Kristian Monsen | 25f6136 | 2010-05-21 11:50:48 +0100 | [diff] [blame] | 1 | // Copyright 2008 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_JUMP_TARGET_LIGHT_H_ |
| 29 | #define V8_JUMP_TARGET_LIGHT_H_ |
| 30 | |
| 31 | #include "macro-assembler.h" |
| 32 | #include "zone-inl.h" |
| 33 | #include "virtual-frame.h" |
| 34 | |
| 35 | namespace v8 { |
| 36 | namespace internal { |
| 37 | |
| 38 | // Forward declarations. |
| 39 | class FrameElement; |
| 40 | class Result; |
| 41 | |
| 42 | // ------------------------------------------------------------------------- |
| 43 | // Jump targets |
| 44 | // |
| 45 | // A jump target is an abstraction of a basic-block entry in generated |
| 46 | // code. It collects all the virtual frames reaching the block by |
| 47 | // forward jumps and pairs them with labels for the merge code along |
| 48 | // all forward-reaching paths. When bound, an expected frame for the |
| 49 | // block is determined and code is generated to merge to the expected |
| 50 | // frame. For backward jumps, the merge code is generated at the edge |
| 51 | // leaving the predecessor block. |
| 52 | // |
| 53 | // A jump target must have been reached via control flow (either by |
| 54 | // jumping, branching, or falling through) at the time it is bound. |
| 55 | // In particular, this means that at least one of the control-flow |
| 56 | // graph edges reaching the target must be a forward edge. |
| 57 | |
| 58 | class JumpTarget : public ZoneObject { // Shadows are dynamically allocated. |
| 59 | public: |
| 60 | // Forward-only jump targets can only be reached by forward CFG edges. |
| 61 | enum Directionality { FORWARD_ONLY, BIDIRECTIONAL }; |
| 62 | |
| 63 | // Construct a jump target. |
| 64 | explicit inline JumpTarget(Directionality direction); |
| 65 | |
| 66 | inline JumpTarget(); |
| 67 | |
| 68 | virtual ~JumpTarget() {} |
| 69 | |
| 70 | void Unuse() { |
| 71 | entry_frame_set_ = false; |
| 72 | entry_label_.Unuse(); |
| 73 | } |
| 74 | |
| 75 | inline CodeGenerator* cgen(); |
| 76 | |
Leon Clarke | f7060e2 | 2010-06-03 12:02:55 +0100 | [diff] [blame] | 77 | Label* entry_label() { return &entry_label_; } |
| 78 | |
Kristian Monsen | 25f6136 | 2010-05-21 11:50:48 +0100 | [diff] [blame] | 79 | const VirtualFrame* entry_frame() const { |
| 80 | return entry_frame_set_ ? &entry_frame_ : NULL; |
| 81 | } |
| 82 | |
| 83 | void set_entry_frame(VirtualFrame* frame) { |
| 84 | entry_frame_ = *frame; |
| 85 | entry_frame_set_ = true; |
| 86 | } |
| 87 | |
| 88 | // Predicates testing the state of the encapsulated label. |
| 89 | bool is_bound() const { return entry_label_.is_bound(); } |
| 90 | bool is_linked() const { return entry_label_.is_linked(); } |
| 91 | bool is_unused() const { return entry_label_.is_unused(); } |
| 92 | |
| 93 | // Copy the state of this jump target to the destination. |
| 94 | inline void CopyTo(JumpTarget* destination) { |
| 95 | *destination = *this; |
| 96 | } |
| 97 | |
| 98 | // Emit a jump to the target. There must be a current frame at the |
| 99 | // jump and there will be no current frame after the jump. |
| 100 | virtual void Jump(); |
| 101 | |
| 102 | // Emit a conditional branch to the target. There must be a current |
| 103 | // frame at the branch. The current frame will fall through to the |
Kristian Monsen | 50ef84f | 2010-07-29 15:18:00 +0100 | [diff] [blame] | 104 | // code after the branch. |
Kristian Monsen | 25f6136 | 2010-05-21 11:50:48 +0100 | [diff] [blame] | 105 | virtual void Branch(Condition cc, Hint hint = no_hint); |
| 106 | |
| 107 | // Bind a jump target. If there is no current frame at the binding |
| 108 | // site, there must be at least one frame reaching via a forward |
| 109 | // jump. |
| 110 | virtual void Bind(); |
| 111 | |
| 112 | // Emit a call to a jump target. There must be a current frame at |
| 113 | // the call. The frame at the target is the same as the current |
| 114 | // frame except for an extra return address on top of it. The frame |
| 115 | // after the call is the same as the frame before the call. |
| 116 | void Call(); |
| 117 | |
| 118 | protected: |
| 119 | // Has an entry frame been found? |
| 120 | bool entry_frame_set_; |
| 121 | |
Steve Block | 8defd9f | 2010-07-08 12:39:36 +0100 | [diff] [blame] | 122 | // Can we branch backwards to this label? |
| 123 | Directionality direction_; |
| 124 | |
Kristian Monsen | 25f6136 | 2010-05-21 11:50:48 +0100 | [diff] [blame] | 125 | // The frame used on entry to the block and expected at backward |
| 126 | // jumps to the block. Set the first time something branches to this |
| 127 | // jump target. |
| 128 | VirtualFrame entry_frame_; |
| 129 | |
| 130 | // The actual entry label of the block. |
| 131 | Label entry_label_; |
| 132 | |
| 133 | // Implementations of Jump, Branch, and Bind with all arguments and |
| 134 | // return values using the virtual frame. |
| 135 | void DoJump(); |
| 136 | void DoBranch(Condition cc, Hint hint); |
| 137 | void DoBind(); |
| 138 | }; |
| 139 | |
| 140 | |
| 141 | // ------------------------------------------------------------------------- |
| 142 | // Break targets |
| 143 | // |
| 144 | // A break target is a jump target that can be used to break out of a |
| 145 | // statement that keeps extra state on the stack (eg, for/in or |
| 146 | // try/finally). They know the expected stack height at the target |
| 147 | // and will drop state from nested statements as part of merging. |
| 148 | // |
| 149 | // Break targets are used for return, break, and continue targets. |
| 150 | |
| 151 | class BreakTarget : public JumpTarget { |
| 152 | public: |
| 153 | // Construct a break target. |
| 154 | inline BreakTarget(); |
Ben Murdoch | b0fe162 | 2011-05-05 13:52:32 +0100 | [diff] [blame^] | 155 | |
Steve Block | 8defd9f | 2010-07-08 12:39:36 +0100 | [diff] [blame] | 156 | inline BreakTarget(JumpTarget::Directionality direction); |
Kristian Monsen | 25f6136 | 2010-05-21 11:50:48 +0100 | [diff] [blame] | 157 | |
| 158 | virtual ~BreakTarget() {} |
| 159 | |
| 160 | // Copy the state of this jump target to the destination. |
| 161 | inline void CopyTo(BreakTarget* destination) { |
| 162 | *destination = *this; |
| 163 | } |
| 164 | |
| 165 | // Emit a jump to the target. There must be a current frame at the |
| 166 | // jump and there will be no current frame after the jump. |
| 167 | virtual void Jump(); |
| 168 | |
| 169 | // Emit a conditional branch to the target. There must be a current |
| 170 | // frame at the branch. The current frame will fall through to the |
| 171 | // code after the branch. |
| 172 | virtual void Branch(Condition cc, Hint hint = no_hint); |
| 173 | |
| 174 | // Bind a break target. If there is no current frame at the binding |
| 175 | // site, there must be at least one frame reaching via a forward |
| 176 | // jump. |
| 177 | virtual void Bind(); |
| 178 | |
| 179 | // Setter for expected height. |
| 180 | void set_expected_height(int expected) { expected_height_ = expected; } |
| 181 | |
| 182 | // Uses the current frame to set the expected height. |
| 183 | void SetExpectedHeight(); |
| 184 | |
| 185 | private: |
| 186 | // The expected height of the expression stack where the target will |
| 187 | // be bound, statically known at initialization time. |
| 188 | int expected_height_; |
| 189 | }; |
| 190 | |
| 191 | } } // namespace v8::internal |
| 192 | |
| 193 | #endif // V8_JUMP_TARGET_LIGHT_H_ |