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Issue 131733002: Skip back edge creation for "do ... while(false)" loops (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Created 6 years, 11 months ago
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1 // Copyright 2013 the V8 project authors. All rights reserved. 1 // Copyright 2013 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without 2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are 3 // modification, are permitted provided that the following conditions are
4 // met: 4 // met:
5 // 5 //
6 // * Redistributions of source code must retain the above copyright 6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer. 7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above 8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following 9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided 10 // disclaimer in the documentation and/or other materials provided
(...skipping 4301 matching lines...) Expand 10 before | Expand all | Expand 10 after
4312 ASSERT(current_block() != NULL); 4312 ASSERT(current_block() != NULL);
4313 HBasicBlock* loop_entry = BuildLoopEntry(stmt); 4313 HBasicBlock* loop_entry = BuildLoopEntry(stmt);
4314 4314
4315 BreakAndContinueInfo break_info(stmt); 4315 BreakAndContinueInfo break_info(stmt);
4316 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info)); 4316 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info));
4317 HBasicBlock* body_exit = 4317 HBasicBlock* body_exit =
4318 JoinContinue(stmt, current_block(), break_info.continue_block()); 4318 JoinContinue(stmt, current_block(), break_info.continue_block());
4319 HBasicBlock* loop_successor = NULL; 4319 HBasicBlock* loop_successor = NULL;
4320 if (body_exit != NULL && !stmt->cond()->ToBooleanIsTrue()) { 4320 if (body_exit != NULL && !stmt->cond()->ToBooleanIsTrue()) {
4321 set_current_block(body_exit); 4321 set_current_block(body_exit);
4322 // The block for a true condition, the actual predecessor block of the
4323 // back edge.
4324 body_exit = graph()->CreateBasicBlock();
4325 loop_successor = graph()->CreateBasicBlock(); 4322 loop_successor = graph()->CreateBasicBlock();
4326 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_exit, loop_successor)); 4323 if (stmt->cond()->ToBooleanIsFalse()) {
4327 if (body_exit->HasPredecessor()) { 4324 Goto(loop_successor);
4325 body_exit = NULL;
4326 } else {
4327 // The block for a true condition, the actual predecessor block of the
4328 // back edge.
4329 body_exit = graph()->CreateBasicBlock();
4330 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_exit, loop_successor));
4331 ASSERT(body_exit->HasPredecessor());
titzer 2014/01/09 14:19:53 I don't think this is strictly correct, e.g. if th
Jakob Kummerow 2014/01/09 15:01:44 I disagree. We are very careful to ensure that all
4328 body_exit->SetJoinId(stmt->BackEdgeId()); 4332 body_exit->SetJoinId(stmt->BackEdgeId());
4329 } else {
4330 body_exit = NULL;
4331 } 4333 }
4332 if (loop_successor->HasPredecessor()) { 4334 ASSERT(loop_successor->HasPredecessor());
4333 loop_successor->SetJoinId(stmt->ExitId()); 4335 loop_successor->SetJoinId(stmt->ExitId());
4334 } else {
4335 loop_successor = NULL;
4336 }
4337 } 4336 }
4338 HBasicBlock* loop_exit = CreateLoop(stmt, 4337 HBasicBlock* loop_exit = CreateLoop(stmt,
4339 loop_entry, 4338 loop_entry,
4340 body_exit, 4339 body_exit,
4341 loop_successor, 4340 loop_successor,
4342 break_info.break_block()); 4341 break_info.break_block());
4343 set_current_block(loop_exit); 4342 set_current_block(loop_exit);
4344 } 4343 }
4345 4344
4346 4345
4347 void HOptimizedGraphBuilder::VisitWhileStatement(WhileStatement* stmt) { 4346 void HOptimizedGraphBuilder::VisitWhileStatement(WhileStatement* stmt) {
4348 ASSERT(!HasStackOverflow()); 4347 ASSERT(!HasStackOverflow());
4349 ASSERT(current_block() != NULL); 4348 ASSERT(current_block() != NULL);
4350 ASSERT(current_block()->HasPredecessor()); 4349 ASSERT(current_block()->HasPredecessor());
4351 ASSERT(current_block() != NULL); 4350 ASSERT(current_block() != NULL);
4352 HBasicBlock* loop_entry = BuildLoopEntry(stmt); 4351 HBasicBlock* loop_entry = BuildLoopEntry(stmt);
4353 4352
4354 // If the condition is constant true, do not generate a branch. 4353 // If the condition is constant true, do not generate a branch.
4355 HBasicBlock* loop_successor = NULL; 4354 HBasicBlock* loop_successor = NULL;
4356 if (!stmt->cond()->ToBooleanIsTrue()) { 4355 if (!stmt->cond()->ToBooleanIsTrue()) {
4357 HBasicBlock* body_entry = graph()->CreateBasicBlock(); 4356 HBasicBlock* body_entry = graph()->CreateBasicBlock();
4358 loop_successor = graph()->CreateBasicBlock(); 4357 loop_successor = graph()->CreateBasicBlock();
4359 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_entry, loop_successor)); 4358 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_entry, loop_successor));
4360 if (body_entry->HasPredecessor()) { 4359 ASSERT(body_entry->HasPredecessor());
titzer 2014/01/09 14:19:53 Same here.
4361 body_entry->SetJoinId(stmt->BodyId()); 4360 body_entry->SetJoinId(stmt->BodyId());
4362 set_current_block(body_entry); 4361 set_current_block(body_entry);
4363 } 4362 ASSERT(loop_successor->HasPredecessor());
4364 if (loop_successor->HasPredecessor()) { 4363 loop_successor->SetJoinId(stmt->ExitId());
4365 loop_successor->SetJoinId(stmt->ExitId());
4366 } else {
4367 loop_successor = NULL;
4368 }
4369 } 4364 }
4370 4365
4371 BreakAndContinueInfo break_info(stmt); 4366 BreakAndContinueInfo break_info(stmt);
4372 if (current_block() != NULL) { 4367 if (current_block() != NULL) {
4373 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info)); 4368 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info));
4374 } 4369 }
4375 HBasicBlock* body_exit = 4370 HBasicBlock* body_exit =
4376 JoinContinue(stmt, current_block(), break_info.continue_block()); 4371 JoinContinue(stmt, current_block(), break_info.continue_block());
4377 HBasicBlock* loop_exit = CreateLoop(stmt, 4372 HBasicBlock* loop_exit = CreateLoop(stmt,
4378 loop_entry, 4373 loop_entry,
(...skipping 12 matching lines...) Expand all
4391 CHECK_ALIVE(Visit(stmt->init())); 4386 CHECK_ALIVE(Visit(stmt->init()));
4392 } 4387 }
4393 ASSERT(current_block() != NULL); 4388 ASSERT(current_block() != NULL);
4394 HBasicBlock* loop_entry = BuildLoopEntry(stmt); 4389 HBasicBlock* loop_entry = BuildLoopEntry(stmt);
4395 4390
4396 HBasicBlock* loop_successor = NULL; 4391 HBasicBlock* loop_successor = NULL;
4397 if (stmt->cond() != NULL) { 4392 if (stmt->cond() != NULL) {
4398 HBasicBlock* body_entry = graph()->CreateBasicBlock(); 4393 HBasicBlock* body_entry = graph()->CreateBasicBlock();
4399 loop_successor = graph()->CreateBasicBlock(); 4394 loop_successor = graph()->CreateBasicBlock();
4400 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_entry, loop_successor)); 4395 CHECK_BAILOUT(VisitForControl(stmt->cond(), body_entry, loop_successor));
4401 if (body_entry->HasPredecessor()) { 4396 ASSERT(body_entry->HasPredecessor());
4402 body_entry->SetJoinId(stmt->BodyId()); 4397 body_entry->SetJoinId(stmt->BodyId());
4403 set_current_block(body_entry); 4398 set_current_block(body_entry);
4404 } 4399 ASSERT(loop_successor->HasPredecessor());
4405 if (loop_successor->HasPredecessor()) { 4400 loop_successor->SetJoinId(stmt->ExitId());
4406 loop_successor->SetJoinId(stmt->ExitId());
4407 } else {
4408 loop_successor = NULL;
4409 }
4410 } 4401 }
4411 4402
4412 BreakAndContinueInfo break_info(stmt); 4403 BreakAndContinueInfo break_info(stmt);
4413 if (current_block() != NULL) { 4404 if (current_block() != NULL) {
4414 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info)); 4405 CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info));
4415 } 4406 }
4416 HBasicBlock* body_exit = 4407 HBasicBlock* body_exit =
4417 JoinContinue(stmt, current_block(), break_info.continue_block()); 4408 JoinContinue(stmt, current_block(), break_info.continue_block());
4418 4409
4419 if (stmt->next() != NULL && body_exit != NULL) { 4410 if (stmt->next() != NULL && body_exit != NULL) {
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10944 if (ShouldProduceTraceOutput()) { 10935 if (ShouldProduceTraceOutput()) {
10945 isolate()->GetHTracer()->TraceHydrogen(name(), graph_); 10936 isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
10946 } 10937 }
10947 10938
10948 #ifdef DEBUG 10939 #ifdef DEBUG
10949 graph_->Verify(false); // No full verify. 10940 graph_->Verify(false); // No full verify.
10950 #endif 10941 #endif
10951 } 10942 }
10952 10943
10953 } } // namespace v8::internal 10944 } } // namespace v8::internal
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