From 5c3a486639443e2fa62433b95108d956088e73bd Mon Sep 17 00:00:00 2001 From: Jacob Young Date: Sun, 30 Oct 2022 15:09:45 -0400 Subject: [PATCH] AstGen: avoid accessing value from inner scope While continue expressions can access the capture, so ensure that it is unwrapped in an outer scope. --- src/AstGen.zig | 72 ++++++++++++++++++++++++++------------------------ 1 file changed, 38 insertions(+), 34 deletions(-) diff --git a/src/AstGen.zig b/src/AstGen.zig index 48e6a480f3..d71a2fd13d 100644 --- a/src/AstGen.zig +++ b/src/AstGen.zig @@ -5910,8 +5910,8 @@ fn whileExpr( defer loop_scope.unstack(); defer loop_scope.labeled_breaks.deinit(astgen.gpa); - var continue_scope = parent_gz.makeSubBlock(&loop_scope.base); - defer continue_scope.unstack(); + var cond_scope = parent_gz.makeSubBlock(&loop_scope.base); + defer cond_scope.unstack(); const payload_is_ref = if (while_full.payload_token) |payload_token| token_tags[payload_token] == .asterisk @@ -5925,22 +5925,22 @@ fn whileExpr( } = c: { if (while_full.error_token) |_| { const cond_ri: ResultInfo = .{ .rl = if (payload_is_ref) .ref else .none }; - const err_union = try expr(&continue_scope, &continue_scope.base, cond_ri, while_full.ast.cond_expr); + const err_union = try expr(&cond_scope, &cond_scope.base, cond_ri, while_full.ast.cond_expr); const tag: Zir.Inst.Tag = if (payload_is_ref) .is_non_err_ptr else .is_non_err; break :c .{ .inst = err_union, - .bool_bit = try continue_scope.addUnNode(tag, err_union, while_full.ast.then_expr), + .bool_bit = try cond_scope.addUnNode(tag, err_union, while_full.ast.then_expr), }; } else if (while_full.payload_token) |_| { const cond_ri: ResultInfo = .{ .rl = if (payload_is_ref) .ref else .none }; - const optional = try expr(&continue_scope, &continue_scope.base, cond_ri, while_full.ast.cond_expr); + const optional = try expr(&cond_scope, &cond_scope.base, cond_ri, while_full.ast.cond_expr); const tag: Zir.Inst.Tag = if (payload_is_ref) .is_non_null_ptr else .is_non_null; break :c .{ .inst = optional, - .bool_bit = try continue_scope.addUnNode(tag, optional, while_full.ast.then_expr), + .bool_bit = try cond_scope.addUnNode(tag, optional, while_full.ast.then_expr), }; } else { - const cond = try expr(&continue_scope, &continue_scope.base, bool_ri, while_full.ast.cond_expr); + const cond = try expr(&cond_scope, &cond_scope.base, bool_ri, while_full.ast.cond_expr); break :c .{ .inst = cond, .bool_bit = cond, @@ -5949,16 +5949,16 @@ fn whileExpr( }; const condbr_tag: Zir.Inst.Tag = if (is_inline) .condbr_inline else .condbr; - const condbr = try continue_scope.addCondBr(condbr_tag, node); + const condbr = try cond_scope.addCondBr(condbr_tag, node); const block_tag: Zir.Inst.Tag = if (is_inline) .block_inline else .block; const cond_block = try loop_scope.makeBlockInst(block_tag, node); - try continue_scope.setBlockBody(cond_block); - // continue_scope unstacked now, can add new instructions to loop_scope + try cond_scope.setBlockBody(cond_block); + // cond_scope unstacked now, can add new instructions to loop_scope try loop_scope.instructions.append(astgen.gpa, cond_block); // make scope now but don't stack on parent_gz until loop_scope // gets unstacked after cont_expr is emitted and added below - var then_scope = parent_gz.makeSubBlock(&continue_scope.base); + var then_scope = parent_gz.makeSubBlock(&cond_scope.base); then_scope.instructions_top = GenZir.unstacked_top; defer then_scope.unstack(); @@ -6026,24 +6026,17 @@ fn whileExpr( } }; - // This code could be improved to avoid emitting the continue expr when there - // are no jumps to it. This happens when the last statement of a while body is noreturn - // and there are no `continue` statements. - // Tracking issue: https://github.com/ziglang/zig/issues/9185 - try then_scope.addDbgBlockBegin(); - if (dbg_var_name) |some| { - try then_scope.addDbgVar(.dbg_var_val, some, dbg_var_inst); - } - if (while_full.ast.cont_expr != 0) { - _ = try unusedResultExpr(&loop_scope, then_sub_scope, while_full.ast.cont_expr); - } - try then_scope.addDbgBlockEnd(); + var continue_scope = parent_gz.makeSubBlock(then_sub_scope); + continue_scope.instructions_top = GenZir.unstacked_top; + defer continue_scope.unstack(); + const continue_block = try then_scope.makeBlockInst(block_tag, node); + const repeat_tag: Zir.Inst.Tag = if (is_inline) .repeat_inline else .repeat; _ = try loop_scope.addNode(repeat_tag, node); try loop_scope.setBlockBody(loop_block); loop_scope.break_block = loop_block; - loop_scope.continue_block = cond_block; + loop_scope.continue_block = continue_block; if (while_full.label_token) |label_token| { loop_scope.label = @as(?GenZir.Label, GenZir.Label{ .token = label_token, @@ -6054,18 +6047,30 @@ fn whileExpr( // done adding instructions to loop_scope, can now stack then_scope then_scope.instructions_top = then_scope.instructions.items.len; - if (payload_inst != 0) try then_scope.instructions.append(astgen.gpa, payload_inst); try then_scope.addDbgBlockBegin(); - if (dbg_var_name) |some| { - try then_scope.addDbgVar(.dbg_var_val, some, dbg_var_inst); + if (payload_inst != 0) try then_scope.instructions.append(astgen.gpa, payload_inst); + if (dbg_var_name) |name| try then_scope.addDbgVar(.dbg_var_val, name, dbg_var_inst); + try then_scope.instructions.append(astgen.gpa, continue_block); + // This code could be improved to avoid emitting the continue expr when there + // are no jumps to it. This happens when the last statement of a while body is noreturn + // and there are no `continue` statements. + // Tracking issue: https://github.com/ziglang/zig/issues/9185 + if (while_full.ast.cont_expr != 0) { + _ = try unusedResultExpr(&then_scope, then_sub_scope, while_full.ast.cont_expr); } - const then_result = try expr(&then_scope, then_sub_scope, .{ .rl = .none }, while_full.ast.then_expr); - _ = try addEnsureResult(&then_scope, then_result, while_full.ast.then_expr); - - try checkUsed(parent_gz, &then_scope.base, then_sub_scope); try then_scope.addDbgBlockEnd(); - var else_scope = parent_gz.makeSubBlock(&continue_scope.base); + continue_scope.instructions_top = continue_scope.instructions.items.len; + _ = try unusedResultExpr(&continue_scope, &continue_scope.base, while_full.ast.then_expr); + try checkUsed(parent_gz, &then_scope.base, then_sub_scope); + const break_tag: Zir.Inst.Tag = if (is_inline) .break_inline else .@"break"; + if (!continue_scope.endsWithNoReturn()) { + const break_inst = try continue_scope.makeBreak(break_tag, continue_block, .void_value); + try then_scope.instructions.append(astgen.gpa, break_inst); + } + try continue_scope.setBlockBody(continue_block); + + var else_scope = parent_gz.makeSubBlock(&cond_scope.base); defer else_scope.unstack(); const else_node = while_full.ast.else_expr; @@ -6128,7 +6133,6 @@ fn whileExpr( try astgen.appendErrorTok(some.token, "unused while loop label", .{}); } } - const break_tag: Zir.Inst.Tag = if (is_inline) .break_inline else .@"break"; const result = try finishThenElseBlock( parent_gz, ri, @@ -6138,7 +6142,7 @@ fn whileExpr( &else_scope, condbr, cond.bool_bit, - then_result, + .void_value, else_info.result, loop_block, cond_block,