Merge pull request #13719 from Vexu/debug

Improve debuggability of programs built by the self hosted compiler

lib/build_runner.zig

@@ -142,6 +142,8 @@ pub fn main() !void {
                     return usageAndErr(builder, false, stderr_stream);
                 };
                 try debug_log_scopes.append(next_arg);
+            } else if (mem.eql(u8, arg, "--debug-compile-errors")) {
+                builder.debug_compile_errors = true;
             } else if (mem.eql(u8, arg, "--glibc-runtimes")) {
                 builder.glibc_runtimes_dir = nextArg(args, &arg_idx) orelse {
                     std.debug.print("Expected argument after --glibc-runtimes\n\n", .{});

lib/std/build.zig

@@ -72,6 +72,7 @@ pub const Builder = struct {
     pkg_config_pkg_list: ?(PkgConfigError![]const PkgConfigPkg) = null,
     args: ?[][]const u8 = null,
     debug_log_scopes: []const []const u8 = &.{},
+    debug_compile_errors: bool = false,
 
     /// Experimental. Use system Darling installation to run cross compiled macOS build artifacts.
     enable_darling: bool = false,
@@ -2674,6 +2675,10 @@ pub const LibExeObjStep = struct {
             try zig_args.append(log_scope);
         }
 
+        if (builder.debug_compile_errors) {
+            try zig_args.append("--debug-compile-errors");
+        }
+
         if (builder.verbose_cimport) zig_args.append("--verbose-cimport") catch unreachable;
         if (builder.verbose_air) zig_args.append("--verbose-air") catch unreachable;
         if (builder.verbose_llvm_ir) zig_args.append("--verbose-llvm-ir") catch unreachable;

src/Sema.zig

@@ -2091,10 +2091,16 @@ fn failWithOwnedErrorMsg(sema: *Sema, err_msg: *Module.ErrorMsg) CompileError {
     @setCold(true);
 
     if (crash_report.is_enabled and sema.mod.comp.debug_compile_errors) {
-        std.debug.print("compile error during Sema: {s}, src: {s}:{}\n", .{
+        const err_path = err_msg.src_loc.file_scope.fullPath(sema.mod.gpa) catch unreachable;
+        const err_source = err_msg.src_loc.file_scope.getSource(sema.mod.gpa) catch unreachable;
+        const err_span = err_msg.src_loc.span(sema.mod.gpa) catch unreachable;
+        const err_loc = std.zig.findLineColumn(err_source.bytes, err_span.main);
+        std.debug.print("compile error during Sema:\n{s}:{d}:{d}: error: {s}\n{s}\n\n", .{
+            err_path,
+            err_loc.line + 1,
+            err_loc.column + 1,
             err_msg.msg,
-            err_msg.src_loc.file_scope.sub_file_path,
+            err_loc.source_line,
-            err_msg.src_loc.lazy,
         });
         crash_report.compilerPanic("unexpected compile error occurred", null, null);
     }

src/codegen/llvm.zig

@@ -6090,6 +6090,12 @@ pub const FuncGen = struct {
         const insert_block = self.builder.getInsertBlock();
         if (isByRef(operand_ty)) {
             _ = dib.insertDeclareAtEnd(operand, di_local_var, debug_loc, insert_block);
+        } else if (self.dg.module.comp.bin_file.options.optimize_mode == .Debug) {
+            const alignment = operand_ty.abiAlignment(self.dg.module.getTarget());
+            const alloca = self.buildAlloca(operand.typeOf(), alignment);
+            const store_inst = self.builder.buildStore(operand, alloca);
+            store_inst.setAlignment(alignment);
+            _ = dib.insertDeclareAtEnd(alloca, di_local_var, debug_loc, insert_block);
         } else {
             _ = dib.insertDbgValueIntrinsicAtEnd(operand, di_local_var, debug_loc, insert_block);
         }
@@ -8028,6 +8034,12 @@ pub const FuncGen = struct {
             const insert_block = self.builder.getInsertBlock();
             if (isByRef(inst_ty)) {
                 _ = dib.insertDeclareAtEnd(arg_val, di_local_var, debug_loc, insert_block);
+            } else if (self.dg.module.comp.bin_file.options.optimize_mode == .Debug) {
+                const alignment = inst_ty.abiAlignment(self.dg.module.getTarget());
+                const alloca = self.buildAlloca(arg_val.typeOf(), alignment);
+                const store_inst = self.builder.buildStore(arg_val, alloca);
+                store_inst.setAlignment(alignment);
+                _ = dib.insertDeclareAtEnd(alloca, di_local_var, debug_loc, insert_block);
             } else {
                 _ = dib.insertDbgValueIntrinsicAtEnd(arg_val, di_local_var, debug_loc, insert_block);
             }

src/main.zig

@@ -3752,6 +3752,7 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
         var override_global_cache_dir: ?[]const u8 = try optionalStringEnvVar(arena, "ZIG_GLOBAL_CACHE_DIR");
         var override_local_cache_dir: ?[]const u8 = try optionalStringEnvVar(arena, "ZIG_LOCAL_CACHE_DIR");
         var child_argv = std.ArrayList([]const u8).init(arena);
+        var debug_compile_errors = false;
 
         const argv_index_exe = child_argv.items.len;
         _ = try child_argv.addOne();
@@ -3807,6 +3808,9 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
                         try child_argv.append(arg);
                     } else if (mem.eql(u8, arg, "-fno-reference-trace")) {
                         try child_argv.append(arg);
+                    } else if (mem.eql(u8, arg, "--debug-compile-errors")) {
+                        try child_argv.append(arg);
+                        debug_compile_errors = true;
                     }
                 }
                 try child_argv.append(arg);
@@ -3940,6 +3944,7 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
             .thread_pool = &thread_pool,
             .use_stage1 = use_stage1,
             .cache_mode = .whole,
+            .debug_compile_errors = debug_compile_errors,
         }) catch |err| {
             fatal("unable to create compilation: {s}", .{@errorName(err)});
         };