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 "pc_relative_fixups_x86.h"
18#include "code_generator_x86.h"
19#include "intrinsics_x86.h"
20
21namespace art {
22namespace x86 {
23
24/**
25 * Finds instructions that need the constant area base as an input.
26 */
27class PCRelativeHandlerVisitor : public HGraphVisitor {
28 public:
29  PCRelativeHandlerVisitor(HGraph* graph, CodeGenerator* codegen)
30      : HGraphVisitor(graph),
31        codegen_(down_cast<CodeGeneratorX86*>(codegen)),
32        base_(nullptr) {}
33
34  void MoveBaseIfNeeded() {
35    if (base_ != nullptr) {
36      // Bring the base closer to the first use (previously, it was in the
37      // entry block) and relieve some pressure on the register allocator
38      // while avoiding recalculation of the base in a loop.
39      base_->MoveBeforeFirstUserAndOutOfLoops();
40    }
41  }
42
43 private:
44  void VisitAdd(HAdd* add) OVERRIDE {
45    BinaryFP(add);
46  }
47
48  void VisitSub(HSub* sub) OVERRIDE {
49    BinaryFP(sub);
50  }
51
52  void VisitMul(HMul* mul) OVERRIDE {
53    BinaryFP(mul);
54  }
55
56  void VisitDiv(HDiv* div) OVERRIDE {
57    BinaryFP(div);
58  }
59
60  void VisitCompare(HCompare* compare) OVERRIDE {
61    BinaryFP(compare);
62  }
63
64  void VisitReturn(HReturn* ret) OVERRIDE {
65    HConstant* value = ret->InputAt(0)->AsConstant();
66    if ((value != nullptr && Primitive::IsFloatingPointType(value->GetType()))) {
67      ReplaceInput(ret, value, 0, true);
68    }
69  }
70
71  void VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) OVERRIDE {
72    HandleInvoke(invoke);
73  }
74
75  void VisitInvokeVirtual(HInvokeVirtual* invoke) OVERRIDE {
76    HandleInvoke(invoke);
77  }
78
79  void VisitInvokeInterface(HInvokeInterface* invoke) OVERRIDE {
80    HandleInvoke(invoke);
81  }
82
83  void VisitLoadString(HLoadString* load_string) OVERRIDE {
84    HLoadString::LoadKind load_kind = load_string->GetLoadKind();
85    if (load_kind == HLoadString::LoadKind::kBootImageLinkTimePcRelative ||
86        load_kind == HLoadString::LoadKind::kDexCachePcRelative) {
87      InitializePCRelativeBasePointer();
88      load_string->AddSpecialInput(base_);
89    }
90  }
91
92  void BinaryFP(HBinaryOperation* bin) {
93    HConstant* rhs = bin->InputAt(1)->AsConstant();
94    if (rhs != nullptr && Primitive::IsFloatingPointType(rhs->GetType())) {
95      ReplaceInput(bin, rhs, 1, false);
96    }
97  }
98
99  void VisitEqual(HEqual* cond) OVERRIDE {
100    BinaryFP(cond);
101  }
102
103  void VisitNotEqual(HNotEqual* cond) OVERRIDE {
104    BinaryFP(cond);
105  }
106
107  void VisitLessThan(HLessThan* cond) OVERRIDE {
108    BinaryFP(cond);
109  }
110
111  void VisitLessThanOrEqual(HLessThanOrEqual* cond) OVERRIDE {
112    BinaryFP(cond);
113  }
114
115  void VisitGreaterThan(HGreaterThan* cond) OVERRIDE {
116    BinaryFP(cond);
117  }
118
119  void VisitGreaterThanOrEqual(HGreaterThanOrEqual* cond) OVERRIDE {
120    BinaryFP(cond);
121  }
122
123  void VisitNeg(HNeg* neg) OVERRIDE {
124    if (Primitive::IsFloatingPointType(neg->GetType())) {
125      // We need to replace the HNeg with a HX86FPNeg in order to address the constant area.
126      InitializePCRelativeBasePointer();
127      HGraph* graph = GetGraph();
128      HBasicBlock* block = neg->GetBlock();
129      HX86FPNeg* x86_fp_neg = new (graph->GetArena()) HX86FPNeg(
130          neg->GetType(),
131          neg->InputAt(0),
132          base_,
133          neg->GetDexPc());
134      block->ReplaceAndRemoveInstructionWith(neg, x86_fp_neg);
135    }
136  }
137
138  void VisitPackedSwitch(HPackedSwitch* switch_insn) OVERRIDE {
139    if (switch_insn->GetNumEntries() <=
140        InstructionCodeGeneratorX86::kPackedSwitchJumpTableThreshold) {
141      return;
142    }
143    // We need to replace the HPackedSwitch with a HX86PackedSwitch in order to
144    // address the constant area.
145    InitializePCRelativeBasePointer();
146    HGraph* graph = GetGraph();
147    HBasicBlock* block = switch_insn->GetBlock();
148    HX86PackedSwitch* x86_switch = new (graph->GetArena()) HX86PackedSwitch(
149        switch_insn->GetStartValue(),
150        switch_insn->GetNumEntries(),
151        switch_insn->InputAt(0),
152        base_,
153        switch_insn->GetDexPc());
154    block->ReplaceAndRemoveInstructionWith(switch_insn, x86_switch);
155  }
156
157  void InitializePCRelativeBasePointer() {
158    // Ensure we only initialize the pointer once.
159    if (base_ != nullptr) {
160      return;
161    }
162    // Insert the base at the start of the entry block, move it to a better
163    // position later in MoveBaseIfNeeded().
164    base_ = new (GetGraph()->GetArena()) HX86ComputeBaseMethodAddress();
165    HBasicBlock* entry_block = GetGraph()->GetEntryBlock();
166    entry_block->InsertInstructionBefore(base_, entry_block->GetFirstInstruction());
167    DCHECK(base_ != nullptr);
168  }
169
170  void ReplaceInput(HInstruction* insn, HConstant* value, int input_index, bool materialize) {
171    InitializePCRelativeBasePointer();
172    HX86LoadFromConstantTable* load_constant =
173        new (GetGraph()->GetArena()) HX86LoadFromConstantTable(base_, value);
174    if (!materialize) {
175      load_constant->MarkEmittedAtUseSite();
176    }
177    insn->GetBlock()->InsertInstructionBefore(load_constant, insn);
178    insn->ReplaceInput(load_constant, input_index);
179  }
180
181  void HandleInvoke(HInvoke* invoke) {
182    // If this is an invoke-static/-direct with PC-relative dex cache array
183    // addressing, we need the PC-relative address base.
184    HInvokeStaticOrDirect* invoke_static_or_direct = invoke->AsInvokeStaticOrDirect();
185    // We can't add a pointer to the constant area if we already have a current
186    // method pointer. This may arise when sharpening doesn't remove the current
187    // method pointer from the invoke.
188    if (invoke_static_or_direct != nullptr &&
189        invoke_static_or_direct->HasCurrentMethodInput()) {
190      DCHECK(!invoke_static_or_direct->HasPcRelativeDexCache());
191      return;
192    }
193
194    bool base_added = false;
195    if (invoke_static_or_direct != nullptr &&
196        invoke_static_or_direct->HasPcRelativeDexCache() &&
197        !WillHaveCallFreeIntrinsicsCodeGen(invoke)) {
198      InitializePCRelativeBasePointer();
199      // Add the extra parameter base_.
200      invoke_static_or_direct->AddSpecialInput(base_);
201      base_added = true;
202    }
203
204    // Ensure that we can load FP arguments from the constant area.
205    for (size_t i = 0, e = invoke->InputCount(); i < e; i++) {
206      HConstant* input = invoke->InputAt(i)->AsConstant();
207      if (input != nullptr && Primitive::IsFloatingPointType(input->GetType())) {
208        ReplaceInput(invoke, input, i, true);
209      }
210    }
211
212    // These intrinsics need the constant area.
213    switch (invoke->GetIntrinsic()) {
214      case Intrinsics::kMathAbsDouble:
215      case Intrinsics::kMathAbsFloat:
216      case Intrinsics::kMathMaxDoubleDouble:
217      case Intrinsics::kMathMaxFloatFloat:
218      case Intrinsics::kMathMinDoubleDouble:
219      case Intrinsics::kMathMinFloatFloat:
220        if (!base_added) {
221          DCHECK(invoke_static_or_direct != nullptr);
222          DCHECK(!invoke_static_or_direct->HasCurrentMethodInput());
223          InitializePCRelativeBasePointer();
224          invoke_static_or_direct->AddSpecialInput(base_);
225        }
226        break;
227      default:
228        break;
229    }
230  }
231
232  bool WillHaveCallFreeIntrinsicsCodeGen(HInvoke* invoke) {
233    if (invoke->GetIntrinsic() != Intrinsics::kNone) {
234      // This invoke may have intrinsic code generation defined. However, we must
235      // now also determine if this code generation is truly there and call-free
236      // (not unimplemented, no bail on instruction features, or call on slow path).
237      // This is done by actually calling the locations builder on the instruction
238      // and clearing out the locations once result is known. We assume this
239      // call only has creating locations as side effects!
240      IntrinsicLocationsBuilderX86 builder(codegen_);
241      bool success = builder.TryDispatch(invoke) && !invoke->GetLocations()->CanCall();
242      invoke->SetLocations(nullptr);
243      return success;
244    }
245    return false;
246  }
247
248  CodeGeneratorX86* codegen_;
249
250  // The generated HX86ComputeBaseMethodAddress in the entry block needed as an
251  // input to the HX86LoadFromConstantTable instructions.
252  HX86ComputeBaseMethodAddress* base_;
253};
254
255void PcRelativeFixups::Run() {
256  if (graph_->HasIrreducibleLoops()) {
257    // Do not run this optimization, as irreducible loops do not work with an instruction
258    // that can be live-in at the irreducible loop header.
259    return;
260  }
261  PCRelativeHandlerVisitor visitor(graph_, codegen_);
262  visitor.VisitInsertionOrder();
263  visitor.MoveBaseIfNeeded();
264}
265
266}  // namespace x86
267}  // namespace art
268