1// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
2// for details. All rights reserved. Use of this source code is governed by a
3// BSD-style license that can be found in the LICENSE file.
4// Classes that describe assembly patterns as used by inline caches.
5
6#ifndef RUNTIME_VM_INSTRUCTIONS_X64_H_
7#define RUNTIME_VM_INSTRUCTIONS_X64_H_
8
9#ifndef RUNTIME_VM_INSTRUCTIONS_H_
10#error "Do not include instructions_x64.h directly; use instructions.h instead."
11#endif
12
13#include "platform/unaligned.h"
14#include "vm/allocation.h"
15
16namespace dart {
17
18intptr_t IndexFromPPLoadDisp8(uword start);
19intptr_t IndexFromPPLoadDisp32(uword start);
20
21// Template class for all instruction pattern classes.
22// P has to specify a static pattern and a pattern length method.
23template <class P>
24class InstructionPattern : public ValueObject {
25 public:
26 explicit InstructionPattern(uword pc) : start_(pc) { ASSERT(pc != 0); }
27
28 // Call to check if the instruction pattern at 'pc' match the instruction.
29 // 'P::pattern()' returns the expected byte pattern in form of an integer
30 // array with length of 'P::pattern_length_in_bytes()'. A '-1' element means
31 // 'any byte'.
32 bool IsValid() const {
33 return TestBytesWith(P::pattern(), P::pattern_length_in_bytes());
34 }
35
36 protected:
37 uword start() const { return start_; }
38
39 private:
40 // Returns true if the 'num_bytes' bytes at 'start_' correspond to
41 // array of integers 'data'. 'data' elements are either a byte or -1, which
42 // represents any byte.
43 bool TestBytesWith(const int* data, int num_bytes) const {
44 ASSERT(data != NULL);
45 const uint8_t* byte_array = reinterpret_cast<const uint8_t*>(start_);
46 for (int i = 0; i < num_bytes; i++) {
47 // Skip comparison for data[i] < 0.
48 if ((data[i] >= 0) && (byte_array[i] != (0xFF & data[i]))) {
49 return false;
50 }
51 }
52 return true;
53 }
54
55 const uword start_;
56
57 DISALLOW_COPY_AND_ASSIGN(InstructionPattern);
58};
59
60class ReturnPattern : public InstructionPattern<ReturnPattern> {
61 public:
62 explicit ReturnPattern(uword pc) : InstructionPattern(pc) {}
63
64 static const int* pattern() {
65 static const int kReturnPattern[kLengthInBytes] = {0xC3};
66 return kReturnPattern;
67 }
68
69 static int pattern_length_in_bytes() { return kLengthInBytes; }
70
71 private:
72 static const int kLengthInBytes = 1;
73};
74
75// push rbp
76// mov rbp, rsp
77class ProloguePattern : public InstructionPattern<ProloguePattern> {
78 public:
79 explicit ProloguePattern(uword pc) : InstructionPattern(pc) {}
80
81 static const int* pattern() {
82 static const int kProloguePattern[kLengthInBytes] = {0x55, 0x48, 0x89,
83 0xe5};
84 return kProloguePattern;
85 }
86
87 static int pattern_length_in_bytes() { return kLengthInBytes; }
88
89 private:
90 static const int kLengthInBytes = 4;
91};
92
93// mov rbp, rsp
94class SetFramePointerPattern
95 : public InstructionPattern<SetFramePointerPattern> {
96 public:
97 explicit SetFramePointerPattern(uword pc) : InstructionPattern(pc) {}
98
99 static const int* pattern() {
100 static const int kFramePointerPattern[kLengthInBytes] = {0x48, 0x89, 0xe5};
101 return kFramePointerPattern;
102 }
103
104 static int pattern_length_in_bytes() { return kLengthInBytes; }
105
106 private:
107 static const int kLengthInBytes = 3;
108};
109
110// callq *[rip+offset]
111class PcRelativeCallPattern : public InstructionPattern<PcRelativeCallPattern> {
112 public:
113 static const intptr_t kLowerCallingRange = -(DART_UINT64_C(1) << 31);
114 static const intptr_t kUpperCallingRange = (DART_UINT64_C(1) << 31) - 1;
115
116 explicit PcRelativeCallPattern(uword pc) : InstructionPattern(pc) {}
117
118 int32_t distance() {
119 return LoadUnaligned(reinterpret_cast<int32_t*>(start() + 1)) +
120 kLengthInBytes;
121 }
122
123 void set_distance(int32_t distance) {
124 // [distance] is relative to the start of the instruction, x64 considers the
125 // offset relative to next PC.
126 StoreUnaligned(reinterpret_cast<int32_t*>(start() + 1),
127 distance - kLengthInBytes);
128 }
129
130 static const int* pattern() {
131 static const int kPattern[kLengthInBytes] = {0xe8, -1, -1, -1, -1};
132 return kPattern;
133 }
134
135 static int pattern_length_in_bytes() { return kLengthInBytes; }
136
137 static const int kLengthInBytes = 5;
138};
139
140// Instruction pattern for a tail call to a signed 32-bit PC-relative offset
141//
142// The AOT compiler can emit PC-relative calls. If the destination of such a
143// call is not in range for the "bl.<cond> <offset>" instruction, the AOT
144// compiler will emit a trampoline which is in range. That trampoline will
145// then tail-call to the final destination (also via PC-relative offset, but it
146// supports a full signed 32-bit offset).
147//
148// The pattern of the trampoline looks like:
149//
150// jmp $rip + <offset>
151//
152// (Strictly speaking the pc-relative call distance on X64 is big enough, but
153// for making AOT relocation code (i.e. relocation.cc) platform independent and
154// allow testing of trampolines on X64 we have it nonetheless)
155class PcRelativeTrampolineJumpPattern : public ValueObject {
156 public:
157 static const int kLengthInBytes = 5;
158
159 explicit PcRelativeTrampolineJumpPattern(uword pattern_start)
160 : pattern_start_(pattern_start) {}
161
162 void Initialize() {
163 uint8_t* pattern = reinterpret_cast<uint8_t*>(pattern_start_);
164 pattern[0] = 0xe9;
165 }
166
167 int32_t distance() {
168 return LoadUnaligned(reinterpret_cast<int32_t*>(pattern_start_ + 1)) +
169 kLengthInBytes;
170 }
171
172 void set_distance(int32_t distance) {
173 // [distance] is relative to the start of the instruction, x64 considers the
174 // offset relative to next PC.
175 StoreUnaligned(reinterpret_cast<int32_t*>(pattern_start_ + 1),
176 distance - kLengthInBytes);
177 }
178
179 bool IsValid() const {
180 uint8_t* pattern = reinterpret_cast<uint8_t*>(pattern_start_);
181 return pattern[0] == 0xe9;
182 }
183
184 private:
185 uword pattern_start_;
186};
187
188class PcRelativeTailCallPattern : public PcRelativeTrampolineJumpPattern {
189 public:
190 static const intptr_t kLowerCallingRange = -(1ul << 31) + kLengthInBytes;
191 static const intptr_t kUpperCallingRange = (1ul << 31) - 1;
192
193 explicit PcRelativeTailCallPattern(uword pc)
194 : PcRelativeTrampolineJumpPattern(pc) {}
195};
196
197} // namespace dart
198
199#endif // RUNTIME_VM_INSTRUCTIONS_X64_H_
200