Commit 7345976261
Changed files (2)
src
link
MachO
src/link/MachO/Object.zig
@@ -197,11 +197,9 @@ const SymbolAtIndex = struct {
return mem.sliceTo(@ptrCast([*:0]const u8, ctx.strtab.ptr + sym.n_strx), 0);
}
+ /// Returns whether lhs is less than rhs by allocated address in object file.
+ /// Undefined symbols are pushed to the back (always evaluate to true).
fn lessThan(ctx: Context, lhs_index: SymbolAtIndex, rhs_index: SymbolAtIndex) bool {
- // We sort by type: defined < undefined, and
- // afterwards by address in each group. Normally, dysymtab should
- // be enough to guarantee the sort, but turns out not every compiler
- // is kind enough to specify the symbols in the correct order.
const lhs = lhs_index.getSymbol(ctx);
const rhs = rhs_index.getSymbol(ctx);
if (lhs.sect()) {
@@ -215,6 +213,29 @@ const SymbolAtIndex = struct {
return false;
}
}
+
+ /// Returns whether lhs is less senior than rhs. The rules are:
+ /// 1. ext
+ /// 2. weak
+ /// 3. local
+ /// 4. temp (local starting with `l` prefix).
+ fn lessThanBySeniority(ctx: Context, lhs_index: SymbolAtIndex, rhs_index: SymbolAtIndex) bool {
+ const lhs = lhs_index.getSymbol(ctx);
+ const rhs = rhs_index.getSymbol(ctx);
+ if (!rhs.ext()) {
+ const lhs_name = lhs_index.getSymbolName(ctx);
+ return mem.startsWith(u8, lhs_name, "l") or mem.startsWith(u8, lhs_name, "L");
+ } else if (rhs.pext() or rhs.weakDef()) {
+ return !lhs.ext();
+ } else {
+ return false;
+ }
+ }
+
+ /// Like lessThanBySeniority but negated.
+ fn greaterThanBySeniority(ctx: Context, lhs_index: SymbolAtIndex, rhs_index: SymbolAtIndex) bool {
+ return !lessThanBySeniority(ctx, lhs_index, rhs_index);
+ }
};
fn filterSymbolsByAddress(
@@ -295,6 +316,10 @@ pub fn splitIntoAtomsOneShot(
sorted_all_syms.appendAssumeCapacity(.{ .index = @intCast(u32, index) });
}
+ // We sort by type: defined < undefined, and
+ // afterwards by address in each group. Normally, dysymtab should
+ // be enough to guarantee the sort, but turns out not every compiler
+ // is kind enough to specify the symbols in the correct order.
sort.sort(SymbolAtIndex, sorted_all_syms.items, context, SymbolAtIndex.lessThan);
// Well, shit, sometimes compilers skip the dysymtab load command altogether, meaning we
@@ -409,10 +434,18 @@ pub fn splitIntoAtomsOneShot(
);
next_sym_count += atom_syms.len;
+ // We want to bubble up the first externally defined symbol here.
assert(atom_syms.len > 0);
- const sym_index = for (atom_syms) |atom_sym| {
- if (atom_sym.getSymbol(context).ext()) break atom_sym.index;
- } else atom_syms[0].index;
+ var sorted_atom_syms = std.ArrayList(SymbolAtIndex).init(gpa);
+ defer sorted_atom_syms.deinit();
+ try sorted_atom_syms.appendSlice(atom_syms);
+ sort.sort(
+ SymbolAtIndex,
+ sorted_atom_syms.items,
+ context,
+ SymbolAtIndex.greaterThanBySeniority,
+ );
+
const atom_size = blk: {
const end_addr = if (next_sym_count < filtered_syms.len)
filtered_syms[next_sym_count].getSymbol(context).n_value
@@ -432,12 +465,12 @@ pub fn splitIntoAtomsOneShot(
const atom = try self.createAtomFromSubsection(
macho_file,
object_id,
- sym_index,
+ sorted_atom_syms.items[0].index,
atom_size,
atom_align,
atom_code,
relocs,
- atom_syms[1..],
+ sorted_atom_syms.items[1..],
match,
sect,
gc_roots,
@@ -552,12 +585,7 @@ fn createAtomFromSubsection(
// the filtered symbols and note which symbol is contained within so that
// we can properly allocate addresses down the line.
// While we're at it, we need to update segment,section mapping of each symbol too.
- try atom.contained.ensureTotalCapacity(gpa, indexes.len + 1);
- atom.contained.appendAssumeCapacity(.{
- .sym_index = sym_index,
- .offset = 0,
- });
-
+ try atom.contained.ensureTotalCapacity(gpa, indexes.len);
for (indexes) |inner_sym_index| {
const inner_sym = &self.symtab.items[inner_sym_index.index];
inner_sym.n_sect = macho_file.getSectionOrdinal(match);
src/link/MachO.zig
@@ -2940,12 +2940,6 @@ fn createTentativeDefAtoms(self: *MachO) !void {
if (global.file) |file| {
const object = &self.objects.items[file];
-
- try atom.contained.append(gpa, .{
- .sym_index = global.sym_index,
- .offset = 0,
- });
-
try object.managed_atoms.append(gpa, atom);
try object.atom_by_index_table.putNoClobber(gpa, global.sym_index, atom);
} else {
@@ -5594,6 +5588,7 @@ fn gcAtoms(self: *MachO, gc_roots: *std.AutoHashMap(*Atom, void)) !void {
const global = atom.getSymbolWithLoc();
const sym = atom.getSymbolPtr(self);
+ const match = self.getMatchingSectionFromOrdinal(sym.n_sect);
if (sym.n_desc == N_DESC_GCED) continue;
if (!sym.ext()) {
@@ -5605,15 +5600,6 @@ fn gcAtoms(self: *MachO, gc_roots: *std.AutoHashMap(*Atom, void)) !void {
} else continue;
}
- loop = true;
- const match = self.getMatchingSectionFromOrdinal(sym.n_sect);
-
- // TODO don't dedup eh_frame info yet until we actually implement parsing unwind records
- if (match.eql(.{
- .seg = self.text_segment_cmd_index,
- .sect = self.eh_frame_section_index,
- })) continue;
-
self.logAtom(atom);
sym.n_desc = N_DESC_GCED;
self.removeAtomFromSection(atom, match);
@@ -5644,6 +5630,8 @@ fn gcAtoms(self: *MachO, gc_roots: *std.AutoHashMap(*Atom, void)) !void {
const tlv_ptr_sym = tlv_ptr_atom.getSymbolPtr(self);
tlv_ptr_sym.n_desc = N_DESC_GCED;
}
+
+ loop = true;
}
}
}
@@ -6831,7 +6819,6 @@ pub fn generateSymbolStabs(
};
const tu_name = try compile_unit.die.getAttrString(&debug_info.inner, dwarf.AT.name);
const tu_comp_dir = try compile_unit.die.getAttrString(&debug_info.inner, dwarf.AT.comp_dir);
- const source_symtab = object.getSourceSymtab();
// Open scope
try locals.ensureUnusedCapacity(3);
@@ -6857,71 +6844,27 @@ pub fn generateSymbolStabs(
.n_value = object.mtime,
});
+ var stabs_buf: [4]macho.nlist_64 = undefined;
+
for (object.managed_atoms.items) |atom| {
+ const stabs = try self.generateSymbolStabsForSymbol(
+ atom.getSymbolWithLoc(),
+ debug_info,
+ &stabs_buf,
+ );
+ try locals.appendSlice(stabs);
+
for (atom.contained.items) |sym_at_off| {
const sym_loc = SymbolWithLoc{
.sym_index = sym_at_off.sym_index,
.file = atom.file,
};
- const sym = self.getSymbol(sym_loc);
- const sym_name = self.getSymbolName(sym_loc);
- if (sym.n_strx == 0) continue;
- if (sym.n_desc == N_DESC_GCED) continue;
- if (self.symbolIsTemp(sym_loc)) continue;
- if (sym_at_off.sym_index >= source_symtab.len) continue; // synthetic, linker generated
-
- const source_sym = source_symtab[sym_at_off.sym_index];
- const size: ?u64 = size: {
- if (source_sym.tentative()) break :size null;
- for (debug_info.inner.func_list.items) |func| {
- if (func.pc_range) |range| {
- if (source_sym.n_value >= range.start and source_sym.n_value < range.end) {
- break :size range.end - range.start;
- }
- }
- }
- break :size null;
- };
-
- if (size) |ss| {
- try locals.ensureUnusedCapacity(4);
- locals.appendAssumeCapacity(.{
- .n_strx = 0,
- .n_type = macho.N_BNSYM,
- .n_sect = sym.n_sect,
- .n_desc = 0,
- .n_value = sym.n_value,
- });
- locals.appendAssumeCapacity(.{
- .n_strx = try self.strtab.insert(gpa, sym_name),
- .n_type = macho.N_FUN,
- .n_sect = sym.n_sect,
- .n_desc = 0,
- .n_value = sym.n_value,
- });
- locals.appendAssumeCapacity(.{
- .n_strx = 0,
- .n_type = macho.N_FUN,
- .n_sect = 0,
- .n_desc = 0,
- .n_value = ss,
- });
- locals.appendAssumeCapacity(.{
- .n_strx = 0,
- .n_type = macho.N_ENSYM,
- .n_sect = sym.n_sect,
- .n_desc = 0,
- .n_value = ss,
- });
- } else {
- try locals.append(.{
- .n_strx = try self.strtab.insert(gpa, sym_name),
- .n_type = macho.N_STSYM,
- .n_sect = sym.n_sect,
- .n_desc = 0,
- .n_value = sym.n_value,
- });
- }
+ const contained_stabs = try self.generateSymbolStabsForSymbol(
+ sym_loc,
+ debug_info,
+ &stabs_buf,
+ );
+ try locals.appendSlice(contained_stabs);
}
}
@@ -6935,6 +6878,78 @@ pub fn generateSymbolStabs(
});
}
+fn generateSymbolStabsForSymbol(
+ self: *MachO,
+ sym_loc: SymbolWithLoc,
+ debug_info: DebugInfo,
+ buf: *[4]macho.nlist_64,
+) ![]const macho.nlist_64 {
+ const gpa = self.base.allocator;
+ const object = self.objects.items[sym_loc.file.?];
+ const source_symtab = object.getSourceSymtab();
+ const sym = self.getSymbol(sym_loc);
+ const sym_name = self.getSymbolName(sym_loc);
+
+ if (sym.n_strx == 0) return buf[0..0];
+ if (sym.n_desc == N_DESC_GCED) return buf[0..0];
+ if (self.symbolIsTemp(sym_loc)) return buf[0..0];
+ if (sym_loc.sym_index >= source_symtab.len) return buf[0..0]; // synthetic, linker generated
+
+ const source_sym = source_symtab[sym_loc.sym_index];
+ const size: ?u64 = size: {
+ if (source_sym.tentative()) break :size null;
+ for (debug_info.inner.func_list.items) |func| {
+ if (func.pc_range) |range| {
+ if (source_sym.n_value >= range.start and source_sym.n_value < range.end) {
+ break :size range.end - range.start;
+ }
+ }
+ }
+ break :size null;
+ };
+
+ if (size) |ss| {
+ buf[0] = .{
+ .n_strx = 0,
+ .n_type = macho.N_BNSYM,
+ .n_sect = sym.n_sect,
+ .n_desc = 0,
+ .n_value = sym.n_value,
+ };
+ buf[1] = .{
+ .n_strx = try self.strtab.insert(gpa, sym_name),
+ .n_type = macho.N_FUN,
+ .n_sect = sym.n_sect,
+ .n_desc = 0,
+ .n_value = sym.n_value,
+ };
+ buf[2] = .{
+ .n_strx = 0,
+ .n_type = macho.N_FUN,
+ .n_sect = 0,
+ .n_desc = 0,
+ .n_value = ss,
+ };
+ buf[3] = .{
+ .n_strx = 0,
+ .n_type = macho.N_ENSYM,
+ .n_sect = sym.n_sect,
+ .n_desc = 0,
+ .n_value = ss,
+ };
+ return buf;
+ } else {
+ buf[0] = .{
+ .n_strx = try self.strtab.insert(gpa, sym_name),
+ .n_type = macho.N_STSYM,
+ .n_sect = sym.n_sect,
+ .n_desc = 0,
+ .n_value = sym.n_value,
+ };
+ return buf[0..1];
+ }
+}
+
fn snapshotState(self: *MachO) !void {
const emit = self.base.options.emit orelse {
log.debug("no emit directory found; skipping snapshot...", .{});