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macho: refactor management of section ordinals

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Instead of storing a two-way relation (seg,sect) <=> ordinal
we get the latter with `getIndex((seg, sect))`.
This commit is contained in:
Jakub Konka 2021-08-02 18:15:27 +02:00
parent f3b328ee8c
commit bf25650974
3 changed files with 26 additions and 45 deletions
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55
src/link/MachO.zig
View File

@ -168,8 +168,7 @@ strtab_needs_relocation: bool = false,
has_dices: bool = false,
has_stabs: bool = false,
section_ordinals: std.ArrayListUnmanaged(MatchingSection) = .{},
section_to_ordinal: std.AutoHashMapUnmanaged(MatchingSection, u8) = .{},
section_ordinals: std.AutoArrayHashMapUnmanaged(MatchingSection, void) = .{},
pending_updates: std.ArrayListUnmanaged(struct {
kind: enum {
@ -940,13 +939,6 @@ fn linkWithZld(self: *MachO, comp: *Compilation) !void {
});
try self.strtab.append(self.base.allocator, 0);
// Initialize section ordinals with null ordinal pointing at
// PAGEZERO segment.
try self.section_ordinals.append(self.base.allocator, .{
.seg = 0,
.sect = 0,
});
try self.populateMetadata();
try self.parseInputFiles(positionals.items, self.base.options.sysroot);
try self.parseLibs(libs.items, self.base.options.sysroot);
@ -1454,7 +1446,7 @@ pub fn getMatchingSection(self: *MachO, sect: macho.section_64) !?MatchingSectio
};
if (res) |match| {
try self.createSectionOrdinal(match);
_ = try self.section_ordinals.getOrPut(self.base.allocator, match);
}
return res;
@ -1586,32 +1578,29 @@ fn sortSections(self: *MachO) !void {
{
// Create new section ordinals.
self.section_ordinals.clearRetainingCapacity();
self.section_to_ordinal.clearRetainingCapacity();
// First ordinal is always null
self.section_ordinals.appendAssumeCapacity(.{
.seg = 0,
.sect = 0,
});
const text_seg = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
for (text_seg.sections.items) |_, sect_id| {
try self.createSectionOrdinal(.{
const res = self.section_ordinals.getOrPutAssumeCapacity(.{
.seg = self.text_segment_cmd_index.?,
.sect = @intCast(u16, sect_id),
});
assert(!res.found_existing);
}
const data_const_seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
for (data_const_seg.sections.items) |_, sect_id| {
try self.createSectionOrdinal(.{
const res = self.section_ordinals.getOrPutAssumeCapacity(.{
.seg = self.data_const_segment_cmd_index.?,
.sect = @intCast(u16, sect_id),
});
assert(!res.found_existing);
}
const data_seg = self.load_commands.items[self.data_segment_cmd_index.?].Segment;
for (data_seg.sections.items) |_, sect_id| {
try self.createSectionOrdinal(.{
const res = self.section_ordinals.getOrPutAssumeCapacity(.{
.seg = self.data_segment_cmd_index.?,
.sect = @intCast(u16, sect_id),
});
assert(!res.found_existing);
}
}
}
@ -1740,7 +1729,7 @@ fn allocateTextBlocks(self: *MachO) !void {
const sect = seg.sections.items[match.sect];
var base_addr: u64 = sect.addr;
const n_sect = self.section_to_ordinal.get(match) orelse unreachable;
const n_sect = @intCast(u8, self.section_ordinals.getIndex(match).? + 1);
log.debug(" within section {s},{s}", .{ commands.segmentName(sect), commands.sectionName(sect) });
log.debug(" {}", .{sect});
@ -2262,7 +2251,7 @@ fn resolveSymbols(self: *MachO) !void {
.sect = self.common_section_index.?,
};
};
try self.createSectionOrdinal(match);
_ = try self.section_ordinals.getOrPut(self.base.allocator, match);
const size = sym.n_value;
const code = try self.base.allocator.alloc(u8, size);
@ -2275,7 +2264,7 @@ fn resolveSymbols(self: *MachO) !void {
var nlist = macho.nlist_64{
.n_strx = sym.n_strx,
.n_type = macho.N_SECT,
.n_sect = self.section_to_ordinal.get(match) orelse unreachable,
.n_sect = @intCast(u8, self.section_ordinals.getIndex(match).? + 1),
.n_desc = 0,
.n_value = 0,
};
@ -2391,7 +2380,7 @@ fn resolveSymbols(self: *MachO) !void {
var nlist = macho.nlist_64{
.n_strx = undef.n_strx,
.n_type = macho.N_SECT,
.n_sect = self.section_to_ordinal.get(match) orelse unreachable,
.n_sect = @intCast(u8, self.section_ordinals.getIndex(match).? + 1),
.n_desc = 0,
.n_value = 0,
};
@ -2487,7 +2476,7 @@ fn populateMetadata(self: *MachO) !void {
.@"align" = alignment,
.flags = macho.S_REGULAR | macho.S_ATTR_PURE_INSTRUCTIONS | macho.S_ATTR_SOME_INSTRUCTIONS,
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.text_section_index.?,
});
@ -2511,7 +2500,7 @@ fn populateMetadata(self: *MachO) !void {
.flags = macho.S_SYMBOL_STUBS | macho.S_ATTR_PURE_INSTRUCTIONS | macho.S_ATTR_SOME_INSTRUCTIONS,
.reserved2 = stub_size,
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stubs_section_index.?,
});
@ -2535,7 +2524,7 @@ fn populateMetadata(self: *MachO) !void {
.@"align" = alignment,
.flags = macho.S_REGULAR | macho.S_ATTR_PURE_INSTRUCTIONS | macho.S_ATTR_SOME_INSTRUCTIONS,
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
});
@ -2558,7 +2547,7 @@ fn populateMetadata(self: *MachO) !void {
.@"align" = 3, // 2^3 = @sizeOf(u64)
.flags = macho.S_NON_LAZY_SYMBOL_POINTERS,
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
});
@ -2581,7 +2570,7 @@ fn populateMetadata(self: *MachO) !void {
.@"align" = 3, // 2^3 = @sizeOf(u64)
.flags = macho.S_LAZY_SYMBOL_POINTERS,
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.la_symbol_ptr_section_index.?,
});
@ -2593,7 +2582,7 @@ fn populateMetadata(self: *MachO) !void {
try data_seg.addSection(self.base.allocator, "__data", .{
.@"align" = 3, // 2^3 = @sizeOf(u64)
});
try self.createSectionOrdinal(.{
_ = try self.section_ordinals.getOrPut(self.base.allocator, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.data_section_index.?,
});
@ -3324,7 +3313,6 @@ pub fn deinit(self: *MachO) void {
}
self.section_ordinals.deinit(self.base.allocator);
self.section_to_ordinal.deinit(self.base.allocator);
self.pending_updates.deinit(self.base.allocator);
self.got_entries.deinit(self.base.allocator);
self.got_entries_map.deinit(self.base.allocator);
@ -5882,13 +5870,6 @@ pub fn findFirst(comptime T: type, haystack: []T, start: usize, predicate: anyty
return i;
}
fn createSectionOrdinal(self: *MachO, match: MatchingSection) !void {
if (self.section_to_ordinal.contains(match)) return;
const ordinal = @intCast(u8, self.section_ordinals.items.len);
try self.section_ordinals.append(self.base.allocator, match);
try self.section_to_ordinal.putNoClobber(self.base.allocator, match, ordinal);
}
fn printSymtabAndTextBlock(self: *MachO) void {
log.debug("locals", .{});
for (self.locals.items) |sym, id| {

10
src/link/MachO/Object.zig
View File

@ -402,7 +402,7 @@ const TextBlockParser = struct {
const senior_nlist = aliases.pop();
const senior_sym = &context.macho_file.locals.items[senior_nlist.index];
senior_sym.n_sect = context.macho_file.section_to_ordinal.get(context.match) orelse unreachable;
senior_sym.n_sect = @intCast(u8, context.macho_file.section_ordinals.getIndex(context.match).? + 1);
const start_addr = senior_nlist.nlist.n_value - self.section.addr;
const end_addr = if (next_nlist) |n| n.nlist.n_value - self.section.addr else self.section.size;
@ -446,7 +446,7 @@ const TextBlockParser = struct {
for (aliases.items) |alias| {
block.aliases.appendAssumeCapacity(alias.index);
const sym = &context.macho_file.locals.items[alias.index];
sym.n_sect = context.macho_file.section_to_ordinal.get(context.match) orelse unreachable;
sym.n_sect = @intCast(u8, context.macho_file.section_ordinals.getIndex(context.match).? + 1);
}
try block.parseRelocs(self.relocs, .{
@ -588,7 +588,7 @@ pub fn parseTextBlocks(
try macho_file.locals.append(allocator, .{
.n_strx = try macho_file.makeString(sym_name),
.n_type = macho.N_SECT,
.n_sect = macho_file.section_to_ordinal.get(match) orelse unreachable,
.n_sect = @intCast(u8, macho_file.section_ordinals.getIndex(match).? + 1),
.n_desc = 0,
.n_value = sect.addr,
});
@ -733,7 +733,7 @@ pub fn parseTextBlocks(
try macho_file.locals.append(allocator, .{
.n_strx = try macho_file.makeString(sym_name),
.n_type = macho.N_SECT,
.n_sect = macho_file.section_to_ordinal.get(match) orelse unreachable,
.n_sect = @intCast(u8, macho_file.section_ordinals.getIndex(match).? + 1),
.n_desc = 0,
.n_value = sect.addr,
});
@ -781,7 +781,7 @@ pub fn parseTextBlocks(
const nlist = nlist_with_index.nlist;
const local_sym_index = self.symbol_mapping.get(nlist_with_index.index) orelse unreachable;
const local = &macho_file.locals.items[local_sym_index];
local.n_sect = macho_file.section_to_ordinal.get(match) orelse unreachable;
local.n_sect = @intCast(u8, macho_file.section_ordinals.getIndex(match).? + 1);
const stab: ?TextBlock.Stab = if (self.debug_info) |di| blk: {
// TODO there has to be a better to handle this.

6
src/link/MachO/TextBlock.zig
View File

@ -637,7 +637,7 @@ fn initRelocFromObject(rel: macho.relocation_info, context: RelocContext) !Reloc
try context.macho_file.locals.append(context.allocator, .{
.n_strx = try context.macho_file.makeString(sym_name),
.n_type = macho.N_SECT,
.n_sect = context.macho_file.section_to_ordinal.get(match) orelse unreachable,
.n_sect = @intCast(u8, context.macho_file.section_ordinals.getIndex(match).? + 1),
.n_desc = 0,
.n_value = sect.addr,
});
@ -844,7 +844,7 @@ pub fn parseRelocs(self: *TextBlock, relocs: []macho.relocation_info, context: R
},
.local => {
const source_sym = context.macho_file.locals.items[self.local_sym_index];
const match = context.macho_file.section_ordinals.items[source_sym.n_sect];
const match = context.macho_file.section_ordinals.keys()[source_sym.n_sect - 1];
const seg = context.macho_file.load_commands.items[match.seg].Segment;
const sect = seg.sections.items[match.sect];
const sect_type = commands.sectionType(sect);
@ -1108,7 +1108,7 @@ pub fn resolveRelocs(self: *TextBlock, macho_file: *MachO) !void {
const sym = macho_file.locals.items[rel.where_index];
const is_tlv = is_tlv: {
const source_sym = macho_file.locals.items[self.local_sym_index];
const match = macho_file.section_ordinals.items[source_sym.n_sect];
const match = macho_file.section_ordinals.keys()[source_sym.n_sect - 1];
const seg = macho_file.load_commands.items[match.seg].Segment;
const sect = seg.sections.items[match.sect];
break :is_tlv commands.sectionType(sect) == macho.S_THREAD_LOCAL_VARIABLES;