.
const name_strp = try self.makeDebugString(allocator, module.root_pkg.root_src_path);
const comp_dir_strp = try self.makeDebugString(allocator, module.root_pkg.root_src_directory.path orelse ".");
const producer_strp = try self.makeDebugString(allocator, link.producer_string);
// Currently only one compilation unit is supported, so the address range is simply
// identical to the main program header virtual address and memory size.
const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const text_section = text_segment.sections.items[self.text_section_index.?];
const low_pc = text_section.addr;
const high_pc = text_section.addr + text_section.size;
di_buf.appendAssumeCapacity(abbrev_compile_unit);
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), 0); // DW.AT_stmt_list, DW.FORM_sec_offset
mem.writeIntLittle(u64, di_buf.addManyAsArrayAssumeCapacity(8), low_pc);
mem.writeIntLittle(u64, di_buf.addManyAsArrayAssumeCapacity(8), high_pc);
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, name_strp));
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, comp_dir_strp));
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, producer_strp));
// We are still waiting on dwarf-std.org to assign DW_LANG_Zig a number:
// http://dwarfstd.org/ShowIssue.php?issue=171115.1
// Until then we say it is C99.
mem.writeIntLittle(u16, di_buf.addManyAsArrayAssumeCapacity(2), DW.LANG_C99);
if (di_buf.items.len > first_dbg_info_decl.dbg_info_off) {
// Move the first N decls to the end to make more padding for the header.
@panic("TODO: handle __debug_info header exceeding its padding");
}
const jmp_amt = first_dbg_info_decl.dbg_info_off - di_buf.items.len;
try self.pwriteDbgInfoNops(0, di_buf.items, jmp_amt, false, debug_info_sect.offset);
self.debug_info_header_dirty = false;
}
if (self.debug_aranges_section_dirty) {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_aranges_sect = &dwarf_segment.sections.items[self.debug_aranges_section_index.?];
const debug_info_sect = dwarf_segment.sections.items[self.debug_info_section_index.?];
var di_buf = std.ArrayList(u8).init(allocator);
defer di_buf.deinit();
// Enough for all the data without resizing. When support for more compilation units
// is added, the size of this section will become more variable.
try di_buf.ensureCapacity(100);
// initial length - length of the .debug_aranges contribution for this compilation unit,
// not including the initial length itself.
// We have to come back and write it later after we know the size.
const init_len_index = di_buf.items.len;
di_buf.items.len += init_len_size;
const after_init_len = di_buf.items.len;
mem.writeIntLittle(u16, di_buf.addManyAsArrayAssumeCapacity(2), 2); // version
// When more than one compilation unit is supported, this will be the offset to it.
// For now it is always at offset 0 in .debug_info.
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), 0); // __debug_info offset
di_buf.appendAssumeCapacity(@sizeOf(u64)); // address_size
di_buf.appendAssumeCapacity(0); // segment_selector_size
const end_header_offset = di_buf.items.len;
const begin_entries_offset = mem.alignForward(end_header_offset, @sizeOf(u64) * 2);
di_buf.appendNTimesAssumeCapacity(0, begin_entries_offset - end_header_offset);
// Currently only one compilation unit is supported, so the address range is simply
// identical to the main program header virtual address and memory size.
const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const text_section = text_segment.sections.items[self.text_section_index.?];
mem.writeIntLittle(u64, di_buf.addManyAsArrayAssumeCapacity(8), text_section.addr);
mem.writeIntLittle(u64, di_buf.addManyAsArrayAssumeCapacity(8), text_section.size);
// Sentinel.
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), 0);
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), 0);
// Go back and populate the initial length.
const init_len = di_buf.items.len - after_init_len;
// initial length - length of the .debug_aranges contribution for this compilation unit,
// not including the initial length itself.
mem.writeIntLittle(u32, di_buf.items[init_len_index..][0..4], @intCast(u32, init_len));
const needed_size = di_buf.items.len;
const allocated_size = dwarf_segment.allocatedSize(debug_aranges_sect.offset);
if (needed_size > allocated_size) {
debug_aranges_sect.size = 0; // free the space
const new_offset = dwarf_segment.findFreeSpace(needed_size, 16, null);
debug_aranges_sect.addr = dwarf_segment.inner.vmaddr + new_offset - dwarf_segment.inner.fileoff;
debug_aranges_sect.offset = @intCast(u32, new_offset);
}
debug_aranges_sect.size = needed_size;
log.debug("__debug_aranges start=0x{x} end=0x{x}", .{
debug_aranges_sect.offset,
debug_aranges_sect.offset + needed_size,
});
try self.file.pwriteAll(di_buf.items, debug_aranges_sect.offset);
self.load_commands_dirty = true;
self.debug_aranges_section_dirty = false;
}
if (self.debug_line_header_dirty) debug_line: {
if (self.dbg_line_fn_first == null) {
break :debug_line; // Error in module; leave debug_line_header_dirty=true.
}
const dbg_line_prg_off = self.getDebugLineProgramOff();
const dbg_line_prg_end = self.getDebugLineProgramEnd();
assert(dbg_line_prg_end != 0);
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_line_sect = &dwarf_segment.sections.items[self.debug_line_section_index.?];
var di_buf = std.ArrayList(u8).init(allocator);
defer di_buf.deinit();
// The size of this header is variable, depending on the number of directories,
// files, and padding. We have a function to compute the upper bound size, however,
// because it's needed for determining where to put the offset of the first `SrcFn`.
try di_buf.ensureCapacity(self.dbgLineNeededHeaderBytes(module));
// initial length - length of the .debug_line contribution for this compilation unit,
// not including the initial length itself.
const after_init_len = di_buf.items.len + init_len_size;
const init_len = dbg_line_prg_end - after_init_len;
mem.writeIntLittle(u32, di_buf.addManyAsArrayAssumeCapacity(4), @intCast(u32, init_len));
mem.writeIntLittle(u16, di_buf.addManyAsArrayAssumeCapacity(2), 4); // version
// Empirically, debug info consumers do not respect this field, or otherwise
// consider it to be an error when it does not point exactly to the end of the header.
// Therefore we rely on the NOP jump at the beginning of the Line Number Program for
// padding rather than this field.
const before_header_len = di_buf.items.len;
di_buf.items.len += @sizeOf(u32); // We will come back and write this.
const after_header_len = di_buf.items.len;
const opcode_base = DW.LNS_set_isa + 1;
di_buf.appendSliceAssumeCapacity(&[_]u8{
1, // minimum_instruction_length
1, // maximum_operations_per_instruction
1, // default_is_stmt
1, // line_base (signed)
1, // line_range
opcode_base,
// Standard opcode lengths. The number of items here is based on `opcode_base`.
// The value is the number of LEB128 operands the instruction takes.
0, // `DW.LNS_copy`
1, // `DW.LNS_advance_pc`
1, // `DW.LNS_advance_line`
1, // `DW.LNS_set_file`
1, // `DW.LNS_set_column`
0, // `DW.LNS_negate_stmt`
0, // `DW.LNS_set_basic_block`
0, // `DW.LNS_const_add_pc`
1, // `DW.LNS_fixed_advance_pc`
0, // `DW.LNS_set_prologue_end`
0, // `DW.LNS_set_epilogue_begin`
1, // `DW.LNS_set_isa`
0, // include_directories (none except the compilation unit cwd)
});
// file_names[0]
di_buf.appendSliceAssumeCapacity(module.root_pkg.root_src_path); // relative path name
di_buf.appendSliceAssumeCapacity(&[_]u8{
0, // null byte for the relative path name
0, // directory_index
0, // mtime (TODO supply this)
0, // file size bytes (TODO supply this)
0, // file_names sentinel
});
const header_len = di_buf.items.len - after_header_len;
mem.writeIntLittle(u32, di_buf.items[before_header_len..][0..4], @intCast(u32, header_len));
// We use NOPs because consumers empirically do not respect the header length field.
if (di_buf.items.len > dbg_line_prg_off) {
// Move the first N files to the end to make more padding for the header.
@panic("TODO: handle __debug_line header exceeding its padding");
}
const jmp_amt = dbg_line_prg_off - di_buf.items.len;
try self.pwriteDbgLineNops(0, di_buf.items, jmp_amt, debug_line_sect.offset);
self.debug_line_header_dirty = false;
}
{
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_strtab_sect = &dwarf_segment.sections.items[self.debug_str_section_index.?];
if (self.debug_string_table_dirty or self.debug_string_table.items.len != debug_strtab_sect.size) {
const allocated_size = dwarf_segment.allocatedSize(debug_strtab_sect.offset);
const needed_size = self.debug_string_table.items.len;
if (needed_size > allocated_size) {
debug_strtab_sect.size = 0; // free the space
const new_offset = dwarf_segment.findFreeSpace(needed_size, 1, null);
debug_strtab_sect.addr = dwarf_segment.inner.vmaddr + new_offset - dwarf_segment.inner.fileoff;
debug_strtab_sect.offset = @intCast(u32, new_offset);
}
debug_strtab_sect.size = @intCast(u32, needed_size);
log.debug("__debug_strtab start=0x{x} end=0x{x}", .{
debug_strtab_sect.offset,
debug_strtab_sect.offset + needed_size,
});
try self.file.pwriteAll(self.debug_string_table.items, debug_strtab_sect.offset);
self.load_commands_dirty = true;
self.debug_string_table_dirty = false;
}
}
try self.writeStringTable();
self.updateDwarfSegment();
try self.writeLoadCommands(allocator);
try self.writeHeader();
assert(!self.header_dirty);
assert(!self.load_commands_dirty);
assert(!self.string_table_dirty);
assert(!self.debug_abbrev_section_dirty);
assert(!self.debug_aranges_section_dirty);
assert(!self.debug_string_table_dirty);
}
pub fn deinit(self: *DebugSymbols, allocator: *Allocator) void {
self.dbg_info_decl_free_list.deinit(allocator);
self.dbg_line_fn_free_list.deinit(allocator);
self.debug_string_table.deinit(allocator);
for (self.load_commands.items) |*lc| {
lc.deinit(allocator);
}
self.load_commands.deinit(allocator);
self.file.close();
}
fn copySegmentCommand(self: *DebugSymbols, allocator: *Allocator, base_cmd: SegmentCommand) !SegmentCommand {
var cmd = SegmentCommand.empty(.{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = base_cmd.inner.cmdsize,
.segname = undefined,
.vmaddr = base_cmd.inner.vmaddr,
.vmsize = base_cmd.inner.vmsize,
.fileoff = 0,
.filesize = 0,
.maxprot = base_cmd.inner.maxprot,
.initprot = base_cmd.inner.initprot,
.nsects = base_cmd.inner.nsects,
.flags = base_cmd.inner.flags,
});
mem.copy(u8, &cmd.inner.segname, &base_cmd.inner.segname);
try cmd.sections.ensureCapacity(allocator, cmd.inner.nsects);
for (base_cmd.sections.items) |base_sect, i| {
var sect = macho.section_64{
.sectname = undefined,
.segname = undefined,
.addr = base_sect.addr,
.size = base_sect.size,
.offset = 0,
.@"align" = base_sect.@"align",
.reloff = 0,
.nreloc = 0,
.flags = base_sect.flags,
.reserved1 = base_sect.reserved1,
.reserved2 = base_sect.reserved2,
.reserved3 = base_sect.reserved3,
};
mem.copy(u8, &sect.sectname, &base_sect.sectname);
mem.copy(u8, &sect.segname, &base_sect.segname);
if (self.base.text_section_index.? == i) {
self.text_section_index = @intCast(u16, i);
}
cmd.sections.appendAssumeCapacity(sect);
}
return cmd;
}
fn updateDwarfSegment(self: *DebugSymbols) void {
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
var file_size: u64 = 0;
for (dwarf_segment.sections.items) |sect| {
file_size += sect.size;
}
if (file_size != dwarf_segment.inner.filesize) {
dwarf_segment.inner.filesize = file_size;
if (dwarf_segment.inner.vmsize < dwarf_segment.inner.filesize) {
dwarf_segment.inner.vmsize = mem.alignForwardGeneric(u64, dwarf_segment.inner.filesize, page_size);
}
self.load_commands_dirty = true;
}
}
/// Writes all load commands and section headers.
fn writeLoadCommands(self: *DebugSymbols, allocator: *Allocator) !void {
if (!self.load_commands_dirty) return;
var sizeofcmds: u32 = 0;
for (self.load_commands.items) |lc| {
sizeofcmds += lc.cmdsize();
}
var buffer = try allocator.alloc(u8, sizeofcmds);
defer allocator.free(buffer);
var writer = std.io.fixedBufferStream(buffer).writer();
for (self.load_commands.items) |lc| {
try lc.write(writer);
}
const off = @sizeOf(macho.mach_header_64);
log.debug("writing {} dSym load commands from 0x{x} to 0x{x}", .{ self.load_commands.items.len, off, off + sizeofcmds });
try self.file.pwriteAll(buffer, off);
self.load_commands_dirty = false;
}
fn writeHeader(self: *DebugSymbols) !void {
if (!self.header_dirty) return;
self.header.?.ncmds = @intCast(u32, self.load_commands.items.len);
var sizeofcmds: u32 = 0;
for (self.load_commands.items) |cmd| {
sizeofcmds += cmd.cmdsize();
}
self.header.?.sizeofcmds = sizeofcmds;
log.debug("writing Mach-O dSym header {}", .{self.header.?});
try self.file.pwriteAll(mem.asBytes(&self.header.?), 0);
self.header_dirty = false;
}
fn allocatedSizeLinkedit(self: *DebugSymbols, start: u64) u64 {
assert(start > 0);
var min_pos: u64 = std.math.maxInt(u64);
if (self.symtab_cmd_index) |idx| {
const symtab = self.load_commands.items[idx].Symtab;
if (symtab.symoff >= start and symtab.symoff < min_pos) min_pos = symtab.symoff;
if (symtab.stroff >= start and symtab.stroff < min_pos) min_pos = symtab.stroff;
}
return min_pos - start;
}
fn detectAllocCollisionLinkedit(self: *DebugSymbols, start: u64, size: u64) ?u64 {
const end = start + padToIdeal(size);
if (self.symtab_cmd_index) |idx| outer: {
if (self.load_commands.items.len == idx) break :outer;
const symtab = self.load_commands.items[idx].Symtab;
{
// Symbol table
const symsize = symtab.nsyms * @sizeOf(macho.nlist_64);
const increased_size = padToIdeal(symsize);
const test_end = symtab.symoff + increased_size;
if (end > symtab.symoff and start < test_end) {
return test_end;
}
}
{
// String table
const increased_size = padToIdeal(symtab.strsize);
const test_end = symtab.stroff + increased_size;
if (end > symtab.stroff and start < test_end) {
return test_end;
}
}
}
return null;
}
fn findFreeSpaceLinkedit(self: *DebugSymbols, object_size: u64, min_alignment: u16) u64 {
var start: u64 = self.linkedit_off;
while (self.detectAllocCollisionLinkedit(start, object_size)) |item_end| {
start = mem.alignForwardGeneric(u64, item_end, min_alignment);
}
return start;
}
fn relocateSymbolTable(self: *DebugSymbols) !void {
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const nlocals = self.base.locals.items.len;
const nglobals = self.base.globals.items.len;
const nsyms = nlocals + nglobals;
if (symtab.nsyms < nsyms) {
const linkedit_segment = self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const needed_size = nsyms * @sizeOf(macho.nlist_64);
if (needed_size > self.allocatedSizeLinkedit(symtab.symoff)) {
// Move the entire symbol table to a new location
const new_symoff = self.findFreeSpaceLinkedit(needed_size, @alignOf(macho.nlist_64));
const existing_size = symtab.nsyms * @sizeOf(macho.nlist_64);
assert(new_symoff + existing_size <= self.linkedit_off + self.linkedit_size); // TODO expand LINKEDIT segment.
log.debug("relocating dSym symbol table from 0x{x}-0x{x} to 0x{x}-0x{x}", .{
symtab.symoff,
symtab.symoff + existing_size,
new_symoff,
new_symoff + existing_size,
});
const amt = try self.file.copyRangeAll(symtab.symoff, self.file, new_symoff, existing_size);
if (amt != existing_size) return error.InputOutput;
symtab.symoff = @intCast(u32, new_symoff);
}
symtab.nsyms = @intCast(u32, nsyms);
self.load_commands_dirty = true;
}
}
pub fn writeLocalSymbol(self: *DebugSymbols, index: usize) !void {
const tracy = trace(@src());
defer tracy.end();
try self.relocateSymbolTable();
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const off = symtab.symoff + @sizeOf(macho.nlist_64) * index;
log.debug("writing dSym local symbol {} at 0x{x}", .{ index, off });
try self.file.pwriteAll(mem.asBytes(&self.base.locals.items[index]), off);
}
fn writeStringTable(self: *DebugSymbols) !void {
if (!self.string_table_dirty) return;
const tracy = trace(@src());
defer tracy.end();
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const allocated_size = self.allocatedSizeLinkedit(symtab.stroff);
const needed_size = mem.alignForwardGeneric(u64, self.base.string_table.items.len, @alignOf(u64));
if (needed_size > allocated_size) {
symtab.strsize = 0;
symtab.stroff = @intCast(u32, self.findFreeSpaceLinkedit(needed_size, 1));
}
symtab.strsize = @intCast(u32, needed_size);
log.debug("writing dSym string table from 0x{x} to 0x{x}", .{ symtab.stroff, symtab.stroff + symtab.strsize });
try self.file.pwriteAll(self.base.string_table.items, symtab.stroff);
self.load_commands_dirty = true;
self.string_table_dirty = false;
}
pub fn updateDeclLineNumber(self: *DebugSymbols, module: *Module, decl: *const Module.Decl) !void {
const tracy = trace(@src());
defer tracy.end();
const tree = decl.container.file_scope.tree;
const node_tags = tree.nodes.items(.tag);
const node_datas = tree.nodes.items(.data);
const token_starts = tree.tokens.items(.start);
// TODO Look into improving the performance here by adding a token-index-to-line
// lookup table. Currently this involves scanning over the source code for newlines.
const fn_decl = decl.src_node;
assert(node_tags[fn_decl] == .fn_decl);
const block = node_datas[fn_decl].rhs;
const lbrace = tree.firstToken(block);
const line_delta = std.zig.lineDelta(tree.source, 0, token_starts[lbrace]);
const casted_line_off = @intCast(u28, line_delta);
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const shdr = &dwarf_segment.sections.items[self.debug_line_section_index.?];
const file_pos = shdr.offset + decl.fn_link.macho.off + getRelocDbgLineOff();
var data: [4]u8 = undefined;
leb.writeUnsignedFixed(4, &data, casted_line_off);
try self.file.pwriteAll(&data, file_pos);
}
pub const DeclDebugBuffers = struct {
dbg_line_buffer: std.ArrayList(u8),
dbg_info_buffer: std.ArrayList(u8),
dbg_info_type_relocs: link.File.DbgInfoTypeRelocsTable,
};
/// Caller owns the returned memory.
pub fn initDeclDebugBuffers(
self: *DebugSymbols,
allocator: *Allocator,
module: *Module,
decl: *Module.Decl,
) !DeclDebugBuffers {
const tracy = trace(@src());
defer tracy.end();
var dbg_line_buffer = std.ArrayList(u8).init(allocator);
var dbg_info_buffer = std.ArrayList(u8).init(allocator);
var dbg_info_type_relocs: link.File.DbgInfoTypeRelocsTable = .{};
const typed_value = decl.typed_value.most_recent.typed_value;
switch (typed_value.ty.zigTypeTag()) {
.Fn => {
// For functions we need to add a prologue to the debug line program.
try dbg_line_buffer.ensureCapacity(26);
const line_off: u28 = blk: {
const tree = decl.container.file_scope.tree;
const node_tags = tree.nodes.items(.tag);
const node_datas = tree.nodes.items(.data);
const token_starts = tree.tokens.items(.start);
// TODO Look into improving the performance here by adding a token-index-to-line
// lookup table. Currently this involves scanning over the source code for newlines.
const fn_decl = decl.src_node;
assert(node_tags[fn_decl] == .fn_decl);
const block = node_datas[fn_decl].rhs;
const lbrace = tree.firstToken(block);
const line_delta = std.zig.lineDelta(tree.source, 0, token_starts[lbrace]);
break :blk @intCast(u28, line_delta);
};
dbg_line_buffer.appendSliceAssumeCapacity(&[_]u8{
DW.LNS_extended_op,
@sizeOf(u64) + 1,
DW.LNE_set_address,
});
// This is the "relocatable" vaddr, corresponding to `code_buffer` index `0`.
assert(dbg_line_vaddr_reloc_index == dbg_line_buffer.items.len);
dbg_line_buffer.items.len += @sizeOf(u64);
dbg_line_buffer.appendAssumeCapacity(DW.LNS_advance_line);
// This is the "relocatable" relative line offset from the previous function's end curly
// to this function's begin curly.
assert(getRelocDbgLineOff() == dbg_line_buffer.items.len);
// Here we use a ULEB128-fixed-4 to make sure this field can be overwritten later.
leb.writeUnsignedFixed(4, dbg_line_buffer.addManyAsArrayAssumeCapacity(4), line_off);
dbg_line_buffer.appendAssumeCapacity(DW.LNS_set_file);
assert(getRelocDbgFileIndex() == dbg_line_buffer.items.len);
// Once we support more than one source file, this will have the ability to be more
// than one possible value.
const file_index = 1;
leb.writeUnsignedFixed(4, dbg_line_buffer.addManyAsArrayAssumeCapacity(4), file_index);
// Emit a line for the begin curly with prologue_end=false. The codegen will
// do the work of setting prologue_end=true and epilogue_begin=true.
dbg_line_buffer.appendAssumeCapacity(DW.LNS_copy);
// .debug_info subprogram
const decl_name_with_null = decl.name[0 .. mem.lenZ(decl.name) + 1];
try dbg_info_buffer.ensureCapacity(dbg_info_buffer.items.len + 27 + decl_name_with_null.len);
const fn_ret_type = typed_value.ty.fnReturnType();
const fn_ret_has_bits = fn_ret_type.hasCodeGenBits();
if (fn_ret_has_bits) {
dbg_info_buffer.appendAssumeCapacity(abbrev_subprogram);
} else {
dbg_info_buffer.appendAssumeCapacity(abbrev_subprogram_retvoid);
}
// These get overwritten after generating the machine code. These values are
// "relocations" and have to be in this fixed place so that functions can be
// moved in virtual address space.
assert(dbg_info_low_pc_reloc_index == dbg_info_buffer.items.len);
dbg_info_buffer.items.len += @sizeOf(u64); // DW.AT_low_pc, DW.FORM_addr
assert(getRelocDbgInfoSubprogramHighPC() == dbg_info_buffer.items.len);
dbg_info_buffer.items.len += 4; // DW.AT_high_pc, DW.FORM_data4
if (fn_ret_has_bits) {
const gop = try dbg_info_type_relocs.getOrPut(allocator, fn_ret_type);
if (!gop.found_existing) {
gop.entry.value = .{
.off = undefined,
.relocs = .{},
};
}
try gop.entry.value.relocs.append(allocator, @intCast(u32, dbg_info_buffer.items.len));
dbg_info_buffer.items.len += 4; // DW.AT_type, DW.FORM_ref4
}
dbg_info_buffer.appendSliceAssumeCapacity(decl_name_with_null); // DW.AT_name, DW.FORM_string
mem.writeIntLittle(u32, dbg_info_buffer.addManyAsArrayAssumeCapacity(4), line_off + 1); // DW.AT_decl_line, DW.FORM_data4
dbg_info_buffer.appendAssumeCapacity(file_index); // DW.AT_decl_file, DW.FORM_data1
},
else => {
// TODO implement .debug_info for global variables
},
}
return DeclDebugBuffers{
.dbg_info_buffer = dbg_info_buffer,
.dbg_line_buffer = dbg_line_buffer,
.dbg_info_type_relocs = dbg_info_type_relocs,
};
}
pub fn commitDeclDebugInfo(
self: *DebugSymbols,
allocator: *Allocator,
module: *Module,
decl: *Module.Decl,
debug_buffers: *DeclDebugBuffers,
target: std.Target,
) !void {
const tracy = trace(@src());
defer tracy.end();
var dbg_line_buffer = &debug_buffers.dbg_line_buffer;
var dbg_info_buffer = &debug_buffers.dbg_info_buffer;
var dbg_info_type_relocs = &debug_buffers.dbg_info_type_relocs;
const symbol = self.base.locals.items[decl.link.macho.local_sym_index];
const text_block = &decl.link.macho;
// If the Decl is a function, we need to update the __debug_line program.
const typed_value = decl.typed_value.most_recent.typed_value;
switch (typed_value.ty.zigTypeTag()) {
.Fn => {
// Perform the relocations based on vaddr.
{
const ptr = dbg_line_buffer.items[dbg_line_vaddr_reloc_index..][0..8];
mem.writeIntLittle(u64, ptr, symbol.n_value);
}
{
const ptr = dbg_info_buffer.items[dbg_info_low_pc_reloc_index..][0..8];
mem.writeIntLittle(u64, ptr, symbol.n_value);
}
{
const ptr = dbg_info_buffer.items[getRelocDbgInfoSubprogramHighPC()..][0..4];
mem.writeIntLittle(u32, ptr, @intCast(u32, text_block.size));
}
try dbg_line_buffer.appendSlice(&[_]u8{ DW.LNS_extended_op, 1, DW.LNE_end_sequence });
// Now we have the full contents and may allocate a region to store it.
// This logic is nearly identical to the logic below in `updateDeclDebugInfo` for
// `TextBlock` and the .debug_info. If you are editing this logic, you
// probably need to edit that logic too.
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_line_sect = &dwarf_segment.sections.items[self.debug_line_section_index.?];
const src_fn = &decl.fn_link.macho;
src_fn.len = @intCast(u32, dbg_line_buffer.items.len);
if (self.dbg_line_fn_last) |last| blk: {
if (src_fn == last) break :blk;
if (src_fn.next) |next| {
// Update existing function - non-last item.
if (src_fn.off + src_fn.len + min_nop_size > next.off) {
// It grew too big, so we move it to a new location.
if (src_fn.prev) |prev| {
self.dbg_line_fn_free_list.put(allocator, prev, {}) catch {};
prev.next = src_fn.next;
}
next.prev = src_fn.prev;
src_fn.next = null;
// Populate where it used to be with NOPs.
const file_pos = debug_line_sect.offset + src_fn.off;
try self.pwriteDbgLineNops(0, &[0]u8{}, src_fn.len, file_pos);
// TODO Look at the free list before appending at the end.
src_fn.prev = last;
last.next = src_fn;
self.dbg_line_fn_last = src_fn;
src_fn.off = last.off + padToIdeal(last.len);
}
} else if (src_fn.prev == null) {
// Append new function.
// TODO Look at the free list before appending at the end.
src_fn.prev = last;
last.next = src_fn;
self.dbg_line_fn_last = src_fn;
src_fn.off = last.off + padToIdeal(last.len);
}
} else {
// This is the first function of the Line Number Program.
self.dbg_line_fn_first = src_fn;
self.dbg_line_fn_last = src_fn;
src_fn.off = padToIdeal(self.dbgLineNeededHeaderBytes(module));
}
const last_src_fn = self.dbg_line_fn_last.?;
const needed_size = last_src_fn.off + last_src_fn.len;
if (needed_size != debug_line_sect.size) {
if (needed_size > dwarf_segment.allocatedSize(debug_line_sect.offset)) {
const new_offset = dwarf_segment.findFreeSpace(needed_size, 1, null);
const existing_size = last_src_fn.off;
log.debug("moving __debug_line section: {} bytes from 0x{x} to 0x{x}", .{
existing_size,
debug_line_sect.offset,
new_offset,
});
const amt = try self.file.copyRangeAll(debug_line_sect.offset, self.file, new_offset, existing_size);
if (amt != existing_size) return error.InputOutput;
debug_line_sect.offset = @intCast(u32, new_offset);
debug_line_sect.addr = dwarf_segment.inner.vmaddr + new_offset - dwarf_segment.inner.fileoff;
}
debug_line_sect.size = needed_size;
self.load_commands_dirty = true; // TODO look into making only the one section dirty
self.debug_line_header_dirty = true;
}
const prev_padding_size: u32 = if (src_fn.prev) |prev| src_fn.off - (prev.off + prev.len) else 0;
const next_padding_size: u32 = if (src_fn.next) |next| next.off - (src_fn.off + src_fn.len) else 0;
// We only have support for one compilation unit so far, so the offsets are directly
// from the .debug_line section.
const file_pos = debug_line_sect.offset + src_fn.off;
try self.pwriteDbgLineNops(prev_padding_size, dbg_line_buffer.items, next_padding_size, file_pos);
// .debug_info - End the TAG_subprogram children.
try dbg_info_buffer.append(0);
},
else => {},
}
// 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
// relocations yet.
var it = dbg_info_type_relocs.iterator();
while (it.next()) |entry| {
entry.value.off = @intCast(u32, dbg_info_buffer.items.len);
try self.addDbgInfoType(entry.key, dbg_info_buffer, target);
}
try self.updateDeclDebugInfoAllocation(allocator, text_block, @intCast(u32, dbg_info_buffer.items.len));
// Now that we have the offset assigned we can finally perform type relocations.
it = dbg_info_type_relocs.iterator();
while (it.next()) |entry| {
for (entry.value.relocs.items) |off| {
mem.writeIntLittle(
u32,
dbg_info_buffer.items[off..][0..4],
text_block.dbg_info_off + entry.value.off,
);
}
}
try self.writeDeclDebugInfo(text_block, dbg_info_buffer.items);
}
/// Asserts the type has codegen bits.
fn addDbgInfoType(
self: *DebugSymbols,
ty: Type,
dbg_info_buffer: *std.ArrayList(u8),
target: std.Target,
) !void {
switch (ty.zigTypeTag()) {
.Void => unreachable,
.NoReturn => unreachable,
.Bool => {
try dbg_info_buffer.appendSlice(&[_]u8{
abbrev_base_type,
DW.ATE_boolean, // DW.AT_encoding , DW.FORM_data1
1, // DW.AT_byte_size, DW.FORM_data1
'b',
'o',
'o',
'l',
0, // DW.AT_name, DW.FORM_string
});
},
.Int => {
const info = ty.intInfo(target);
try dbg_info_buffer.ensureCapacity(dbg_info_buffer.items.len + 12);
dbg_info_buffer.appendAssumeCapacity(abbrev_base_type);
// DW.AT_encoding, DW.FORM_data1
dbg_info_buffer.appendAssumeCapacity(switch (info.signedness) {
.signed => DW.ATE_signed,
.unsigned => DW.ATE_unsigned,
});
// DW.AT_byte_size, DW.FORM_data1
dbg_info_buffer.appendAssumeCapacity(@intCast(u8, ty.abiSize(target)));
// DW.AT_name, DW.FORM_string
try dbg_info_buffer.writer().print("{}\x00", .{ty});
},
else => {
std.log.scoped(.compiler).err("TODO implement .debug_info for type '{}'", .{ty});
try dbg_info_buffer.append(abbrev_pad1);
},
}
}
fn updateDeclDebugInfoAllocation(
self: *DebugSymbols,
allocator: *Allocator,
text_block: *TextBlock,
len: u32,
) !void {
const tracy = trace(@src());
defer tracy.end();
// This logic is nearly identical to the logic above in `updateDecl` for
// `SrcFn` and the line number programs. If you are editing this logic, you
// probably need to edit that logic too.
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_info_sect = &dwarf_segment.sections.items[self.debug_info_section_index.?];
text_block.dbg_info_len = len;
if (self.dbg_info_decl_last) |last| blk: {
if (text_block == last) break :blk;
if (text_block.dbg_info_next) |next| {
// Update existing Decl - non-last item.
if (text_block.dbg_info_off + text_block.dbg_info_len + min_nop_size > next.dbg_info_off) {
// It grew too big, so we move it to a new location.
if (text_block.dbg_info_prev) |prev| {
self.dbg_info_decl_free_list.put(allocator, prev, {}) catch {};
prev.dbg_info_next = text_block.dbg_info_next;
}
next.dbg_info_prev = text_block.dbg_info_prev;
text_block.dbg_info_next = null;
// Populate where it used to be with NOPs.
const file_pos = debug_info_sect.offset + text_block.dbg_info_off;
try self.pwriteDbgInfoNops(0, &[0]u8{}, text_block.dbg_info_len, false, file_pos);
// TODO Look at the free list before appending at the end.
text_block.dbg_info_prev = last;
last.dbg_info_next = text_block;
self.dbg_info_decl_last = text_block;
text_block.dbg_info_off = last.dbg_info_off + padToIdeal(last.dbg_info_len);
}
} else if (text_block.dbg_info_prev == null) {
// Append new Decl.
// TODO Look at the free list before appending at the end.
text_block.dbg_info_prev = last;
last.dbg_info_next = text_block;
self.dbg_info_decl_last = text_block;
text_block.dbg_info_off = last.dbg_info_off + padToIdeal(last.dbg_info_len);
}
} else {
// This is the first Decl of the .debug_info
self.dbg_info_decl_first = text_block;
self.dbg_info_decl_last = text_block;
text_block.dbg_info_off = padToIdeal(self.dbgInfoNeededHeaderBytes());
}
}
fn writeDeclDebugInfo(self: *DebugSymbols, text_block: *TextBlock, dbg_info_buf: []const u8) !void {
const tracy = trace(@src());
defer tracy.end();
// This logic is nearly identical to the logic above in `updateDecl` for
// `SrcFn` and the line number programs. If you are editing this logic, you
// probably need to edit that logic too.
const dwarf_segment = &self.load_commands.items[self.dwarf_segment_cmd_index.?].Segment;
const debug_info_sect = &dwarf_segment.sections.items[self.debug_info_section_index.?];
const last_decl = self.dbg_info_decl_last.?;
// +1 for a trailing zero to end the children of the decl tag.
const needed_size = last_decl.dbg_info_off + last_decl.dbg_info_len + 1;
if (needed_size != debug_info_sect.size) {
if (needed_size > dwarf_segment.allocatedSize(debug_info_sect.offset)) {
const new_offset = dwarf_segment.findFreeSpace(needed_size, 1, null);
const existing_size = last_decl.dbg_info_off;
log.debug("moving __debug_info section: {} bytes from 0x{x} to 0x{x}", .{
existing_size,
debug_info_sect.offset,
new_offset,
});
const amt = try self.file.copyRangeAll(debug_info_sect.offset, self.file, new_offset, existing_size);
if (amt != existing_size) return error.InputOutput;
debug_info_sect.offset = @intCast(u32, new_offset);
debug_info_sect.addr = dwarf_segment.inner.vmaddr + new_offset - dwarf_segment.inner.fileoff;
}
debug_info_sect.size = needed_size;
self.load_commands_dirty = true; // TODO look into making only the one section dirty
self.debug_info_header_dirty = true;
}
const prev_padding_size: u32 = if (text_block.dbg_info_prev) |prev|
text_block.dbg_info_off - (prev.dbg_info_off + prev.dbg_info_len)
else
0;
const next_padding_size: u32 = if (text_block.dbg_info_next) |next|
next.dbg_info_off - (text_block.dbg_info_off + text_block.dbg_info_len)
else
0;
// To end the children of the decl tag.
const trailing_zero = text_block.dbg_info_next == null;
// We only have support for one compilation unit so far, so the offsets are directly
// from the .debug_info section.
const file_pos = debug_info_sect.offset + text_block.dbg_info_off;
try self.pwriteDbgInfoNops(prev_padding_size, dbg_info_buf, next_padding_size, trailing_zero, file_pos);
}
fn getDebugLineProgramOff(self: DebugSymbols) u32 {
return self.dbg_line_fn_first.?.off;
}
fn getDebugLineProgramEnd(self: DebugSymbols) u32 {
return self.dbg_line_fn_last.?.off + self.dbg_line_fn_last.?.len;
}
/// TODO Improve this to use a table.
fn makeDebugString(self: *DebugSymbols, allocator: *Allocator, bytes: []const u8) !u32 {
try self.debug_string_table.ensureCapacity(allocator, self.debug_string_table.items.len + bytes.len + 1);
const result = self.debug_string_table.items.len;
self.debug_string_table.appendSliceAssumeCapacity(bytes);
self.debug_string_table.appendAssumeCapacity(0);
return @intCast(u32, result);
}
/// The reloc offset for the line offset of a function from the previous function's line.
/// It's a fixed-size 4-byte ULEB128.
fn getRelocDbgLineOff() usize {
return dbg_line_vaddr_reloc_index + @sizeOf(u64) + 1;
}
fn getRelocDbgFileIndex() usize {
return getRelocDbgLineOff() + 5;
}
fn getRelocDbgInfoSubprogramHighPC() u32 {
return dbg_info_low_pc_reloc_index + @sizeOf(u64);
}
fn dbgLineNeededHeaderBytes(self: DebugSymbols, module: *Module) u32 {
const directory_entry_format_count = 1;
const file_name_entry_format_count = 1;
const directory_count = 1;
const file_name_count = 1;
const root_src_dir_path_len = if (module.root_pkg.root_src_directory.path) |p| p.len else 1; // "."
return @intCast(u32, 53 + directory_entry_format_count * 2 + file_name_entry_format_count * 2 +
directory_count * 8 + file_name_count * 8 +
// These are encoded as DW.FORM_string rather than DW.FORM_strp as we would like
// because of a workaround for readelf and gdb failing to understand DWARFv5 correctly.
root_src_dir_path_len +
module.root_pkg.root_src_path.len);
}
fn dbgInfoNeededHeaderBytes(self: DebugSymbols) u32 {
return 120;
}
/// Writes to the file a buffer, prefixed and suffixed by the specified number of
/// bytes of NOPs. Asserts each padding size is at least `min_nop_size` and total padding bytes
/// are less than 126,976 bytes (if this limit is ever reached, this function can be
/// improved to make more than one pwritev call, or the limit can be raised by a fixed
/// amount by increasing the length of `vecs`).
fn pwriteDbgLineNops(
self: *DebugSymbols,
prev_padding_size: usize,
buf: []const u8,
next_padding_size: usize,
offset: u64,
) !void {
const tracy = trace(@src());
defer tracy.end();
const page_of_nops = [1]u8{DW.LNS_negate_stmt} ** 4096;
const three_byte_nop = [3]u8{ DW.LNS_advance_pc, 0b1000_0000, 0 };
var vecs: [32]std.os.iovec_const = undefined;
var vec_index: usize = 0;
{
var padding_left = prev_padding_size;
if (padding_left % 2 != 0) {
vecs[vec_index] = .{
.iov_base = &three_byte_nop,
.iov_len = three_byte_nop.len,
};
vec_index += 1;
padding_left -= three_byte_nop.len;
}
while (padding_left > page_of_nops.len) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = page_of_nops.len,
};
vec_index += 1;
padding_left -= page_of_nops.len;
}
if (padding_left > 0) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = padding_left,
};
vec_index += 1;
}
}
vecs[vec_index] = .{
.iov_base = buf.ptr,
.iov_len = buf.len,
};
vec_index += 1;
{
var padding_left = next_padding_size;
if (padding_left % 2 != 0) {
vecs[vec_index] = .{
.iov_base = &three_byte_nop,
.iov_len = three_byte_nop.len,
};
vec_index += 1;
padding_left -= three_byte_nop.len;
}
while (padding_left > page_of_nops.len) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = page_of_nops.len,
};
vec_index += 1;
padding_left -= page_of_nops.len;
}
if (padding_left > 0) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = padding_left,
};
vec_index += 1;
}
}
try self.file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
}
/// Writes to the file a buffer, prefixed and suffixed by the specified number of
/// bytes of padding.
fn pwriteDbgInfoNops(
self: *DebugSymbols,
prev_padding_size: usize,
buf: []const u8,
next_padding_size: usize,
trailing_zero: bool,
offset: u64,
) !void {
const tracy = trace(@src());
defer tracy.end();
const page_of_nops = [1]u8{abbrev_pad1} ** 4096;
var vecs: [32]std.os.iovec_const = undefined;
var vec_index: usize = 0;
{
var padding_left = prev_padding_size;
while (padding_left > page_of_nops.len) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = page_of_nops.len,
};
vec_index += 1;
padding_left -= page_of_nops.len;
}
if (padding_left > 0) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = padding_left,
};
vec_index += 1;
}
}
vecs[vec_index] = .{
.iov_base = buf.ptr,
.iov_len = buf.len,
};
vec_index += 1;
{
var padding_left = next_padding_size;
while (padding_left > page_of_nops.len) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = page_of_nops.len,
};
vec_index += 1;
padding_left -= page_of_nops.len;
}
if (padding_left > 0) {
vecs[vec_index] = .{
.iov_base = &page_of_nops,
.iov_len = padding_left,
};
vec_index += 1;
}
}
if (trailing_zero) {
var zbuf = [1]u8{0};
vecs[vec_index] = .{
.iov_base = &zbuf,
.iov_len = zbuf.len,
};
vec_index += 1;
}
try self.file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
}