Commit a9df098cd2

Jakub Konka <kubkon@jakubkonka.com>
2023-09-05 23:10:04
elf: make everything upside down - track by Symbol.Index rather than Atom.Index
1 parent d9fffd4
src/arch/aarch64/CodeGen.zig
@@ -4314,10 +4314,10 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
     if (try self.air.value(callee, mod)) |func_value| {
         if (func_value.getFunction(mod)) |func| {
             if (self.bin_file.cast(link.File.Elf)) |elf_file| {
-                const atom_index = try elf_file.getOrCreateAtomForDecl(func.owner_decl);
-                const atom = elf_file.atom(atom_index);
-                _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-                const got_addr = @as(u32, @intCast(atom.getOffsetTableAddress(elf_file)));
+                const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
+                const sym = elf_file.symbol(sym_index);
+                _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+                const got_addr = @as(u32, @intCast(sym.getOffsetTableAddress(elf_file)));
                 try self.genSetReg(Type.usize, .x30, .{ .memory = got_addr });
             } else if (self.bin_file.cast(link.File.MachO)) |macho_file| {
                 const atom = try macho_file.getOrCreateAtomForDecl(func.owner_decl);
src/arch/arm/CodeGen.zig
@@ -4294,10 +4294,10 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
     if (try self.air.value(callee, mod)) |func_value| {
         if (func_value.getFunction(mod)) |func| {
             if (self.bin_file.cast(link.File.Elf)) |elf_file| {
-                const atom_index = try elf_file.getOrCreateAtomForDecl(func.owner_decl);
-                const atom = elf_file.atom(atom_index);
-                _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-                const got_addr = @as(u32, @intCast(atom.getOffsetTableAddress(elf_file)));
+                const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
+                const sym = elf_file.symbol(sym_index);
+                _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+                const got_addr = @as(u32, @intCast(sym.getOffsetTableAddress(elf_file)));
                 try self.genSetReg(Type.usize, .lr, .{ .memory = got_addr });
             } else if (self.bin_file.cast(link.File.MachO)) |_| {
                 unreachable; // unsupported architecture for MachO
src/arch/riscv64/CodeGen.zig
@@ -1747,10 +1747,10 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
         if (try self.air.value(callee, mod)) |func_value| {
             switch (mod.intern_pool.indexToKey(func_value.ip_index)) {
                 .func => |func| {
-                    const atom_index = try elf_file.getOrCreateAtomForDecl(func.owner_decl);
-                    const atom = elf_file.atom(atom_index);
-                    _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-                    const got_addr = @as(u32, @intCast(atom.getOffsetTableAddress(elf_file)));
+                    const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
+                    const sym = elf_file.symbol(sym_index);
+                    _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+                    const got_addr = @as(u32, @intCast(sym.getOffsetTableAddress(elf_file)));
                     try self.genSetReg(Type.usize, .ra, .{ .memory = got_addr });
                     _ = try self.addInst(.{
                         .tag = .jalr,
src/arch/sparc64/CodeGen.zig
@@ -1349,10 +1349,10 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
             switch (mod.intern_pool.indexToKey(func_value.ip_index)) {
                 .func => |func| {
                     const got_addr = if (self.bin_file.cast(link.File.Elf)) |elf_file| blk: {
-                        const atom_index = try elf_file.getOrCreateAtomForDecl(func.owner_decl);
-                        const atom = elf_file.atom(atom_index);
-                        _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-                        break :blk @as(u32, @intCast(atom.getOffsetTableAddress(elf_file)));
+                        const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
+                        const sym = elf_file.symbol(sym_index);
+                        _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+                        break :blk @as(u32, @intCast(sym.getOffsetTableAddress(elf_file)));
                     } else unreachable;
 
                     try self.genSetReg(Type.usize, .o7, .{ .memory = got_addr });
src/arch/x86_64/CodeGen.zig
@@ -8149,10 +8149,10 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
             else => null,
         }) |owner_decl| {
             if (self.bin_file.cast(link.File.Elf)) |elf_file| {
-                const atom_index = try elf_file.getOrCreateAtomForDecl(owner_decl);
-                const atom = elf_file.atom(atom_index);
-                _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-                const got_addr = atom.getOffsetTableAddress(elf_file);
+                const sym_index = try elf_file.getOrCreateMetadataForDecl(owner_decl);
+                const sym = elf_file.symbol(sym_index);
+                _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+                const got_addr = sym.getOffsetTableAddress(elf_file);
                 try self.asmMemory(.{ ._, .call }, Memory.sib(.qword, .{
                     .base = .{ .reg = .ds },
                     .disp = @intCast(got_addr),
@@ -10215,11 +10215,11 @@ fn genLazySymbolRef(
     lazy_sym: link.File.LazySymbol,
 ) InnerError!void {
     if (self.bin_file.cast(link.File.Elf)) |elf_file| {
-        const atom_index = elf_file.getOrCreateAtomForLazySymbol(lazy_sym) catch |err|
+        const sym_index = elf_file.getOrCreateMetadataForLazySymbol(lazy_sym) catch |err|
             return self.fail("{s} creating lazy symbol", .{@errorName(err)});
-        const atom = elf_file.atom(atom_index);
-        _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-        const got_addr = atom.getOffsetTableAddress(elf_file);
+        const sym = elf_file.symbol(sym_index);
+        _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+        const got_addr = sym.getOffsetTableAddress(elf_file);
         const got_mem =
             Memory.sib(.qword, .{ .base = .{ .reg = .ds }, .disp = @intCast(got_addr) });
         switch (tag) {
src/link/Elf/Atom.zig
@@ -1,81 +1,65 @@
-/// Each decl always gets a local symbol with the fully qualified name.
-/// The vaddr and size are found here directly.
-/// The file offset is found by computing the vaddr offset from the section vaddr
-/// the symbol references, and adding that to the file offset of the section.
-/// If this field is 0, it means the codegen size = 0 and there is no symbol or
-/// offset table entry.
-sym_index: u32 = 0,
+/// Address allocated for this Atom.
+value: u64 = 0,
 
-/// Points to the previous and next neighbors, based on the `text_offset`.
-/// This can be used to find, for example, the capacity of this `TextBlock`.
-prev_index: ?Index = null,
-next_index: ?Index = null,
+/// Name of this Atom.
+name_offset: u32 = 0,
 
-pub const Index = u32;
+/// Index into linker's input file table.
+file_index: File.Index = 0,
 
-pub const Reloc = struct {
-    target: u32,
-    offset: u64,
-    addend: u32,
-    prev_vaddr: u64,
-};
+/// Size of this atom
+size: u64 = 0,
 
-pub fn symbolIndex(self: *const Atom) ?u32 {
-    if (self.sym_index == 0) return null;
-    return self.sym_index;
-}
+/// Alignment of this atom as a power of two.
+alignment: u8 = 0,
 
-pub fn symbol(self: *const Atom, elf_file: *Elf) *elf.Elf64_Sym {
-    return elf_file.symbol(self.symbolIndex().?);
-}
+/// Index of the input section.
+input_section_index: u16 = 0,
 
-pub fn name(self: *const Atom, elf_file: *Elf) []const u8 {
-    return elf_file.symbolName(self.symbolIndex().?);
-}
+/// Index of the output section.
+output_section_index: u16 = 0,
 
-/// If entry already exists, returns index to it.
-/// Otherwise, creates a new entry in the Global Offset Table for this Atom.
-pub fn getOrCreateOffsetTableEntry(self: *const Atom, elf_file: *Elf) !u32 {
-    const sym_index = self.symbolIndex().?;
-    if (elf_file.got_table.lookup.get(sym_index)) |index| return index;
-    const index = try elf_file.got_table.allocateEntry(elf_file.base.allocator, sym_index);
-    elf_file.got_table_count_dirty = true;
-    return index;
-}
+/// Index of the input section containing this atom's relocs.
+relocs_section_index: u16 = 0,
 
-pub fn getOffsetTableAddress(self: *const Atom, elf_file: *Elf) u64 {
-    const sym_index = self.symbolIndex().?;
-    const got_entry_index = elf_file.got_table.lookup.get(sym_index).?;
-    const target = elf_file.base.options.target;
-    const ptr_bits = target.ptrBitWidth();
-    const ptr_bytes: u64 = @divExact(ptr_bits, 8);
-    const got = elf_file.program_headers.items[elf_file.phdr_got_index.?];
-    return got.p_vaddr + got_entry_index * ptr_bytes;
+/// Index of this atom in the linker's atoms table.
+atom_index: Index = 0,
+
+/// Specifies whether this atom is alive or has been garbage collected.
+alive: bool = true,
+
+/// Specifies if the atom has been visited during garbage collection.
+visited: bool = false,
+
+/// Start index of FDEs referencing this atom.
+fde_start: u32 = 0,
+
+/// End index of FDEs referencing this atom.
+fde_end: u32 = 0,
+
+/// Points to the previous and next neighbors, based on the `text_offset`.
+/// This can be used to find, for example, the capacity of this `TextBlock`.
+prev_index: ?Index = null,
+next_index: ?Index = null,
+
+pub fn name(self: Atom, elf_file: *Elf) []const u8 {
+    return elf_file.strtab.getAssumeExists(self.name_offset);
 }
 
 /// Returns how much room there is to grow in virtual address space.
 /// File offset relocation happens transparently, so it is not included in
 /// this calculation.
-pub fn capacity(self: *const Atom, elf_file: *Elf) u64 {
-    const self_sym = self.symbol(elf_file);
-    if (self.next_index) |next_index| {
-        const next = elf_file.atom(next_index);
-        const next_sym = next.symbol(elf_file);
-        return next_sym.st_value - self_sym.st_value;
-    } else {
-        // We are the last block. The capacity is limited only by virtual address space.
-        return std.math.maxInt(u32) - self_sym.st_value;
-    }
+pub fn capacity(self: Atom, elf_file: *Elf) u64 {
+    const next_value = if (self.next_index) |next_index| elf_file.atom(next_index).value else std.math.maxInt(u32);
+    return next_value - self.value;
 }
 
-pub fn freeListEligible(self: *const Atom, elf_file: *Elf) bool {
+pub fn freeListEligible(self: Atom, elf_file: *Elf) bool {
     // No need to keep a free list node for the last block.
     const next_index = self.next_index orelse return false;
     const next = elf_file.atom(next_index);
-    const self_sym = self.symbol(elf_file);
-    const next_sym = next.symbol(elf_file);
-    const cap = next_sym.st_value - self_sym.st_value;
-    const ideal_cap = Elf.padToIdeal(self_sym.st_size);
+    const cap = next.value - self.value;
+    const ideal_cap = Elf.padToIdeal(self.size);
     if (cap <= ideal_cap) return false;
     const surplus = cap - ideal_cap;
     return surplus >= Elf.min_text_capacity;
@@ -95,10 +79,149 @@ pub fn freeRelocations(elf_file: *Elf, atom_index: Index) void {
     if (removed_relocs) |*relocs| relocs.value.deinit(elf_file.base.allocator);
 }
 
-const Atom = @This();
+pub fn allocate(self: *Atom, elf_file: *Elf) !u64 {
+    const phdr_index = elf_file.sections.items(.phdr_index)[self.output_section_index];
+    const phdr = &elf_file.program_headers.items[phdr_index];
+    const shdr = &elf_file.sections.items(.shdr)[self.output_section_index];
+    const free_list = &elf_file.sections.items(.free_list)[self.output_section_index];
+    const maybe_last_atom_index = &elf_file.sections.items(.last_atom_index)[self.output_section_index];
+    const new_atom_ideal_capacity = Elf.padToIdeal(self.size);
+    const alignment = try std.math.powi(u64, 2, self.alignment);
+
+    // We use these to indicate our intention to update metadata, placing the new atom,
+    // and possibly removing a free list node.
+    // It would be simpler to do it inside the for loop below, but that would cause a
+    // problem if an error was returned later in the function. So this action
+    // is actually carried out at the end of the function, when errors are no longer possible.
+    var atom_placement: ?Atom.Index = null;
+    var free_list_removal: ?usize = null;
+
+    // First we look for an appropriately sized free list node.
+    // The list is unordered. We'll just take the first thing that works.
+    const vaddr = blk: {
+        var i: usize = if (elf_file.base.child_pid == null) 0 else free_list.items.len;
+        while (i < free_list.items.len) {
+            const big_atom_index = free_list.items[i];
+            const big_atom = elf_file.atom(big_atom_index);
+            // We now have a pointer to a live atom that has too much capacity.
+            // Is it enough that we could fit this new atom?
+            const cap = big_atom.capacity(elf_file);
+            const ideal_capacity = Elf.padToIdeal(cap);
+            const ideal_capacity_end_vaddr = std.math.add(u64, big_atom.value, ideal_capacity) catch ideal_capacity;
+            const capacity_end_vaddr = big_atom.value + cap;
+            const new_start_vaddr_unaligned = capacity_end_vaddr - new_atom_ideal_capacity;
+            const new_start_vaddr = std.mem.alignBackward(u64, new_start_vaddr_unaligned, alignment);
+            if (new_start_vaddr < ideal_capacity_end_vaddr) {
+                // Additional bookkeeping here to notice if this free list node
+                // should be deleted because the block that it points to has grown to take up
+                // more of the extra capacity.
+                if (!big_atom.freeListEligible(elf_file)) {
+                    _ = free_list.swapRemove(i);
+                } else {
+                    i += 1;
+                }
+                continue;
+            }
+            // At this point we know that we will place the new block here. But the
+            // remaining question is whether there is still yet enough capacity left
+            // over for there to still be a free list node.
+            const remaining_capacity = new_start_vaddr - ideal_capacity_end_vaddr;
+            const keep_free_list_node = remaining_capacity >= Elf.min_text_capacity;
+
+            // Set up the metadata to be updated, after errors are no longer possible.
+            atom_placement = big_atom_index;
+            if (!keep_free_list_node) {
+                free_list_removal = i;
+            }
+            break :blk new_start_vaddr;
+        } else if (maybe_last_atom_index.*) |last_index| {
+            const last = elf_file.atom(last_index);
+            const ideal_capacity = Elf.padToIdeal(last.size);
+            const ideal_capacity_end_vaddr = last.value + ideal_capacity;
+            const new_start_vaddr = std.mem.alignForward(u64, ideal_capacity_end_vaddr, alignment);
+            // Set up the metadata to be updated, after errors are no longer possible.
+            atom_placement = last_index;
+            break :blk new_start_vaddr;
+        } else {
+            break :blk phdr.p_vaddr;
+        }
+    };
+
+    const expand_section = if (atom_placement) |placement_index|
+        elf_file.atom(placement_index).next_index == null
+    else
+        true;
+    if (expand_section) {
+        const needed_size = (vaddr + self.size) - phdr.p_vaddr;
+        try elf_file.growAllocSection(self.output_section_index, needed_size);
+        maybe_last_atom_index.* = self.atom_index;
+
+        if (elf_file.dwarf) |_| {
+            // The .debug_info section has `low_pc` and `high_pc` values which is the virtual address
+            // range of the compilation unit. When we expand the text section, this range changes,
+            // so the DW_TAG.compile_unit tag of the .debug_info section becomes dirty.
+            elf_file.debug_info_header_dirty = true;
+            // This becomes dirty for the same reason. We could potentially make this more
+            // fine-grained with the addition of support for more compilation units. It is planned to
+            // model each package as a different compilation unit.
+            elf_file.debug_aranges_section_dirty = true;
+        }
+    }
+    shdr.sh_addralign = @max(shdr.sh_addralign, alignment);
+
+    // This function can also reallocate an atom.
+    // In this case we need to "unplug" it from its previous location before
+    // plugging it in to its new location.
+    if (self.prev_index) |prev_index| {
+        const prev = elf_file.atom(prev_index);
+        prev.next_index = self.next_index;
+    }
+    if (self.next_index) |next_index| {
+        const next = elf_file.atom(next_index);
+        next.prev_index = self.prev_index;
+    }
+
+    if (atom_placement) |big_atom_index| {
+        const big_atom = elf_file.atom(big_atom_index);
+        self.prev_index = big_atom_index;
+        self.next_index = big_atom.next_index;
+        big_atom.next_index = self.atom_index;
+    } else {
+        self.prev_index = null;
+        self.next_index = null;
+    }
+    if (free_list_removal) |i| {
+        _ = free_list.swapRemove(i);
+    }
+    return vaddr;
+}
+
+pub fn shrink(self: *Atom, elf_file: *Elf) void {
+    _ = self;
+    _ = elf_file;
+}
+
+pub fn grow(self: *Atom, elf_file: *Elf) !u64 {
+    const alignment = try std.math.powi(u64, 2, self.alignment);
+    const align_ok = std.mem.alignBackward(u64, self.value, alignment) == self.value;
+    const need_realloc = !align_ok or self.size > self.capacity(elf_file);
+    if (!need_realloc) return self.value;
+    return self.allocate(elf_file);
+}
+
+pub const Index = u32;
+
+pub const Reloc = struct {
+    target: u32,
+    offset: u64,
+    addend: u32,
+    prev_vaddr: u64,
+};
 
 const std = @import("std");
 const assert = std.debug.assert;
 const elf = std.elf;
 
+const Atom = @This();
 const Elf = @import("../Elf.zig");
+const File = @import("file.zig").File;
src/link/Elf/file.zig
@@ -10,6 +10,12 @@ pub const File = union(enum) {
         };
     }
 
+    pub fn sourceSymbol(file: File, symbol_index: Symbol.Index) *elf.Elf64_Sym {
+        return switch (file) {
+            inline else => |x| x.sourceSymbol(symbol_index),
+        };
+    }
+
     pub fn fmtPath(file: File) std.fmt.Formatter(formatPath) {
         return .{ .data = file };
     }
@@ -107,4 +113,5 @@ const Elf = @import("../Elf.zig");
 const LinkerDefined = @import("LinkerDefined.zig");
 // const Object = @import("Object.zig");
 // const SharedObject = @import("SharedObject.zig");
+const Symbol = @import("Symbol.zig");
 const ZigModule = @import("ZigModule.zig");
src/link/Elf/LinkerDefined.zig
@@ -23,14 +23,14 @@ pub fn addGlobal(self: *LinkerDefined, name: [:0]const u8, elf_file: *Elf) !u32
         .st_size = 0,
     });
     const off = try elf_file.internString("{s}", .{name});
-    const gop = try elf_file.getOrCreateGlobal(off);
+    const gop = try elf_file.getOrPutGlobal(off);
     self.symbols.addOneAssumeCapacity().* = gop.index;
     return gop.index;
 }
 
 pub fn resolveSymbols(self: *LinkerDefined, elf_file: *Elf) void {
     for (self.symbols.items, 0..) |index, i| {
-        const sym_idx = @as(u32, @intCast(i));
+        const sym_idx = @as(Symbol.Index, @intCast(i));
         const this_sym = self.symtab.items[sym_idx];
 
         if (this_sym.st_shndx == elf.SHN_UNDEF) continue;
@@ -86,15 +86,19 @@ pub fn resolveSymbols(self: *LinkerDefined, elf_file: *Elf) void {
 //     }
 // }
 
-pub fn asFile(self: *LinkerDefined) File {
-    return .{ .linker_defined = self };
+pub fn sourceSymbol(self: *LinkerDefined, symbol_index: Symbol.Index) *elf.Elf64_Sym {
+    return &self.symtab.items[symbol_index];
 }
 
-pub inline fn getGlobals(self: *LinkerDefined) []const u32 {
+pub fn globals(self: *LinkerDefined) []const Symbol.Index {
     return self.symbols.items;
 }
 
-pub fn fmtSymtab(self: *InternalObject, elf_file: *Elf) std.fmt.Formatter(formatSymtab) {
+pub fn asFile(self: *LinkerDefined) File {
+    return .{ .linker_defined = self };
+}
+
+pub fn fmtSymtab(self: *LinkerDefined, elf_file: *Elf) std.fmt.Formatter(formatSymtab) {
     return .{ .data = .{
         .self = self,
         .elf_file = elf_file,
@@ -102,7 +106,7 @@ pub fn fmtSymtab(self: *InternalObject, elf_file: *Elf) std.fmt.Formatter(format
 }
 
 const FormatContext = struct {
-    self: *InternalObject,
+    self: *LinkerDefined,
     elf_file: *Elf,
 };
 
@@ -115,8 +119,8 @@ fn formatSymtab(
     _ = unused_fmt_string;
     _ = options;
     try writer.writeAll("  globals\n");
-    for (ctx.self.getGlobals()) |index| {
-        const global = ctx.elf_file.getSymbol(index);
+    for (ctx.self.globals()) |index| {
+        const global = ctx.elf_file.symbol(index);
         try writer.print("    {}\n", .{global.fmt(ctx.elf_file)});
     }
 }
src/link/Elf/Symbol.zig
@@ -32,9 +32,8 @@ extra_index: u32 = 0,
 
 pub fn isAbs(symbol: Symbol, elf_file: *Elf) bool {
     const file_ptr = symbol.file(elf_file).?;
-    if (file_ptr == .shared) return symbol.sourceSymbol(elf_file).st_shndx == elf.SHN_ABS;
-    return !symbol.flags.import and symbol.atom(elf_file) == null and symbol.shndx == 0 
-        and file_ptr != .linker_defined and file_ptr != .zig_module;
+    // if (file_ptr == .shared) return symbol.sourceSymbol(elf_file).st_shndx == elf.SHN_ABS;
+    return !symbol.flags.import and symbol.atom(elf_file) == null and symbol.output_section_index == 0 and file_ptr != .linker_defined and file_ptr != .zig_module;
 }
 
 pub fn isLocal(symbol: Symbol) bool {
@@ -42,34 +41,30 @@ pub fn isLocal(symbol: Symbol) bool {
 }
 
 pub inline fn isIFunc(symbol: Symbol, elf_file: *Elf) bool {
-    return symbol.@"type"(elf_file) == elf.STT_GNU_IFUNC;
+    return symbol.type(elf_file) == elf.STT_GNU_IFUNC;
 }
 
 pub fn @"type"(symbol: Symbol, elf_file: *Elf) u4 {
-    const file_ptr = symbol.file(elf_file).?;
     const s_sym = symbol.sourceSymbol(elf_file);
-    if (s_sym.st_type() == elf.STT_GNU_IFUNC and file_ptr == .shared) return elf.STT_FUNC;
+    // const file_ptr = symbol.file(elf_file).?;
+    // if (s_sym.st_type() == elf.STT_GNU_IFUNC and file_ptr == .shared) return elf.STT_FUNC;
     return s_sym.st_type();
 }
 
 pub fn name(symbol: Symbol, elf_file: *Elf) [:0]const u8 {
-    return elf_file.strtab.getAssumeExists(symbol.name);
+    return elf_file.strtab.getAssumeExists(symbol.name_offset);
 }
 
 pub fn atom(symbol: Symbol, elf_file: *Elf) ?*Atom {
-    return elf_file.atom(symbol.atom);
+    return elf_file.atom(symbol.atom_index);
 }
 
 pub fn file(symbol: Symbol, elf_file: *Elf) ?File {
-    return elf_file.file(symbol.file);
+    return elf_file.file(symbol.file_index);
 }
 
-pub fn sourceSymbol(symbol: Symbol, elf_file: *Elf) elf.Elf64_Sym {
-    const file_ptr = symbol.file(elf_file).?;
-    return switch (file_ptr) {
-        .linker_defined, .zig_module => |x| x.symtab.items[symbol.sym_idx],
-        inline else => |x| x.symtab[symbol.sym_idx],
-    };
+pub fn sourceSymbol(symbol: Symbol, elf_file: *Elf) *elf.Elf64_Sym {
+    return symbol.file(elf_file).?.sourceSymbol(symbol.symbol_index);
 }
 
 pub fn symbolRank(symbol: Symbol, elf_file: *Elf) u32 {
@@ -82,9 +77,29 @@ pub fn symbolRank(symbol: Symbol, elf_file: *Elf) u32 {
     return file_ptr.symbolRank(sym, in_archive);
 }
 
+/// If entry already exists, returns index to it.
+/// Otherwise, creates a new entry in the Global Offset Table for this Symbol.
+pub fn getOrCreateOffsetTableEntry(self: Symbol, elf_file: *Elf) !Symbol.Index {
+    if (elf_file.got_table.lookup.get(self.symbol_index)) |index| return index;
+    const index = try elf_file.got_table.allocateEntry(elf_file.base.allocator, self.symbol_index);
+    elf_file.got_table_count_dirty = true;
+    return index;
+}
+
+pub fn getOffsetTableAddress(self: Symbol, elf_file: *Elf) u64 {
+    const got_entry_index = elf_file.got_table.lookup.get(self.symbol_index).?;
+    const target = elf_file.base.options.target;
+    const ptr_bits = target.ptrBitWidth();
+    const ptr_bytes: u64 = @divExact(ptr_bits, 8);
+    const got = elf_file.program_headers.items[elf_file.phdr_got_index.?];
+    return got.p_vaddr + got_entry_index * ptr_bytes;
+}
+
 pub fn address(symbol: Symbol, opts: struct {
     plt: bool = true,
 }, elf_file: *Elf) u64 {
+    _ = elf_file;
+    _ = opts;
     // if (symbol.flags.copy_rel) {
     //     return elf_file.sectionAddress(elf_file.copy_rel_sect_index.?) + symbol.value;
     // }
@@ -100,11 +115,11 @@ pub fn address(symbol: Symbol, opts: struct {
     return symbol.value;
 }
 
-pub fn gotAddress(symbol: Symbol, elf_file: *Elf) u64 {
-    if (!symbol.flags.got) return 0;
-    const extra = symbol.extra(elf_file).?;
-    return elf_file.gotEntryAddress(extra.got);
-}
+// pub fn gotAddress(symbol: Symbol, elf_file: *Elf) u64 {
+//     if (!symbol.flags.got) return 0;
+//     const extra = symbol.extra(elf_file).?;
+//     return elf_file.gotEntryAddress(extra.got);
+// }
 
 // pub fn tlsGdAddress(symbol: Symbol, elf_file: *Elf) u64 {
 //     if (!symbol.flags.tlsgd) return 0;
@@ -136,22 +151,22 @@ pub fn gotAddress(symbol: Symbol, elf_file: *Elf) u64 {
 //         @min(alignment, try std.math.powi(u64, 2, @ctz(s_sym.st_value)));
 // }
 
-pub fn addExtra(symbol: *Symbol, extra: Extra, elf_file: *Elf) !void {
-    symbol.extra = try elf_file.addSymbolExtra(extra);
+pub fn addExtra(symbol: *Symbol, extras: Extra, elf_file: *Elf) !void {
+    symbol.extra = try elf_file.addSymbolExtra(extras);
 }
 
 pub fn extra(symbol: Symbol, elf_file: *Elf) ?Extra {
-    return elf_file.symbolExtra(symbol.extra);
+    return elf_file.symbolExtra(symbol.extra_index);
 }
 
-pub fn setExtra(symbol: Symbol, extra: Extra, elf_file: *Elf) void {
-    elf_file.setSymbolExtra(symbol.extra, extra);
+pub fn setExtra(symbol: Symbol, extras: Extra, elf_file: *Elf) void {
+    elf_file.setSymbolExtra(symbol.extra_index, extras);
 }
 
 pub fn asElfSym(symbol: Symbol, st_name: u32, elf_file: *Elf) elf.Elf64_Sym {
     const file_ptr = symbol.file(elf_file).?;
     const s_sym = symbol.sourceSymbol(elf_file);
-    const st_type = symbol.@"type"(elf_file);
+    const st_type = symbol.type(elf_file);
     const st_bind: u8 = blk: {
         if (symbol.isLocal()) break :blk 0;
         if (symbol.flags.weak) break :blk elf.STB_WEAK;
@@ -161,7 +176,7 @@ pub fn asElfSym(symbol: Symbol, st_name: u32, elf_file: *Elf) elf.Elf64_Sym {
     const st_shndx = blk: {
         // if (symbol.flags.copy_rel) break :blk elf_file.copy_rel_sect_index.?;
         // if (file_ptr == .shared or s_sym.st_shndx == elf.SHN_UNDEF) break :blk elf.SHN_UNDEF;
-        if (symbol.atom(elf_file) == null and file_ptr != .linker_defined and file_ptr != .zig_module) 
+        if (symbol.atom(elf_file) == null and file_ptr != .linker_defined and file_ptr != .zig_module)
             break :blk elf.SHN_ABS;
         break :blk symbol.shndx;
     };
@@ -221,13 +236,13 @@ fn formatName(
     _ = unused_fmt_string;
     const elf_file = ctx.elf_file;
     const symbol = ctx.symbol;
-    try writer.writeAll(symbol.getName(elf_file));
-    switch (symbol.ver_idx & elf.VERSYM_VERSION) {
+    try writer.writeAll(symbol.name(elf_file));
+    switch (symbol.version_index & elf.VERSYM_VERSION) {
         elf.VER_NDX_LOCAL, elf.VER_NDX_GLOBAL => {},
         else => {
             unreachable;
             // const shared = symbol.getFile(elf_file).?.shared;
-            // try writer.print("@{s}", .{shared.getVersionString(symbol.ver_idx)});
+            // try writer.print("@{s}", .{shared.getVersionString(symbol.version_index)});
         },
     }
 }
@@ -248,29 +263,27 @@ fn format2(
     _ = options;
     _ = unused_fmt_string;
     const symbol = ctx.symbol;
-    try writer.print("%{d} : {s} : @{x}", .{ symbol.sym_idx, symbol.fmtName(ctx.elf_file), symbol.value });
-    if (symbol.getFile(ctx.elf_file)) |file| {
+    try writer.print("%{d} : {s} : @{x}", .{ symbol.symbol_index, symbol.fmtName(ctx.elf_file), symbol.value });
+    if (symbol.file(ctx.elf_file)) |file_ptr| {
         if (symbol.isAbs(ctx.elf_file)) {
-            if (symbol.getSourceSymbol(ctx.elf_file).st_shndx == elf.SHN_UNDEF) {
+            if (symbol.sourceSymbol(ctx.elf_file).st_shndx == elf.SHN_UNDEF) {
                 try writer.writeAll(" : undef");
             } else {
                 try writer.writeAll(" : absolute");
             }
-        } else if (symbol.shndx != 0) {
-            try writer.print(" : sect({d})", .{symbol.shndx});
+        } else if (symbol.output_section_index != 0) {
+            try writer.print(" : sect({d})", .{symbol.output_section_index});
         }
-        if (symbol.getAtom(ctx.elf_file)) |atom| {
-            try writer.print(" : atom({d})", .{atom.atom_index});
+        if (symbol.atom(ctx.elf_file)) |atom_ptr| {
+            try writer.print(" : atom({d})", .{atom_ptr.atom_index});
         }
         var buf: [2]u8 = .{'_'} ** 2;
         if (symbol.flags.@"export") buf[0] = 'E';
         if (symbol.flags.import) buf[1] = 'I';
         try writer.print(" : {s}", .{&buf});
         if (symbol.flags.weak) try writer.writeAll(" : weak");
-        switch (file) {
-            .internal => |x| try writer.print(" : internal({d})", .{x.index}),
-            .object => |x| try writer.print(" : object({d})", .{x.index}),
-            .shared => |x| try writer.print(" : shared({d})", .{x.index}),
+        switch (file_ptr) {
+            inline else => |x| try writer.print(" : {s}({d})", .{ @tagName(file_ptr), x.index }),
         }
     } else try writer.writeAll(" : unresolved");
 }
@@ -331,7 +344,8 @@ const elf = std.elf;
 const Atom = @import("Atom.zig");
 const Elf = @import("../Elf.zig");
 const File = @import("file.zig").File;
-const InternalObject = @import("InternalObject.zig");
-const Object = @import("Object.zig");
-const SharedObject = @import("SharedObject.zig");
+const LinkerDefined = @import("LinkerDefined.zig");
+// const Object = @import("Object.zig");
+// const SharedObject = @import("SharedObject.zig");
 const Symbol = @This();
+const ZigModule = @import("ZigModule.zig");
src/link/Elf/ZigModule.zig
@@ -1,29 +1,89 @@
 index: File.Index,
-elf_locals: std.ArrayListUnmanaged(elf.Elf64_Sym) = .{},
-locals: std.ArrayListUnmanaged(Symbol.Index) = .{},
-elf_globals: std.ArrayListUnmanaged(elf.Elf64_Sym) = .{},
-globals: std.ArrayListUnmanaged(Symbol.Index) = .{},
+
+elf_local_symbols: std.ArrayListUnmanaged(elf.Elf64_Sym) = .{},
+local_symbols: std.AutoArrayHashMapUnmanaged(Symbol.Index, void) = .{},
+
+elf_global_symbols: std.ArrayListUnmanaged(elf.Elf64_Sym) = .{},
+global_symbols: std.AutoArrayHashMapUnmanaged(Symbol.Index, void) = .{},
+
+atoms: std.ArrayListUnmanaged(Atom.Index) = .{},
+
 alive: bool = true,
 
 // output_symtab_size: Elf.SymtabSize = .{},
 
 pub fn deinit(self: *ZigModule, allocator: Allocator) void {
-    self.elf_locals.deinit(allocator);
-    self.locals.deinit(allocator);
-    self.elf_globals.deinit(allocator);
-    self.globals.deinit(allocator);
+    self.elf_local_symbols.deinit(allocator);
+    self.local_symbols.deinit(allocator);
+    self.elf_global_symbols.deinit(allocator);
+    self.global_symbols.deinit(allocator);
+    self.atoms.deinit(allocator);
 }
 
-pub fn asFile(self: *ZigModule) File {
-    return .{ .zig_module = self };
+pub fn createAtom(self: *ZigModule, output_section_index: u16, elf_file: *Elf) !Symbol.Index {
+    const gpa = elf_file.base.allocator;
+    const atom_index = try elf_file.addAtom();
+    const symbol_index = try elf_file.addSymbol();
+
+    const atom_ptr = elf_file.atom(atom_index);
+    atom_ptr.file_index = self.index;
+    atom_ptr.output_section_index = output_section_index;
+
+    const symbol_ptr = elf_file.symbol(symbol_index);
+    symbol_ptr.file_index = self.index;
+    symbol_ptr.atom_index = atom_index;
+    symbol_ptr.output_section_index = output_section_index;
+
+    const local_esym = try self.elf_local_symbols.addOne(gpa);
+    local_esym.* = .{
+        .st_name = 0,
+        .st_info = elf.STB_LOCAL << 4,
+        .st_other = 0,
+        .st_shndx = output_section_index,
+        .st_value = 0,
+        .st_size = 0,
+    };
+
+    try self.atoms.append(gpa, atom_index);
+    try self.local_symbols.putNoClobber(gpa, symbol_index, {});
+
+    return symbol_index;
+}
+
+pub fn addGlobal(self: *ZigModule, name: [:0]const u8, elf_file: *Elf) !Symbol.Index {
+    const gpa = elf_file.base.allocator;
+    try self.elf_global_symbols.ensureUnusedCapacity(gpa, 1);
+    try self.global_symbols.ensureUnusedCapacity(gpa, 1);
+    const off = try elf_file.strtab.insert(gpa, name);
+    self.elf_global_symbols.appendAssumeCapacity(.{
+        .st_name = off,
+        .st_info = elf.STB_GLOBAL << 4,
+        .st_other = 0,
+        .st_shndx = 0,
+        .st_value = 0,
+        .st_size = 0,
+    });
+    const gop = try elf_file.getOrPutGlobal(off);
+    self.global_symbols.putAssumeCapacityNoClobber(gop.index, {});
+    return gop.index;
+}
+
+pub fn sourceSymbol(self: *ZigModule, symbol_index: Symbol.Index) *elf.Elf64_Sym {
+    if (self.local_symbols.get(symbol_index)) |_| return &self.elf_local_symbols.items[symbol_index];
+    assert(self.global_symbols.get(symbol_index) != null);
+    return &self.elf_global_symbols.items[symbol_index];
 }
 
-pub fn getLocals(self: *ZigModule) []const Symbol.Index {
-    return self.locals.items;
+pub fn locals(self: *ZigModule) []const Symbol.Index {
+    return self.local_symbols.keys();
 }
 
-pub fn getGlobals(self: *ZigModule) []const Symbol.Index {
-    return self.globals.items;
+pub fn globals(self: *ZigModule) []const Symbol.Index {
+    return self.global_symbols.keys();
+}
+
+pub fn asFile(self: *ZigModule) File {
+    return .{ .zig_module = self };
 }
 
 pub fn fmtSymtab(self: *ZigModule, elf_file: *Elf) std.fmt.Formatter(formatSymtab) {
@@ -47,23 +107,26 @@ fn formatSymtab(
     _ = unused_fmt_string;
     _ = options;
     try writer.writeAll("  locals\n");
-    for (ctx.self.getLocals()) |index| {
+    for (ctx.self.locals()) |index| {
         const local = ctx.elf_file.symbol(index);
         try writer.print("    {}\n", .{local.fmt(ctx.elf_file)});
     }
     try writer.writeAll("  globals\n");
-    for (ctx.self.getGlobals()) |index| {
-        const global = ctx.elf_file.getSymbol(index);
+    for (ctx.self.globals()) |index| {
+        const global = ctx.elf_file.symbol(index);
         try writer.print("    {}\n", .{global.fmt(ctx.elf_file)});
     }
 }
 
+const assert = std.debug.assert;
 const std = @import("std");
 const elf = std.elf;
 
 const Allocator = std.mem.Allocator;
+const Atom = @import("Atom.zig");
 const Elf = @import("../Elf.zig");
 const File = @import("file.zig").File;
+const Module = @import("../../Module.zig");
 const ZigModule = @This();
 // const Object = @import("Object.zig");
 const Symbol = @import("Symbol.zig");
src/link/Elf.zig
@@ -1,4 +1,4 @@
-base: File,
+base: link.File,
 dwarf: ?Dwarf = null,
 
 ptr_width: PtrWidth,
@@ -6,7 +6,7 @@ ptr_width: PtrWidth,
 /// If this is not null, an object file is created by LLVM and linked with LLD afterwards.
 llvm_object: ?*LlvmObject = null,
 
-files: std.MutliArrayList(File.Entry) = .{},
+files: std.MultiArrayList(File.Entry) = .{},
 zig_module_index: ?File.Index = null,
 linker_defined_index: ?File.Index = null,
 
@@ -56,14 +56,12 @@ shstrtab_section_index: ?u16 = null,
 strtab_section_index: ?u16 = null,
 
 symbols: std.ArrayListUnmanaged(Symbol) = .{},
-globals: std.ArrayListUnmanaged(Symbol.Index) = .{},
-resolver: std.StringHashMapUnmanaged(u32) = .{},
+resolver: std.AutoArrayHashMapUnmanaged(u32, Symbol.Index) = .{},
 unresolved: std.AutoArrayHashMapUnmanaged(u32, void) = .{},
 
-symbols_free_list: std.ArrayListUnmanaged(u32) = .{},
-globals_free_list: std.ArrayListUnmanaged(u32) = .{},
+symbols_free_list: std.ArrayListUnmanaged(Symbol.Index) = .{},
 
-got_table: TableSection(u32) = .{},
+got_table: TableSection(Symbol.Index) = .{},
 
 phdr_table_dirty: bool = false,
 shdr_table_dirty: bool = false,
@@ -88,9 +86,6 @@ decls: std.AutoHashMapUnmanaged(Module.Decl.Index, DeclMetadata) = .{},
 /// List of atoms that are owned directly by the linker.
 atoms: std.ArrayListUnmanaged(Atom) = .{},
 
-/// Table of atoms indexed by the symbol index.
-atom_by_index_table: std.AutoHashMapUnmanaged(u32, Atom.Index) = .{},
-
 /// Table of unnamed constants associated with a parent `Decl`.
 /// We store them here so that we can free the constants whenever the `Decl`
 /// needs updating or is freed.
@@ -113,12 +108,10 @@ atom_by_index_table: std.AutoHashMapUnmanaged(u32, Atom.Index) = .{},
 unnamed_const_atoms: UnnamedConstTable = .{},
 
 /// A table of relocations indexed by the owning them `TextBlock`.
-/// Note that once we refactor `TextBlock`'s lifetime and ownership rules,
-/// this will be a table indexed by index into the list of Atoms.
 relocs: RelocTable = .{},
 
 const RelocTable = std.AutoHashMapUnmanaged(Atom.Index, std.ArrayListUnmanaged(Atom.Reloc));
-const UnnamedConstTable = std.AutoHashMapUnmanaged(Module.Decl.Index, std.ArrayListUnmanaged(Atom.Index));
+const UnnamedConstTable = std.AutoHashMapUnmanaged(Module.Decl.Index, std.ArrayListUnmanaged(Symbol.Index));
 const LazySymbolTable = std.AutoArrayHashMapUnmanaged(Module.Decl.OptionalIndex, LazySymbolMetadata);
 
 /// When allocating, the ideal_capacity is calculated by
@@ -143,13 +136,12 @@ pub fn openPath(allocator: Allocator, sub_path: []const u8, options: link.Option
     const self = try createEmpty(allocator, options);
     errdefer self.base.destroy();
 
-    const file = try options.emit.?.directory.handle.createFile(sub_path, .{
+    self.base.file = try options.emit.?.directory.handle.createFile(sub_path, .{
         .truncate = false,
         .read = true,
         .mode = link.determineMode(options),
     });
 
-    self.base.file = file;
     self.shdr_table_dirty = true;
 
     // Index 0 is always a null symbol.
@@ -243,19 +235,10 @@ pub fn deinit(self: *Elf) void {
     self.strtab.deinit(gpa);
     self.symbols.deinit(gpa);
     self.symbols_free_list.deinit(gpa);
-    self.globals.deinit(gpa);
-    self.globals_free_list.deinit(gpa);
     self.got_table.deinit(gpa);
+    self.resolver.deinit(gpa);
     self.unresolved.deinit(gpa);
 
-    {
-        var it = self.resolver.keyIterator();
-        while (it.next()) |key_ptr| {
-            gpa.free(key_ptr.*);
-        }
-        self.resolver.deinit(gpa);
-    }
-
     {
         var it = self.decls.iterator();
         while (it.next()) |entry| {
@@ -265,7 +248,6 @@ pub fn deinit(self: *Elf) void {
     }
 
     self.atoms.deinit(gpa);
-    self.atom_by_index_table.deinit(gpa);
     self.lazy_syms.deinit(gpa);
 
     {
@@ -292,13 +274,12 @@ pub fn deinit(self: *Elf) void {
 pub fn getDeclVAddr(self: *Elf, decl_index: Module.Decl.Index, reloc_info: link.File.RelocInfo) !u64 {
     assert(self.llvm_object == null);
 
-    const this_atom_index = try self.getOrCreateAtomForDecl(decl_index);
-    const this_atom = self.atom(this_atom_index);
-    const target = this_atom.symbolIndex().?;
-    const vaddr = this_atom.symbol(self).st_value;
-    const atom_index = self.atomIndexForSymbol(reloc_info.parent_atom_index).?;
-    try Atom.addRelocation(self, atom_index, .{
-        .target = target,
+    const this_sym_index = try self.getOrCreateMetadataForDecl(decl_index);
+    const this_sym = self.symbol(this_sym_index);
+    const vaddr = this_sym.value;
+    const parent_atom_index = self.symbol(reloc_info.parent_atom_index).atom_index;
+    try Atom.addRelocation(self, parent_atom_index, .{
+        .target = this_sym,
         .offset = reloc_info.offset,
         .addend = reloc_info.addend,
         .prev_vaddr = vaddr,
@@ -851,7 +832,7 @@ pub fn populateMissingMetadata(self: *Elf) !void {
     }
 }
 
-fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
+pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
     // TODO Also detect virtual address collisions.
     const shdr = &self.sections.items(.shdr)[shdr_index];
     const phdr_index = self.sections.items(.phdr_index)[shdr_index];
@@ -863,8 +844,7 @@ fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
         const new_offset = self.findFreeSpace(needed_size, self.page_size);
         const existing_size = if (maybe_last_atom_index) |last_atom_index| blk: {
             const last = self.atom(last_atom_index);
-            const sym = last.symbol(self);
-            break :blk (sym.st_value + sym.st_size) - phdr.p_vaddr;
+            break :blk (last.value + last.size) - phdr.p_vaddr;
         } else if (shdr_index == self.got_section_index.?) blk: {
             break :blk shdr.sh_size;
         } else 0;
@@ -985,6 +965,7 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
     // TODO This linker code currently assumes there is only 1 compilation unit and it
     // corresponds to the Zig source code.
     const module = self.base.options.module orelse return error.LinkingWithoutZigSourceUnimplemented;
+    _ = module;
 
     self.zig_module_index = blk: {
         const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
@@ -992,9 +973,9 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
         break :blk index;
     };
 
-    self.linker_defined = blk: {
+    self.linker_defined_index = blk: {
         const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
-        self.files.set(index, .{ .linker_defined = .{} });
+        self.files.set(index, .{ .linker_defined = .{ .index = index } });
         break :blk index;
     };
 
@@ -2157,193 +2138,12 @@ fn freeAtom(self: *Elf, atom_index: Atom.Index) void {
     const sym_index = atom_ptr.symbolIndex().?;
 
     log.debug("adding %{d} to local symbols free list", .{sym_index});
-    self.locals_free_list.append(gpa, sym_index) catch {};
-    self.locals.items[sym_index] = null_sym;
-    _ = self.atom_by_index_table.remove(sym_index);
+    self.symbols_free_list.append(gpa, sym_index) catch {};
+    self.symbols.items[sym_index] = .{};
     atom_ptr.sym_index = 0;
     self.got_table.freeEntry(gpa, sym_index);
 }
 
-fn shrinkAtom(self: *Elf, atom_index: Atom.Index, new_block_size: u64) void {
-    _ = self;
-    _ = atom_index;
-    _ = new_block_size;
-}
-
-fn growAtom(self: *Elf, atom_index: Atom.Index, new_block_size: u64, alignment: u64) !u64 {
-    const atom_ptr = self.atom(atom_index);
-    const sym = atom_ptr.symbol(self);
-    const align_ok = mem.alignBackward(u64, sym.st_value, alignment) == sym.st_value;
-    const need_realloc = !align_ok or new_block_size > atom_ptr.capacity(self);
-    if (!need_realloc) return sym.st_value;
-    return self.allocateAtom(atom_index, new_block_size, alignment);
-}
-
-pub fn createAtom(self: *Elf) !Atom.Index {
-    const gpa = self.base.allocator;
-    const atom_index = @as(Atom.Index, @intCast(self.atoms.items.len));
-    const atom_ptr = try self.atoms.addOne(gpa);
-    const sym_index = try self.allocateSymbol();
-    try self.atom_by_index_table.putNoClobber(gpa, sym_index, atom_index);
-    atom_ptr.* = .{ .sym_index = sym_index };
-    log.debug("creating ATOM(%{d}) at index {d}", .{ sym_index, atom_index });
-    return atom_index;
-}
-
-fn allocateAtom(self: *Elf, atom_index: Atom.Index, new_block_size: u64, alignment: u64) !u64 {
-    const sym = self.atom(atom_index).symbol(self);
-    const phdr_index = self.sections.items(.phdr_index)[sym.st_shndx];
-    const phdr = &self.program_headers.items[phdr_index];
-    const shdr = &self.sections.items(.shdr)[sym.st_shndx];
-    const free_list = &self.sections.items(.free_list)[sym.st_shndx];
-    const maybe_last_atom_index = &self.sections.items(.last_atom_index)[sym.st_shndx];
-    const new_atom_ideal_capacity = padToIdeal(new_block_size);
-
-    // We use these to indicate our intention to update metadata, placing the new atom,
-    // and possibly removing a free list node.
-    // It would be simpler to do it inside the for loop below, but that would cause a
-    // problem if an error was returned later in the function. So this action
-    // is actually carried out at the end of the function, when errors are no longer possible.
-    var atom_placement: ?Atom.Index = null;
-    var free_list_removal: ?usize = null;
-
-    // First we look for an appropriately sized free list node.
-    // The list is unordered. We'll just take the first thing that works.
-    const vaddr = blk: {
-        var i: usize = if (self.base.child_pid == null) 0 else free_list.items.len;
-        while (i < free_list.items.len) {
-            const big_atom_index = free_list.items[i];
-            const big_atom = self.atom(big_atom_index);
-            // We now have a pointer to a live atom that has too much capacity.
-            // Is it enough that we could fit this new atom?
-            const big_atom_sym = big_atom.symbol(self);
-            const capacity = big_atom.capacity(self);
-            const ideal_capacity = padToIdeal(capacity);
-            const ideal_capacity_end_vaddr = std.math.add(u64, big_atom_sym.st_value, ideal_capacity) catch ideal_capacity;
-            const capacity_end_vaddr = big_atom_sym.st_value + capacity;
-            const new_start_vaddr_unaligned = capacity_end_vaddr - new_atom_ideal_capacity;
-            const new_start_vaddr = mem.alignBackward(u64, new_start_vaddr_unaligned, alignment);
-            if (new_start_vaddr < ideal_capacity_end_vaddr) {
-                // Additional bookkeeping here to notice if this free list node
-                // should be deleted because the block that it points to has grown to take up
-                // more of the extra capacity.
-                if (!big_atom.freeListEligible(self)) {
-                    _ = free_list.swapRemove(i);
-                } else {
-                    i += 1;
-                }
-                continue;
-            }
-            // At this point we know that we will place the new block here. But the
-            // remaining question is whether there is still yet enough capacity left
-            // over for there to still be a free list node.
-            const remaining_capacity = new_start_vaddr - ideal_capacity_end_vaddr;
-            const keep_free_list_node = remaining_capacity >= min_text_capacity;
-
-            // Set up the metadata to be updated, after errors are no longer possible.
-            atom_placement = big_atom_index;
-            if (!keep_free_list_node) {
-                free_list_removal = i;
-            }
-            break :blk new_start_vaddr;
-        } else if (maybe_last_atom_index.*) |last_index| {
-            const last = self.atom(last_index);
-            const last_sym = last.symbol(self);
-            const ideal_capacity = padToIdeal(last_sym.st_size);
-            const ideal_capacity_end_vaddr = last_sym.st_value + ideal_capacity;
-            const new_start_vaddr = mem.alignForward(u64, ideal_capacity_end_vaddr, alignment);
-            // Set up the metadata to be updated, after errors are no longer possible.
-            atom_placement = last_index;
-            break :blk new_start_vaddr;
-        } else {
-            break :blk phdr.p_vaddr;
-        }
-    };
-
-    const expand_section = if (atom_placement) |placement_index|
-        self.atom(placement_index).next_index == null
-    else
-        true;
-    if (expand_section) {
-        const needed_size = (vaddr + new_block_size) - phdr.p_vaddr;
-        try self.growAllocSection(sym.st_shndx, needed_size);
-        maybe_last_atom_index.* = atom_index;
-
-        if (self.dwarf) |_| {
-            // The .debug_info section has `low_pc` and `high_pc` values which is the virtual address
-            // range of the compilation unit. When we expand the text section, this range changes,
-            // so the DW_TAG.compile_unit tag of the .debug_info section becomes dirty.
-            self.debug_info_header_dirty = true;
-            // This becomes dirty for the same reason. We could potentially make this more
-            // fine-grained with the addition of support for more compilation units. It is planned to
-            // model each package as a different compilation unit.
-            self.debug_aranges_section_dirty = true;
-        }
-    }
-    shdr.sh_addralign = @max(shdr.sh_addralign, alignment);
-
-    // This function can also reallocate an atom.
-    // In this case we need to "unplug" it from its previous location before
-    // plugging it in to its new location.
-    const atom_ptr = self.atom(atom_index);
-    if (atom_ptr.prev_index) |prev_index| {
-        const prev = self.atom(prev_index);
-        prev.next_index = atom_ptr.next_index;
-    }
-    if (atom_ptr.next_index) |next_index| {
-        const next = self.atom(next_index);
-        next.prev_index = atom_ptr.prev_index;
-    }
-
-    if (atom_placement) |big_atom_index| {
-        const big_atom = self.atom(big_atom_index);
-        atom_ptr.prev_index = big_atom_index;
-        atom_ptr.next_index = big_atom.next_index;
-        big_atom.next_index = atom_index;
-    } else {
-        atom_ptr.prev_index = null;
-        atom_ptr.next_index = null;
-    }
-    if (free_list_removal) |i| {
-        _ = free_list.swapRemove(i);
-    }
-    return vaddr;
-}
-
-pub fn allocateSymbol(self: *Elf) !u32 {
-    try self.locals.ensureUnusedCapacity(self.base.allocator, 1);
-    const index = blk: {
-        if (self.locals_free_list.popOrNull()) |index| {
-            log.debug("  (reusing symbol index {d})", .{index});
-            break :blk index;
-        } else {
-            log.debug("  (allocating symbol index {d})", .{self.locals.items.len});
-            const index = @as(u32, @intCast(self.locals.items.len));
-            _ = self.locals.addOneAssumeCapacity();
-            break :blk index;
-        }
-    };
-    self.locals.items[index] = null_sym;
-    return index;
-}
-
-fn allocateGlobal(self: *Elf) !u32 {
-    try self.globals.ensureUnusedCapacity(self.base.allocator, 1);
-    const index = blk: {
-        if (self.globals_free_list.popOrNull()) |index| {
-            log.debug("  (reusing global index {d})", .{index});
-            break :blk index;
-        } else {
-            log.debug("  (allocating global index {d})", .{self.globals.items.len});
-            const index = @as(u32, @intCast(self.globals.items.len));
-            _ = self.globals.addOneAssumeCapacity();
-            break :blk index;
-        }
-    };
-    self.globals.items[index] = 0;
-    return index;
-}
-
 fn freeUnnamedConsts(self: *Elf, decl_index: Module.Decl.Index) void {
     const unnamed_consts = self.unnamed_const_atoms.getPtr(decl_index) orelse return;
     for (unnamed_consts.items) |atom_index| {
@@ -2372,40 +2172,50 @@ pub fn freeDecl(self: *Elf, decl_index: Module.Decl.Index) void {
     }
 }
 
-pub fn getOrCreateAtomForLazySymbol(self: *Elf, sym: link.File.LazySymbol) !Atom.Index {
+pub fn getOrCreateMetadataForLazySymbol(self: *Elf, sym: link.File.LazySymbol) !Symbol.Index {
     const mod = self.base.options.module.?;
     const gop = try self.lazy_syms.getOrPut(self.base.allocator, sym.getDecl(mod));
     errdefer _ = if (!gop.found_existing) self.lazy_syms.pop();
     if (!gop.found_existing) gop.value_ptr.* = .{};
-    const metadata: struct { atom: *Atom.Index, state: *LazySymbolMetadata.State } = switch (sym.kind) {
-        .code => .{ .atom = &gop.value_ptr.text_atom, .state = &gop.value_ptr.text_state },
-        .const_data => .{ .atom = &gop.value_ptr.rodata_atom, .state = &gop.value_ptr.rodata_state },
+    const metadata: struct {
+        symbol_index: *Symbol.Index,
+        state: *LazySymbolMetadata.State,
+    } = switch (sym.kind) {
+        .code => .{
+            .symbol_index = &gop.value_ptr.text_symbol_index,
+            .state = &gop.value_ptr.text_state,
+        },
+        .const_data => .{
+            .symbol_index = &gop.value_ptr.rodata_symbol_index,
+            .state = &gop.value_ptr.rodata_state,
+        },
     };
+    const zig_module = self.file(self.zig_module_index.?).?.zig_module;
     switch (metadata.state.*) {
-        .unused => metadata.atom.* = try self.createAtom(),
+        .unused => metadata.symbol_index.* = try zig_module.createAtom(switch (sym.kind) {
+            .code => self.text_section_index.?,
+            .const_data => self.rodata_section_index.?,
+        }, self),
         .pending_flush => return metadata.atom.*,
         .flushed => {},
     }
     metadata.state.* = .pending_flush;
-    const atom_index = metadata.atom.*;
+    const symbol_index = metadata.symbol_index.*;
     // anyerror needs to be deferred until flushModule
-    if (sym.getDecl(mod) != .none) try self.updateLazySymbolAtom(sym, atom_index, switch (sym.kind) {
-        .code => self.text_section_index.?,
-        .const_data => self.rodata_section_index.?,
-    });
-    return atom_index;
+    if (sym.getDecl(mod) != .none) try self.updateLazySymbol(sym, symbol_index);
+    return symbol_index;
 }
 
-pub fn getOrCreateAtomForDecl(self: *Elf, decl_index: Module.Decl.Index) !Atom.Index {
+pub fn getOrCreateMetadataForDecl(self: *Elf, decl_index: Module.Decl.Index) !Symbol.Index {
     const gop = try self.decls.getOrPut(self.base.allocator, decl_index);
     if (!gop.found_existing) {
+        const zig_module = self.file(self.zig_module_index.?).?.zig_module;
         gop.value_ptr.* = .{
-            .atom = try self.createAtom(),
-            .shdr = self.getDeclShdrIndex(decl_index),
+            .symbol_index = try zig_module.createAtom(self.getDeclShdrIndex(decl_index), self),
             .exports = .{},
         };
     }
-    return gop.value_ptr.atom;
+    return gop.value_ptr.symbol_index;
 }
 
 fn getDeclShdrIndex(self: *Elf, decl_index: Module.Decl.Index) u16 {
@@ -2434,7 +2244,13 @@ fn getDeclShdrIndex(self: *Elf, decl_index: Module.Decl.Index) u16 {
     return shdr_index;
 }
 
-fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, stt_bits: u8) !*elf.Elf64_Sym {
+fn updateDeclCode(
+    self: *Elf,
+    decl_index: Module.Decl.Index,
+    sym_index: Symbol.Index,
+    code: []const u8,
+    stt_bits: u8,
+) !void {
     const gpa = self.base.allocator;
     const mod = self.base.options.module.?;
     const decl = mod.declPtr(decl_index);
@@ -2444,60 +2260,52 @@ fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, s
     log.debug("updateDeclCode {s}{*}", .{ decl_name, decl });
     const required_alignment = decl.getAlignment(mod);
 
-    const decl_metadata = self.decls.get(decl_index).?;
-    const atom_index = decl_metadata.atom;
-    const atom_ptr = self.atom(atom_index);
-    const local_sym_index = atom_ptr.symbolIndex().?;
-    const local_sym = atom_ptr.symbol(self);
+    const sym = self.symbol(sym_index);
+    const esym = sym.sourceSymbol(self);
+    const atom_ptr = sym.atom(self).?;
+    const shdr_index = sym.output_section_index;
 
-    const shdr_index = decl_metadata.shdr;
-    if (atom_ptr.symbol(self).st_size != 0 and self.base.child_pid == null) {
-        local_sym.st_name = try self.strtab.insert(gpa, decl_name);
-        local_sym.st_info = (elf.STB_LOCAL << 4) | stt_bits;
-        local_sym.st_other = 0;
-        local_sym.st_shndx = shdr_index;
+    sym.name_offset = try self.strtab.insert(gpa, decl_name);
+    esym.st_name = sym.name_offset;
+    esym.st_info |= stt_bits;
+    esym.st_size = code.len;
 
-        const capacity = atom_ptr.capacity(self);
-        const need_realloc = code.len > capacity or
-            !mem.isAlignedGeneric(u64, local_sym.st_value, required_alignment);
+    const old_size = atom_ptr.size;
+    atom_ptr.alignment = math.log2_int(u64, required_alignment);
+    atom_ptr.size = code.len;
 
+    if (old_size > 0 and self.base.child_pid == null) {
+        const capacity = atom_ptr.capacity(self);
+        const need_realloc = code.len > capacity or !mem.isAlignedGeneric(u64, sym.value, required_alignment);
         if (need_realloc) {
-            const vaddr = try self.growAtom(atom_index, code.len, required_alignment);
-            log.debug("growing {s} from 0x{x} to 0x{x}", .{ decl_name, local_sym.st_value, vaddr });
-            if (vaddr != local_sym.st_value) {
-                local_sym.st_value = vaddr;
+            const vaddr = try atom_ptr.grow(self);
+            log.debug("growing {s} from 0x{x} to 0x{x}", .{ decl_name, sym.value, vaddr });
+            if (vaddr != sym.value) {
+                sym.value = vaddr;
+                esym.st_value = vaddr;
 
                 log.debug("  (writing new offset table entry)", .{});
-                const got_entry_index = self.got_table.lookup.get(local_sym_index).?;
-                self.got_table.entries.items[got_entry_index] = local_sym_index;
+                const got_entry_index = self.got_table.lookup.get(sym_index).?;
+                self.got_table.entries.items[got_entry_index] = sym_index;
                 try self.writeOffsetTableEntry(got_entry_index);
             }
-        } else if (code.len < local_sym.st_size) {
-            self.shrinkAtom(atom_index, code.len);
+        } else if (code.len < old_size) {
+            atom_ptr.shrink(self);
         }
-        local_sym.st_size = code.len;
     } else {
-        local_sym.* = .{
-            .st_name = try self.strtab.insert(gpa, decl_name),
-            .st_info = (elf.STB_LOCAL << 4) | stt_bits,
-            .st_other = 0,
-            .st_shndx = shdr_index,
-            .st_value = 0,
-            .st_size = 0,
-        };
-        const vaddr = try self.allocateAtom(atom_index, code.len, required_alignment);
-        errdefer self.freeAtom(atom_index);
+        const vaddr = try atom_ptr.allocate(self);
+        errdefer self.freeAtom(atom_ptr);
         log.debug("allocated text block for {s} at 0x{x}", .{ decl_name, vaddr });
 
-        local_sym.st_value = vaddr;
-        local_sym.st_size = code.len;
+        sym.value = vaddr;
+        esym.st_value = vaddr;
 
-        const got_entry_index = try atom_ptr.getOrCreateOffsetTableEntry(self);
+        const got_entry_index = try sym.getOrCreateOffsetTableEntry(self);
         try self.writeOffsetTableEntry(got_entry_index);
     }
 
     const phdr_index = self.sections.items(.phdr_index)[shdr_index];
-    const section_offset = local_sym.st_value - self.program_headers.items[phdr_index].p_vaddr;
+    const section_offset = sym.value - self.program_headers.items[phdr_index].p_vaddr;
     const file_offset = self.sections.items(.shdr)[shdr_index].sh_offset + section_offset;
 
     if (self.base.child_pid) |pid| {
@@ -2508,7 +2316,7 @@ fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, s
                     .iov_len = code.len,
                 }};
                 var remote_vec: [1]std.os.iovec_const = .{.{
-                    .iov_base = @as([*]u8, @ptrFromInt(@as(usize, @intCast(local_sym.st_value)))),
+                    .iov_base = @as([*]u8, @ptrFromInt(@as(usize, @intCast(sym.value)))),
                     .iov_len = code.len,
                 }};
                 const rc = std.os.linux.process_vm_writev(pid, &code_vec, &remote_vec, 0);
@@ -2522,8 +2330,6 @@ fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, s
     }
 
     try self.base.file.?.pwriteAll(code, file_offset);
-
-    return local_sym;
 }
 
 pub fn updateFunc(self: *Elf, mod: *Module, func_index: InternPool.Index, air: Air, liveness: Liveness) !void {
@@ -2539,9 +2345,9 @@ pub fn updateFunc(self: *Elf, mod: *Module, func_index: InternPool.Index, air: A
     const decl_index = func.owner_decl;
     const decl = mod.declPtr(decl_index);
 
-    const atom_index = try self.getOrCreateAtomForDecl(decl_index);
+    const sym_index = try self.getOrCreateMetadataForDecl(decl_index);
     self.freeUnnamedConsts(decl_index);
-    Atom.freeRelocations(self, atom_index);
+    Atom.freeRelocations(self, self.symbol(sym_index).atom_index);
 
     var code_buffer = std.ArrayList(u8).init(self.base.allocator);
     defer code_buffer.deinit();
@@ -2564,13 +2370,14 @@ pub fn updateFunc(self: *Elf, mod: *Module, func_index: InternPool.Index, air: A
             return;
         },
     };
-    const local_sym = try self.updateDeclCode(decl_index, code, elf.STT_FUNC);
+    try self.updateDeclCode(decl_index, sym_index, code, elf.STT_FUNC);
     if (decl_state) |*ds| {
+        const sym = self.symbol(sym_index);
         try self.dwarf.?.commitDeclState(
             mod,
             decl_index,
-            local_sym.st_value,
-            local_sym.st_size,
+            sym.value,
+            sym.atom(self).?.size,
             ds,
         );
     }
@@ -2604,8 +2411,8 @@ pub fn updateDecl(
         }
     }
 
-    const atom_index = try self.getOrCreateAtomForDecl(decl_index);
-    Atom.freeRelocations(self, atom_index);
+    const sym_index = try self.getOrCreateMetadataForDecl(decl_index);
+    Atom.freeRelocations(self, self.symbol(sym_index).atom_index);
 
     var code_buffer = std.ArrayList(u8).init(self.base.allocator);
     defer code_buffer.deinit();
@@ -2622,14 +2429,14 @@ pub fn updateDecl(
         }, &code_buffer, .{
             .dwarf = ds,
         }, .{
-            .parent_atom_index = self.atom(atom_index).symbolIndex().?,
+            .parent_atom_index = sym_index,
         })
     else
         try codegen.generateSymbol(&self.base, decl.srcLoc(mod), .{
             .ty = decl.ty,
             .val = decl_val,
         }, &code_buffer, .none, .{
-            .parent_atom_index = self.atom(atom_index).symbolIndex().?,
+            .parent_atom_index = sym_index,
         });
 
     const code = switch (res) {
@@ -2641,13 +2448,14 @@ pub fn updateDecl(
         },
     };
 
-    const local_sym = try self.updateDeclCode(decl_index, code, elf.STT_OBJECT);
+    try self.updateDeclCode(decl_index, sym_index, code, elf.STT_OBJECT);
     if (decl_state) |*ds| {
+        const sym = self.symbol(sym_index);
         try self.dwarf.?.commitDeclState(
             mod,
             decl_index,
-            local_sym.st_value,
-            local_sym.st_size,
+            sym.value,
+            sym.atom(self).?.size,
             ds,
         );
     }
@@ -2657,12 +2465,7 @@ pub fn updateDecl(
     return self.updateDeclExports(mod, decl_index, mod.getDeclExports(decl_index));
 }
 
-fn updateLazySymbolAtom(
-    self: *Elf,
-    sym: link.File.LazySymbol,
-    atom_index: Atom.Index,
-    shdr_index: u16,
-) !void {
+fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.Index) !void {
     const gpa = self.base.allocator;
     const mod = self.base.options.module.?;
 
@@ -2680,9 +2483,6 @@ fn updateLazySymbolAtom(
     };
     const name = self.strtab.get(name_str_index).?;
 
-    const atom_ptr = self.atom(atom_index);
-    const local_sym_index = atom_ptr.symbolIndex().?;
-
     const src = if (sym.ty.getOwnerDeclOrNull(mod)) |owner_decl|
         mod.declPtr(owner_decl).srcLoc(mod)
     else
@@ -2698,7 +2498,7 @@ fn updateLazySymbolAtom(
         &required_alignment,
         &code_buffer,
         .none,
-        .{ .parent_atom_index = local_sym_index },
+        .{ .parent_atom_index = symbol_index },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -2708,28 +2508,28 @@ fn updateLazySymbolAtom(
         },
     };
 
-    const phdr_index = self.sections.items(.phdr_index)[shdr_index];
-    const local_sym = atom_ptr.symbol(self);
-    local_sym.* = .{
-        .st_name = name_str_index,
-        .st_info = (elf.STB_LOCAL << 4) | elf.STT_OBJECT,
-        .st_other = 0,
-        .st_shndx = shdr_index,
-        .st_value = 0,
-        .st_size = 0,
-    };
-    const vaddr = try self.allocateAtom(atom_index, code.len, required_alignment);
-    errdefer self.freeAtom(atom_index);
+    const local_sym = self.symbol(symbol_index);
+    const phdr_index = self.sections.items(.phdr_index)[local_sym.output_section_index];
+    local_sym.name_offset = name_str_index;
+    const local_esym = local_sym.sourceSymbol(self);
+    local_esym.st_name = name_str_index;
+    local_esym.st_info |= elf.STT_OBJECT;
+    local_esym.st_size = code.len;
+    const atom_ptr = local_sym.atom(self).?;
+    atom_ptr.alignment = math.log2_int(u64, required_alignment);
+    atom_ptr.size = code.len;
+    const vaddr = try atom_ptr.allocate(self);
+    errdefer self.freeAtom(atom_ptr);
     log.debug("allocated text block for {s} at 0x{x}", .{ name, vaddr });
 
-    local_sym.st_value = vaddr;
-    local_sym.st_size = code.len;
+    local_sym.value = vaddr;
+    local_esym.st_value = vaddr;
 
-    const got_entry_index = try atom_ptr.getOrCreateOffsetTableEntry(self);
+    const got_entry_index = try local_sym.getOrCreateOffsetTableEntry(self);
     try self.writeOffsetTableEntry(got_entry_index);
 
     const section_offset = vaddr - self.program_headers.items[phdr_index].p_vaddr;
-    const file_offset = self.sections.items(.shdr)[shdr_index].sh_offset + section_offset;
+    const file_offset = self.sections.items(.shdr)[local_sym.output_section_index].sh_offset + section_offset;
     try self.base.file.?.pwriteAll(code, file_offset);
 }
 
@@ -2756,12 +2556,13 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
     };
     const name = self.strtab.get(name_str_index).?;
 
-    const atom_index = try self.createAtom();
+    const zig_module = self.file(self.zig_module_index.?).?.zig_module;
+    const sym_index = try zig_module.createAtom(self.rodata_section_index.?, self);
 
     const res = try codegen.generateSymbol(&self.base, decl.srcLoc(mod), typed_value, &code_buffer, .{
         .none = {},
     }, .{
-        .parent_atom_index = self.atom(atom_index).symbolIndex().?,
+        .parent_atom_index = sym_index,
     });
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -2776,24 +2577,30 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
     const required_alignment = typed_value.ty.abiAlignment(mod);
     const shdr_index = self.rodata_section_index.?;
     const phdr_index = self.sections.items(.phdr_index)[shdr_index];
-    const local_sym = self.atom(atom_index).symbol(self);
-    local_sym.st_name = name_str_index;
-    local_sym.st_info = (elf.STB_LOCAL << 4) | elf.STT_OBJECT;
-    local_sym.st_other = 0;
-    local_sym.st_shndx = shdr_index;
-    local_sym.st_size = code.len;
-    local_sym.st_value = try self.allocateAtom(atom_index, code.len, required_alignment);
-    errdefer self.freeAtom(atom_index);
+    const local_sym = self.symbol(sym_index);
+    local_sym.name_offset = name_str_index;
+    const local_esym = local_sym.sourceSymbol(self);
+    local_esym.st_name = name_str_index;
+    local_esym.st_info |= elf.STT_OBJECT;
+    local_esym.st_size = code.len;
+    const atom_ptr = local_sym.atom(self).?;
+    atom_ptr.alignment = math.log2_int(u64, required_alignment);
+    atom_ptr.size = code.len;
+    const vaddr = try atom_ptr.allocateAtom(self);
+    errdefer self.freeAtom(atom_ptr);
 
     log.debug("allocated text block for {s} at 0x{x}", .{ name, local_sym.st_value });
 
-    try unnamed_consts.append(gpa, atom_index);
+    local_sym.value = vaddr;
+    local_esym.st_value = vaddr;
 
-    const section_offset = local_sym.st_value - self.program_headers.items[phdr_index].p_vaddr;
+    try unnamed_consts.append(gpa, atom_ptr.atom_index);
+
+    const section_offset = local_sym.value - self.program_headers.items[phdr_index].p_vaddr;
     const file_offset = self.sections.items(.shdr)[shdr_index].sh_offset + section_offset;
     try self.base.file.?.pwriteAll(code, file_offset);
 
-    return self.atom(atom_index).symbolIndex().?;
+    return sym_index;
 }
 
 pub fn updateDeclExports(
@@ -2815,11 +2622,10 @@ pub fn updateDeclExports(
     const gpa = self.base.allocator;
 
     const decl = mod.declPtr(decl_index);
-    const atom_index = try self.getOrCreateAtomForDecl(decl_index);
-    const atom_ptr = self.atom(atom_index);
-    const decl_sym = atom_ptr.symbol(self);
+    const decl_sym_index = try self.getOrCreateMetadataForDecl(decl_index);
+    const decl_sym = self.symbol(decl_sym_index);
+    const decl_esym = symbol.sourceSymbol(self);
     const decl_metadata = self.decls.getPtr(decl_index).?;
-    const shdr_index = decl_metadata.shdr;
 
     for (exports) |exp| {
         const exp_name = mod.intern_pool.stringToSlice(exp.opts.name);
@@ -2838,7 +2644,7 @@ pub fn updateDeclExports(
             .Strong => blk: {
                 const entry_name = self.base.options.entry orelse "_start";
                 if (mem.eql(u8, exp_name, entry_name)) {
-                    self.entry_addr = decl_sym.st_value;
+                    self.entry_addr = decl_sym.value;
                 }
                 break :blk elf.STB_GLOBAL;
             },
@@ -2855,22 +2661,18 @@ pub fn updateDeclExports(
         const stt_bits: u8 = @as(u4, @truncate(decl_sym.st_info));
 
         const sym_index = if (decl_metadata.@"export"(self, exp_name)) |exp_index| exp_index.* else blk: {
-            const sym_index = try self.allocateSymbol();
+            const zig_module = self.file(self.zig_module_index.?).?.zig_module;
+            const sym_index = try zig_module.addGlobal(exp_name, self);
             try decl_metadata.exports.append(gpa, sym_index);
             break :blk sym_index;
         };
         const sym = self.symbol(sym_index);
-        sym.* = .{
-            .st_name = try self.strtab.insert(gpa, exp_name),
-            .st_info = (stb_bits << 4) | stt_bits,
-            .st_other = 0,
-            .st_shndx = shdr_index,
-            .st_value = decl_sym.st_value,
-            .st_size = decl_sym.st_size,
-        };
-        const sym_name = self.symbolName(sym_index);
-        const gop = try self.getOrPutGlobal(sym_name);
-        gop.value_ptr.* = sym_index;
+        sym.value = decl_sym.value;
+        sym.atom_index = decl_sym.atom_index;
+        sym.output_section_index = decl_sym.output_section_index;
+        const esym = sym.sourceSymbol(self);
+        esym.* = decl_esym.*;
+        esym.st_info = (stb_bits << 4) | stt_bits;
     }
 }
 
@@ -2901,16 +2703,21 @@ pub fn deleteDeclExport(
     const mod = self.base.options.module.?;
     const exp_name = mod.intern_pool.stringToSlice(name);
     const sym_index = metadata.@"export"(self, exp_name) orelse return;
-    const sym = self.symbol(sym_index.*);
     log.debug("deleting export '{s}'", .{exp_name});
-    sym.* = null_sym;
-    self.locals_free_list.append(gpa, sym_index.*) catch {};
-
-    if (self.resolver.fetchRemove(exp_name)) |entry| {
-        self.globals_free_list.append(gpa, entry.value) catch {};
-        self.globals.items[entry.value] = 0;
-    }
-
+    const sym = self.symbol(sym_index.*);
+    const esym = sym.sourceSymbol(self);
+    assert(self.resolver.fetchSwapRemove(sym.name_offset) != null); // TODO don't delete it if it's not dominant
+    sym.* = .{};
+    // TODO free list for esym!
+    esym.* = .{
+        .st_name = 0,
+        .st_info = 0,
+        .st_other = 0,
+        .st_shndx = 0,
+        .st_value = 0,
+        .st_size = 0,
+    };
+    self.symbols_free_list.append(gpa, sym_index.*) catch {};
     sym_index.* = 0;
 }
 
@@ -2971,7 +2778,7 @@ fn writeOffsetTableEntry(self: *Elf, index: @TypeOf(self.got_table).Index) !void
     const phdr = &self.program_headers.items[self.phdr_got_index.?];
     const vaddr = phdr.p_vaddr + @as(u64, entry_size) * index;
     const got_entry = self.got_table.entries.items[index];
-    const got_value = self.symbol(got_entry).st_value;
+    const got_value = self.symbol(got_entry).value;
     switch (entry_size) {
         2 => {
             var buf: [2]u8 = undefined;
@@ -3374,98 +3181,99 @@ const CsuObjects = struct {
     }
 };
 
-fn logSymtab(self: Elf) void {
-    log.debug("locals:", .{});
-    for (self.locals.items, 0..) |sym, id| {
-        log.debug("  {d}: {?s}: @{x} in {d}", .{ id, self.strtab.get(sym.st_name), sym.st_value, sym.st_shndx });
-    }
-    log.debug("globals:", .{});
-    for (self.globals.items, 0..) |glob, id| {
-        const sym = self.symbol(glob);
-        log.debug("  {d}: {?s}: @{x} in {d}", .{ id, self.strtab.get(sym.st_name), sym.st_value, sym.st_shndx });
-    }
-}
-
-/// Returns pointer-to-symbol described at sym_index.
-pub fn symbol(self: *const Elf, sym_index: u32) *elf.Elf64_Sym {
-    return &self.locals.items[sym_index];
+pub fn atom(self: *Elf, atom_index: Atom.Index) *Atom {
+    assert(atom_index < self.atoms.items.len);
+    return &self.atoms.items[atom_index];
 }
 
-/// Returns name of the symbol at sym_index.
-pub fn symbolName(self: *const Elf, sym_index: u32) []const u8 {
-    const sym = self.locals.items[sym_index];
-    return self.strtab.get(sym.st_name).?;
+pub fn addAtom(self: *Elf) !Atom.Index {
+    const index = @as(Atom.Index, @intCast(self.atoms.items.len));
+    const atom_ptr = try self.atoms.addOne(self.base.allocator);
+    atom_ptr.* = .{ .atom_index = index };
+    return index;
 }
 
-/// Returns pointer to the global entry for `name` if one exists.
-pub fn global(self: *const Elf, name: []const u8) ?*u32 {
-    const global_index = self.resolver.get(name) orelse return null;
-    return &self.globals.items[global_index];
+pub fn file(self: *Elf, index: File.Index) ?File {
+    const tag = self.files.items(.tags)[index];
+    return switch (tag) {
+        .null => null,
+        .linker_defined => .{ .linker_defined = &self.files.items(.data)[index].linker_defined },
+        .zig_module => .{ .zig_module = &self.files.items(.data)[index].zig_module },
+    };
 }
 
-/// Returns the index of the global entry for `name` if one exists.
-pub fn globalIndex(self: *const Elf, name: []const u8) ?u32 {
-    return self.resolver.get(name);
+/// Returns pointer-to-symbol described at sym_index.
+pub fn symbol(self: *Elf, sym_index: Symbol.Index) *Symbol {
+    return &self.symbols.items[sym_index];
 }
 
-/// Returns global entry at `index`.
-pub fn globalByIndex(self: *const Elf, index: u32) u32 {
-    assert(index < self.globals.items.len);
-    return self.globals.items[index];
+pub fn addSymbol(self: *Elf) !Symbol.Index {
+    try self.symbols.ensureUnusedCapacity(self.base.allocator, 1);
+    const index = blk: {
+        if (self.symbols_free_list.popOrNull()) |index| {
+            log.debug("  (reusing symbol index {d})", .{index});
+            break :blk index;
+        } else {
+            log.debug("  (allocating symbol index {d})", .{self.symbols.items.len});
+            const index = @as(Symbol.Index, @intCast(self.symbols.items.len));
+            _ = self.symbols.addOneAssumeCapacity();
+            break :blk index;
+        }
+    };
+    self.symbols.items[index] = .{ .symbol_index = index };
+    return index;
 }
 
 const GetOrPutGlobalResult = struct {
     found_existing: bool,
-    value_ptr: *u32,
+    index: Symbol.Index,
 };
 
-/// Return pointer to the global entry for `name` if one exists.
-/// Puts a new global entry for `name` if one doesn't exist, and
-/// returns a pointer to it.
-pub fn getOrPutGlobal(self: *Elf, name: []const u8) !GetOrPutGlobalResult {
-    if (self.global(name)) |ptr| {
-        return GetOrPutGlobalResult{ .found_existing = true, .value_ptr = ptr };
-    }
+pub fn getOrPutGlobal(self: *Elf, name_off: u32) !GetOrPutGlobalResult {
     const gpa = self.base.allocator;
-    const global_index = try self.allocateGlobal();
-    const global_name = try gpa.dupe(u8, name);
-    _ = try self.resolver.put(gpa, global_name, global_index);
-    const ptr = &self.globals.items[global_index];
-    return GetOrPutGlobalResult{ .found_existing = false, .value_ptr = ptr };
-}
-
-pub fn atom(self: *Elf, atom_index: Atom.Index) *Atom {
-    assert(atom_index < self.atoms.items.len);
-    return &self.atoms.items[atom_index];
+    const gop = try self.resolver.getOrPut(gpa, name_off);
+    if (!gop.found_existing) {
+        const index = try self.addSymbol();
+        const global = self.symbol(index);
+        global.name_offset = name_off;
+        gop.value_ptr.* = index;
+    }
+    return .{
+        .found_existing = gop.found_existing,
+        .index = gop.value_ptr.*,
+    };
 }
 
-/// Returns atom if there is an atom referenced by the symbol.
-/// Returns null on failure.
-pub fn atomIndexForSymbol(self: *Elf, sym_index: u32) ?Atom.Index {
-    return self.atom_by_index_table.get(sym_index);
+pub fn getGlobalByName(self: *Elf, name: []const u8) ?Symbol.Index {
+    const name_off = self.strtab.getOffset(name) orelse return null;
+    return self.resolver.get(name_off);
 }
 
-fn dumpState(self: *Elf ) std.fmt.Formatter(fmtDumpState) {
+fn dumpState(self: *Elf) std.fmt.Formatter(fmtDumpState) {
     return .{ .data = self };
 }
 
-fn fmtDumpState(self: *Elf,
+fn fmtDumpState(
+    self: *Elf,
     comptime unused_fmt_string: []const u8,
     options: std.fmt.FormatOptions,
     writer: anytype,
 ) !void {
+    _ = unused_fmt_string;
+    _ = options;
 
+    if (self.zig_module_index) |index| {
+        const zig_module = self.file(index).?.zig_module;
+        try writer.print("zig_module({d}) : (zig module)\n", .{index});
+        try writer.print("{}\n", .{zig_module.fmtSymtab(self)});
+    }
+    if (self.linker_defined_index) |index| {
+        const linker_defined = self.file(index).?.linker_defined;
+        try writer.print("linker_defined({d}) : (linker defined)\n", .{index});
+        try writer.print("{}\n", .{linker_defined.fmtSymtab(self)});
+    }
 }
 
-pub const null_sym = elf.Elf64_Sym{
-    .st_name = 0,
-    .st_info = 0,
-    .st_other = 0,
-    .st_shndx = 0,
-    .st_value = 0,
-    .st_size = 0,
-};
-
 const default_entry_addr = 0x8000000;
 
 pub const base_tag: link.File.Tag = .elf;
@@ -3497,21 +3305,20 @@ const Section = struct {
 
 const LazySymbolMetadata = struct {
     const State = enum { unused, pending_flush, flushed };
-    text_atom: Atom.Index = undefined,
-    rodata_atom: Atom.Index = undefined,
+    text_symbol_index: Symbol.Index = undefined,
+    rodata_symbol_index: Symbol.Index = undefined,
     text_state: State = .unused,
     rodata_state: State = .unused,
 };
 
 const DeclMetadata = struct {
-    atom: Atom.Index,
-    shdr: u16,
+    symbol_index: Symbol.Index,
     /// A list of all exports aliases of this Decl.
-    exports: std.ArrayListUnmanaged(u32) = .{},
+    exports: std.ArrayListUnmanaged(Symbol.Index) = .{},
 
-    fn @"export"(m: DeclMetadata, elf_file: *const Elf, name: []const u8) ?*u32 {
+    fn @"export"(m: DeclMetadata, elf_file: *Elf, name: []const u8) ?*u32 {
         for (m.exports.items) |*exp| {
-            if (mem.eql(u8, name, elf_file.symbolName(exp.*))) return exp;
+            if (mem.eql(u8, name, elf_file.symbol(exp.*).name(elf_file))) return exp;
         }
         return null;
     }
@@ -3543,13 +3350,14 @@ pub const Atom = @import("Elf/Atom.zig");
 const Cache = std.Build.Cache;
 const Compilation = @import("../Compilation.zig");
 const Dwarf = @import("Dwarf.zig");
-const File = @import("Elf/File.zig");
+const File = @import("Elf/file.zig").File;
 const LinkerDefined = @import("Elf/LinkerDefined.zig");
 const Liveness = @import("../Liveness.zig");
 const LlvmObject = @import("../codegen/llvm.zig").Object;
 const Module = @import("../Module.zig");
 const InternPool = @import("../InternPool.zig");
 const Package = @import("../Package.zig");
+const Symbol = @import("Elf/Symbol.zig");
 const StringTable = @import("strtab.zig").StringTable;
 const TableSection = @import("table_section.zig").TableSection;
 const Type = @import("../type.zig").Type;
src/link/strtab.zig
@@ -100,13 +100,13 @@ pub fn StringTable(comptime log_scope: @Type(.EnumLiteral)) type {
             });
         }
 
-        pub fn get(self: Self, off: u32) ?[]const u8 {
+        pub fn get(self: Self, off: u32) ?[:0]const u8 {
             log.debug("getting string at 0x{x}", .{off});
             if (off >= self.buffer.items.len) return null;
             return mem.sliceTo(@as([*:0]const u8, @ptrCast(self.buffer.items.ptr + off)), 0);
         }
 
-        pub fn getAssumeExists(self: Self, off: u32) []const u8 {
+        pub fn getAssumeExists(self: Self, off: u32) [:0]const u8 {
             return self.get(off) orelse unreachable;
         }
 
src/codegen.zig
@@ -854,10 +854,10 @@ fn genDeclRef(
     const is_threadlocal = tv.val.isPtrToThreadLocal(mod) and !bin_file.options.single_threaded;
 
     if (bin_file.cast(link.File.Elf)) |elf_file| {
-        const atom_index = try elf_file.getOrCreateAtomForDecl(decl_index);
-        const atom = elf_file.atom(atom_index);
-        _ = try atom.getOrCreateOffsetTableEntry(elf_file);
-        return GenResult.mcv(.{ .memory = atom.getOffsetTableAddress(elf_file) });
+        const sym_index = try elf_file.getOrCreateMetadataForDecl(decl_index);
+        const sym = elf_file.symbol(sym_index);
+        _ = try sym.getOrCreateOffsetTableEntry(elf_file);
+        return GenResult.mcv(.{ .memory = sym.getOffsetTableAddress(elf_file) });
     } else if (bin_file.cast(link.File.MachO)) |macho_file| {
         const atom_index = try macho_file.getOrCreateAtomForDecl(decl_index);
         const sym_index = macho_file.getAtom(atom_index).getSymbolIndex().?;
@@ -892,7 +892,7 @@ fn genUnnamedConst(
         return GenResult.fail(bin_file.allocator, src_loc, "lowering unnamed constant failed: {s}", .{@errorName(err)});
     };
     if (bin_file.cast(link.File.Elf)) |elf_file| {
-        return GenResult.mcv(.{ .memory = elf_file.symbol(local_sym_index).st_value });
+        return GenResult.mcv(.{ .memory = elf_file.symbol(local_sym_index).value });
     } else if (bin_file.cast(link.File.MachO)) |_| {
         return GenResult.mcv(.{ .load_direct = local_sym_index });
     } else if (bin_file.cast(link.File.Coff)) |_| {