1 /*
2  * Copyright (C) 2015 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "dex_cache_array_fixups_arm.h"
18 
19 #include "base/arena_containers.h"
20 #ifdef ART_USE_OLD_ARM_BACKEND
21 #include "code_generator_arm.h"
22 #include "intrinsics_arm.h"
23 #else
24 #include "code_generator_arm_vixl.h"
25 #include "intrinsics_arm_vixl.h"
26 #endif
27 #include "utils/dex_cache_arrays_layout-inl.h"
28 
29 namespace art {
30 namespace arm {
31 #ifdef ART_USE_OLD_ARM_BACKEND
32 typedef CodeGeneratorARM CodeGeneratorARMType;
33 typedef IntrinsicLocationsBuilderARM IntrinsicLocationsBuilderARMType;
34 #else
35 typedef CodeGeneratorARMVIXL CodeGeneratorARMType;
36 typedef IntrinsicLocationsBuilderARMVIXL IntrinsicLocationsBuilderARMType;
37 #endif
38 
39 /**
40  * Finds instructions that need the dex cache arrays base as an input.
41  */
42 class DexCacheArrayFixupsVisitor : public HGraphVisitor {
43  public:
DexCacheArrayFixupsVisitor(HGraph * graph,CodeGenerator * codegen)44   DexCacheArrayFixupsVisitor(HGraph* graph, CodeGenerator* codegen)
45       : HGraphVisitor(graph),
46         codegen_(down_cast<CodeGeneratorARMType*>(codegen)),
47         dex_cache_array_bases_(std::less<const DexFile*>(),
48                                // Attribute memory use to code generator.
49                                graph->GetArena()->Adapter(kArenaAllocCodeGenerator)) {}
50 
MoveBasesIfNeeded()51   void MoveBasesIfNeeded() {
52     for (const auto& entry : dex_cache_array_bases_) {
53       // Bring the base closer to the first use (previously, it was in the
54       // entry block) and relieve some pressure on the register allocator
55       // while avoiding recalculation of the base in a loop.
56       HArmDexCacheArraysBase* base = entry.second;
57       base->MoveBeforeFirstUserAndOutOfLoops();
58     }
59   }
60 
61  private:
VisitInvokeStaticOrDirect(HInvokeStaticOrDirect * invoke)62   void VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) OVERRIDE {
63     // If this is an invoke with PC-relative access to the dex cache methods array,
64     // we need to add the dex cache arrays base as the special input.
65     if (invoke->HasPcRelativeDexCache() &&
66         !IsCallFreeIntrinsic<IntrinsicLocationsBuilderARMType>(invoke, codegen_)) {
67       HArmDexCacheArraysBase* base =
68           GetOrCreateDexCacheArrayBase(invoke, invoke->GetDexFileForPcRelativeDexCache());
69       // Update the element offset in base.
70       DexCacheArraysLayout layout(kArmPointerSize, &invoke->GetDexFileForPcRelativeDexCache());
71       base->UpdateElementOffset(layout.MethodOffset(invoke->GetDexMethodIndex()));
72       // Add the special argument base to the method.
73       DCHECK(!invoke->HasCurrentMethodInput());
74       invoke->AddSpecialInput(base);
75     }
76   }
77 
GetOrCreateDexCacheArrayBase(HInstruction * cursor,const DexFile & dex_file)78   HArmDexCacheArraysBase* GetOrCreateDexCacheArrayBase(HInstruction* cursor,
79                                                        const DexFile& dex_file) {
80     if (GetGraph()->HasIrreducibleLoops()) {
81       HArmDexCacheArraysBase* base = new (GetGraph()->GetArena()) HArmDexCacheArraysBase(dex_file);
82       cursor->GetBlock()->InsertInstructionBefore(base, cursor);
83       return base;
84     } else {
85       // Ensure we only initialize the pointer once for each dex file.
86       auto lb = dex_cache_array_bases_.lower_bound(&dex_file);
87       if (lb != dex_cache_array_bases_.end() &&
88           !dex_cache_array_bases_.key_comp()(&dex_file, lb->first)) {
89         return lb->second;
90       }
91 
92       // Insert the base at the start of the entry block, move it to a better
93       // position later in MoveBaseIfNeeded().
94       HArmDexCacheArraysBase* base = new (GetGraph()->GetArena()) HArmDexCacheArraysBase(dex_file);
95       HBasicBlock* entry_block = GetGraph()->GetEntryBlock();
96       entry_block->InsertInstructionBefore(base, entry_block->GetFirstInstruction());
97       dex_cache_array_bases_.PutBefore(lb, &dex_file, base);
98       return base;
99     }
100   }
101 
102   CodeGeneratorARMType* codegen_;
103 
104   using DexCacheArraysBaseMap =
105       ArenaSafeMap<const DexFile*, HArmDexCacheArraysBase*, std::less<const DexFile*>>;
106   DexCacheArraysBaseMap dex_cache_array_bases_;
107 };
108 
Run()109 void DexCacheArrayFixups::Run() {
110   DexCacheArrayFixupsVisitor visitor(graph_, codegen_);
111   visitor.VisitInsertionOrder();
112   visitor.MoveBasesIfNeeded();
113 }
114 
115 }  // namespace arm
116 }  // namespace art
117