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Revert of Add a separate scope for switch (patchset #7 id:120001 of https://codereview.chromium.org/1293283002/ )

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Reason for revert:
Breaks cctest/test-cpu-profiler/SourceLocation on nosnap

Original issue's description:
> Add a separate scope for switch
>
> The ES2015 specification for switch statements 13.12.11 specifies that
> they get their own lexical scope. This patch introduces such a scope
> through a complex desugaring in terms of blocks, done so that Crankshaft
> does not have to be updated to support multiple constructs providing
> scopes.
>
> BUG=v8:4377
> LOG=Y
> R=adamk
>
> Committed: https://crrev.com/9edbc1f21eb1050cabbe3b8bc9aebf89ada7ebd7
> Cr-Commit-Position: refs/heads/master@{#30314}

TBR=adamk@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4377

Review URL: https://codereview.chromium.org/1309043004

Cr-Commit-Position: refs/heads/master@{#30316}
This commit is contained in:
littledan 2015-08-21 18:24:18 -07:00 committed by Commit bot
parent 9c79e69e6c
commit 31b8018029
6 changed files with 15 additions and 161 deletions
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1
src/ast-value-factory.h
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@ -255,7 +255,6 @@ class AstValue : public ZoneObject {
F(dot_iterator, ".iterator") \
F(dot_module, ".module") \
F(dot_result, ".result") \
F(dot_switch_tag, ".switch_tag") \
F(empty, "") \
F(eval, "eval") \
F(get_template_callsite, "$getTemplateCallSite") \

57
src/parser.cc
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@ -2967,72 +2967,31 @@ CaseClause* Parser::ParseCaseClause(bool* default_seen_ptr, bool* ok) {
}
Statement* Parser::ParseSwitchStatement(ZoneList<const AstRawString*>* labels,
bool* ok) {
SwitchStatement* Parser::ParseSwitchStatement(
ZoneList<const AstRawString*>* labels, bool* ok) {
// SwitchStatement ::
// 'switch' '(' Expression ')' '{' CaseClause* '}'
// In order to get the CaseClauses to execute in their own lexical scope,
// but without requiring downstream code to have special scope handling
// code for switch statements, desugar into blocks as follows:
// { // To group the statements--harmless to evaluate Expression in scope
// .tag_variable = Expression;
// { // To give CaseClauses a scope
// switch (.tag_variable) { CaseClause* }
// }
// }
Block* switch_block =
factory()->NewBlock(NULL, 2, true, RelocInfo::kNoPosition);
int switch_pos = peek_position();
SwitchStatement* statement =
factory()->NewSwitchStatement(labels, peek_position());
Target target(&this->target_stack_, statement);
Expect(Token::SWITCH, CHECK_OK);
Expect(Token::LPAREN, CHECK_OK);
Expression* tag = ParseExpression(true, CHECK_OK);
Expect(Token::RPAREN, CHECK_OK);
Variable* tag_variable =
scope_->NewTemporary(ast_value_factory()->dot_switch_tag_string());
Assignment* tag_assign = factory()->NewAssignment(
Token::ASSIGN, factory()->NewVariableProxy(tag_variable), tag,
tag->position());
Statement* tag_statement =
factory()->NewExpressionStatement(tag_assign, RelocInfo::kNoPosition);
switch_block->AddStatement(tag_statement, zone());
Block* cases_block =
factory()->NewBlock(NULL, 1, true, RelocInfo::kNoPosition);
Scope* cases_scope = NewScope(scope_, BLOCK_SCOPE);
SwitchStatement* switch_statement =
factory()->NewSwitchStatement(labels, switch_pos);
cases_scope->set_start_position(scanner()->location().beg_pos);
{
BlockState cases_block_state(&scope_, cases_scope);
Target target(&this->target_stack_, switch_statement);
Expression* tag_read = factory()->NewVariableProxy(tag_variable);
bool default_seen = false;
ZoneList<CaseClause*>* cases =
new (zone()) ZoneList<CaseClause*>(4, zone());
ZoneList<CaseClause*>* cases = new(zone()) ZoneList<CaseClause*>(4, zone());
Expect(Token::LBRACE, CHECK_OK);
while (peek() != Token::RBRACE) {
CaseClause* clause = ParseCaseClause(&default_seen, CHECK_OK);
cases->Add(clause, zone());
}
switch_statement->Initialize(tag_read, cases);
cases_block->AddStatement(switch_statement, zone());
}
Expect(Token::RBRACE, CHECK_OK);
cases_scope->set_end_position(scanner()->location().end_pos);
cases_scope = cases_scope->FinalizeBlockScope();
cases_block->set_scope(cases_scope);
switch_block->AddStatement(cases_block, zone());
return switch_block;
if (statement) statement->Initialize(tag, cases);
return statement;
}

2
src/parser.h
View File

@ -1070,7 +1070,7 @@ class Parser : public ParserBase<ParserTraits> {
Statement* ParseWithStatement(ZoneList<const AstRawString*>* labels,
bool* ok);
CaseClause* ParseCaseClause(bool* default_seen_ptr, bool* ok);
Statement* ParseSwitchStatement(ZoneList<const AstRawString*>* labels,
SwitchStatement* ParseSwitchStatement(ZoneList<const AstRawString*>* labels,
bool* ok);
DoWhileStatement* ParseDoWhileStatement(ZoneList<const AstRawString*>* labels,
bool* ok);

4
src/scopes.h
View File

@ -246,10 +246,6 @@ class Scope: public ZoneObject {
// for (let x ...) stmt
// start position: start position of '('
// end position: end position of last token of 'stmt'
// * For the scope of a switch statement
// switch (tag) { cases }
// start position: start position of '{'
// end position: end position of '}'
int start_position() const { return start_position_; }
void set_start_position(int statement_pos) {
start_position_ = statement_pos;

45
test/mjsunit/regress/regress-4377.js
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@ -1,45 +0,0 @@
// Copyright 2015 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.
// See: http://code.google.com/p/v8/issues/detail?id=4377
// Switch statements should introduce their own lexical scope
'use strict';
switch (1) { case 1: let x = 2; }
assertThrows(() => x, ReferenceError);
{
let result;
let x = 1;
switch (x) {
case 1:
let x = 2;
result = x;
break;
default:
result = 0;
break;
}
assertEquals(1, x);
assertEquals(2, result);
}
{
let result;
let x = 1;
switch (eval('x')) {
case 1:
let x = 2;
result = x;
break;
default:
result = 0;
break;
}
assertEquals(1, x);
assertEquals(2, result);
}

55
test/mjsunit/switch.js
View File

@ -460,58 +460,3 @@ function test_switches(opt) {
test_switches(false);
test_switches(true);
// Test labeled and anonymous breaks in switch statements
(function test_switch_break() {
A: for (var i = 1; i < 10; i++) {
switch (i) {
case 1:
break A;
}
}
assertEquals(1, i);
for (var i = 1; i < 10; i++) {
B: switch (i) {
case 1:
break B;
}
}
assertEquals(10, i);
for (var i = 1; i < 10; i++) {
switch (i) {
case 1:
break;
}
}
assertEquals(10, i);
switch (1) {
case 1:
C: for (var i = 1; i < 10; i++) {
break C;
}
i = 2;
}
assertEquals(2, i);
switch (1) {
case 1:
for (var i = 1; i < 10; i++) {
break;
}
i = 2;
}
assertEquals(2, i);
D: switch (1) {
case 1:
for (var i = 1; i < 10; i++) {
break D;
}
i = 2;
}
assertEquals(1, i);
})();