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macho: fix symbol index dereference in codegen wrt ZigObject

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This is incredibly confusing and I really need to simplify it.
Elf also possesses this shortcoming so once I get Coff up to speed
it should hopefully become clear on how to refactor this.
This commit is contained in:
Jakub Konka 2024-01-18 21:55:31 +01:00
parent 30b7d3e45f
commit a8629fb850
6 changed files with 76 additions and 26 deletions
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5
src/arch/x86_64/Emit.zig
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@ -156,9 +156,10 @@ pub fn emitMir(emit: *Emit) Error!void {
.Lib => emit.lower.link_mode == .Static,
};
const atom = macho_file.getSymbol(data.atom_index).getAtom(macho_file).?;
const sym = macho_file.getSymbol(data.sym_index);
const sym_index = macho_file.getZigObject().?.symbols.items[data.sym_index];
const sym = macho_file.getSymbol(sym_index);
if (sym.flags.needs_zig_got and !is_obj_or_static_lib) {
_ = try sym.getOrCreateZigGotEntry(data.sym_index, macho_file);
_ = try sym.getOrCreateZigGotEntry(sym_index, macho_file);
}
const @"type": link.File.MachO.Relocation.Type = if (sym.flags.needs_zig_got and !is_obj_or_static_lib)
.zig_got_load

2
src/codegen.zig
View File

@ -993,7 +993,7 @@ fn genDeclRef(
else
null;
const sym_index = try macho_file.getGlobalSymbol(sym_name, lib_name);
macho_file.getSymbol(sym_index).flags.needs_got = true;
macho_file.getSymbol(macho_file.getZigObject().?.symbols.items[sym_index]).flags.needs_got = true;
return GenResult.mcv(.{ .load_symbol = sym_index });
}
const sym_index = try macho_file.getZigObject().?.getOrCreateMetadataForDecl(macho_file, decl_index);

27
src/link/MachO.zig
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@ -542,8 +542,6 @@ pub fn flushModule(self: *MachO, arena: Allocator, prog_node: *std.Progress.Node
self.internal_object = index;
}
state_log.debug("{}", .{self.dumpState()});
try self.addUndefinedGlobals();
try self.resolveSymbols();
try self.resolveSyntheticSymbols();
@ -2389,14 +2387,23 @@ fn initDyldInfoSections(self: *MachO) !void {
if (self.la_symbol_ptr_sect_index != null) try self.la_symbol_ptr.addDyldRelocs(self);
try self.initExportTrie();
var objects = try std.ArrayList(File.Index).initCapacity(gpa, self.objects.items.len + 1);
defer objects.deinit();
if (self.getZigObject()) |zo| objects.appendAssumeCapacity(zo.index);
objects.appendSliceAssumeCapacity(self.objects.items);
var nrebases: usize = 0;
var nbinds: usize = 0;
var nweak_binds: usize = 0;
for (self.objects.items) |index| {
const object = self.getFile(index).?.object;
nrebases += object.num_rebase_relocs;
nbinds += object.num_bind_relocs;
nweak_binds += object.num_weak_bind_relocs;
for (objects.items) |index| {
const ctx = switch (self.getFile(index).?) {
.zig_object => |x| x.dynamic_relocs,
.object => |x| x.dynamic_relocs,
else => unreachable,
};
nrebases += ctx.rebase_relocs;
nbinds += ctx.bind_relocs;
nweak_binds += ctx.weak_bind_relocs;
}
try self.rebase.entries.ensureUnusedCapacity(gpa, nrebases);
try self.bind.entries.ensureUnusedCapacity(gpa, nbinds);
@ -3947,6 +3954,12 @@ const HotUpdateState = struct {
mach_task: ?std.os.darwin.MachTask = null,
};
pub const DynamicRelocs = struct {
rebase_relocs: u32 = 0,
bind_relocs: u32 = 0,
weak_bind_relocs: u32 = 0,
};
pub const SymtabCtx = struct {
ilocal: u32 = 0,
istab: u32 = 0,

31
src/link/MachO/Atom.zig
View File

@ -402,7 +402,11 @@ pub fn scanRelocs(self: Atom, macho_file: *MachO) !void {
defer tracy.end();
assert(self.flags.alive);
const object = self.getFile(macho_file).object;
const dynrel_ctx = switch (self.getFile(macho_file)) {
.zig_object => |x| &x.dynamic_relocs,
.object => |x| &x.dynamic_relocs,
else => unreachable,
};
const relocs = self.getRelocs(macho_file);
for (relocs) |rel| {
@ -437,6 +441,10 @@ pub fn scanRelocs(self: Atom, macho_file: *MachO) !void {
}
},
.zig_got_load => {
assert(rel.getTargetSymbol(macho_file).flags.has_zig_got);
},
.got => {
rel.getTargetSymbol(macho_file).flags.needs_got = true;
},
@ -448,7 +456,7 @@ pub fn scanRelocs(self: Atom, macho_file: *MachO) !void {
const symbol = rel.getTargetSymbol(macho_file);
if (!symbol.flags.tlv) {
try macho_file.reportParseError2(
object.index,
self.getFile(macho_file).getIndex(),
"{s}: illegal thread-local variable reference to regular symbol {s}",
.{ self.getName(macho_file), symbol.getName(macho_file) },
);
@ -470,27 +478,34 @@ pub fn scanRelocs(self: Atom, macho_file: *MachO) !void {
continue;
}
if (symbol.flags.import) {
object.num_bind_relocs += 1;
dynrel_ctx.bind_relocs += 1;
if (symbol.flags.weak) {
object.num_weak_bind_relocs += 1;
dynrel_ctx.weak_bind_relocs += 1;
macho_file.binds_to_weak = true;
}
continue;
}
if (symbol.flags.@"export") {
if (symbol.flags.weak) {
object.num_weak_bind_relocs += 1;
dynrel_ctx.weak_bind_relocs += 1;
macho_file.binds_to_weak = true;
} else if (symbol.flags.interposable) {
object.num_bind_relocs += 1;
dynrel_ctx.bind_relocs += 1;
}
}
}
object.num_rebase_relocs += 1;
dynrel_ctx.rebase_relocs += 1;
}
},
else => {},
.signed,
.signed1,
.signed2,
.signed4,
.page,
.pageoff,
.subtractor,
=> {},
}
}
}

4
src/link/MachO/Object.zig
View File

@ -25,10 +25,8 @@ unwind_records: std.ArrayListUnmanaged(UnwindInfo.Record.Index) = .{},
alive: bool = true,
hidden: bool = false,
num_rebase_relocs: u32 = 0,
num_bind_relocs: u32 = 0,
num_weak_bind_relocs: u32 = 0,
dynamic_relocs: MachO.DynamicRelocs = .{},
output_symtab_ctx: MachO.SymtabCtx = .{},
pub fn isObject(path: []const u8) !bool {

33
src/link/MachO/ZigObject.zig
View File

@ -41,6 +41,7 @@ anon_decls: AnonDeclTable = .{},
/// A table of relocations.
relocs: RelocationTable = .{},
dynamic_relocs: MachO.DynamicRelocs = .{},
output_symtab_ctx: MachO.SymtabCtx = .{},
pub fn init(self: *ZigObject, macho_file: *MachO) !void {
@ -222,10 +223,31 @@ pub fn markLive(self: *ZigObject, macho_file: *MachO) void {
}
pub fn checkDuplicates(self: *ZigObject, dupes: anytype, macho_file: *MachO) !void {
_ = self;
_ = dupes;
_ = macho_file;
@panic("TODO checkDuplicates");
for (self.symbols.items, 0..) |index, nlist_idx| {
const sym = macho_file.getSymbol(index);
if (sym.visibility != .global) continue;
const file = sym.getFile(macho_file) orelse continue;
if (file.getIndex() == self.index) continue;
const nlist = self.symtab.items(.nlist)[nlist_idx];
if (!nlist.undf() and !nlist.tentative() and !(nlist.weakDef() or nlist.pext())) {
const gop = try dupes.getOrPut(index);
if (!gop.found_existing) {
gop.value_ptr.* = .{};
}
try gop.value_ptr.append(macho_file.base.comp.gpa, self.index);
}
}
}
pub fn scanRelocs(self: *ZigObject, macho_file: *MachO) !void {
for (self.atoms.items) |atom_index| {
const atom = macho_file.getAtom(atom_index) orelse continue;
if (!atom.flags.alive) continue;
const sect = atom.getInputSection(macho_file);
if (sect.isZerofill()) continue;
try atom.scanRelocs(macho_file);
}
}
pub fn calcSymtabSize(self: *ZigObject, macho_file: *MachO) !void {
@ -537,7 +559,8 @@ pub fn updateDecl(
const name = mod.intern_pool.stringToSlice(decl.name);
const lib_name = mod.intern_pool.stringToSliceUnwrap(variable.lib_name);
const index = try self.getGlobalSymbol(macho_file, name, lib_name);
macho_file.getSymbol(index).flags.needs_got = true;
const actual_index = self.symbols.items[index];
macho_file.getSymbol(actual_index).flags.needs_got = true;
return;
}