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 "x86_memory_gen.h"
18 #include "code_generator.h"
19 #include "driver/compiler_options.h"
20
21 namespace art {
22 namespace x86 {
23
24 /**
25 * Replace instructions with memory operand forms.
26 */
27 class MemoryOperandVisitor : public HGraphVisitor {
28 public:
MemoryOperandVisitor(HGraph * graph,bool do_implicit_null_checks)29 MemoryOperandVisitor(HGraph* graph, bool do_implicit_null_checks)
30 : HGraphVisitor(graph),
31 do_implicit_null_checks_(do_implicit_null_checks) {}
32
33 private:
VisitBoundsCheck(HBoundsCheck * check)34 void VisitBoundsCheck(HBoundsCheck* check) override {
35 // Replace the length by the array itself, so that we can do compares to memory.
36 HArrayLength* array_len = check->InputAt(1)->AsArrayLength();
37
38 // We only want to replace an ArrayLength.
39 if (array_len == nullptr) {
40 return;
41 }
42
43 HInstruction* array = array_len->InputAt(0);
44 DCHECK_EQ(array->GetType(), DataType::Type::kReference);
45
46 // Don't apply this optimization when the array is nullptr.
47 if (array->IsConstant() || (array->IsNullCheck() && array->InputAt(0)->IsConstant())) {
48 return;
49 }
50
51 // Is there a null check that could be an implicit check?
52 if (array->IsNullCheck() && do_implicit_null_checks_) {
53 // The ArrayLen may generate the implicit null check. Can the
54 // bounds check do so as well?
55 if (array_len->GetNextDisregardingMoves() != check) {
56 // No, it won't. Leave as is.
57 return;
58 }
59 }
60
61 // Can we suppress the ArrayLength and generate at BoundCheck?
62 if (array_len->HasOnlyOneNonEnvironmentUse()) {
63 array_len->MarkEmittedAtUseSite();
64 // We need the ArrayLength just before the BoundsCheck.
65 array_len->MoveBefore(check);
66 }
67 }
68
69 bool do_implicit_null_checks_;
70 };
71
X86MemoryOperandGeneration(HGraph * graph,CodeGenerator * codegen,OptimizingCompilerStats * stats)72 X86MemoryOperandGeneration::X86MemoryOperandGeneration(HGraph* graph,
73 CodeGenerator* codegen,
74 OptimizingCompilerStats* stats)
75 : HOptimization(graph, kX86MemoryOperandGenerationPassName, stats),
76 do_implicit_null_checks_(codegen->GetCompilerOptions().GetImplicitNullChecks()) {
77 }
78
Run()79 bool X86MemoryOperandGeneration::Run() {
80 MemoryOperandVisitor visitor(graph_, do_implicit_null_checks_);
81 visitor.VisitInsertionOrder();
82 return true;
83 }
84
85 } // namespace x86
86 } // namespace art
87