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elf: claim unresolved dangling symbols as undef externs when emitting object

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This commit is contained in:
Jakub Konka 2023-11-02 11:45:22 +01:00
parent dbe13200f1
commit 7c5c59191e
2 changed files with 97 additions and 12 deletions
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8
src/link/Elf.zig
View File

@ -1523,6 +1523,8 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
pub fn flushObject(self: *Elf, comp: *Compilation) link.File.FlushError!void {
_ = comp;
self.claimUnresolvedObject();
try self.initSections();
try self.sortShdrs();
try self.updateSectionSizes();
@ -1924,6 +1926,12 @@ fn claimUnresolved(self: *Elf) void {
}
}
fn claimUnresolvedObject(self: *Elf) void {
if (self.zigObjectPtr()) |zig_object| {
zig_object.claimUnresolvedObject(self);
}
}
/// In scanRelocs we will go over all live atoms and scan their relocs.
/// This will help us work out what synthetics to emit, GOT indirection, etc.
/// This is also the point where we will report undefined symbols for any

101
src/link/Elf/ZigObject.zig
View File

@ -210,6 +210,8 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf) !void {
self.saveDebugSectionsSizes(elf_file);
}
try self.sortSymbols(elf_file);
// The point of flushModule() is to commit changes, so in theory, nothing should
// be dirty after this. However, it is possible for some things to remain
// dirty because they fail to be written in the event of compile errors,
@ -353,7 +355,7 @@ pub fn resolveSymbols(self: *ZigObject, elf_file: *Elf) void {
}
}
pub fn claimUnresolved(self: *ZigObject, elf_file: *Elf) void {
pub fn claimUnresolved(self: ZigObject, elf_file: *Elf) void {
for (self.globals(), 0..) |index, i| {
const esym_index = @as(Symbol.Index, @intCast(i)) | global_symbol_bit;
const esym = self.global_esyms.items(.elf_sym)[i];
@ -381,6 +383,26 @@ pub fn claimUnresolved(self: *ZigObject, elf_file: *Elf) void {
}
}
pub fn claimUnresolvedObject(self: ZigObject, elf_file: *Elf) void {
for (self.globals(), 0..) |index, i| {
const esym_index = @as(Symbol.Index, @intCast(i)) | global_symbol_bit;
const esym = self.global_esyms.items(.elf_sym)[i];
if (esym.st_shndx != elf.SHN_UNDEF) continue;
const global = elf_file.symbol(index);
if (global.file(elf_file)) |file| {
if (global.elfSym(elf_file).st_shndx != elf.SHN_UNDEF or
file.index() <= self.index) continue;
}
global.value = 0;
global.atom_index = 0;
global.esym_index = esym_index;
global.file_index = self.index;
}
}
pub fn scanRelocs(self: *ZigObject, elf_file: *Elf, undefs: anytype) !void {
for (self.atoms.items) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
@ -414,6 +436,72 @@ pub fn markLive(self: *ZigObject, elf_file: *Elf) void {
}
}
fn sortSymbols(self: *ZigObject, elf_file: *Elf) error{OutOfMemory}!void {
_ = self;
_ = elf_file;
// const Entry = struct {
// index: Symbol.Index,
// const Ctx = struct {
// zobj: ZigObject,
// efile: *Elf,
// };
// pub fn lessThan(ctx: Ctx, lhs: @This(), rhs: @This()) bool {
// const lhs_sym = ctx.efile.symbol(zobj.symbol(lhs.index));
// const rhs_sym = ctx.efile.symbol(zobj.symbol(rhs.index));
// if (lhs_sym.outputShndx() != null and rhs_sym.outputShndx() != null) {
// if (lhs_sym.output_section_index == rhs_sym.output_section_index) {
// if (lhs_sym.value == rhs_sym.value) {
// return lhs_sym.name_offset < rhs_sym.name_offset;
// }
// return lhs_sym.value < rhs_sym.value;
// }
// return lhs_sym.output_section_index < rhs_sym.output_section_index;
// }
// if (lhs_sym.outputShndx() != null) {
// if (rhs_sym.isAbs(ctx.efile)) return false;
// return true;
// }
// return false;
// }
// };
// const gpa = elf_file.base.allocator;
// {
// const sorted = try gpa.alloc(Entry, self.local_symbols.items.len);
// defer gpa.free(sorted);
// for (0..self.local_symbols.items.len) |index| {
// sorted[i] = .{ .index = @as(Symbol.Index, @intCast(index)) };
// }
// mem.sort(Entry, sorted, .{ .zobj = self, .efile = elf_file }, Entry.lessThan);
// const backlinks = try gpa.alloc(Symbol.Index, sorted.len);
// defer gpa.free(backlinks);
// for (sorted, 0..) |entry, i| {
// backlinks[entry.index] = @as(Symbol.Index, @intCast(i));
// }
// const local_symbols = try self.local_symbols.toOwnedSlice(gpa);
// defer gpa.free(local_symbols);
// try self.local_symbols.ensureTotalCapacityPrecise(gpa, local_symbols.len);
// for (sorted) |entry| {
// self.local_symbols.appendAssumeCapacity(local_symbols[entry.index]);
// }
// for (self.)
// }
// const sorted_globals = try gpa.alloc(Entry, self.global_symbols.items.len);
// defer gpa.free(sorted_globals);
// for (self.global_symbols.items, 0..) |index, i| {
// sorted_globals[i] = .{ .index = index };
// }
// mem.sort(Entry, sorted_globals, elf_file, Entry.lessThan);
}
pub fn updateRelaSectionSizes(self: ZigObject, elf_file: *Elf) void {
_ = self;
@ -451,16 +539,6 @@ pub fn updateRelaSectionSizes(self: ZigObject, elf_file: *Elf) void {
pub fn writeRelaSections(self: ZigObject, elf_file: *Elf) !void {
const gpa = elf_file.base.allocator;
// const getSectionSymbol = struct {
// fn getSectionSymbol(zig_object: ZigObject, shndx: u16, ctx: *Elf) Symbol.Index {
// for (zig_object.locals()) |local_index| {
// const local = ctx.symbol(local_index);
// if (local.type(ctx) == elf.STT_SECTION and local.output_section_index == shndx)
// return local.esym_index;
// } else unreachable;
// }
// }.getSectionSymbol;
for (&[_]?u16{
elf_file.zig_text_rela_section_index,
elf_file.zig_data_rel_ro_rela_section_index,
@ -485,7 +563,6 @@ pub fn writeRelaSections(self: ZigObject, elf_file: *Elf) !void {
(target.esym_index & symbol_mask) + @as(u32, @intCast(self.local_esyms.slice().len))
else
target.esym_index;
// getSectionSymbol(self, target.outputShndx().?, elf_file);
const r_type = switch (rel.r_type()) {
Elf.R_X86_64_ZIG_GOT32,
Elf.R_X86_64_ZIG_GOTPCREL,