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1 /*
2  * Copyright (C) 2011 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 "assembler.h"
18 
19 #include <algorithm>
20 #include <vector>
21 
22 #include "base/casts.h"
23 #include "base/globals.h"
24 #include "base/memory_region.h"
25 
26 namespace art {
27 
AssemblerBuffer(ArenaAllocator * allocator)28 AssemblerBuffer::AssemblerBuffer(ArenaAllocator* allocator)
29     : allocator_(allocator) {
30   static const size_t kInitialBufferCapacity = 4 * KB;
31   contents_ = allocator_->AllocArray<uint8_t>(kInitialBufferCapacity, kArenaAllocAssembler);
32   cursor_ = contents_;
33   limit_ = ComputeLimit(contents_, kInitialBufferCapacity);
34   fixup_ = nullptr;
35   slow_path_ = nullptr;
36 #ifndef NDEBUG
37   has_ensured_capacity_ = false;
38   fixups_processed_ = false;
39 #endif
40 
41   // Verify internal state.
42   CHECK_EQ(Capacity(), kInitialBufferCapacity);
43   CHECK_EQ(Size(), 0U);
44 }
45 
46 
~AssemblerBuffer()47 AssemblerBuffer::~AssemblerBuffer() {
48   if (allocator_->IsRunningOnMemoryTool()) {
49     allocator_->MakeInaccessible(contents_, Capacity());
50   }
51 }
52 
53 
ProcessFixups(const MemoryRegion & region)54 void AssemblerBuffer::ProcessFixups(const MemoryRegion& region) {
55   AssemblerFixup* fixup = fixup_;
56   while (fixup != nullptr) {
57     fixup->Process(region, fixup->position());
58     fixup = fixup->previous();
59   }
60 }
61 
62 
FinalizeInstructions(const MemoryRegion & instructions)63 void AssemblerBuffer::FinalizeInstructions(const MemoryRegion& instructions) {
64   // Copy the instructions from the buffer.
65   MemoryRegion from(reinterpret_cast<void*>(contents()), Size());
66   instructions.CopyFrom(0, from);
67   // Process fixups in the instructions.
68   ProcessFixups(instructions);
69 #ifndef NDEBUG
70   fixups_processed_ = true;
71 #endif
72 }
73 
74 
ExtendCapacity(size_t min_capacity)75 void AssemblerBuffer::ExtendCapacity(size_t min_capacity) {
76   size_t old_size = Size();
77   size_t old_capacity = Capacity();
78   DCHECK_GT(min_capacity, old_capacity);
79   size_t new_capacity = std::min(old_capacity * 2, old_capacity + 1 * MB);
80   new_capacity = std::max(new_capacity, min_capacity);
81 
82   // Allocate the new data area and copy contents of the old one to it.
83   contents_ = reinterpret_cast<uint8_t*>(
84       allocator_->Realloc(contents_, old_capacity, new_capacity, kArenaAllocAssembler));
85 
86   // Update the cursor and recompute the limit.
87   cursor_ = contents_ + old_size;
88   limit_ = ComputeLimit(contents_, new_capacity);
89 
90   // Verify internal state.
91   CHECK_EQ(Capacity(), new_capacity);
92   CHECK_EQ(Size(), old_size);
93 }
94 
ImplicitlyAdvancePC()95 void DebugFrameOpCodeWriterForAssembler::ImplicitlyAdvancePC() {
96   uint32_t pc = dchecked_integral_cast<uint32_t>(assembler_->CodeSize());
97   if (delay_emitting_advance_pc_) {
98     uint32_t stream_pos = dchecked_integral_cast<uint32_t>(opcodes_.size());
99     delayed_advance_pcs_.push_back(DelayedAdvancePC {stream_pos, pc});
100   } else {
101     AdvancePC(pc);
102   }
103 }
104 
105 }  // namespace art
106