wasm: Add basic debug info references

src/link.zig

@@ -485,8 +485,9 @@ pub const File = struct {
             .elf => return @fieldParentPtr(Elf, "base", base).updateDeclLineNumber(module, decl),
             .macho => return @fieldParentPtr(MachO, "base", base).updateDeclLineNumber(module, decl),
             .c => return @fieldParentPtr(C, "base", base).updateDeclLineNumber(module, decl),
+            .wasm => return @fieldParentPtr(Wasm, "base", base).updateDeclLineNumber(module, decl),
             .plan9 => @panic("TODO: implement updateDeclLineNumber for plan9"),
-            .wasm, .spirv, .nvptx => {},
+            .spirv, .nvptx => {},
         }
     }
 

src/link/Dwarf.zig

@@ -735,6 +735,7 @@ pub fn initDeclState(self: *Dwarf, mod: *Module, decl: *Module.Decl) !DeclState
                 const atom = switch (self.tag) {
                     .elf => &decl.link.elf.dbg_info_atom,
                     .macho => &decl.link.macho.dbg_info_atom,
+                    .wasm => &decl.link.wasm.dbg_info_atom,
                     else => unreachable,
                 };
                 try decl_state.addTypeReloc(
@@ -1250,6 +1251,10 @@ pub fn updateDeclLineNumber(self: *Dwarf, file: *File, decl: *const Module.Decl)
             const file_pos = sect.offset + decl.fn_link.macho.off + self.getRelocDbgLineOff();
             try d_sym.file.pwriteAll(&data, file_pos);
         },
+        .wasm => {
+            const wasm_file = file.cast(File.Wasm).?;
+            _ = wasm_file; // TODO, update .debug_line
+        },
         else => unreachable,
     }
 }
@@ -1285,6 +1290,7 @@ pub fn freeDecl(self: *Dwarf, decl: *Module.Decl) void {
     const fn_link = switch (self.tag) {
         .elf => &decl.fn_link.elf,
         .macho => &decl.fn_link.macho,
+        .wasm => &decl.fn_link.wasm.src_fn,
         else => unreachable,
     };
     _ = self.dbg_line_fn_free_list.remove(fn_link);

src/link/Wasm.zig

@@ -11,6 +11,7 @@ const log = std.log.scoped(.link);
 const wasm = std.wasm;
 
 const Atom = @import("Wasm/Atom.zig");
+const Dwarf = @import("Dwarf.zig");
 const Module = @import("../Module.zig");
 const Compilation = @import("../Compilation.zig");
 const CodeGen = @import("../arch/wasm/CodeGen.zig");
@@ -82,6 +83,8 @@ data_segments: std.StringArrayHashMapUnmanaged(u32) = .{},
 segment_info: std.ArrayListUnmanaged(types.Segment) = .{},
 /// Deduplicated string table for strings used by symbols, imports and exports.
 string_table: StringTable = .{},
+/// Debug information for wasm
+dwarf: ?Dwarf = null,
 
 // Output sections
 /// Output type section
@@ -137,10 +140,15 @@ pub const Segment = struct {
 };
 
 pub const FnData = struct {
+    /// Reference to the wasm type that represents this function.
     type_index: u32,
+    /// Contains debug information related to this function.
+    /// For Wasm, the offset is relative to the code-section.
+    src_fn: Dwarf.SrcFn,
 
     pub const empty: FnData = .{
         .type_index = undefined,
+        .src_fn = Dwarf.SrcFn.empty,
     };
 };
 
@@ -318,6 +326,11 @@ pub fn createEmpty(gpa: Allocator, options: link.Options) !*Wasm {
         },
         .name = undefined,
     };
+
+    if (!options.strip and options.module != null) {
+        self.dwarf = Dwarf.init(gpa, .wasm, options.target);
+    }
+
     const use_llvm = build_options.have_llvm and options.use_llvm;
     const use_stage1 = build_options.is_stage1 and options.use_stage1;
     if (use_llvm and !use_stage1) {
@@ -479,6 +492,10 @@ pub fn deinit(self: *Wasm) void {
     self.exports.deinit(gpa);
 
     self.string_table.deinit(gpa);
+
+    if (self.dwarf) |*dwarf| {
+        dwarf.deinit();
+    }
 }
 
 pub fn allocateDeclIndexes(self: *Wasm, decl_index: Module.Decl.Index) !void {
@@ -515,12 +532,19 @@ pub fn updateFunc(self: *Wasm, mod: *Module, func: *Module.Fn, air: Air, livenes
     if (build_options.have_llvm) {
         if (self.llvm_object) |llvm_object| return llvm_object.updateFunc(mod, func, air, liveness);
     }
+
+    const tracy = trace(@src());
+    defer tracy.end();
+
     const decl_index = func.owner_decl;
     const decl = mod.declPtr(decl_index);
     assert(decl.link.wasm.sym_index != 0); // Must call allocateDeclIndexes()
 
     decl.link.wasm.clear();
 
+    var decl_state: ?Dwarf.DeclState = if (self.dwarf) |*dwarf| try dwarf.initDeclState(mod, decl) else null;
+    defer if (decl_state) |*ds| ds.deinit();
+
     var code_writer = std.ArrayList(u8).init(self.base.allocator);
     defer code_writer.deinit();
     const result = try codegen.generateFunction(
@@ -530,7 +554,7 @@ pub fn updateFunc(self: *Wasm, mod: *Module, func: *Module.Fn, air: Air, livenes
         air,
         liveness,
         &code_writer,
-        .none,
+        if (decl_state) |*ds| .{ .dwarf = ds } else .none,
     );
 
     const code = switch (result) {
@@ -555,6 +579,9 @@ pub fn updateDecl(self: *Wasm, mod: *Module, decl_index: Module.Decl.Index) !voi
         if (self.llvm_object) |llvm_object| return llvm_object.updateDecl(mod, decl_index);
     }
 
+    const tracy = trace(@src());
+    defer tracy.end();
+
     const decl = mod.declPtr(decl_index);
     assert(decl.link.wasm.sym_index != 0); // Must call allocateDeclIndexes()
 
@@ -596,6 +623,20 @@ pub fn updateDecl(self: *Wasm, mod: *Module, decl_index: Module.Decl.Index) !voi
     return self.finishUpdateDecl(decl, code);
 }
 
+pub fn updateDeclLineNumber(self: *Wasm, mod: *Module, decl: *const Module.Decl) !void {
+    if (self.llvm_object) |_| return;
+    if (self.dwarf) |*dw| {
+        const tracy = trace(@src());
+        defer tracy.end();
+
+        const decl_name = try decl.getFullyQualifiedName(mod);
+        defer self.base.allocator.free(decl_name);
+
+        log.debug("updateDeclLineNumber {s}{*}", .{ decl_name, decl });
+        try dw.updateDeclLineNumber(&self.base, decl);
+    }
+}
+
 fn finishUpdateDecl(self: *Wasm, decl: *Module.Decl, code: []const u8) !void {
     if (code.len == 0) return;
     const mod = self.base.options.module.?;
@@ -852,6 +893,12 @@ pub fn freeDecl(self: *Wasm, decl_index: Module.Decl.Index) void {
     }
     _ = self.resolved_symbols.swapRemove(atom.symbolLoc());
     _ = self.symbol_atom.remove(atom.symbolLoc());
+
+    if (self.dwarf) |*dwarf| {
+        dwarf.freeDecl(decl);
+        dwarf.freeAtom(&atom.dbg_info_atom);
+    }
+
     atom.deinit(self.base.allocator);
 }
 

src/link/Wasm/Atom.zig

@@ -4,6 +4,7 @@ const std = @import("std");
 const types = @import("types.zig");
 const Wasm = @import("../Wasm.zig");
 const Symbol = @import("Symbol.zig");
+const Dwarf = @import("../Dwarf.zig");
 
 const leb = std.leb;
 const log = std.log.scoped(.link);
@@ -38,6 +39,9 @@ prev: ?*Atom,
 /// When the parent atom is being freed, it will also do so for all local atoms.
 locals: std.ArrayListUnmanaged(Atom) = .{},
 
+/// Represents the debug Atom that holds all debug information of this Atom.
+dbg_info_atom: Dwarf.Atom,
+
 /// Represents a default empty wasm `Atom`
 pub const empty: Atom = .{
     .alignment = 0,
@@ -47,6 +51,7 @@ pub const empty: Atom = .{
     .prev = null,
     .size = 0,
     .sym_index = 0,
+    .dbg_info_atom = undefined,
 };
 
 /// Frees all resources owned by this `Atom`.