1 // Copyright 2013 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #include "src/crankshaft/hydrogen-osr.h"
6 
7 #include "src/crankshaft/hydrogen.h"
8 
9 namespace v8 {
10 namespace internal {
11 
12 // True iff. we are compiling for OSR and the statement is the entry.
HasOsrEntryAt(IterationStatement * statement)13 bool HOsrBuilder::HasOsrEntryAt(IterationStatement* statement) {
14   return statement->OsrEntryId() == builder_->current_info()->osr_ast_id();
15 }
16 
17 
BuildOsrLoopEntry(IterationStatement * statement)18 HBasicBlock* HOsrBuilder::BuildOsrLoopEntry(IterationStatement* statement) {
19   DCHECK(HasOsrEntryAt(statement));
20 
21   Zone* zone = builder_->zone();
22   HGraph* graph = builder_->graph();
23 
24   // only one OSR point per compile is allowed.
25   DCHECK(graph->osr() == NULL);
26 
27   // remember this builder as the one OSR builder in the graph.
28   graph->set_osr(this);
29 
30   HBasicBlock* non_osr_entry = graph->CreateBasicBlock();
31   osr_entry_ = graph->CreateBasicBlock();
32   HValue* true_value = graph->GetConstantTrue();
33   HBranch* test = builder_->New<HBranch>(true_value, ToBooleanStub::Types(),
34                                          non_osr_entry, osr_entry_);
35   builder_->FinishCurrentBlock(test);
36 
37   HBasicBlock* loop_predecessor = graph->CreateBasicBlock();
38   builder_->Goto(non_osr_entry, loop_predecessor);
39 
40   builder_->set_current_block(osr_entry_);
41   osr_entry_->set_osr_entry();
42   BailoutId osr_entry_id = statement->OsrEntryId();
43 
44   HEnvironment *environment = builder_->environment();
45   int first_expression_index = environment->first_expression_index();
46   int length = environment->length();
47   osr_values_ = new(zone) ZoneList<HUnknownOSRValue*>(length, zone);
48 
49   for (int i = 0; i < first_expression_index; ++i) {
50     HUnknownOSRValue* osr_value
51         = builder_->Add<HUnknownOSRValue>(environment, i);
52     environment->Bind(i, osr_value);
53     osr_values_->Add(osr_value, zone);
54   }
55 
56   if (first_expression_index != length) {
57     environment->Drop(length - first_expression_index);
58     for (int i = first_expression_index; i < length; ++i) {
59       HUnknownOSRValue* osr_value
60           = builder_->Add<HUnknownOSRValue>(environment, i);
61       environment->Push(osr_value);
62       osr_values_->Add(osr_value, zone);
63     }
64   }
65 
66   unoptimized_frame_slots_ =
67       environment->local_count() + environment->push_count();
68 
69   // Keep a copy of the old environment, since the OSR values need it
70   // to figure out where exactly they are located in the unoptimized frame.
71   environment = environment->Copy();
72   builder_->current_block()->UpdateEnvironment(environment);
73 
74   builder_->Add<HSimulate>(osr_entry_id);
75   builder_->Add<HOsrEntry>(osr_entry_id);
76   HContext* context = builder_->Add<HContext>();
77   environment->BindContext(context);
78   builder_->Goto(loop_predecessor);
79   loop_predecessor->SetJoinId(statement->EntryId());
80   builder_->set_current_block(loop_predecessor);
81 
82   // Create the final loop entry
83   osr_loop_entry_ = builder_->BuildLoopEntry();
84   return osr_loop_entry_;
85 }
86 
87 
FinishGraph()88 void HOsrBuilder::FinishGraph() {
89   // do nothing for now.
90 }
91 
92 
FinishOsrValues()93 void HOsrBuilder::FinishOsrValues() {
94   const ZoneList<HPhi*>* phis = osr_loop_entry_->phis();
95   for (int j = 0; j < phis->length(); j++) {
96     HPhi* phi = phis->at(j);
97     if (phi->HasMergedIndex()) {
98       osr_values_->at(phi->merged_index())->set_incoming_value(phi);
99     }
100   }
101 }
102 
103 }  // namespace internal
104 }  // namespace v8
105