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
29namespace art {
30namespace arm {
31#ifdef ART_USE_OLD_ARM_BACKEND
32typedef CodeGeneratorARM CodeGeneratorARMType;
33typedef IntrinsicLocationsBuilderARM IntrinsicLocationsBuilderARMType;
34#else
35typedef CodeGeneratorARMVIXL CodeGeneratorARMType;
36typedef IntrinsicLocationsBuilderARMVIXL IntrinsicLocationsBuilderARMType;
37#endif
38
39/**
40 * Finds instructions that need the dex cache arrays base as an input.
41 */
42class DexCacheArrayFixupsVisitor : public HGraphVisitor {
43 public:
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
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:
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
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
109void DexCacheArrayFixups::Run() {
110  DexCacheArrayFixupsVisitor visitor(graph_, codegen_);
111  visitor.VisitInsertionOrder();
112  visitor.MoveBasesIfNeeded();
113}
114
115}  // namespace arm
116}  // namespace art
117