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Side by Side Diff: src/frame-element.h

Issue 7060010: Merge bleeding edge into the GC branch up to 7948. The asserts (Closed) Base URL: http://v8.googlecode.com/svn/branches/experimental/gc/
Patch Set: Created 9 years, 7 months ago
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1 // Copyright 2009 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28 #ifndef V8_FRAME_ELEMENT_H_
29 #define V8_FRAME_ELEMENT_H_
30
31 #include "type-info.h"
32 #include "macro-assembler.h"
33 #include "zone.h"
34
35 namespace v8 {
36 namespace internal {
37
38 // -------------------------------------------------------------------------
39 // Virtual frame elements
40 //
41 // The internal elements of the virtual frames. There are several kinds of
42 // elements:
43 // * Invalid: elements that are uninitialized or not actually part
44 // of the virtual frame. They should not be read.
45 // * Memory: an element that resides in the actual frame. Its address is
46 // given by its position in the virtual frame.
47 // * Register: an element that resides in a register.
48 // * Constant: an element whose value is known at compile time.
49
50 class FrameElement BASE_EMBEDDED {
51 public:
52 enum SyncFlag {
53 NOT_SYNCED,
54 SYNCED
55 };
56
57 inline TypeInfo type_info() {
58 // Copied elements do not have type info. Instead
59 // we have to inspect their backing element in the frame.
60 ASSERT(!is_copy());
61 return TypeInfo::FromInt(TypeInfoField::decode(value_));
62 }
63
64 inline void set_type_info(TypeInfo info) {
65 // Copied elements do not have type info. Instead
66 // we have to inspect their backing element in the frame.
67 ASSERT(!is_copy());
68 value_ = value_ & ~TypeInfoField::mask();
69 value_ = value_ | TypeInfoField::encode(info.ToInt());
70 }
71
72 // The default constructor creates an invalid frame element.
73 FrameElement() {
74 value_ = TypeField::encode(INVALID)
75 | CopiedField::encode(false)
76 | SyncedField::encode(false)
77 | TypeInfoField::encode(TypeInfo::Uninitialized().ToInt())
78 | DataField::encode(0);
79 }
80
81 // Factory function to construct an invalid frame element.
82 static FrameElement InvalidElement() {
83 FrameElement result;
84 return result;
85 }
86
87 // Factory function to construct an in-memory frame element.
88 static FrameElement MemoryElement(TypeInfo info) {
89 FrameElement result(MEMORY, no_reg, SYNCED, info);
90 return result;
91 }
92
93 // Factory function to construct an in-register frame element.
94 static FrameElement RegisterElement(Register reg,
95 SyncFlag is_synced,
96 TypeInfo info) {
97 return FrameElement(REGISTER, reg, is_synced, info);
98 }
99
100 // Factory function to construct a frame element whose value is known at
101 // compile time.
102 static FrameElement ConstantElement(Handle<Object> value,
103 SyncFlag is_synced) {
104 TypeInfo info = TypeInfo::TypeFromValue(value);
105 FrameElement result(value, is_synced, info);
106 return result;
107 }
108
109 static bool ConstantPoolOverflowed() {
110 return !DataField::is_valid(
111 Isolate::Current()->frame_element_constant_list()->length());
112 }
113
114 bool is_synced() const { return SyncedField::decode(value_); }
115
116 void set_sync() {
117 ASSERT(type() != MEMORY);
118 value_ = value_ | SyncedField::encode(true);
119 }
120
121 void clear_sync() {
122 ASSERT(type() != MEMORY);
123 value_ = value_ & ~SyncedField::mask();
124 }
125
126 bool is_valid() const { return type() != INVALID; }
127 bool is_memory() const { return type() == MEMORY; }
128 bool is_register() const { return type() == REGISTER; }
129 bool is_constant() const { return type() == CONSTANT; }
130 bool is_copy() const { return type() == COPY; }
131
132 bool is_copied() const { return CopiedField::decode(value_); }
133 void set_copied() { value_ = value_ | CopiedField::encode(true); }
134 void clear_copied() { value_ = value_ & ~CopiedField::mask(); }
135
136 // An untagged int32 FrameElement represents a signed int32
137 // on the stack. These are only allowed in a side-effect-free
138 // int32 calculation, and if a non-int32 input shows up or an overflow
139 // occurs, we bail out and drop all the int32 values.
140 void set_untagged_int32(bool value) {
141 value_ &= ~UntaggedInt32Field::mask();
142 value_ |= UntaggedInt32Field::encode(value);
143 }
144 bool is_untagged_int32() const { return UntaggedInt32Field::decode(value_); }
145
146 Register reg() const {
147 ASSERT(is_register());
148 uint32_t reg = DataField::decode(value_);
149 Register result;
150 result.code_ = reg;
151 return result;
152 }
153
154 Handle<Object> handle() const {
155 ASSERT(is_constant());
156 return Isolate::Current()->frame_element_constant_list()->
157 at(DataField::decode(value_));
158 }
159
160 int index() const {
161 ASSERT(is_copy());
162 return DataField::decode(value_);
163 }
164
165 bool Equals(FrameElement other) {
166 uint32_t masked_difference = (value_ ^ other.value_) & ~CopiedField::mask();
167 if (!masked_difference) {
168 // The elements are equal if they agree exactly except on copied field.
169 return true;
170 } else {
171 // If two constants have the same value, and agree otherwise, return true.
172 return !(masked_difference & ~DataField::mask()) &&
173 is_constant() &&
174 handle().is_identical_to(other.handle());
175 }
176 }
177
178 // Test if two FrameElements refer to the same memory or register location.
179 bool SameLocation(FrameElement* other) {
180 if (type() == other->type()) {
181 if (value_ == other->value_) return true;
182 if (is_constant() && handle().is_identical_to(other->handle())) {
183 return true;
184 }
185 }
186 return false;
187 }
188
189 // Given a pair of non-null frame element pointers, return one of them
190 // as an entry frame candidate or null if they are incompatible.
191 FrameElement* Combine(FrameElement* other) {
192 // If either is invalid, the result is.
193 if (!is_valid()) return this;
194 if (!other->is_valid()) return other;
195
196 if (!SameLocation(other)) return NULL;
197 // If either is unsynced, the result is.
198 FrameElement* result = is_synced() ? other : this;
199 return result;
200 }
201
202 private:
203 enum Type {
204 INVALID,
205 MEMORY,
206 REGISTER,
207 CONSTANT,
208 COPY
209 };
210
211 // Used to construct memory and register elements.
212 FrameElement(Type type,
213 Register reg,
214 SyncFlag is_synced,
215 TypeInfo info) {
216 value_ = TypeField::encode(type)
217 | CopiedField::encode(false)
218 | SyncedField::encode(is_synced != NOT_SYNCED)
219 | TypeInfoField::encode(info.ToInt())
220 | DataField::encode(reg.code_ > 0 ? reg.code_ : 0);
221 }
222
223 // Used to construct constant elements.
224 FrameElement(Handle<Object> value, SyncFlag is_synced, TypeInfo info) {
225 ZoneObjectList* constant_list =
226 Isolate::Current()->frame_element_constant_list();
227 value_ = TypeField::encode(CONSTANT)
228 | CopiedField::encode(false)
229 | SyncedField::encode(is_synced != NOT_SYNCED)
230 | TypeInfoField::encode(info.ToInt())
231 | DataField::encode(constant_list->length());
232 constant_list->Add(value);
233 }
234
235 Type type() const { return TypeField::decode(value_); }
236 void set_type(Type type) {
237 value_ = value_ & ~TypeField::mask();
238 value_ = value_ | TypeField::encode(type);
239 }
240
241 void set_index(int new_index) {
242 ASSERT(is_copy());
243 value_ = value_ & ~DataField::mask();
244 value_ = value_ | DataField::encode(new_index);
245 }
246
247 void set_reg(Register new_reg) {
248 ASSERT(is_register());
249 value_ = value_ & ~DataField::mask();
250 value_ = value_ | DataField::encode(new_reg.code_);
251 }
252
253 // Encode type, copied, synced and data in one 32 bit integer.
254 uint32_t value_;
255
256 // Declare BitFields with template parameters <type, start, size>.
257 class TypeField: public BitField<Type, 0, 3> {};
258 class CopiedField: public BitField<bool, 3, 1> {};
259 class SyncedField: public BitField<bool, 4, 1> {};
260 class UntaggedInt32Field: public BitField<bool, 5, 1> {};
261 class TypeInfoField: public BitField<int, 6, 7> {};
262 class DataField: public BitField<uint32_t, 13, 32 - 13> {};
263
264 friend class VirtualFrame;
265 };
266
267 } } // namespace v8::internal
268
269 #endif // V8_FRAME_ELEMENT_H_
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