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macho: clean up allocating atom logic

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Instead of checking for stage1 at every callsite, move the logic
inside `allocateAtom`. This is fine since this logic will disappear
anyhow once I add expanding and shifting segments and sections.
This commit is contained in:
Jakub Konka
2021-09-01 11:55:32 +02:00
parent d0dc622638
commit 7a99cd069a
3 changed files with 90 additions and 163 deletions
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188
src/link/MachO.zig
View File

@@ -760,27 +760,6 @@ pub fn flush(self: *MachO, comp: *Compilation) !void {
try self.addCodeSignatureLC();
if (use_stage1) {
{
const atom = try self.createDyldPrivateAtom();
try self.allocateAtomStage1(atom, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.data_section_index.?,
});
}
{
const atom = try self.createStubHelperPreambleAtom();
try self.allocateAtomStage1(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
});
// TODO this is just a temp
// We already prealloc stub helper size in populateMissingMetadata(), but
// perhaps it's not needed after all?
const seg = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[self.stub_helper_section_index.?];
sect.size -= atom.size;
}
try self.parseTextBlocks();
try self.allocateTextSegment();
try self.allocateDataConstSegment();
@@ -1919,55 +1898,70 @@ pub fn createEmptyAtom(self: *MachO, local_sym_index: u32, size: u64, alignment:
pub fn allocateAtom(self: *MachO, atom: *TextBlock, match: MatchingSection) !u64 {
const seg = &self.load_commands.items[match.seg].Segment;
const sect = &seg.sections.items[match.sect];
const sym = &self.locals.items[atom.local_sym_index];
const use_stage1 = build_options.is_stage1 and self.base.options.use_stage1;
var atom_placement: ?*TextBlock = null;
const vaddr = outer: {
if (!use_stage1) {
const sym = &self.locals.items[atom.local_sym_index];
// TODO converge with `allocateTextBlock` and handle free list
const vaddr = if (self.blocks.get(match)) |last| blk: {
const last_atom_sym = self.locals.items[last.local_sym_index];
const ideal_capacity = padToIdeal(last.size);
const ideal_capacity_end_vaddr = last_atom_sym.n_value + ideal_capacity;
const last_atom_alignment = try math.powi(u32, 2, atom.alignment);
const new_start_vaddr = mem.alignForwardGeneric(u64, ideal_capacity_end_vaddr, last_atom_alignment);
atom_placement = last;
break :blk new_start_vaddr;
} else sect.addr;
var atom_placement: ?*TextBlock = null;
log.debug("allocating atom for symbol {s} at address 0x{x}", .{ self.getString(sym.n_strx), vaddr });
// TODO converge with `allocateTextBlock` and handle free list
const vaddr = if (self.blocks.get(match)) |last| blk: {
const last_atom_sym = self.locals.items[last.local_sym_index];
const ideal_capacity = padToIdeal(last.size);
const ideal_capacity_end_vaddr = last_atom_sym.n_value + ideal_capacity;
const last_atom_alignment = try math.powi(u32, 2, atom.alignment);
const new_start_vaddr = mem.alignForwardGeneric(u64, ideal_capacity_end_vaddr, last_atom_alignment);
atom_placement = last;
break :blk new_start_vaddr;
} else sect.addr;
const expand_section = atom_placement == null or atom_placement.?.next == null;
if (expand_section) {
const needed_size = (vaddr + atom.size) - sect.addr;
const end_addr = blk: {
const next_ordinal = self.section_ordinals.getIndex(match).?; // Ordinals are +1 to begin with.
const end_addr = if (self.section_ordinals.keys().len > next_ordinal) inner: {
const next_match = self.section_ordinals.keys()[next_ordinal];
const next_seg = self.load_commands.items[next_match.seg].Segment;
const next_sect = next_seg.sections.items[next_match.sect];
break :inner next_sect.addr;
} else seg.inner.filesize;
break :blk end_addr;
};
assert(needed_size <= end_addr); // TODO must expand the section
}
const n_sect = @intCast(u8, self.section_ordinals.getIndex(match).? + 1);
sym.n_value = vaddr;
sym.n_sect = n_sect;
log.debug("allocating atom for symbol {s} at address 0x{x}", .{ self.getString(sym.n_strx), vaddr });
// Update each alias (if any)
for (atom.aliases.items) |index| {
const alias_sym = &self.locals.items[index];
alias_sym.n_value = vaddr;
alias_sym.n_sect = n_sect;
}
const expand_section = atom_placement == null or atom_placement.?.next == null;
if (expand_section) {
const needed_size = (vaddr + atom.size) - sect.addr;
const end_addr = blk: {
const next_ordinal = self.section_ordinals.getIndex(match).?; // Ordinals are +1 to begin with.
const end_addr = if (self.section_ordinals.keys().len > next_ordinal) inner: {
const next_match = self.section_ordinals.keys()[next_ordinal];
const next_seg = self.load_commands.items[next_match.seg].Segment;
const next_sect = next_seg.sections.items[next_match.sect];
break :inner next_sect.addr;
} else seg.inner.filesize;
break :blk end_addr;
};
assert(needed_size <= end_addr); // TODO must expand the section
}
const n_sect = @intCast(u8, self.section_ordinals.getIndex(match).? + 1);
sym.n_value = vaddr;
sym.n_sect = n_sect;
// Update each symbol contained within the TextBlock
for (atom.contained.items) |sym_at_off| {
const contained_sym = &self.locals.items[sym_at_off.local_sym_index];
contained_sym.n_value = vaddr + sym_at_off.offset;
contained_sym.n_sect = n_sect;
}
// Update each alias (if any)
for (atom.aliases.items) |index| {
const alias_sym = &self.locals.items[index];
alias_sym.n_value = vaddr;
alias_sym.n_sect = n_sect;
}
// Update each symbol contained within the TextBlock
for (atom.contained.items) |sym_at_off| {
const contained_sym = &self.locals.items[sym_at_off.local_sym_index];
contained_sym.n_value = vaddr + sym_at_off.offset;
contained_sym.n_sect = n_sect;
}
break :outer vaddr;
} else {
const new_alignment = math.max(sect.@"align", atom.alignment);
const new_alignment_pow_2 = try math.powi(u32, 2, new_alignment);
const new_size = mem.alignForwardGeneric(u64, sect.size, new_alignment_pow_2) + atom.size;
sect.size = new_size;
sect.@"align" = new_alignment;
break :outer 0;
}
};
if (self.blocks.getPtr(match)) |last| {
last.*.next = atom;
@@ -2017,27 +2011,6 @@ fn allocateGlobalSymbols(self: *MachO) !void {
}
}
pub fn allocateAtomStage1(self: *MachO, atom: *TextBlock, match: MatchingSection) !void {
// Update target section's metadata
// TODO should we update segment's size here too?
// How does it tie with incremental space allocs?
const tseg = &self.load_commands.items[match.seg].Segment;
const tsect = &tseg.sections.items[match.sect];
const new_alignment = math.max(tsect.@"align", atom.alignment);
const new_alignment_pow_2 = try math.powi(u32, 2, new_alignment);
const new_size = mem.alignForwardGeneric(u64, tsect.size, new_alignment_pow_2) + atom.size;
tsect.size = new_size;
tsect.@"align" = new_alignment;
if (self.blocks.getPtr(match)) |last| {
last.*.next = atom;
atom.prev = last.*;
last.* = atom;
} else {
try self.blocks.putNoClobber(self.base.allocator, match, atom);
}
}
fn writeAtoms(self: *MachO) !void {
var it = self.blocks.iterator();
while (it.next()) |entry| {
@@ -2607,8 +2580,6 @@ fn resolveSymbolsInObject(
}
fn resolveSymbols(self: *MachO) !void {
const use_stage1 = build_options.is_stage1 and self.base.options.use_stage1;
var tentatives = std.AutoArrayHashMap(u32, void).init(self.base.allocator);
defer tentatives.deinit();
@@ -2668,27 +2639,23 @@ fn resolveSymbols(self: *MachO) !void {
resolv.local_sym_index = local_sym_index;
const atom = try self.createEmptyAtom(local_sym_index, size, alignment);
if (use_stage1) {
try self.allocateAtomStage1(atom, match);
}
_ = try self.allocateAtom(atom, match);
}
try self.resolveDyldStubBinder();
if (!use_stage1) {
{
const atom = try self.createDyldPrivateAtom();
_ = try self.allocateAtom(atom, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.data_section_index.?,
});
}
{
const atom = try self.createStubHelperPreambleAtom();
_ = try self.allocateAtom(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
});
}
{
const atom = try self.createDyldPrivateAtom();
_ = try self.allocateAtom(atom, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.data_section_index.?,
});
}
{
const atom = try self.createStubHelperPreambleAtom();
_ = try self.allocateAtom(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
});
}
// Third pass, resolve symbols in dynamic libraries.
@@ -2800,9 +2767,7 @@ fn resolveSymbols(self: *MachO) !void {
// TODO perhaps we should special-case special symbols? Create a separate
// linked list of atoms?
const atom = try self.createEmptyAtom(local_sym_index, 0, 0);
if (use_stage1) {
try self.allocateAtomStage1(atom, match);
}
_ = try self.allocateAtom(atom, match);
}
for (self.unresolved.keys()) |index| {
@@ -2869,12 +2834,7 @@ fn resolveDyldStubBinder(self: *MachO) !void {
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
};
// TODO remove once we can incrementally update in stage1 too.
if (!(build_options.is_stage1 and self.base.options.use_stage1)) {
_ = try self.allocateAtom(atom, match);
} else {
try self.allocateAtomStage1(atom, match);
}
_ = try self.allocateAtom(atom, match);
self.binding_info_dirty = true;
}

19
src/link/MachO/Object.zig
View File

@@ -453,7 +453,6 @@ pub fn parseTextBlocks(
object_id: u16,
macho_file: *MachO,
) !void {
const use_stage1 = build_options.is_stage1 and macho_file.base.options.use_stage1;
const seg = self.load_commands.items[self.segment_cmd_index.?].Segment;
log.debug("analysing {s}", .{self.name});
@@ -590,11 +589,7 @@ pub fn parseTextBlocks(
}
}
if (use_stage1) {
try macho_file.allocateAtomStage1(block, match);
} else {
_ = try macho_file.allocateAtom(block, match);
}
_ = try macho_file.allocateAtom(block, match);
try self.text_blocks.append(allocator, block);
}
@@ -641,11 +636,7 @@ pub fn parseTextBlocks(
}
}
if (use_stage1) {
try macho_file.allocateAtomStage1(block, match);
} else {
_ = try macho_file.allocateAtom(block, match);
}
_ = try macho_file.allocateAtom(block, match);
try self.text_blocks.append(allocator, block);
}
@@ -734,11 +725,7 @@ pub fn parseTextBlocks(
});
}
if (use_stage1) {
try macho_file.allocateAtomStage1(block, match);
} else {
_ = try macho_file.allocateAtom(block, match);
}
_ = try macho_file.allocateAtom(block, match);
try self.text_blocks.append(allocator, block);
}
}

46
src/link/MachO/TextBlock.zig
View File

@@ -843,11 +843,7 @@ pub fn parseRelocs(self: *TextBlock, relocs: []macho.relocation_info, context: R
.seg = context.macho_file.data_const_segment_cmd_index.?,
.sect = context.macho_file.got_section_index.?,
};
if (!(build_options.is_stage1 and context.macho_file.base.options.use_stage1)) {
_ = try context.macho_file.allocateAtom(atom, match);
} else {
try context.macho_file.allocateAtomStage1(atom, match);
}
_ = try context.macho_file.allocateAtom(atom, match);
} else if (parsed_rel.payload == .unsigned) {
switch (parsed_rel.where) {
.undef => {
@@ -910,34 +906,18 @@ pub fn parseRelocs(self: *TextBlock, relocs: []macho.relocation_info, context: R
);
const stub_atom = try context.macho_file.createStubAtom(laptr_atom.local_sym_index);
try context.macho_file.stubs_map.putNoClobber(context.allocator, parsed_rel.where_index, stub_atom);
if (build_options.is_stage1 and context.macho_file.base.options.use_stage1) {
try context.macho_file.allocateAtomStage1(stub_helper_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stub_helper_section_index.?,
});
try context.macho_file.allocateAtomStage1(laptr_atom, .{
.seg = context.macho_file.data_segment_cmd_index.?,
.sect = context.macho_file.la_symbol_ptr_section_index.?,
});
try context.macho_file.allocateAtomStage1(stub_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stubs_section_index.?,
});
} else {
_ = try context.macho_file.allocateAtom(stub_helper_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stub_helper_section_index.?,
});
_ = try context.macho_file.allocateAtom(laptr_atom, .{
.seg = context.macho_file.data_segment_cmd_index.?,
.sect = context.macho_file.la_symbol_ptr_section_index.?,
});
_ = try context.macho_file.allocateAtom(stub_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stubs_section_index.?,
});
}
_ = try context.macho_file.allocateAtom(stub_helper_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stub_helper_section_index.?,
});
_ = try context.macho_file.allocateAtom(laptr_atom, .{
.seg = context.macho_file.data_segment_cmd_index.?,
.sect = context.macho_file.la_symbol_ptr_section_index.?,
});
_ = try context.macho_file.allocateAtom(stub_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stubs_section_index.?,
});
}
}
}