Commit f760272200

@@ -882,6 +882,8 @@ fn genFunc(self: *Self) InnerError!void {
     self.args = cc_result.args;
     self.return_value = cc_result.return_value;
 
+    try self.addTag(.dbg_prologue_end);
+
     // Generate MIR for function body
     try self.genBody(self.air.getMainBody());
     // In case we have a return value, but the last instruction is a noreturn (such as a while loop)
@@ -896,6 +898,8 @@ fn genFunc(self: *Self) InnerError!void {
     // End of function body
     try self.addTag(.end);
 
+    try self.addTag(.dbg_epilogue_begin);
+
     // check if we have to initialize and allocate anything into the stack frame.
     // If so, create enough stack space and insert the instructions at the front of the list.
     if (self.stack_size > 0) {
@@ -942,6 +946,10 @@ fn genFunc(self: *Self) InnerError!void {
         .code = self.code,
         .locals = self.locals.items,
         .decl = self.decl,
+        .dbg_output = self.debug_output,
+        .prev_di_line = 0,
+        .prev_di_column = 0,
+        .prev_di_offset = 0,
     };
 
     emit.emitMir() catch |err| switch (err) {

@@ -6,6 +6,7 @@ const std = @import("std");
 const Mir = @import("Mir.zig");
 const link = @import("../../link.zig");
 const Module = @import("../../Module.zig");
+const codegen = @import("../../codegen.zig");
 const leb128 = std.leb;
 
 /// Contains our list of instructions
@@ -22,6 +23,16 @@ locals: []const u8,
 /// The declaration that code is being generated for.
 decl: *Module.Decl,
 
+// Debug information
+/// Holds the debug information for this emission
+dbg_output: codegen.DebugInfoOutput,
+/// Previous debug info line
+prev_di_line: u32,
+/// Previous debug info column
+prev_di_column: u32,
+/// Previous offset relative to code section
+prev_di_offset: u32,
+
 const InnerError = error{
     OutOfMemory,
     EmitFail,
@@ -40,6 +51,10 @@ pub fn emitMir(emit: *Emit) InnerError!void {
             .block => try emit.emitBlock(tag, inst),
             .loop => try emit.emitBlock(tag, inst),
 
+            .dbg_line => try emit.emitDbgLine(inst),
+            .dbg_epilogue_begin => try emit.emitDbgEpilogueBegin(),
+            .dbg_prologue_end => try emit.emitDbgPrologueEnd(),
+
             // branch instructions
             .br_if => try emit.emitLabel(tag, inst),
             .br_table => try emit.emitBrTable(inst),
@@ -419,3 +434,43 @@ fn emitMemFill(emit: *Emit) !void {
     // For now we will always emit index 0.
     try leb128.writeULEB128(emit.code.writer(), @as(u32, 0));
 }
+
+fn emitDbgLine(emit: *Emit, inst: Mir.Inst.Index) !void {
+    const extra_index = emit.mir.instructions.items(.data)[inst].payload;
+    const dbg_line = emit.mir.extraData(Mir.DbgLineColumn, extra_index).data;
+    try emit.dbgAdvancePCAndLine(dbg_line.line, dbg_line.column);
+}
+
+fn dbgAdvancePCAndLine(emit: *Emit, line: u32, column: u32) !void {
+    if (emit.dbg_output != .dwarf) return;
+
+    const dbg_line = &emit.dbg_output.dwarf.dbg_line;
+    try dbg_line.ensureUnusedCapacity(11);
+    dbg_line.appendAssumeCapacity(std.dwarf.LNS.advance_pc);
+    // TODO: This must emit a relocation to calculate the offset relative
+    // to the code section start.
+    leb128.writeULEB128(dbg_line.writer(), emit.offset() - emit.prev_di_offset) catch unreachable;
+    const delta_line = @intCast(i32, line) - @intCast(i32, emit.prev_di_line);
+    if (delta_line != 0) {
+        dbg_line.appendAssumeCapacity(std.dwarf.LNS.advance_line);
+        leb128.writeILEB128(dbg_line.writer(), delta_line) catch unreachable;
+    }
+    dbg_line.appendAssumeCapacity(std.dwarf.LNS.copy);
+    emit.prev_di_line = line;
+    emit.prev_di_column = column;
+    emit.prev_di_offset = emit.offset();
+}
+
+fn emitDbgPrologueEnd(emit: *Emit) !void {
+    if (emit.dbg_output != .dwarf) return;
+
+    try emit.dbg_output.dwarf.dbg_line.append(std.dwarf.LNS.set_prologue_end);
+    try emit.dbgAdvancePCAndLine(emit.prev_di_line, emit.prev_di_column);
+}
+
+fn emitDbgEpilogueBegin(emit: *Emit) !void {
+    if (emit.dbg_output != .dwarf) return;
+
+    try emit.dbg_output.dwarf.dbg_line.append(std.dwarf.LNS.set_epilogue_begin);
+    try emit.dbgAdvancePCAndLine(emit.prev_di_line, emit.prev_di_column);
+}

@@ -47,6 +47,19 @@ pub const Inst = struct {
         ///
         /// Type of the loop is given in data `block_type`
         loop = 0x03,
+        /// Inserts debug information about the current line and column
+        /// of the source code
+        ///
+        /// Uses `payload` of which the payload type is `DbgLineColumn`
+        dbg_line = 0x06,
+        /// Emits epilogue begin debug information
+        ///
+        /// Uses `nop`
+        dbg_epilogue_begin = 0x07,
+        /// Emits prologue end debug information
+        ///
+        /// Uses `nop`
+        dbg_prologue_end = 0x08,
         /// Represents the end of a function body or an initialization expression
         ///
         /// Payload is `nop`
@@ -645,3 +658,9 @@ pub const Memory = struct {
     pointer: u32,
     offset: u32,
 };
+
+/// Maps a source line with wasm bytecode
+pub const DbgLineColumn = struct {
+    line: u32,
+    column: u32,
+};