ager@chromium.org | 9258b6b | 2008-09-11 09:11:10 +0000 | [diff] [blame] | 1 | // Copyright 2006-2008 the V8 project authors. All rights reserved. |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 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_VARIABLES_H_ |
| 29 | #define V8_VARIABLES_H_ |
| 30 | |
| 31 | #include "zone.h" |
| 32 | |
| 33 | namespace v8 { namespace internal { |
| 34 | |
| 35 | class UseCount BASE_EMBEDDED { |
| 36 | public: |
| 37 | UseCount(); |
| 38 | |
| 39 | // Inform the node of a "use". The weight can be used to indicate |
| 40 | // heavier use, for instance if the variable is accessed inside a loop. |
| 41 | void RecordRead(int weight); |
| 42 | void RecordWrite(int weight); |
| 43 | void RecordAccess(int weight); // records a read & write |
| 44 | void RecordUses(UseCount* uses); |
| 45 | |
| 46 | int nreads() const { return nreads_; } |
| 47 | int nwrites() const { return nwrites_; } |
| 48 | int nuses() const { return nreads_ + nwrites_; } |
| 49 | |
| 50 | bool is_read() const { return nreads() > 0; } |
| 51 | bool is_written() const { return nwrites() > 0; } |
| 52 | bool is_used() const { return nuses() > 0; } |
| 53 | |
| 54 | #ifdef DEBUG |
| 55 | void Print(); |
| 56 | #endif |
| 57 | |
| 58 | private: |
| 59 | int nreads_; |
| 60 | int nwrites_; |
| 61 | }; |
| 62 | |
| 63 | |
kasperl@chromium.org | 9bbf968 | 2008-10-30 11:53:07 +0000 | [diff] [blame] | 64 | // Variables and AST expression nodes can track their "type" to enable |
| 65 | // optimizations and removal of redundant checks when generating code. |
| 66 | |
| 67 | class StaticType BASE_EMBEDDED { |
| 68 | public: |
| 69 | enum Kind { |
| 70 | UNKNOWN, |
| 71 | LIKELY_SMI |
| 72 | }; |
| 73 | |
| 74 | StaticType() : kind_(UNKNOWN) {} |
| 75 | |
| 76 | bool Is(Kind kind) const { return kind_ == kind; } |
| 77 | |
| 78 | bool IsKnown() const { return !Is(UNKNOWN); } |
| 79 | bool IsUnknown() const { return Is(UNKNOWN); } |
| 80 | bool IsLikelySmi() const { return Is(LIKELY_SMI); } |
| 81 | |
| 82 | void CopyFrom(StaticType* other) { |
| 83 | kind_ = other->kind_; |
| 84 | } |
| 85 | |
| 86 | static const char* Type2String(StaticType* type); |
| 87 | |
| 88 | // LIKELY_SMI accessors |
| 89 | void SetAsLikelySmi() { |
| 90 | kind_ = LIKELY_SMI; |
| 91 | } |
| 92 | |
| 93 | void SetAsLikelySmiIfUnknown() { |
| 94 | if (IsUnknown()) { |
| 95 | SetAsLikelySmi(); |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | private: |
| 100 | Kind kind_; |
| 101 | |
| 102 | DISALLOW_COPY_AND_ASSIGN(StaticType); |
| 103 | }; |
| 104 | |
| 105 | |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 106 | // The AST refers to variables via VariableProxies - placeholders for the actual |
| 107 | // variables. Variables themselves are never directly referred to from the AST, |
| 108 | // they are maintained by scopes, and referred to from VariableProxies and Slots |
| 109 | // after binding and variable allocation. |
| 110 | |
| 111 | class Variable: public ZoneObject { |
| 112 | public: |
| 113 | enum Mode { |
| 114 | // User declared variables: |
| 115 | VAR, // declared via 'var', and 'function' declarations |
| 116 | CONST, // declared via 'const' declarations |
| 117 | |
| 118 | // Variables introduced by the compiler: |
| 119 | DYNAMIC, // always require dynamic lookup (we don't know the declaration) |
| 120 | INTERNAL, // like VAR, but not user-visible (may or may not be in a |
| 121 | // context) |
| 122 | TEMPORARY // temporary variables (not user-visible), never in a context |
| 123 | }; |
| 124 | |
| 125 | // Printing support |
| 126 | static const char* Mode2String(Mode mode); |
| 127 | |
| 128 | // Type testing & conversion |
| 129 | Property* AsProperty(); |
| 130 | Variable* AsVariable(); |
| 131 | bool IsValidLeftHandSide() { return is_valid_LHS_; } |
| 132 | |
| 133 | // The source code for an eval() call may refer to a variable that is |
| 134 | // in an outer scope about which we don't know anything (it may not |
| 135 | // be the global scope). scope() is NULL in that case. Currently the |
| 136 | // scope is only used to follow the context chain length. |
| 137 | Scope* scope() const { return scope_; } |
| 138 | // If this assertion fails it means that some code has tried to |
| 139 | // treat the special this variable as an ordinary variable with |
| 140 | // the name "this". |
| 141 | Handle<String> name() const { return name_; } |
| 142 | Mode mode() const { return mode_; } |
| 143 | bool is_accessed_from_inner_scope() const { |
| 144 | return is_accessed_from_inner_scope_; |
| 145 | } |
| 146 | UseCount* var_uses() { return &var_uses_; } |
| 147 | UseCount* obj_uses() { return &obj_uses_; } |
| 148 | |
| 149 | bool IsVariable(Handle<String> n) { |
| 150 | return !is_this() && name().is_identical_to(n); |
| 151 | } |
| 152 | |
| 153 | bool is_global() const; |
| 154 | bool is_this() const { return is_this_; } |
| 155 | |
| 156 | Expression* rewrite() const { return rewrite_; } |
| 157 | Slot* slot() const; |
| 158 | |
kasperl@chromium.org | 9bbf968 | 2008-10-30 11:53:07 +0000 | [diff] [blame] | 159 | StaticType* type() { return &type_; } |
| 160 | |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 161 | private: |
| 162 | Variable(Scope* scope, Handle<String> name, Mode mode, bool is_valid_LHS, |
| 163 | bool is_this); |
| 164 | |
| 165 | Scope* scope_; |
| 166 | Handle<String> name_; |
| 167 | Mode mode_; |
| 168 | bool is_valid_LHS_; |
| 169 | bool is_this_; |
| 170 | |
| 171 | // Usage info. |
| 172 | bool is_accessed_from_inner_scope_; // set by variable resolver |
| 173 | UseCount var_uses_; // uses of the variable value |
| 174 | UseCount obj_uses_; // uses of the object the variable points to |
| 175 | |
kasperl@chromium.org | 9bbf968 | 2008-10-30 11:53:07 +0000 | [diff] [blame] | 176 | // Static type information |
| 177 | StaticType type_; |
| 178 | |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 179 | // Code generation. |
| 180 | // rewrite_ is usually a Slot or a Property, but maybe any expression. |
| 181 | Expression* rewrite_; |
| 182 | |
| 183 | friend class VariableProxy; |
| 184 | friend class Scope; |
| 185 | friend class LocalsMap; |
| 186 | friend class AstBuildingParser; |
| 187 | }; |
| 188 | |
| 189 | |
| 190 | } } // namespace v8::internal |
| 191 | |
| 192 | #endif // V8_VARIABLES_H_ |