codegen: implement output to the `.debug_info` section

6 files changed, 274 insertions, 157 deletions

diff --git a/src/link/Coff.zig b/src/link/Coff.zig
index 6bf47e2602..f67c7d54d7 100644
--- a/src/link/Coff.zig
+++ b/src/link/Coff.zig
@@ -1163,8 +1163,8 @@ fn lowerConst(
     try self.setSymbolName(sym, name);
     sym.section_number = @as(coff.SectionNumber, @enumFromInt(sect_id + 1));
 
-    const res = try codegen.generateSymbol(&self.base, pt, src_loc, val, &code_buffer, .none, .{
-        .parent_atom_index = self.getAtom(atom_index).getSymbolIndex().?,
+    const res = try codegen.generateSymbol(&self.base, pt, src_loc, val, &code_buffer, .{
+        .atom_index = self.getAtom(atom_index).getSymbolIndex().?,
     });
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -1235,8 +1235,7 @@ pub fn updateNav(
             zcu.navSrcLoc(nav_index),
             nav_init,
             &code_buffer,
-            .none,
-            .{ .parent_atom_index = atom.getSymbolIndex().? },
+            .{ .atom_index = atom.getSymbolIndex().? },
         );
         const code = switch (res) {
             .ok => code_buffer.items,
@@ -1284,7 +1283,7 @@ fn updateLazySymbolAtom(
         &required_alignment,
         &code_buffer,
         .none,
-        .{ .parent_atom_index = local_sym_index },
+        .{ .atom_index = local_sym_index },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -1823,7 +1822,10 @@ pub fn getNavVAddr(
         .@"extern" => |@"extern"| try self.getGlobalSymbol(nav.name.toSlice(ip), @"extern".lib_name.toSlice(ip)),
         else => self.getAtom(try self.getOrCreateAtomForNav(nav_index)).getSymbolIndex().?,
     };
-    const atom_index = self.getAtomIndexForSymbol(.{ .sym_index = reloc_info.parent_atom_index, .file = null }).?;
+    const atom_index = self.getAtomIndexForSymbol(.{
+        .sym_index = reloc_info.parent.atom_index,
+        .file = null,
+    }).?;
     const target = SymbolWithLoc{ .sym_index = sym_index, .file = null };
     try Atom.addRelocation(self, atom_index, .{
         .type = .direct,
@@ -1901,7 +1903,10 @@ pub fn getUavVAddr(
 
     const this_atom_index = self.uavs.get(uav).?.atom;
     const sym_index = self.getAtom(this_atom_index).getSymbolIndex().?;
-    const atom_index = self.getAtomIndexForSymbol(.{ .sym_index = reloc_info.parent_atom_index, .file = null }).?;
+    const atom_index = self.getAtomIndexForSymbol(.{
+        .sym_index = reloc_info.parent.atom_index,
+        .file = null,
+    }).?;
     const target = SymbolWithLoc{ .sym_index = sym_index, .file = null };
     try Atom.addRelocation(self, atom_index, .{
         .type = .direct,
diff --git a/src/link/Dwarf.zig b/src/link/Dwarf.zig
index 2a9fd8f8f9..ab71e0ec64 100644
--- a/src/link/Dwarf.zig
+++ b/src/link/Dwarf.zig
@@ -19,8 +19,8 @@ debug_rnglists: DebugRngLists,
 debug_str: StringSection,
 
 pub const UpdateError = error{
+    CodegenFail,
     ReinterpretDeclRef,
-    IllDefinedMemoryLayout,
     Unimplemented,
     OutOfMemory,
     EndOfStream,
@@ -1584,6 +1584,18 @@ pub const WipNav = struct {
         wip_nav.func = func;
     }
 
+    fn externalReloc(wip_nav: *WipNav, sec: *Section, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+        try sec.getUnit(wip_nav.unit).getEntry(wip_nav.entry).external_relocs.append(wip_nav.dwarf.gpa, reloc);
+    }
+
+    pub fn infoExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+        try wip_nav.externalReloc(&wip_nav.dwarf.debug_info.section, reloc);
+    }
+
+    fn frameExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+        try wip_nav.externalReloc(&wip_nav.dwarf.debug_frame.section, reloc);
+    }
+
     fn abbrevCode(wip_nav: *WipNav, abbrev_code: AbbrevCode) UpdateError!void {
         try uleb128(wip_nav.debug_info.writer(wip_nav.dwarf.gpa), try wip_nav.dwarf.refAbbrevCode(abbrev_code));
     }
@@ -1660,12 +1672,11 @@ pub const WipNav = struct {
     }
 
     fn infoAddrSym(wip_nav: *WipNav, sym_index: u32) UpdateError!void {
-        const dwarf = wip_nav.dwarf;
-        try dwarf.debug_info.section.getUnit(wip_nav.unit).getEntry(wip_nav.entry).external_relocs.append(dwarf.gpa, .{
+        try wip_nav.infoExternalReloc(.{
             .source_off = @intCast(wip_nav.debug_info.items.len),
             .target_sym = sym_index,
         });
-        try wip_nav.debug_info.appendNTimes(dwarf.gpa, 0, @intFromEnum(dwarf.address_size));
+        try wip_nav.debug_info.appendNTimes(wip_nav.dwarf.gpa, 0, @intFromEnum(wip_nav.dwarf.address_size));
     }
 
     fn frameExprloc(wip_nav: *WipNav, loc: Loc) UpdateError!void {
@@ -1692,12 +1703,11 @@ pub const WipNav = struct {
     }
 
     fn frameAddrSym(wip_nav: *WipNav, sym_index: u32) UpdateError!void {
-        const dwarf = wip_nav.dwarf;
-        try dwarf.debug_frame.section.getUnit(wip_nav.unit).getEntry(wip_nav.entry).external_relocs.append(dwarf.gpa, .{
+        try wip_nav.frameExternalReloc(.{
             .source_off = @intCast(wip_nav.debug_frame.items.len),
             .target_sym = sym_index,
         });
-        try wip_nav.debug_frame.appendNTimes(dwarf.gpa, 0, @intFromEnum(dwarf.address_size));
+        try wip_nav.debug_frame.appendNTimes(wip_nav.dwarf.gpa, 0, @intFromEnum(wip_nav.dwarf.address_size));
     }
 
     fn getTypeEntry(wip_nav: *WipNav, ty: Type) UpdateError!struct { Unit.Index, Entry.Index } {
@@ -1749,6 +1759,27 @@ pub const WipNav = struct {
         reloc.target_off = @intCast(wip_nav.debug_info.items.len);
     }
 
+    fn blockValue(wip_nav: *WipNav, src_loc: Zcu.LazySrcLoc, val: Value) UpdateError!void {
+        const ty = val.typeOf(wip_nav.pt.zcu);
+        const diw = wip_nav.debug_info.writer(wip_nav.dwarf.gpa);
+        const bytes = ty.abiSize(wip_nav.pt.zcu);
+        try uleb128(diw, bytes);
+        if (bytes == 0) return;
+        var dim = wip_nav.debug_info.toManaged(wip_nav.dwarf.gpa);
+        defer wip_nav.debug_info = dim.moveToUnmanaged();
+        switch (try codegen.generateSymbol(
+            wip_nav.dwarf.bin_file,
+            wip_nav.pt,
+            src_loc,
+            val,
+            &dim,
+            .{ .debug_output = .{ .dwarf = wip_nav } },
+        )) {
+            .ok => assert(dim.items.len == wip_nav.debug_info.items.len + bytes),
+            .fail => unreachable,
+        }
+    }
+
     fn enumConstValue(
         wip_nav: *WipNav,
         loaded_enum: InternPool.LoadedEnumType,
@@ -1814,8 +1845,8 @@ pub const WipNav = struct {
         }
     }
 
-    fn flush(wip_nav: *WipNav) UpdateError!void {
-        while (wip_nav.pending_types.popOrNull()) |ty| try wip_nav.dwarf.updateType(wip_nav.pt, ty, &wip_nav.pending_types);
+    fn flush(wip_nav: *WipNav, src_loc: Zcu.LazySrcLoc) UpdateError!void {
+        while (wip_nav.pending_types.popOrNull()) |ty| try wip_nav.dwarf.updateType(wip_nav.pt, src_loc, ty, &wip_nav.pending_types);
     }
 };
 
@@ -2171,15 +2202,15 @@ pub fn initWipNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool.Nav.In
             try diw.writeByte(accessibility);
             try wip_nav.strp(nav.name.toSlice(ip));
             try wip_nav.strp(nav.fqn.toSlice(ip));
-            const ty = nav_val.typeOf(zcu);
-            const ty_reloc_index = try wip_nav.refForward();
+            const nav_ty = nav_val.typeOf(zcu);
+            const nav_ty_reloc_index = try wip_nav.refForward();
             try wip_nav.exprloc(.{ .addr = .{ .sym = sym_index } });
             try uleb128(diw, nav.status.resolved.alignment.toByteUnits() orelse
-                ty.abiAlignment(zcu).toByteUnits().?);
+                nav_ty.abiAlignment(zcu).toByteUnits().?);
             try diw.writeByte(@intFromBool(false));
-            wip_nav.finishForward(ty_reloc_index);
+            wip_nav.finishForward(nav_ty_reloc_index);
             try wip_nav.abbrevCode(.is_const);
-            try wip_nav.refType(ty);
+            try wip_nav.refType(nav_ty);
         },
         .variable => |variable| {
             assert(file.zir_loaded);
@@ -2288,20 +2319,16 @@ pub fn initWipNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool.Nav.In
                                 .source_off = @intCast(wip_nav.debug_frame.items.len),
                             });
                             try dfw.writeByteNTimes(0, dwarf.sectionOffsetBytes());
-                            try entry.external_relocs.append(dwarf.gpa, .{
-                                .source_off = @intCast(wip_nav.debug_frame.items.len),
-                                .target_sym = sym_index,
-                            });
-                            try dfw.writeByteNTimes(0, @intFromEnum(dwarf.address_size));
+                            try wip_nav.frameAddrSym(sym_index);
                             try dfw.writeByteNTimes(undefined, @intFromEnum(dwarf.address_size));
                         },
                         .eh_frame => {
                             try dfw.writeInt(u32, undefined, dwarf.endian);
-                            try entry.external_relocs.append(dwarf.gpa, .{
+                            try wip_nav.frameExternalReloc(.{
                                 .source_off = @intCast(wip_nav.debug_frame.items.len),
                                 .target_sym = sym_index,
                             });
-                            try dfw.writeByteNTimes(0, dwarf.sectionOffsetBytes());
+                            try dfw.writeInt(u32, 0, dwarf.endian);
                             try dfw.writeInt(u32, undefined, dwarf.endian);
                             try uleb128(dfw, 0);
                         },
@@ -2481,12 +2508,13 @@ pub fn finishWipNav(
     }
     try dwarf.debug_loclists.section.replaceEntry(wip_nav.unit, wip_nav.entry, dwarf, wip_nav.debug_loclists.items);
 
-    try wip_nav.flush();
+    try wip_nav.flush(zcu.navSrcLoc(nav_index));
 }
 
 pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool.Nav.Index) UpdateError!void {
     const zcu = pt.zcu;
     const ip = &zcu.intern_pool;
+    const nav_src_loc = zcu.navSrcLoc(nav_index);
     const nav_val = zcu.navValue(nav_index);
 
     const nav = ip.getNav(nav_index);
@@ -2548,7 +2576,7 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
     const nav_gop = try dwarf.navs.getOrPut(dwarf.gpa, nav_index);
     errdefer _ = dwarf.navs.pop();
 
-    const tag: enum { done, decl_alias } = switch (ip.indexToKey(nav_val.toIntern())) {
+    const tag: enum { done, decl_alias, decl_const } = switch (ip.indexToKey(nav_val.toIntern())) {
         .int_type,
         .ptr_type,
         .array_type,
@@ -2623,7 +2651,10 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
                             }
                             const field_type = Type.fromInterned(loaded_struct.field_types.get(ip)[field_index]);
                             try wip_nav.refType(field_type);
-                            if (!is_comptime) {
+                            if (is_comptime) try wip_nav.blockValue(
+                                nav_src_loc,
+                                Value.fromInterned(loaded_struct.fieldInit(ip, field_index)),
+                            ) else {
                                 try uleb128(diw, loaded_struct.offsets.get(ip)[field_index]);
                                 try uleb128(diw, loaded_struct.fieldAlign(ip, field_index).toByteUnits() orelse
                                     field_type.abiAlignment(zcu).toByteUnits().?);
@@ -2850,7 +2881,6 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
         },
         .undef,
         .simple_value,
-        .variable,
         .@"extern",
         .int,
         .err,
@@ -2864,10 +2894,8 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
         .opt,
         .aggregate,
         .un,
-        => {
-            _ = dwarf.navs.pop();
-            return;
-        },
+        => .decl_const,
+        .variable => unreachable,
         .func => |func| tag: {
             if (nav_gop.found_existing) {
                 const unit_ptr = dwarf.debug_info.section.getUnit(wip_nav.unit);
@@ -2918,14 +2946,16 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
         // memoization, not types
         .memoized_call => unreachable,
     };
+    if (tag != .done) {
+        if (nav_gop.found_existing)
+            dwarf.debug_info.section.getUnit(wip_nav.unit).getEntry(nav_gop.value_ptr.*).clear()
+        else
+            nav_gop.value_ptr.* = try dwarf.addCommonEntry(wip_nav.unit);
+        wip_nav.entry = nav_gop.value_ptr.*;
+    }
     switch (tag) {
         .done => {},
         .decl_alias => {
-            if (nav_gop.found_existing)
-                dwarf.debug_info.section.getUnit(wip_nav.unit).getEntry(nav_gop.value_ptr.*).clear()
-            else
-                nav_gop.value_ptr.* = try dwarf.addCommonEntry(wip_nav.unit);
-            wip_nav.entry = nav_gop.value_ptr.*;
             const diw = wip_nav.debug_info.writer(dwarf.gpa);
             try wip_nav.abbrevCode(.decl_alias);
             try wip_nav.refType(Type.fromInterned(parent_type));
@@ -2936,14 +2966,35 @@ pub fn updateComptimeNav(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPool
             try wip_nav.strp(nav.name.toSlice(ip));
             try wip_nav.refType(nav_val.toType());
         },
+        .decl_const => {
+            const diw = wip_nav.debug_info.writer(dwarf.gpa);
+            try wip_nav.abbrevCode(.decl_const);
+            try wip_nav.refType(Type.fromInterned(parent_type));
+            assert(wip_nav.debug_info.items.len == DebugInfo.declEntryLineOff(dwarf));
+            try diw.writeInt(u32, @intCast(loc.line + 1), dwarf.endian);
+            try uleb128(diw, loc.column + 1);
+            try diw.writeByte(accessibility);
+            try wip_nav.strp(nav.name.toSlice(ip));
+            try wip_nav.strp(nav.fqn.toSlice(ip));
+            const nav_ty = nav_val.typeOf(zcu);
+            const nav_ty_reloc_index = try wip_nav.refForward();
+            try wip_nav.blockValue(nav_src_loc, nav_val);
+            try uleb128(diw, nav.status.resolved.alignment.toByteUnits() orelse
+                nav_ty.abiAlignment(zcu).toByteUnits().?);
+            try diw.writeByte(@intFromBool(false));
+            wip_nav.finishForward(nav_ty_reloc_index);
+            try wip_nav.abbrevCode(.is_const);
+            try wip_nav.refType(nav_ty);
+        },
     }
     try dwarf.debug_info.section.replaceEntry(wip_nav.unit, wip_nav.entry, dwarf, wip_nav.debug_info.items);
-    try wip_nav.flush();
+    try wip_nav.flush(nav_src_loc);
 }
 
 fn updateType(
     dwarf: *Dwarf,
     pt: Zcu.PerThread,
+    src_loc: Zcu.LazySrcLoc,
     type_index: InternPool.Index,
     pending_types: *std.ArrayListUnmanaged(InternPool.Index),
 ) UpdateError!void {
@@ -3000,15 +3051,10 @@ fn updateType(
                 const ptr_child_type = Type.fromInterned(ptr_type.child);
                 try wip_nav.abbrevCode(if (ptr_type.sentinel == .none) .ptr_type else .ptr_sentinel_type);
                 try wip_nav.strp(name);
-                if (ptr_type.sentinel != .none) {
-                    const bytes = ptr_child_type.abiSize(zcu);
-                    try uleb128(diw, bytes);
-                    const mem = try wip_nav.debug_info.addManyAsSlice(dwarf.gpa, @intCast(bytes));
-                    Value.fromInterned(ptr_type.sentinel).writeToMemory(pt, mem) catch |err| switch (err) {
-                        error.IllDefinedMemoryLayout => @memset(mem, 0),
-                        else => |e| return e,
-                    };
-                }
+                if (ptr_type.sentinel != .none) try wip_nav.blockValue(
+                    src_loc,
+                    Value.fromInterned(ptr_type.sentinel),
+                );
                 try uleb128(diw, ptr_type.flags.alignment.toByteUnits() orelse
                     ptr_child_type.abiAlignment(zcu).toByteUnits().?);
                 try diw.writeByte(@intFromEnum(ptr_type.flags.address_space));
@@ -3054,15 +3100,10 @@ fn updateType(
             const array_child_type = Type.fromInterned(array_type.child);
             try wip_nav.abbrevCode(if (array_type.sentinel == .none) .array_type else .array_sentinel_type);
             try wip_nav.strp(name);
-            if (array_type.sentinel != .none) {
-                const bytes = array_child_type.abiSize(zcu);
-                try uleb128(diw, bytes);
-                const mem = try wip_nav.debug_info.addManyAsSlice(dwarf.gpa, @intCast(bytes));
-                Value.fromInterned(array_type.sentinel).writeToMemory(pt, mem) catch |err| switch (err) {
-                    error.IllDefinedMemoryLayout => @memset(mem, 0),
-                    else => |e| return e,
-                };
-            }
+            if (array_type.sentinel != .none) try wip_nav.blockValue(
+                src_loc,
+                Value.fromInterned(array_type.sentinel),
+            );
             try wip_nav.refType(array_child_type);
             try wip_nav.abbrevCode(.array_index);
             try wip_nav.refType(Type.usize);
@@ -3292,7 +3333,10 @@ fn updateType(
                 }
                 const field_type = Type.fromInterned(anon_struct_type.types.get(ip)[field_index]);
                 try wip_nav.refType(field_type);
-                if (comptime_value == .none) {
+                if (comptime_value != .none) try wip_nav.blockValue(
+                    src_loc,
+                    Value.fromInterned(comptime_value),
+                ) else {
                     const field_align = field_type.abiAlignment(zcu);
                     field_byte_offset = field_align.forward(field_byte_offset);
                     try uleb128(diw, field_byte_offset);
@@ -3359,16 +3403,13 @@ fn updateType(
             }
             if (error_set_type.names.len > 0) try uleb128(diw, @intFromEnum(AbbrevCode.null));
         },
-        .inferred_error_set_type => |func| switch (ip.funcIesResolvedUnordered(func)) {
-            .none => {
-                try wip_nav.abbrevCode(.void_type);
-                try wip_nav.strp(name);
-            },
-            else => |ies| {
-                try wip_nav.abbrevCode(.inferred_error_set_type);
-                try wip_nav.strp(name);
-                try wip_nav.refType(Type.fromInterned(ies));
-            },
+        .inferred_error_set_type => |func| {
+            try wip_nav.abbrevCode(.inferred_error_set_type);
+            try wip_nav.strp(name);
+            try wip_nav.refType(Type.fromInterned(switch (ip.funcIesResolvedUnordered(func)) {
+                .none => .anyerror_type,
+                else => |ies| ies,
+            }));
         },
 
         // values, not types
@@ -3400,6 +3441,7 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
     const zcu = pt.zcu;
     const ip = &zcu.intern_pool;
     const ty = Type.fromInterned(type_index);
+    const ty_src_loc = ty.srcLoc(zcu);
     log.debug("updateContainerType({}({d}))", .{ ty.fmt(pt), @intFromEnum(type_index) });
 
     const inst_info = ty.typeDeclInst(zcu).?.resolveFull(ip).?;
@@ -3447,7 +3489,10 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
                 }
                 const field_type = Type.fromInterned(loaded_struct.field_types.get(ip)[field_index]);
                 try wip_nav.refType(field_type);
-                if (!is_comptime) {
+                if (is_comptime) try wip_nav.blockValue(
+                    ty_src_loc,
+                    Value.fromInterned(loaded_struct.fieldInit(ip, field_index)),
+                ) else {
                     try uleb128(diw, loaded_struct.offsets.get(ip)[field_index]);
                     try uleb128(diw, loaded_struct.fieldAlign(ip, field_index).toByteUnits() orelse
                         field_type.abiAlignment(zcu).toByteUnits().?);
@@ -3457,7 +3502,7 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
         }
 
         try dwarf.debug_info.section.replaceEntry(wip_nav.unit, wip_nav.entry, dwarf, wip_nav.debug_info.items);
-        try wip_nav.flush();
+        try wip_nav.flush(ty_src_loc);
     } else {
         const decl_inst = file.zir.instructions.get(@intFromEnum(inst_info.inst));
         assert(decl_inst.tag == .extended);
@@ -3515,7 +3560,10 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
                                 }
                                 const field_type = Type.fromInterned(loaded_struct.field_types.get(ip)[field_index]);
                                 try wip_nav.refType(field_type);
-                                if (!is_comptime) {
+                                if (is_comptime) try wip_nav.blockValue(
+                                    ty_src_loc,
+                                    Value.fromInterned(loaded_struct.fieldInit(ip, field_index)),
+                                ) else {
                                     try uleb128(diw, loaded_struct.offsets.get(ip)[field_index]);
                                     try uleb128(diw, loaded_struct.fieldAlign(ip, field_index).toByteUnits() orelse
                                         field_type.abiAlignment(zcu).toByteUnits().?);
@@ -3616,7 +3664,7 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
         }
         try dwarf.debug_info.section.replaceEntry(wip_nav.unit, wip_nav.entry, dwarf, wip_nav.debug_info.items);
         try dwarf.debug_loclists.section.replaceEntry(wip_nav.unit, wip_nav.entry, dwarf, wip_nav.debug_loclists.items);
-        try wip_nav.flush();
+        try wip_nav.flush(ty_src_loc);
     }
 }
 
@@ -4085,6 +4133,7 @@ const AbbrevCode = enum {
     decl_packed_struct,
     decl_union,
     decl_var,
+    decl_const,
     decl_func,
     decl_empty_func,
     decl_func_generic,
@@ -4220,6 +4269,16 @@ const AbbrevCode = enum {
                 .{ .external, .flag },
             },
         },
+        .decl_const = .{
+            .tag = .constant,
+            .attrs = decl_abbrev_common_attrs ++ .{
+                .{ .linkage_name, .strp },
+                .{ .type, .ref_addr },
+                .{ .const_value, .block },
+                .{ .alignment, .udata },
+                .{ .external, .flag },
+            },
+        },
         .decl_func = .{
             .tag = .subprogram,
             .children = true,
@@ -4339,9 +4398,10 @@ const AbbrevCode = enum {
         .struct_field_comptime = .{
             .tag = .member,
             .attrs = &.{
+                .{ .const_expr, .flag_present },
                 .{ .name, .strp },
                 .{ .type, .ref_addr },
-                .{ .const_expr, .flag_present },
+                .{ .default_value, .block },
             },
         },
         .packed_struct_field = .{
diff --git a/src/link/Elf/ZigObject.zig b/src/link/Elf/ZigObject.zig
index 0dc4bd9dae..98449d6a5b 100644
--- a/src/link/Elf/ZigObject.zig
+++ b/src/link/Elf/ZigObject.zig
@@ -957,13 +957,26 @@ pub fn getNavVAddr(
     };
     const this_sym = self.symbol(this_sym_index);
     const vaddr = this_sym.address(.{}, elf_file);
-    const parent_atom = self.symbol(reloc_info.parent_atom_index).atom(elf_file).?;
-    const r_type = relocation.encode(.abs, elf_file.getTarget().cpu.arch);
-    try parent_atom.addReloc(elf_file.base.comp.gpa, .{
-        .r_offset = reloc_info.offset,
-        .r_info = (@as(u64, @intCast(this_sym_index)) << 32) | r_type,
-        .r_addend = reloc_info.addend,
-    }, self);
+    switch (reloc_info.parent) {
+        .atom_index => |atom_index| {
+            const parent_atom = self.symbol(atom_index).atom(elf_file).?;
+            const r_type = relocation.encode(.abs, elf_file.getTarget().cpu.arch);
+            try parent_atom.addReloc(elf_file.base.comp.gpa, .{
+                .r_offset = reloc_info.offset,
+                .r_info = (@as(u64, @intCast(this_sym_index)) << 32) | r_type,
+                .r_addend = reloc_info.addend,
+            }, self);
+        },
+        .debug_output => |debug_output| switch (debug_output) {
+            .dwarf => |wip_nav| try wip_nav.infoExternalReloc(.{
+                .source_off = @intCast(reloc_info.offset),
+                .target_sym = this_sym_index,
+                .target_off = reloc_info.addend,
+            }),
+            .plan9 => unreachable,
+            .none => unreachable,
+        },
+    }
     return @intCast(vaddr);
 }
 
@@ -976,13 +989,26 @@ pub fn getUavVAddr(
     const sym_index = self.uavs.get(uav).?.symbol_index;
     const sym = self.symbol(sym_index);
     const vaddr = sym.address(.{}, elf_file);
-    const parent_atom = self.symbol(reloc_info.parent_atom_index).atom(elf_file).?;
-    const r_type = relocation.encode(.abs, elf_file.getTarget().cpu.arch);
-    try parent_atom.addReloc(elf_file.base.comp.gpa, .{
-        .r_offset = reloc_info.offset,
-        .r_info = (@as(u64, @intCast(sym_index)) << 32) | r_type,
-        .r_addend = reloc_info.addend,
-    }, self);
+    switch (reloc_info.parent) {
+        .atom_index => |atom_index| {
+            const parent_atom = self.symbol(atom_index).atom(elf_file).?;
+            const r_type = relocation.encode(.abs, elf_file.getTarget().cpu.arch);
+            try parent_atom.addReloc(elf_file.base.comp.gpa, .{
+                .r_offset = reloc_info.offset,
+                .r_info = (@as(u64, @intCast(sym_index)) << 32) | r_type,
+                .r_addend = reloc_info.addend,
+            }, self);
+        },
+        .debug_output => |debug_output| switch (debug_output) {
+            .dwarf => |wip_nav| try wip_nav.infoExternalReloc(.{
+                .source_off = @intCast(reloc_info.offset),
+                .target_sym = sym_index,
+                .target_off = reloc_info.addend,
+            }),
+            .plan9 => unreachable,
+            .none => unreachable,
+        },
+    }
     return @intCast(vaddr);
 }
 
@@ -1600,15 +1626,13 @@ pub fn updateNav(
         var debug_wip_nav = if (self.dwarf) |*dwarf| try dwarf.initWipNav(pt, nav_index, sym_index) else null;
         defer if (debug_wip_nav) |*wip_nav| wip_nav.deinit();
 
-        // TODO implement .debug_info for global variables
         const res = try codegen.generateSymbol(
             &elf_file.base,
             pt,
             zcu.navSrcLoc(nav_index),
             Value.fromInterned(nav_init),
             &code_buffer,
-            if (debug_wip_nav) |*wip_nav| .{ .dwarf = wip_nav } else .none,
-            .{ .parent_atom_index = sym_index },
+            .{ .atom_index = sym_index },
         );
 
         const code = switch (res) {
@@ -1691,7 +1715,7 @@ fn updateLazySymbol(
         &required_alignment,
         &code_buffer,
         .none,
-        .{ .parent_atom_index = symbol_index },
+        .{ .atom_index = symbol_index },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -1780,8 +1804,7 @@ fn lowerConst(
         src_loc,
         val,
         &code_buffer,
-        .{ .none = {} },
-        .{ .parent_atom_index = sym_index },
+        .{ .atom_index = sym_index },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
diff --git a/src/link/MachO/ZigObject.zig b/src/link/MachO/ZigObject.zig
index 6a771a3b84..3ffa9c4745 100644
--- a/src/link/MachO/ZigObject.zig
+++ b/src/link/MachO/ZigObject.zig
@@ -633,20 +633,33 @@ pub fn getNavVAddr(
     };
     const sym = self.symbols.items[sym_index];
     const vaddr = sym.getAddress(.{}, macho_file);
-    const parent_atom = self.symbols.items[reloc_info.parent_atom_index].getAtom(macho_file).?;
-    try parent_atom.addReloc(macho_file, .{
-        .tag = .@"extern",
-        .offset = @intCast(reloc_info.offset),
-        .target = sym_index,
-        .addend = reloc_info.addend,
-        .type = .unsigned,
-        .meta = .{
-            .pcrel = false,
-            .has_subtractor = false,
-            .length = 3,
-            .symbolnum = @intCast(sym.nlist_idx),
+    switch (reloc_info.parent) {
+        .atom_index => |atom_index| {
+            const parent_atom = self.symbols.items[atom_index].getAtom(macho_file).?;
+            try parent_atom.addReloc(macho_file, .{
+                .tag = .@"extern",
+                .offset = @intCast(reloc_info.offset),
+                .target = sym_index,
+                .addend = reloc_info.addend,
+                .type = .unsigned,
+                .meta = .{
+                    .pcrel = false,
+                    .has_subtractor = false,
+                    .length = 3,
+                    .symbolnum = @intCast(sym.nlist_idx),
+                },
+            });
         },
-    });
+        .debug_output => |debug_output| switch (debug_output) {
+            .dwarf => |wip_nav| try wip_nav.infoExternalReloc(.{
+                .source_off = @intCast(reloc_info.offset),
+                .target_sym = sym_index,
+                .target_off = reloc_info.addend,
+            }),
+            .plan9 => unreachable,
+            .none => unreachable,
+        },
+    }
     return vaddr;
 }
 
@@ -659,20 +672,33 @@ pub fn getUavVAddr(
     const sym_index = self.uavs.get(uav).?.symbol_index;
     const sym = self.symbols.items[sym_index];
     const vaddr = sym.getAddress(.{}, macho_file);
-    const parent_atom = self.symbols.items[reloc_info.parent_atom_index].getAtom(macho_file).?;
-    try parent_atom.addReloc(macho_file, .{
-        .tag = .@"extern",
-        .offset = @intCast(reloc_info.offset),
-        .target = sym_index,
-        .addend = reloc_info.addend,
-        .type = .unsigned,
-        .meta = .{
-            .pcrel = false,
-            .has_subtractor = false,
-            .length = 3,
-            .symbolnum = @intCast(sym.nlist_idx),
+    switch (reloc_info.parent) {
+        .atom_index => |atom_index| {
+            const parent_atom = self.symbols.items[atom_index].getAtom(macho_file).?;
+            try parent_atom.addReloc(macho_file, .{
+                .tag = .@"extern",
+                .offset = @intCast(reloc_info.offset),
+                .target = sym_index,
+                .addend = reloc_info.addend,
+                .type = .unsigned,
+                .meta = .{
+                    .pcrel = false,
+                    .has_subtractor = false,
+                    .length = 3,
+                    .symbolnum = @intCast(sym.nlist_idx),
+                },
+            });
         },
-    });
+        .debug_output => |debug_output| switch (debug_output) {
+            .dwarf => |wip_nav| try wip_nav.infoExternalReloc(.{
+                .source_off = @intCast(reloc_info.offset),
+                .target_sym = sym_index,
+                .target_off = reloc_info.addend,
+            }),
+            .plan9 => unreachable,
+            .none => unreachable,
+        },
+    }
     return vaddr;
 }
 
@@ -903,8 +929,7 @@ pub fn updateNav(
             zcu.navSrcLoc(nav_index),
             Value.fromInterned(nav_init),
             &code_buffer,
-            if (debug_wip_nav) |*wip_nav| .{ .dwarf = wip_nav } else .none,
-            .{ .parent_atom_index = sym_index },
+            .{ .atom_index = sym_index },
         );
 
         const code = switch (res) {
@@ -1212,11 +1237,14 @@ fn lowerConst(
     const name_str = try self.addString(gpa, name);
     const sym_index = try self.newSymbolWithAtom(gpa, name_str, macho_file);
 
-    const res = try codegen.generateSymbol(&macho_file.base, pt, src_loc, val, &code_buffer, .{
-        .none = {},
-    }, .{
-        .parent_atom_index = sym_index,
-    });
+    const res = try codegen.generateSymbol(
+        &macho_file.base,
+        pt,
+        src_loc,
+        val,
+        &code_buffer,
+        .{ .atom_index = sym_index },
+    );
     const code = switch (res) {
         .ok => code_buffer.items,
         .fail => |em| return .{ .fail = em },
@@ -1378,7 +1406,7 @@ fn updateLazySymbol(
         &required_alignment,
         &code_buffer,
         .none,
-        .{ .parent_atom_index = symbol_index },
+        .{ .atom_index = symbol_index },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
diff --git a/src/link/Plan9.zig b/src/link/Plan9.zig
index 080b6853e7..7737c22d05 100644
--- a/src/link/Plan9.zig
+++ b/src/link/Plan9.zig
@@ -422,10 +422,7 @@ pub fn updateFunc(self: *Plan9, pt: Zcu.PerThread, func_index: InternPool.Index,
     );
     const code = switch (res) {
         .ok => try code_buffer.toOwnedSlice(),
-        .fail => |em| {
-            try zcu.failed_codegen.put(gpa, func.owner_nav, em);
-            return;
-        },
+        .fail => |em| return zcu.failed_codegen.put(gpa, func.owner_nav, em),
     };
     self.getAtomPtr(atom_idx).code = .{
         .code_ptr = null,
@@ -463,15 +460,17 @@ pub fn updateNav(self: *Plan9, pt: Zcu.PerThread, nav_index: InternPool.Nav.Inde
         var code_buffer = std.ArrayList(u8).init(gpa);
         defer code_buffer.deinit();
         // TODO we need the symbol index for symbol in the table of locals for the containing atom
-        const res = try codegen.generateSymbol(&self.base, pt, zcu.navSrcLoc(nav_index), nav_init, &code_buffer, .none, .{
-            .parent_atom_index = @intCast(atom_idx),
-        });
+        const res = try codegen.generateSymbol(
+            &self.base,
+            pt,
+            zcu.navSrcLoc(nav_index),
+            nav_init,
+            &code_buffer,
+            .{ .atom_index = @intCast(atom_idx) },
+        );
         const code = switch (res) {
             .ok => code_buffer.items,
-            .fail => |em| {
-                try zcu.failed_codegen.put(gpa, nav_index, em);
-                return;
-            },
+            .fail => |em| return zcu.failed_codegen.put(gpa, nav_index, em),
         };
         try self.data_nav_table.ensureUnusedCapacity(gpa, 1);
         const duped_code = try gpa.dupe(u8, code);
@@ -1116,7 +1115,7 @@ fn updateLazySymbolAtom(self: *Plan9, pt: Zcu.PerThread, sym: File.LazySymbol, a
         &required_alignment,
         &code_buffer,
         .none,
-        .{ .parent_atom_index = @as(Atom.Index, @intCast(atom_index)) },
+        .{ .atom_index = @intCast(atom_index) },
     );
     const code = switch (res) {
         .ok => code_buffer.items,
@@ -1373,21 +1372,21 @@ pub fn getNavVAddr(
     log.debug("getDeclVAddr for {}", .{nav.name.fmt(ip)});
     if (ip.indexToKey(nav.status.resolved.val) == .@"extern") {
         if (nav.name.eqlSlice("etext", ip)) {
-            try self.addReloc(reloc_info.parent_atom_index, .{
+            try self.addReloc(reloc_info.parent.atom_index, .{
                 .target = undefined,
                 .offset = reloc_info.offset,
                 .addend = reloc_info.addend,
                 .type = .special_etext,
             });
         } else if (nav.name.eqlSlice("edata", ip)) {
-            try self.addReloc(reloc_info.parent_atom_index, .{
+            try self.addReloc(reloc_info.parent.atom_index, .{
                 .target = undefined,
                 .offset = reloc_info.offset,
                 .addend = reloc_info.addend,
                 .type = .special_edata,
             });
         } else if (nav.name.eqlSlice("end", ip)) {
-            try self.addReloc(reloc_info.parent_atom_index, .{
+            try self.addReloc(reloc_info.parent.atom_index, .{
                 .target = undefined,
                 .offset = reloc_info.offset,
                 .addend = reloc_info.addend,
@@ -1400,7 +1399,7 @@ pub fn getNavVAddr(
     // otherwise, we just add a relocation
     const atom_index = try self.seeNav(pt, nav_index);
     // the parent_atom_index in this case is just the decl_index of the parent
-    try self.addReloc(reloc_info.parent_atom_index, .{
+    try self.addReloc(reloc_info.parent.atom_index, .{
         .target = atom_index,
         .offset = reloc_info.offset,
         .addend = reloc_info.addend,
@@ -1435,7 +1434,7 @@ pub fn lowerUav(
     gop.value_ptr.* = index;
     // we need to free name latex
     var code_buffer = std.ArrayList(u8).init(gpa);
-    const res = try codegen.generateSymbol(&self.base, pt, src_loc, val, &code_buffer, .{ .none = {} }, .{ .parent_atom_index = index });
+    const res = try codegen.generateSymbol(&self.base, pt, src_loc, val, &code_buffer, .{ .atom_index = index });
     const code = switch (res) {
         .ok => code_buffer.items,
         .fail => |em| return .{ .fail = em },
@@ -1459,7 +1458,7 @@ pub fn lowerUav(
 
 pub fn getUavVAddr(self: *Plan9, uav: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
     const atom_index = self.uavs.get(uav).?;
-    try self.addReloc(reloc_info.parent_atom_index, .{
+    try self.addReloc(reloc_info.parent.atom_index, .{
         .target = atom_index,
         .offset = reloc_info.offset,
         .addend = reloc_info.addend,
diff --git a/src/link/Wasm/ZigObject.zig b/src/link/Wasm/ZigObject.zig
index c0d531582f..afb0216fd7 100644
--- a/src/link/Wasm/ZigObject.zig
+++ b/src/link/Wasm/ZigObject.zig
@@ -277,8 +277,7 @@ pub fn updateNav(
             zcu.navSrcLoc(nav_index),
             nav_init,
             &code_writer,
-            .none,
-            .{ .parent_atom_index = @intFromEnum(atom.sym_index) },
+            .{ .atom_index = @intFromEnum(atom.sym_index) },
         );
 
         const code = switch (res) {
@@ -520,10 +519,7 @@ fn lowerConst(
             src_loc,
             val,
             &value_bytes,
-            .none,
-            .{
-                .parent_atom_index = @intFromEnum(atom.sym_index),
-            },
+            .{ .atom_index = @intFromEnum(atom.sym_index) },
         );
         break :code switch (result) {
             .ok => value_bytes.items,
@@ -762,8 +758,11 @@ pub fn getNavVAddr(
         else => {},
     }
 
-    std.debug.assert(reloc_info.parent_atom_index != 0);
-    const atom_index = wasm_file.symbol_atom.get(.{ .file = zig_object.index, .index = @enumFromInt(reloc_info.parent_atom_index) }).?;
+    std.debug.assert(reloc_info.parent.atom_index != 0);
+    const atom_index = wasm_file.symbol_atom.get(.{
+        .file = zig_object.index,
+        .index = @enumFromInt(reloc_info.parent.atom_index),
+    }).?;
     const atom = wasm_file.getAtomPtr(atom_index);
     const is_wasm32 = target.cpu.arch == .wasm32;
     if (ip.isFunctionType(ip.getNav(nav_index).typeOf(ip))) {
@@ -800,7 +799,10 @@ pub fn getUavVAddr(
     const atom_index = zig_object.uavs.get(uav).?;
     const target_symbol_index = @intFromEnum(wasm_file.getAtom(atom_index).sym_index);
 
-    const parent_atom_index = wasm_file.symbol_atom.get(.{ .file = zig_object.index, .index = @enumFromInt(reloc_info.parent_atom_index) }).?;
+    const parent_atom_index = wasm_file.symbol_atom.get(.{
+        .file = zig_object.index,
+        .index = @enumFromInt(reloc_info.parent.atom_index),
+    }).?;
     const parent_atom = wasm_file.getAtomPtr(parent_atom_index);
     const is_wasm32 = target.cpu.arch == .wasm32;
     const zcu = wasm_file.base.comp.zcu.?;