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elf: move ownership of ComdatGroups into objects
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@kubkon
kubkon committed Sep 9, 2024
1 parent dc6c8db commit 6aba6f3
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Showing 5 changed files with 157 additions and 138 deletions.
120 changes: 46 additions & 74 deletions src/Elf.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -91,10 +91,6 @@ thunks: std.ArrayListUnmanaged(Thunk) = .{},
merge_sections: std.ArrayListUnmanaged(MergeSection) = .{},
merge_subsections: std.ArrayListUnmanaged(MergeSubsection) = .{},

comdat_groups: std.ArrayListUnmanaged(ComdatGroup) = .{},
comdat_groups_owners: std.ArrayListUnmanaged(ComdatGroupOwner) = .{},
comdat_groups_table: std.AutoHashMapUnmanaged(u32, ComdatGroupOwner.Index) = .{},

has_text_reloc: bool = false,
num_ifunc_dynrelocs: usize = 0,
default_sym_version: elf.Elf64_Versym,
Expand Down Expand Up @@ -154,9 +150,6 @@ pub fn deinit(self: *Elf) void {
}
self.merge_sections.deinit(gpa);
self.merge_subsections.deinit(gpa);
self.comdat_groups.deinit(gpa);
self.comdat_groups_owners.deinit(gpa);
self.comdat_groups_table.deinit(gpa);
self.symbols.deinit(gpa);
self.symbols_extra.deinit(gpa);
self.globals.deinit(gpa);
Expand Down Expand Up @@ -2046,34 +2039,17 @@ fn resolveSymbols(self: *Elf) !void {
} else i += 1;
}

// Dedup comdat groups.
for (self.objects.items) |index| {
const object = self.getFile(index).?.object;
for (object.comdat_groups.items) |cg_index| {
const cg = self.getComdatGroup(cg_index);
const cg_owner = self.getComdatGroupOwner(cg.owner);
const owner_file_index = if (self.getFile(cg_owner.file)) |file|
file.object.index
else
std.math.maxInt(File.Index);
cg_owner.file = @min(owner_file_index, index);
{
// Dedup comdat groups.
var table = std.StringHashMap(Ref).init(self.base.allocator);
defer table.deinit();

for (self.objects.items) |index| {
try self.getFile(index).?.object.resolveComdatGroups(self, &table);
}
}

for (self.objects.items) |index| {
const object = self.getFile(index).?.object;
for (object.comdat_groups.items) |cg_index| {
const cg = self.getComdatGroup(cg_index);
const cg_owner = self.getComdatGroupOwner(cg.owner);
if (cg_owner.file != index) {
for (cg.getComdatGroupMembers(self)) |shndx| {
const atom_index = object.atoms.items[shndx];
if (self.getAtom(atom_index)) |atom| {
atom.flags.alive = false;
atom.markFdesDead(self);
}
}
}
for (self.objects.items) |index| {
self.getFile(index).?.object.markComdatGroupsDead(self);
}
}

Expand Down Expand Up @@ -3019,40 +2995,8 @@ pub fn getMergeSection(self: *Elf, index: MergeSection.Index) *MergeSection {
return &self.merge_sections.items[index];
}

const GetOrCreateComdatGroupOwnerResult = struct {
found_existing: bool,
index: ComdatGroupOwner.Index,
};

pub fn getOrCreateComdatGroupOwner(self: *Elf, off: u32) !GetOrCreateComdatGroupOwnerResult {
const gpa = self.base.allocator;
const gop = try self.comdat_groups_table.getOrPut(gpa, off);
if (!gop.found_existing) {
const index = @as(ComdatGroupOwner.Index, @intCast(self.comdat_groups_owners.items.len));
const owner = try self.comdat_groups_owners.addOne(gpa);
owner.* = .{};
gop.value_ptr.* = index;
}
return .{
.found_existing = gop.found_existing,
.index = gop.value_ptr.*,
};
}

pub fn addComdatGroup(self: *Elf) !ComdatGroup.Index {
const index = @as(ComdatGroup.Index, @intCast(self.comdat_groups.items.len));
_ = try self.comdat_groups.addOne(self.base.allocator);
return index;
}

pub inline fn getComdatGroup(self: *Elf, index: ComdatGroup.Index) *ComdatGroup {
assert(index < self.comdat_groups.items.len);
return &self.comdat_groups.items[index];
}

pub inline fn getComdatGroupOwner(self: *Elf, index: ComdatGroupOwner.Index) *ComdatGroupOwner {
assert(index < self.comdat_groups_owners.items.len);
return &self.comdat_groups_owners.items[index];
pub fn getComdatGroup(self: *Elf, ref: Ref) *ComdatGroup {
return self.getFile(ref.file).?.getComdatGroup(ref.index);
}

const RelaDyn = struct {
Expand Down Expand Up @@ -3294,7 +3238,12 @@ fn fmtDumpState(
try writer.print("merge_sect({d}) : {}\n", .{ index, msec.fmt(self) });
}
try writer.writeByte('\n');
try writer.writeAll("Output sections\n");
try writer.writeAll("Output COMDAT groups\n");
for (self.comdat_group_sections.items) |cg| {
try writer.print(" shdr({d}) : COMDAT({})\n", .{ cg.shndx, cg.cg_ref });
}
try writer.writeByte('\n');
try writer.writeAll("Output shdrs\n");
try writer.print("{}\n", .{self.fmtSections()});
try writer.writeAll("Output phdrs\n");
try writer.print("{}\n", .{self.fmtPhdrs()});
Expand All @@ -3313,21 +3262,44 @@ const Section = struct {
sym_index: u32 = 0,
};

const ComdatGroupOwner = struct {
file: File.Index = 0,
pub const Ref = struct {
index: u32 = 0,
file: u32 = 0,

pub fn eql(ref: Ref, other: Ref) bool {
return ref.index == other.index and ref.file == other.file;
}

const Index = u32;
pub fn format(
ref: Ref,
comptime unused_fmt_string: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = unused_fmt_string;
_ = options;
try writer.print("ref({},{})", .{ ref.index, ref.file });
}
};

pub const ComdatGroup = struct {
owner: ComdatGroupOwner.Index,
file: File.Index,
signature_off: u32,
file_index: File.Index,
shndx: u32,
members_start: u32,
members_len: u32,
alive: bool = true,

pub fn getFile(cg: ComdatGroup, elf_file: *Elf) File {
return elf_file.getFile(cg.file_index).?;
}

pub fn getSignature(cg: ComdatGroup, elf_file: *Elf) [:0]const u8 {
return cg.getFile(elf_file).object.getString(cg.signature_off);
}

pub fn getComdatGroupMembers(cg: ComdatGroup, elf_file: *Elf) []const u32 {
const object = elf_file.getFile(cg.file).?.object;
const object = cg.getFile(elf_file).object;
return object.comdat_group_data.items[cg.members_start..][0..cg.members_len];
}

Expand Down
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