Steve Block | a7e24c1 | 2009-10-30 11:49:00 +0000 | [diff] [blame^] | 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 "register-allocator-inl.h" |
| 32 | |
| 33 | namespace v8 { |
| 34 | namespace internal { |
| 35 | |
| 36 | // ------------------------------------------------------------------------- |
| 37 | // Virtual frame elements |
| 38 | // |
| 39 | // The internal elements of the virtual frames. There are several kinds of |
| 40 | // elements: |
| 41 | // * Invalid: elements that are uninitialized or not actually part |
| 42 | // of the virtual frame. They should not be read. |
| 43 | // * Memory: an element that resides in the actual frame. Its address is |
| 44 | // given by its position in the virtual frame. |
| 45 | // * Register: an element that resides in a register. |
| 46 | // * Constant: an element whose value is known at compile time. |
| 47 | |
| 48 | class FrameElement BASE_EMBEDDED { |
| 49 | public: |
| 50 | enum SyncFlag { |
| 51 | NOT_SYNCED, |
| 52 | SYNCED |
| 53 | }; |
| 54 | |
| 55 | // The default constructor creates an invalid frame element. |
| 56 | FrameElement() { |
| 57 | value_ = TypeField::encode(INVALID) |
| 58 | | CopiedField::encode(false) |
| 59 | | SyncedField::encode(false) |
| 60 | | DataField::encode(0); |
| 61 | } |
| 62 | |
| 63 | // Factory function to construct an invalid frame element. |
| 64 | static FrameElement InvalidElement() { |
| 65 | FrameElement result; |
| 66 | return result; |
| 67 | } |
| 68 | |
| 69 | // Factory function to construct an in-memory frame element. |
| 70 | static FrameElement MemoryElement() { |
| 71 | FrameElement result(MEMORY, no_reg, SYNCED); |
| 72 | return result; |
| 73 | } |
| 74 | |
| 75 | // Factory function to construct an in-register frame element. |
| 76 | static FrameElement RegisterElement(Register reg, |
| 77 | SyncFlag is_synced) { |
| 78 | return FrameElement(REGISTER, reg, is_synced); |
| 79 | } |
| 80 | |
| 81 | // Factory function to construct a frame element whose value is known at |
| 82 | // compile time. |
| 83 | static FrameElement ConstantElement(Handle<Object> value, |
| 84 | SyncFlag is_synced) { |
| 85 | FrameElement result(value, is_synced); |
| 86 | return result; |
| 87 | } |
| 88 | |
| 89 | // Static indirection table for handles to constants. If a frame |
| 90 | // element represents a constant, the data contains an index into |
| 91 | // this table of handles to the actual constants. |
| 92 | typedef ZoneList<Handle<Object> > ZoneObjectList; |
| 93 | |
| 94 | static ZoneObjectList* ConstantList(); |
| 95 | |
| 96 | // Clear the constants indirection table. |
| 97 | static void ClearConstantList() { |
| 98 | ConstantList()->Clear(); |
| 99 | } |
| 100 | |
| 101 | bool is_synced() const { return SyncedField::decode(value_); } |
| 102 | |
| 103 | void set_sync() { |
| 104 | ASSERT(type() != MEMORY); |
| 105 | value_ = value_ | SyncedField::encode(true); |
| 106 | } |
| 107 | |
| 108 | void clear_sync() { |
| 109 | ASSERT(type() != MEMORY); |
| 110 | value_ = value_ & ~SyncedField::mask(); |
| 111 | } |
| 112 | |
| 113 | bool is_valid() const { return type() != INVALID; } |
| 114 | bool is_memory() const { return type() == MEMORY; } |
| 115 | bool is_register() const { return type() == REGISTER; } |
| 116 | bool is_constant() const { return type() == CONSTANT; } |
| 117 | bool is_copy() const { return type() == COPY; } |
| 118 | |
| 119 | bool is_copied() const { return CopiedField::decode(value_); } |
| 120 | void set_copied() { value_ = value_ | CopiedField::encode(true); } |
| 121 | void clear_copied() { value_ = value_ & ~CopiedField::mask(); } |
| 122 | |
| 123 | Register reg() const { |
| 124 | ASSERT(is_register()); |
| 125 | uint32_t reg = DataField::decode(value_); |
| 126 | Register result; |
| 127 | result.code_ = reg; |
| 128 | return result; |
| 129 | } |
| 130 | |
| 131 | Handle<Object> handle() const { |
| 132 | ASSERT(is_constant()); |
| 133 | return ConstantList()->at(DataField::decode(value_)); |
| 134 | } |
| 135 | |
| 136 | int index() const { |
| 137 | ASSERT(is_copy()); |
| 138 | return DataField::decode(value_); |
| 139 | } |
| 140 | |
| 141 | bool Equals(FrameElement other) { |
| 142 | uint32_t masked_difference = (value_ ^ other.value_) & ~CopiedField::mask(); |
| 143 | if (!masked_difference) { |
| 144 | // The elements are equal if they agree exactly except on copied field. |
| 145 | return true; |
| 146 | } else { |
| 147 | // If two constants have the same value, and agree otherwise, return true. |
| 148 | return !(masked_difference & ~DataField::mask()) && |
| 149 | is_constant() && |
| 150 | handle().is_identical_to(other.handle()); |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | // Test if two FrameElements refer to the same memory or register location. |
| 155 | bool SameLocation(FrameElement* other) { |
| 156 | if (type() == other->type()) { |
| 157 | if (value_ == other->value_) return true; |
| 158 | if (is_constant() && handle().is_identical_to(other->handle())) { |
| 159 | return true; |
| 160 | } |
| 161 | } |
| 162 | return false; |
| 163 | } |
| 164 | |
| 165 | // Given a pair of non-null frame element pointers, return one of them |
| 166 | // as an entry frame candidate or null if they are incompatible. |
| 167 | FrameElement* Combine(FrameElement* other) { |
| 168 | // If either is invalid, the result is. |
| 169 | if (!is_valid()) return this; |
| 170 | if (!other->is_valid()) return other; |
| 171 | |
| 172 | if (!SameLocation(other)) return NULL; |
| 173 | // If either is unsynced, the result is. |
| 174 | FrameElement* result = is_synced() ? other : this; |
| 175 | return result; |
| 176 | } |
| 177 | |
| 178 | private: |
| 179 | enum Type { |
| 180 | INVALID, |
| 181 | MEMORY, |
| 182 | REGISTER, |
| 183 | CONSTANT, |
| 184 | COPY |
| 185 | }; |
| 186 | |
| 187 | // Used to construct memory and register elements. |
| 188 | FrameElement(Type type, Register reg, SyncFlag is_synced) { |
| 189 | value_ = TypeField::encode(type) |
| 190 | | CopiedField::encode(false) |
| 191 | | SyncedField::encode(is_synced != NOT_SYNCED) |
| 192 | | DataField::encode(reg.code_ > 0 ? reg.code_ : 0); |
| 193 | } |
| 194 | |
| 195 | // Used to construct constant elements. |
| 196 | FrameElement(Handle<Object> value, SyncFlag is_synced) { |
| 197 | value_ = TypeField::encode(CONSTANT) |
| 198 | | CopiedField::encode(false) |
| 199 | | SyncedField::encode(is_synced != NOT_SYNCED) |
| 200 | | DataField::encode(ConstantList()->length()); |
| 201 | ConstantList()->Add(value); |
| 202 | } |
| 203 | |
| 204 | Type type() const { return TypeField::decode(value_); } |
| 205 | void set_type(Type type) { |
| 206 | value_ = value_ & ~TypeField::mask(); |
| 207 | value_ = value_ | TypeField::encode(type); |
| 208 | } |
| 209 | |
| 210 | void set_index(int new_index) { |
| 211 | ASSERT(is_copy()); |
| 212 | value_ = value_ & ~DataField::mask(); |
| 213 | value_ = value_ | DataField::encode(new_index); |
| 214 | } |
| 215 | |
| 216 | void set_reg(Register new_reg) { |
| 217 | ASSERT(is_register()); |
| 218 | value_ = value_ & ~DataField::mask(); |
| 219 | value_ = value_ | DataField::encode(new_reg.code_); |
| 220 | } |
| 221 | |
| 222 | // Encode type, copied, synced and data in one 32 bit integer. |
| 223 | uint32_t value_; |
| 224 | |
| 225 | class TypeField: public BitField<Type, 0, 3> {}; |
| 226 | class CopiedField: public BitField<uint32_t, 3, 1> {}; |
| 227 | class SyncedField: public BitField<uint32_t, 4, 1> {}; |
| 228 | class DataField: public BitField<uint32_t, 5, 32 - 6> {}; |
| 229 | |
| 230 | friend class VirtualFrame; |
| 231 | }; |
| 232 | |
| 233 | } } // namespace v8::internal |
| 234 | |
| 235 | #endif // V8_FRAME_ELEMENT_H_ |