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1 // Copyright 2013 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 //     * Redistributions of source code must retain the above copyright
7 //       notice, this list of conditions and the following disclaimer.
8 //     * Redistributions in binary form must reproduce the above
9 //       copyright notice, this list of conditions and the following
10 //       disclaimer in the documentation and/or other materials provided
11 //       with the distribution.
12 //     * Neither the name of Google Inc. nor the names of its
13 //       contributors may be used to endorse or promote products derived
14 //       from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 
28 #include "hydrogen.h"
29 #include "hydrogen-osr.h"
30 
31 namespace v8 {
32 namespace internal {
33 
34 // True iff. we are compiling for OSR and the statement is the entry.
HasOsrEntryAt(IterationStatement * statement)35 bool HOsrBuilder::HasOsrEntryAt(IterationStatement* statement) {
36   return statement->OsrEntryId() == builder_->current_info()->osr_ast_id();
37 }
38 
39 
BuildOsrLoopEntry(IterationStatement * statement)40 HBasicBlock* HOsrBuilder::BuildOsrLoopEntry(IterationStatement* statement) {
41   ASSERT(HasOsrEntryAt(statement));
42 
43   Zone* zone = builder_->zone();
44   HGraph* graph = builder_->graph();
45 
46   // only one OSR point per compile is allowed.
47   ASSERT(graph->osr() == NULL);
48 
49   // remember this builder as the one OSR builder in the graph.
50   graph->set_osr(this);
51 
52   HBasicBlock* non_osr_entry = graph->CreateBasicBlock();
53   osr_entry_ = graph->CreateBasicBlock();
54   HValue* true_value = graph->GetConstantTrue();
55   HBranch* test = builder_->New<HBranch>(true_value, ToBooleanStub::Types(),
56                                          non_osr_entry, osr_entry_);
57   builder_->FinishCurrentBlock(test);
58 
59   HBasicBlock* loop_predecessor = graph->CreateBasicBlock();
60   builder_->Goto(non_osr_entry, loop_predecessor);
61 
62   builder_->set_current_block(osr_entry_);
63   osr_entry_->set_osr_entry();
64   BailoutId osr_entry_id = statement->OsrEntryId();
65 
66   HEnvironment *environment = builder_->environment();
67   int first_expression_index = environment->first_expression_index();
68   int length = environment->length();
69   osr_values_ = new(zone) ZoneList<HUnknownOSRValue*>(length, zone);
70 
71   for (int i = 0; i < first_expression_index; ++i) {
72     HUnknownOSRValue* osr_value
73         = builder_->Add<HUnknownOSRValue>(environment, i);
74     environment->Bind(i, osr_value);
75     osr_values_->Add(osr_value, zone);
76   }
77 
78   if (first_expression_index != length) {
79     environment->Drop(length - first_expression_index);
80     for (int i = first_expression_index; i < length; ++i) {
81       HUnknownOSRValue* osr_value
82           = builder_->Add<HUnknownOSRValue>(environment, i);
83       environment->Push(osr_value);
84       osr_values_->Add(osr_value, zone);
85     }
86   }
87 
88   unoptimized_frame_slots_ =
89       environment->local_count() + environment->push_count();
90 
91   // Keep a copy of the old environment, since the OSR values need it
92   // to figure out where exactly they are located in the unoptimized frame.
93   environment = environment->Copy();
94   builder_->current_block()->UpdateEnvironment(environment);
95 
96   builder_->Add<HSimulate>(osr_entry_id);
97   builder_->Add<HOsrEntry>(osr_entry_id);
98   HContext* context = builder_->Add<HContext>();
99   environment->BindContext(context);
100   builder_->Goto(loop_predecessor);
101   loop_predecessor->SetJoinId(statement->EntryId());
102   builder_->set_current_block(loop_predecessor);
103 
104   // Create the final loop entry
105   osr_loop_entry_ = builder_->BuildLoopEntry();
106   return osr_loop_entry_;
107 }
108 
109 
FinishGraph()110 void HOsrBuilder::FinishGraph() {
111   // do nothing for now.
112 }
113 
114 
FinishOsrValues()115 void HOsrBuilder::FinishOsrValues() {
116   const ZoneList<HPhi*>* phis = osr_loop_entry_->phis();
117   for (int j = 0; j < phis->length(); j++) {
118     HPhi* phi = phis->at(j);
119     if (phi->HasMergedIndex()) {
120       osr_values_->at(phi->merged_index())->set_incoming_value(phi);
121     }
122   }
123 }
124 
125 } }  // namespace v8::internal
126