From cb8c45f0e749ba4f6347395d683dd73dd53a9b36 Mon Sep 17 00:00:00 2001 From: adamk Date: Fri, 14 Nov 2014 11:32:53 -0800 Subject: [PATCH 1/2] v8: fix issue with let bindings in for loops Backport b17eaaa5755e625493c5fe537f42b58838923c52 from upstream v8. Original commit message: Fix desugaring of let bindings in for loops to handle continue properly This requires putting the original loop's body inside an inner for loop (with the same labels as the original loop) and re-binding the temp variables in its "next" expression. A second flag is added to the desugared code to ensure the loop body executes at most once per loop. BUG=v8:3683 LOG=y Review URL: https://codereview.chromium.org/720863002 Cr-Commit-Position: refs/heads/master@{#25363} Fixes #9113 and #14411. --- deps/v8/src/parser.cc | 188 ++++++++++++------ .../mjsunit/harmony/regress/regress-3683.js | 84 ++++++++ 2 files changed, 213 insertions(+), 59 deletions(-) create mode 100644 deps/v8/test/mjsunit/harmony/regress/regress-3683.js diff --git a/deps/v8/src/parser.cc b/deps/v8/src/parser.cc index 6c941daa978..0cf621bb501 100644 --- a/deps/v8/src/parser.cc +++ b/deps/v8/src/parser.cc @@ -2846,29 +2846,33 @@ Statement* Parser::DesugarLetBindingsInForStatement( // // We rewrite a for statement of the form // - // for (let x = i; cond; next) body + // labels: for (let x = i; cond; next) body // // into // // { - // let x = i; - // temp_x = x; - // flag = 1; - // for (;;) { - // let x = temp_x; - // if (flag == 1) { - // flag = 0; - // } else { - // next; - // } + // let x = i; + // temp_x = x; + // first = 1; + // outer: for (;;) { + // let x = temp_x; + // if (first == 1) { + // first = 0; + // } else { + // next; + // } + // flag = 1; + // labels: for (; flag == 1; flag = 0, temp_x = x) { // if (cond) { - // + // body // } else { - // break; + // break outer; // } - // b - // temp_x = x; - // } + // } + // if (flag == 1) { + // break; + // } + // } // } DCHECK(names->length() > 0); @@ -2896,24 +2900,33 @@ Statement* Parser::DesugarLetBindingsInForStatement( temps.Add(temp, zone()); } - Variable* flag = scope_->DeclarationScope()->NewTemporary(temp_name); - // Make statement: flag = 1. - { - VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + Variable* first = NULL; + // Make statement: first = 1. + if (next) { + first = scope_->DeclarationScope()->NewTemporary(temp_name); + VariableProxy* first_proxy = factory()->NewVariableProxy(first); Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition); Assignment* assignment = factory()->NewAssignment( - Token::ASSIGN, flag_proxy, const1, RelocInfo::kNoPosition); - Statement* assignment_statement = factory()->NewExpressionStatement( - assignment, RelocInfo::kNoPosition); + Token::ASSIGN, first_proxy, const1, RelocInfo::kNoPosition); + Statement* assignment_statement = + factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition); outer_block->AddStatement(assignment_statement, zone()); } - outer_block->AddStatement(loop, zone()); + // Make statement: outer: for (;;) + // Note that we don't actually create the label, or set this loop up as an + // explicit break target, instead handing it directly to those nodes that + // need to know about it. This should be safe because we don't run any code + // in this function that looks up break targets. + ForStatement* outer_loop = + factory()->NewForStatement(NULL, RelocInfo::kNoPosition); + outer_block->AddStatement(outer_loop, zone()); + outer_block->set_scope(for_scope); scope_ = inner_scope; - Block* inner_block = factory()->NewBlock(NULL, 2 * names->length() + 3, - false, RelocInfo::kNoPosition); + Block* inner_block = factory()->NewBlock(NULL, names->length() + 4, false, + RelocInfo::kNoPosition); int pos = scanner()->location().beg_pos; ZoneList inner_vars(names->length(), zone()); @@ -2935,61 +2948,118 @@ Statement* Parser::DesugarLetBindingsInForStatement( inner_block->AddStatement(assignment_statement, zone()); } - // Make statement: if (flag == 1) { flag = 0; } else { next; }. + // Make statement: if (first == 1) { first = 0; } else { next; } if (next) { + DCHECK(first); Expression* compare = NULL; - // Make compare expresion: flag == 1. + // Make compare expression: first == 1. { Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition); - VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); - compare = factory()->NewCompareOperation( - Token::EQ, flag_proxy, const1, pos); + VariableProxy* first_proxy = factory()->NewVariableProxy(first); + compare = + factory()->NewCompareOperation(Token::EQ, first_proxy, const1, pos); } - Statement* clear_flag = NULL; - // Make statement: flag = 0. + Statement* clear_first = NULL; + // Make statement: first = 0. { - VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + VariableProxy* first_proxy = factory()->NewVariableProxy(first); Expression* const0 = factory()->NewSmiLiteral(0, RelocInfo::kNoPosition); Assignment* assignment = factory()->NewAssignment( - Token::ASSIGN, flag_proxy, const0, RelocInfo::kNoPosition); - clear_flag = factory()->NewExpressionStatement(assignment, pos); + Token::ASSIGN, first_proxy, const0, RelocInfo::kNoPosition); + clear_first = + factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition); } - Statement* clear_flag_or_next = factory()->NewIfStatement( - compare, clear_flag, next, RelocInfo::kNoPosition); - inner_block->AddStatement(clear_flag_or_next, zone()); + Statement* clear_first_or_next = factory()->NewIfStatement( + compare, clear_first, next, RelocInfo::kNoPosition); + inner_block->AddStatement(clear_first_or_next, zone()); } + Variable* flag = scope_->DeclarationScope()->NewTemporary(temp_name); + // Make statement: flag = 1. + { + VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition); + Assignment* assignment = factory()->NewAssignment( + Token::ASSIGN, flag_proxy, const1, RelocInfo::kNoPosition); + Statement* assignment_statement = + factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition); + inner_block->AddStatement(assignment_statement, zone()); + } + + // Make cond expression for main loop: flag == 1. + Expression* flag_cond = NULL; + { + Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition); + VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + flag_cond = + factory()->NewCompareOperation(Token::EQ, flag_proxy, const1, pos); + } - // Make statement: if (cond) { } else { break; }. + // Create chain of expressions "flag = 0, temp_x = x, ..." + Statement* compound_next_statement = NULL; + { + Expression* compound_next = NULL; + // Make expression: flag = 0. + { + VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + Expression* const0 = factory()->NewSmiLiteral(0, RelocInfo::kNoPosition); + compound_next = factory()->NewAssignment(Token::ASSIGN, flag_proxy, + const0, RelocInfo::kNoPosition); + } + + // Make the comma-separated list of temp_x = x assignments. + for (int i = 0; i < names->length(); i++) { + VariableProxy* temp_proxy = factory()->NewVariableProxy(temps.at(i)); + VariableProxy* proxy = factory()->NewVariableProxy(inner_vars.at(i), pos); + Assignment* assignment = factory()->NewAssignment( + Token::ASSIGN, temp_proxy, proxy, RelocInfo::kNoPosition); + compound_next = factory()->NewBinaryOperation( + Token::COMMA, compound_next, assignment, RelocInfo::kNoPosition); + } + + compound_next_statement = factory()->NewExpressionStatement( + compound_next, RelocInfo::kNoPosition); + } + + // Make statement: if (cond) { body; } else { break outer; } + Statement* body_or_stop = body; if (cond) { - Statement* empty = factory()->NewEmptyStatement(RelocInfo::kNoPosition); - BreakableStatement* t = LookupBreakTarget(NULL, CHECK_OK); - Statement* stop = factory()->NewBreakStatement(t, RelocInfo::kNoPosition); - Statement* if_not_cond_break = factory()->NewIfStatement( - cond, empty, stop, cond->position()); - inner_block->AddStatement(if_not_cond_break, zone()); + Statement* stop = + factory()->NewBreakStatement(outer_loop, RelocInfo::kNoPosition); + body_or_stop = + factory()->NewIfStatement(cond, body, stop, cond->position()); } - inner_block->AddStatement(body, zone()); + // Make statement: labels: for (; flag == 1; flag = 0, temp_x = x) + // Note that we re-use the original loop node, which retains it labels + // and ensures that any break or continue statements in body point to + // the right place. + loop->Initialize(NULL, flag_cond, compound_next_statement, body_or_stop); + inner_block->AddStatement(loop, zone()); - // For each let variable x: - // make statement: temp_x = x; - for (int i = 0; i < names->length(); i++) { - VariableProxy* temp_proxy = factory()->NewVariableProxy(temps.at(i)); - int pos = scanner()->location().end_pos; - VariableProxy* proxy = factory()->NewVariableProxy(inner_vars.at(i), pos); - Assignment* assignment = factory()->NewAssignment( - Token::ASSIGN, temp_proxy, proxy, RelocInfo::kNoPosition); - Statement* assignment_statement = factory()->NewExpressionStatement( - assignment, RelocInfo::kNoPosition); - inner_block->AddStatement(assignment_statement, zone()); + // Make statement: if (flag == 1) { break; } + { + Expression* compare = NULL; + // Make compare expresion: flag == 1. + { + Expression* const1 = factory()->NewSmiLiteral(1, RelocInfo::kNoPosition); + VariableProxy* flag_proxy = factory()->NewVariableProxy(flag); + compare = + factory()->NewCompareOperation(Token::EQ, flag_proxy, const1, pos); + } + Statement* stop = + factory()->NewBreakStatement(outer_loop, RelocInfo::kNoPosition); + Statement* empty = factory()->NewEmptyStatement(RelocInfo::kNoPosition); + Statement* if_flag_break = + factory()->NewIfStatement(compare, stop, empty, RelocInfo::kNoPosition); + inner_block->AddStatement(if_flag_break, zone()); } inner_scope->set_end_position(scanner()->location().end_pos); inner_block->set_scope(inner_scope); scope_ = for_scope; - loop->Initialize(NULL, NULL, NULL, inner_block); + outer_loop->Initialize(NULL, NULL, NULL, inner_block); return outer_block; } diff --git a/deps/v8/test/mjsunit/harmony/regress/regress-3683.js b/deps/v8/test/mjsunit/harmony/regress/regress-3683.js new file mode 100644 index 00000000000..a00d82bd1f5 --- /dev/null +++ b/deps/v8/test/mjsunit/harmony/regress/regress-3683.js @@ -0,0 +1,84 @@ +// Copyright 2014 the V8 project authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. +// +// Flags: --harmony-scoping + +"use strict"; + +// Simplest case +var count = 0; +for (let x = 0; x < 10;) { + x++; + count++; + continue; +} +assertEquals(10, count); + +// Labeled +count = 0; +label: for (let x = 0; x < 10;) { + while (true) { + x++; + count++; + continue label; + } +} +assertEquals(10, count); + +// Simple and labeled +count = 0; +label: for (let x = 0; x < 10;) { + x++; + count++; + continue label; +} +assertEquals(10, count); + +// Shadowing loop variable in same scope as continue +count = 0; +for (let x = 0; x < 10;) { + x++; + count++; + { + let x = "hello"; + continue; + } +} +assertEquals(10, count); + +// Nested let-bound for loops, inner continue +count = 0; +for (let x = 0; x < 10;) { + x++; + for (let y = 0; y < 2;) { + y++; + count++; + continue; + } +} +assertEquals(20, count); + +// Nested let-bound for loops, outer continue +count = 0; +for (let x = 0; x < 10;) { + x++; + for (let y = 0; y < 2;) { + y++; + count++; + } + continue; +} +assertEquals(20, count); + +// Nested let-bound for loops, labeled continue +count = 0; +outer: for (let x = 0; x < 10;) { + x++; + for (let y = 0; y < 2;) { + y++; + count++; + if (y == 2) continue outer; + } +} +assertEquals(20, count); From 8d1baac2eb7cb06785ac30bf866ba67acfebeebb Mon Sep 17 00:00:00 2001 From: Julien Gilli Date: Tue, 28 Apr 2015 16:09:16 -0700 Subject: [PATCH 2/2] test: add test for let bindings in for loops 072460265226c047369558b23e9ff2748965bf6c floats a patch on V8 that fixes issue #9113 that would cause let bindings and continue statements in for loops to not work properly. This change adds a regression test that fails if that patch is not properly floated, thus preventing us from not floating that patch after future V8 upgrades. --- .../test-let-bindings-for-loop-harmony.js | 38 +++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 test/simple/test-let-bindings-for-loop-harmony.js diff --git a/test/simple/test-let-bindings-for-loop-harmony.js b/test/simple/test-let-bindings-for-loop-harmony.js new file mode 100644 index 00000000000..830b1a2acbf --- /dev/null +++ b/test/simple/test-let-bindings-for-loop-harmony.js @@ -0,0 +1,38 @@ +// Copyright Joyent, Inc. and other Node contributors. +// +// Permission is hereby granted, free of charge, to any person obtaining a +// copy of this software and associated documentation files (the +// "Software"), to deal in the Software without restriction, including +// without limitation the rights to use, copy, modify, merge, publish, +// distribute, sublicense, and/or sell copies of the Software, and to permit +// persons to whom the Software is furnished to do so, subject to the +// following conditions: +// +// The above copyright notice and this permission notice shall be included +// in all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS +// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN +// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, +// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE +// USE OR OTHER DEALINGS IN THE SOFTWARE. + +/* + * This is a regression test for the issue described at: + * https://github.com/joyent/node/issues/9113. + * + * This problem has been fixed by floating a patch on V8, this test makes + * sure that the appropriate patch is floated even after future V8 upgrades. + * + * If the bug is reproduced, this test stalls and the tests suite makes it + * time out eventually (currently after one minute). Otherwise it exits after + * the for loop completes its execution. + */ +var spawn = require('child_process').spawn; +var args = ['--harmony', + '--use-strict', + '-e', + 'for (let i = 0; i < 3; ++i) { if (i == 1) { continue; } }']; +var child = spawn(process.execPath, args);