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elf: add simplistic symbol resolution

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This commit is contained in:
Jakub Konka 2023-09-12 14:36:55 +02:00
parent 53c3757c00
commit 962b46148d
6 changed files with 63 additions and 45 deletions
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17
src/link/Elf.zig
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@ -1045,6 +1045,9 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
try self.addLinkerDefinedSymbols();
// Resolve symbols
self.resolveSymbols();
if (self.unresolved.keys().len > 0) try self.reportUndefined();
self.allocateLinkerDefinedSymbols();
@ -1321,6 +1324,18 @@ fn parseObject(self: *Elf, in_file: std.fs.File, path: []const u8, ctx: *ParseEr
if (ctx.detected_cpu_arch != self.base.options.target.cpu.arch) return error.InvalidCpuArch;
}
fn resolveSymbols(self: *Elf) void {
if (self.zig_module_index) |index| {
const zig_module = self.file(index).?.zig_module;
zig_module.resolveSymbols(self);
}
for (self.objects.items) |index| {
const object = self.file(index).?.object;
object.resolveSymbols(self);
}
}
fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !void {
const tracy = trace(@src());
defer tracy.end();
@ -2697,7 +2712,7 @@ pub fn updateDeclExports(
const name_off = try self.strtab.insert(gpa, exp_name);
const esym = &zig_module.global_esyms.items[sym_index];
esym.st_value = decl_sym.value;
esym.st_shndx = decl_sym.output_section_index;
esym.st_shndx = decl_sym.atom_index;
esym.st_info = (stb_bits << 4) | stt_bits;
esym.st_name = name_off;

4
src/link/Elf/Atom.zig
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@ -17,7 +17,7 @@ alignment: u8 = 0,
input_section_index: Index = 0,
/// Index of the output section.
output_section_index: u16 = 0,
output_section_index: Index = 0,
/// Index of the input section containing this atom's relocs.
relocs_section_index: Index = 0,
@ -484,7 +484,7 @@ fn format2(
}
}
pub const Index = u32;
pub const Index = u16;
const std = @import("std");
const assert = std.debug.assert;

37
src/link/Elf/Object.zig
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@ -245,10 +245,6 @@ fn initSymtab(self: *Object, elf_file: *Elf) !void {
const off = try elf_file.strtab.insert(gpa, name);
const gop = try elf_file.getOrPutGlobal(off);
self.symbols.addOneAssumeCapacity().* = gop.index;
if (sym.st_shndx == elf.SHN_UNDEF) {
try elf_file.unresolved.put(gpa, gop.index, {});
}
}
}
@ -388,34 +384,29 @@ pub fn scanRelocs(self: *Object, elf_file: *Elf) !void {
pub fn resolveSymbols(self: *Object, elf_file: *Elf) void {
const first_global = self.first_global orelse return;
for (self.globals(), 0..) |index, i| {
const sym_idx = @as(u32, @intCast(first_global + i));
const this_sym = self.symtab[sym_idx];
const esym_index = @as(Symbol.Index, @intCast(first_global + i));
const esym = self.symtab[esym_index];
if (this_sym.st_shndx == elf.SHN_UNDEF) continue;
if (esym.st_shndx == elf.SHN_UNDEF) continue;
if (this_sym.st_shndx != elf.SHN_ABS and this_sym.st_shndx != elf.SHN_COMMON) {
const atom_index = self.atoms.items[this_sym.st_shndx];
if (esym.st_shndx != elf.SHN_ABS and esym.st_shndx != elf.SHN_COMMON) {
const atom_index = self.atoms.items[esym.st_shndx];
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
}
_ = elf_file.unresolved.swapRemove(index);
const global = elf_file.symbol(index);
if (self.asFile().symbolRank(this_sym, !self.alive) < global.symbolRank(elf_file)) {
const atom = switch (this_sym.st_shndx) {
if (self.asFile().symbolRank(esym, !self.alive) < global.symbolRank(elf_file)) {
const atom_index = switch (esym.st_shndx) {
elf.SHN_ABS, elf.SHN_COMMON => 0,
else => self.atoms.items[this_sym.st_shndx],
else => self.atoms.items[esym.st_shndx],
};
global.* = .{
.value = this_sym.st_value,
.name = global.name,
.atom = atom,
.sym_idx = sym_idx,
.file = self.index,
.ver_idx = elf_file.default_sym_version,
};
if (this_sym.st_bind() == elf.STB_WEAK) global.flags.weak = true;
global.value = esym.st_value;
global.atom_index = atom_index;
global.esym_index = esym_index;
global.file_index = self.index;
global.version_index = elf_file.default_sym_version;
if (esym.st_bind() == elf.STB_WEAK) global.flags.weak = true;
}
}
}

7
src/link/Elf/Symbol.zig
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@ -70,9 +70,10 @@ pub fn sourceSymbol(symbol: Symbol, elf_file: *Elf) elf.Elf64_Sym {
const file_ptr = symbol.file(elf_file).?;
switch (file_ptr) {
.zig_module => |x| {
const is_global = x.globals_lookup.contains(symbol.name_offset);
if (is_global) return x.global_esyms.items[symbol.esym_index];
return x.local_esyms.items[symbol.esym_index];
const is_global = symbol.esym_index & 0x10000000 != 0;
const esym_index = symbol.esym_index & 0x0fffffff;
if (is_global) return x.global_esyms.items[esym_index];
return x.local_esyms.items[esym_index];
},
.linker_defined => |x| return x.symtab.items[symbol.esym_index],
.object => |x| return x.symtab[symbol.esym_index],

31
src/link/Elf/ZigModule.zig
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@ -62,7 +62,7 @@ pub fn addAtom(self: *ZigModule, output_section_index: u16, elf_file: *Elf) !Sym
const esym_index = try self.addLocalEsym(gpa);
const esym = &self.local_esyms.items[esym_index];
esym.st_shndx = output_section_index;
esym.st_shndx = atom_index;
symbol_ptr.esym_index = esym_index;
const relocs_index = @as(Atom.Index, @intCast(self.relocs.items.len));
@ -74,9 +74,32 @@ pub fn addAtom(self: *ZigModule, output_section_index: u16, elf_file: *Elf) !Sym
}
pub fn resolveSymbols(self: *ZigModule, elf_file: *Elf) void {
_ = self;
_ = elf_file;
@panic("TODO");
for (self.globals(), 0..) |index, i| {
const esym_index = @as(Symbol.Index, @intCast(i)) | 0x10000000;
const esym = self.global_esyms.items[i];
if (esym.st_shndx == elf.SHN_UNDEF) continue;
if (esym.st_shndx != elf.SHN_ABS and esym.st_shndx != elf.SHN_COMMON) {
const atom_index = self.atoms.keys()[esym.st_shndx];
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
}
const global = elf_file.symbol(index);
if (self.asFile().symbolRank(esym, false) < global.symbolRank(elf_file)) {
const atom_index = switch (esym.st_shndx) {
elf.SHN_ABS, elf.SHN_COMMON => 0,
else => self.atoms.keys()[esym.st_shndx],
};
global.value = esym.st_value;
global.atom_index = atom_index;
global.esym_index = esym_index;
global.file_index = self.index;
global.version_index = elf_file.default_sym_version;
if (esym.st_bind() == elf.STB_WEAK) global.flags.weak = true;
}
}
}
pub fn updateSymtabSize(self: *ZigModule, elf_file: *Elf) void {

12
src/link/Elf/file.zig
View File

@ -30,18 +30,6 @@ pub const File = union(enum) {
}
}
pub fn resolveSymbols(file: File, elf_file: *Elf) void {
switch (file) {
inline else => |x| x.resolveSymbols(elf_file),
}
}
// pub fn resetGlobals(file: File, elf_file: *Elf) void {
// switch (file) {
// inline else => |x| x.resetGlobals(elf_file),
// }
// }
pub fn isAlive(file: File) bool {
return switch (file) {
.zig_module => true,