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Unified Diff: src/parsing/parser.cc

Issue 2233923003: Desugar async/await to create the resulting Promise upfront (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: format Created 4 years, 4 months ago
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Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 9060868a3ff0e08ec3746221078ae87ad75924d5..5967c74cd3a79f7b77f0ee978142624181086417 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -2463,7 +2463,7 @@ Statement* Parser::ParseReturnStatement(bool* ok) {
if (is_generator()) {
return_value = BuildIteratorResult(return_value, true);
} else if (is_async_function()) {
- return_value = BuildPromiseResolve(return_value, return_value->position());
+ return_value = BuildResolvePromise(return_value, return_value->position());
}
result = factory()->NewReturnStatement(return_value, loc.beg_pos);
@@ -3792,12 +3792,11 @@ void Parser::DesugarAsyncFunctionBody(const AstRawString* function_name,
FunctionBodyType body_type,
bool accept_IN, int pos, bool* ok) {
// function async_function() {
- // try {
- // .generator_object = %CreateGeneratorObject();
+ // .generator_object = %CreateGeneratorObject();
+ // BuildRejectPromiseOnException({
// ... function body ...
- // } catch (e) {
- // return Promise.reject(e);
- // }
+ // return %ResolvePromise(.promise, expr), .promise;
+ // })
// }
scope->ForceContextAllocation();
Variable* temp =
@@ -3811,13 +3810,11 @@ void Parser::DesugarAsyncFunctionBody(const AstRawString* function_name,
kNoSourcePosition),
zone());
- Block* try_block = factory()->NewBlock(NULL, 8, true, kNoSourcePosition);
-
- ZoneList<Statement*>* inner_body = try_block->statements();
+ Block* block = factory()->NewBlock(NULL, 8, true, kNoSourcePosition);
Expression* return_value = nullptr;
if (body_type == FunctionBodyType::kNormal) {
- ParseStatementList(inner_body, Token::RBRACE, CHECK_OK_VOID);
+ ParseStatementList(block->statements(), Token::RBRACE, CHECK_OK_VOID);
return_value = factory()->NewUndefinedLiteral(kNoSourcePosition);
} else {
return_value =
@@ -3825,11 +3822,12 @@ void Parser::DesugarAsyncFunctionBody(const AstRawString* function_name,
RewriteNonPattern(classifier, CHECK_OK_VOID);
}
- return_value = BuildPromiseResolve(return_value, return_value->position());
- inner_body->Add(
+ return_value = BuildResolvePromise(return_value, return_value->position());
+ block->statements()->Add(
factory()->NewReturnStatement(return_value, return_value->position()),
zone());
- body->Add(BuildRejectPromiseOnException(try_block), zone());
+ block = BuildRejectPromiseOnException(block, CHECK_OK_VOID);
+ body->Add(block, zone());
scope->set_end_position(scanner()->location().end_pos);
}
@@ -4387,9 +4385,67 @@ Block* Parser::BuildParameterInitializationBlock(
return init_block;
}
-Block* Parser::BuildRejectPromiseOnException(Block* block) {
- // try { <block> } catch (error) { return Promise.reject(error); }
- Block* try_block = block;
+Block* Parser::BuildRejectPromiseOnException(Block* inner_block, bool* ok) {
+ // var .promise = %CreatePromise();
+ // var .debug_is_active = %_DebugIsActive();
+ // if (.debug_is_active) %DebugPushPromise(.promise);
+ // try {
+ // <inner_block>
+ // } catch (.catch) {
+ // %RejectPromise(.promise, .catch);
+ // return .promise;
+ // } finally {
+ // if (.debug_is_active) %DebugPopPromise();
+ // }
+ Block* result = factory()->NewBlock(nullptr, 4, true, kNoSourcePosition);
+
+ // var .promise = %CreatePromise();
+ Statement* set_promise;
+ {
+ DeclareVariable(ast_value_factory()->dot_promise_string(), VAR,
+ kNoSourcePosition, CHECK_OK);
+ Expression* create_promise = factory()->NewCallRuntime(
+ Context::PROMISE_CREATE_INDEX,
+ new (zone()) ZoneList<Expression*>(0, zone()), kNoSourcePosition);
+ Assignment* assign_promise = factory()->NewAssignment(
+ Token::INIT, BuildDotPromise(), create_promise, kNoSourcePosition);
+ set_promise =
+ factory()->NewExpressionStatement(assign_promise, kNoSourcePosition);
+ }
+ result->statements()->Add(set_promise, zone());
+
+ // var .debug_is_active = %_DebugIsActive();
+ Statement* set_debug_is_active;
+ {
+ DeclareVariable(ast_value_factory()->dot_debug_is_active_string(), VAR,
+ kNoSourcePosition, CHECK_OK);
+ Expression* debug_is_active = factory()->NewCallRuntime(
+ Runtime::kInlineDebugIsActive,
+ new (zone()) ZoneList<Expression*>(0, zone()), kNoSourcePosition);
+ Assignment* assign_debug_is_active =
+ factory()->NewAssignment(Token::INIT, BuildDotDebugIsActive(),
+ debug_is_active, kNoSourcePosition);
+ set_debug_is_active = factory()->NewExpressionStatement(
+ assign_debug_is_active, kNoSourcePosition);
+ }
+ result->statements()->Add(set_debug_is_active, zone());
+
+ // if (.debug_is_active) %DebugPushPromise(.promise);
+ Statement* conditionally_debug_push_promise;
+ {
+ ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(1, zone());
+ args->Add(BuildDotPromise(), zone());
+ Expression* call_push_promise = factory()->NewCallRuntime(
+ Runtime::kDebugPushPromise, args, kNoSourcePosition);
+ Statement* debug_push_promise =
+ factory()->NewExpressionStatement(call_push_promise, kNoSourcePosition);
+ conditionally_debug_push_promise = factory()->NewIfStatement(
+ BuildDotDebugIsActive(), debug_push_promise,
+ factory()->NewEmptyStatement(kNoSourcePosition), kNoSourcePosition);
+ }
+ result->statements()->Add(conditionally_debug_push_promise, zone());
+
+ // catch (.catch) { return %RejectPromise(.promise, .catch), .promise }
Scope* catch_scope = NewScope(CATCH_SCOPE);
catch_scope->set_is_hidden();
Variable* catch_variable =
@@ -4397,18 +4453,40 @@ Block* Parser::BuildRejectPromiseOnException(Block* block) {
kCreatedInitialized, Variable::NORMAL);
Block* catch_block = factory()->NewBlock(nullptr, 1, true, kNoSourcePosition);
- Expression* promise_reject = BuildPromiseReject(
+ Expression* promise_reject = BuildRejectPromise(
factory()->NewVariableProxy(catch_variable), kNoSourcePosition);
-
ReturnStatement* return_promise_reject =
factory()->NewReturnStatement(promise_reject, kNoSourcePosition);
catch_block->statements()->Add(return_promise_reject, zone());
+
TryStatement* try_catch_statement = factory()->NewTryCatchStatement(
- try_block, catch_scope, catch_variable, catch_block, kNoSourcePosition);
+ inner_block, catch_scope, catch_variable, catch_block, kNoSourcePosition);
+
+ // There is no TryCatchFinally node, so wrap it in an outer try/finally
+ Block* outer_try_block =
+ factory()->NewBlock(nullptr, 1, true, kNoSourcePosition);
+ outer_try_block->statements()->Add(try_catch_statement, zone());
+
+ // finally { if (.debug_is_active) %DebugPopPromise(); }
+ Block* finally_block =
+ factory()->NewBlock(nullptr, 1, true, kNoSourcePosition);
+ {
+ ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(0, zone());
+ Expression* call_pop_promise = factory()->NewCallRuntime(
+ Runtime::kDebugPopPromise, args, kNoSourcePosition);
+ Statement* debug_pop_promise =
+ factory()->NewExpressionStatement(call_pop_promise, kNoSourcePosition);
+ Statement* conditionally_debug_pop_promise = factory()->NewIfStatement(
+ BuildDotDebugIsActive(), debug_pop_promise,
+ factory()->NewEmptyStatement(kNoSourcePosition), kNoSourcePosition);
+ finally_block->statements()->Add(conditionally_debug_pop_promise, zone());
+ }
+
+ Statement* try_finally_statement = factory()->NewTryFinallyStatement(
+ outer_try_block, finally_block, kNoSourcePosition);
- block = factory()->NewBlock(nullptr, 1, true, kNoSourcePosition);
- block->statements()->Add(try_catch_statement, zone());
- return block;
+ result->statements()->Add(try_finally_statement, zone());
+ return result;
}
Expression* Parser::BuildCreateJSGeneratorObject(int pos, FunctionKind kind) {
@@ -4422,18 +4500,37 @@ Expression* Parser::BuildCreateJSGeneratorObject(int pos, FunctionKind kind) {
pos);
}
-Expression* Parser::BuildPromiseResolve(Expression* value, int pos) {
- ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(1, zone());
+Expression* Parser::BuildResolvePromise(Expression* value, int pos) {
+ // %ResolvePromise(.promise, value), .promise
+ ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(2, zone());
+ args->Add(BuildDotPromise(), zone());
args->Add(value, zone());
- return factory()->NewCallRuntime(Context::PROMISE_CREATE_RESOLVED_INDEX, args,
- pos);
+ Expression* call_runtime =
+ factory()->NewCallRuntime(Context::PROMISE_RESOLVE_INDEX, args, pos);
+ return factory()->NewBinaryOperation(Token::COMMA, call_runtime,
+ BuildDotPromise(), pos);
}
-Expression* Parser::BuildPromiseReject(Expression* value, int pos) {
- ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(1, zone());
+Expression* Parser::BuildRejectPromise(Expression* value, int pos) {
+ // %RejectPromiseNoDebugEvent(.promise, value, true), .promise
+ // The NoDebugEvent variant disables the additional debug event for the
+ // rejection since a debug event already happened for the exception that got
+ // us here.
+ ZoneList<Expression*>* args = new (zone()) ZoneList<Expression*>(2, zone());
+ args->Add(BuildDotPromise(), zone());
args->Add(value, zone());
- return factory()->NewCallRuntime(Context::PROMISE_CREATE_REJECTED_INDEX, args,
- pos);
+ Expression* call_runtime = factory()->NewCallRuntime(
+ Context::REJECT_PROMISE_NO_DEBUG_EVENT_INDEX, args, pos);
+ return factory()->NewBinaryOperation(Token::COMMA, call_runtime,
+ BuildDotPromise(), pos);
+}
+
+VariableProxy* Parser::BuildDotPromise() {
+ return NewUnresolved(ast_value_factory()->dot_promise_string(), VAR);
+}
+
+VariableProxy* Parser::BuildDotDebugIsActive() {
+ return NewUnresolved(ast_value_factory()->dot_debug_is_active_string(), VAR);
}
ZoneList<Statement*>* Parser::ParseEagerFunctionBody(
@@ -4559,8 +4656,9 @@ ZoneList<Statement*>* Parser::ParseEagerFunctionBody(
CHECK_OK);
}
+ // TODO(littledan): Merge the two rejection blocks into one
if (IsAsyncFunction(kind)) {
- init_block = BuildRejectPromiseOnException(init_block);
+ init_block = BuildRejectPromiseOnException(init_block, CHECK_OK);
}
DCHECK_NOT_NULL(init_block);
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