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| 1 | namespace Semantic is | |
| 2 | use IO.Std; | |
| 3 | ||
| 4 | use Logging; | |
| 5 | ||
| 6 | use Types.Type; | |
| 7 | ||
| 8 | use IR.Values; | |
| 9 | ||
| 10 | use IR.TEMP; | |
| 11 | use IR.BRANCH; | |
| 12 | ||
| 13 | class TYPE_CASTER( | |
| 14 | _brancher: IR.BRANCHER, | |
| 15 | _block_context: IR.BlockContext, | |
| 16 | _value_boxer: IR.VALUE_BOXER, | |
| 17 | _value_converter: IR.VALUE_CONVERTER, | |
| 18 | _innate_symbol_lookup: Lookups.InnateSymbolLookup, | |
| 19 | _conversion_lookup: USER_DEFINED_CONVERSION_LOOKUP, | |
| 20 | _logger: Logger | |
| 21 | ) is | |
| 22 | super(); | |
| 23 | ||
| 24 | check_cast_is_valid(location: Source.LOCATION, source_type: Type, target_type: Type) -> bool is | |
| 25 | if source_type.is_type_variable /\ target_type.is_type_variable then | |
| 26 | _logger.error(location, "cannot convert {source_type} to {target_type}"); | |
| 27 | ||
| 28 | return false; | |
| 29 | fi | |
| 30 | ||
| 31 | if source_type.is_type_variable \/ target_type.is_type_variable then | |
| 32 | return true; | |
| 33 | fi | |
| 34 | ||
| 35 | if source_type.is_value_type /\ target_type.is_value_type then | |
| 36 | let decimal_type = _innate_symbol_lookup.get_decimal_type(); | |
| 37 | ||
| 38 | if source_type.matches(decimal_type) \/ target_type.matches(decimal_type) then | |
| 39 | if | |
| 40 | !_value_converter.get_decimal_conversion_instruction(source_type, target_type)? /\ | |
| 41 | !_conversion_lookup.find(source_type, target_type)? | |
| 42 | then | |
| 43 | _logger.error(location, "cannot convert {source_type} to {target_type}"); | |
| 44 | return false; | |
| 45 | fi | |
| 46 | ||
| 47 | return true; | |
| 48 | fi | |
| 49 | ||
| 50 | let instruction = _value_converter.get_instruction(target_type); | |
| 51 | let enum_type = _innate_symbol_lookup.get_enum_type(); | |
| 52 | ||
| 53 | if instruction? then | |
| 54 | // A `conv.*` opcode only accepts a source already on | |
| 55 | // the evaluation stack in a compatible primitive | |
| 56 | // shape - one of the built-in scalars, or an enum | |
| 57 | // (which decays to its underlying integral type on | |
| 58 | // the stack per ECMA-335). A multi-field value type | |
| 59 | // like Half or Int128 is neither, so `get_instruction` | |
| 60 | // being keyed on the target alone isn't enough here. | |
| 61 | if | |
| 62 | !_value_converter.get_instruction(source_type)? /\ | |
| 63 | !enum_type.is_assignable_from(source_type) /\ | |
| 64 | !_conversion_lookup.find(source_type, target_type)? | |
| 65 | then | |
| 66 | _logger.error(location, "cannot convert {source_type} to {target_type}"); | |
| 67 | return false; | |
| 68 | fi | |
| 69 | elif | |
| 70 | // Only a target enum is accepted here, matching | |
| 71 | // cast_value below: `conv.i4` re-annotates the | |
| 72 | // stack value's type as `target_type`, which is | |
| 73 | // only sound when that target itself decays to | |
| 74 | // int32 the same way a source enum does. An enum | |
| 75 | // source with some other non-scalar target is the | |
| 76 | // same unsound-IL shape the check above rejects | |
| 77 | // for a struct source. | |
| 78 | !enum_type.is_assignable_from(target_type) /\ | |
| 79 | !_conversion_lookup.find(source_type, target_type)? | |
| 80 | then | |
| 81 | _logger.error(location, "cannot convert {source_type} to {target_type}"); | |
| 82 | return false; | |
| 83 | fi | |
| 84 | fi | |
| 85 | ||
| 86 | return true; | |
| 87 | si | |
| 88 | ||
| 89 | cast_value( | |
| 90 | location: Source.LOCATION, | |
| 91 | value: IR.Values.Value, | |
| 92 | target_type: Type, | |
| 93 | quiet: bool | |
| 94 | ) -> IR.Values.Value is | |
| 95 | let need_conditional_unbox = false; | |
| 96 | ||
| 97 | if value.type!.is_type_variable /\ target_type.is_type_variable then | |
| 98 | if !quiet then | |
| 99 | _logger.error(location, "cannot convert {value.type} to {target_type}"); | |
| 100 | fi | |
| 101 | ||
| 102 | return | |
| 103 | DUMMY( | |
| 104 | target_type, | |
| 105 | location | |
| 106 | ); | |
| 107 | fi | |
| 108 | ||
| 109 | if value.type!.is_type_variable \/ target_type.is_type_variable then | |
| 110 | let result: IR.Values.Value mut = | |
| 111 | CAST( | |
| 112 | target_type, | |
| 113 | value | |
| 114 | ); | |
| 115 | ||
| 116 | if target_type.is_value_type then | |
| 117 | result = _conditionally_unbox(result, target_type); | |
| 118 | fi | |
| 119 | ||
| 120 | return result; | |
| 121 | fi | |
| 122 | ||
| 123 | if value.type!.is_value_type /\ target_type.is_value_type then | |
| 124 | let decimal_type = _innate_symbol_lookup.get_decimal_type(); | |
| 125 | ||
| 126 | if value.type!.matches(decimal_type) \/ target_type.matches(decimal_type) then | |
| 127 | let decimal_instruction = _value_converter.get_decimal_conversion_instruction(value.type!, target_type); | |
| 128 | ||
| 129 | if !decimal_instruction? then | |
| 130 | let conversion_function = _conversion_lookup.find(value.type!, target_type); | |
| 131 | ||
| 132 | if conversion_function? then | |
| 133 | return _build_conversion_call(value, conversion_function, target_type); | |
| 134 | fi | |
| 135 | ||
| 136 | if !quiet then | |
| 137 | _logger.error(location, "cannot convert {value.type} to {target_type}"); | |
| 138 | fi | |
| 139 | ||
| 140 | return | |
| 141 | DUMMY( | |
| 142 | target_type, | |
| 143 | location | |
| 144 | ); | |
| 145 | fi | |
| 146 | ||
| 147 | return | |
| 148 | CONVERT( | |
| 149 | target_type, | |
| 150 | value, | |
| 151 | decimal_instruction | |
| 152 | ); | |
| 153 | fi | |
| 154 | ||
| 155 | let instruction = _value_converter.get_instruction(target_type); | |
| 156 | let enum_type = _innate_symbol_lookup.get_enum_type(); | |
| 157 | ||
| 158 | if instruction? then | |
| 159 | // See the matching comment in check_cast_is_valid: | |
| 160 | // `get_instruction` is keyed on the target alone, so | |
| 161 | // it says nothing about whether `value` is actually | |
| 162 | // stack-compatible with the resulting `conv.*` | |
| 163 | // opcode. A multi-field value type like Half or | |
| 164 | // Int128 isn't, and reaching the JIT with one gives | |
| 165 | // an InvalidProgramException rather than a compile | |
| 166 | // error. | |
| 167 | if | |
| 168 | _value_converter.get_instruction(value.type!)? \/ | |
| 169 | enum_type.is_assignable_from(value.type!) | |
| 170 | then | |
| 171 | return | |
| 172 | CONVERT( | |
| 173 | target_type, | |
| 174 | value, | |
| 175 | instruction | |
| 176 | ); | |
| 177 | fi | |
| 178 | elif enum_type.is_assignable_from(target_type) then | |
| 179 | return | |
| 180 | CONVERT( | |
| 181 | target_type, | |
| 182 | value, | |
| 183 | "conv.i4" | |
| 184 | ); | |
| 185 | fi | |
| 186 | ||
| 187 | let conversion_function = _conversion_lookup.find(value.type!, target_type); | |
| 188 | ||
| 189 | if conversion_function? then | |
| 190 | return _build_conversion_call(value, conversion_function, target_type); | |
| 191 | fi | |
| 192 | ||
| 193 | if !quiet then | |
| 194 | _logger.error(location, "cannot convert {value.type} to {target_type}"); | |
| 195 | fi | |
| 196 | ||
| 197 | return | |
| 198 | DUMMY( | |
| 199 | target_type, | |
| 200 | location | |
| 201 | ); | |
| 202 | fi | |
| 203 | ||
| 204 | let target_non_optional = target_type.optional_inner_type ?? target_type; | |
| 205 | ||
| 206 | if | |
| 207 | !target_non_optional.is_assignable_from(value.type!) /\ | |
| 208 | !value.type!.is_assignable_from(target_non_optional) | |
| 209 | then | |
| 210 | let conversion_function = _conversion_lookup.find(value.type!, target_type); | |
| 211 | ||
| 212 | if conversion_function? then | |
| 213 | return _build_conversion_call(value, conversion_function, target_type); | |
| 214 | fi | |
| 215 | fi | |
| 216 | ||
| 217 | let result: Value mut = | |
| 218 | CAST( | |
| 219 | target_type, | |
| 220 | value | |
| 221 | ); | |
| 222 | ||
| 223 | if !value.type!.is_value_type /\ target_type.is_value_type then | |
| 224 | result = _conditionally_unbox(result, target_type); | |
| 225 | fi | |
| 226 | ||
| 227 | return result; | |
| 228 | si | |
| 229 | ||
| 230 | // Public so compile_expressions can exclude a cast covered by a | |
| 231 | // user-defined conversion from the impossible-cast warning. | |
| 232 | find_user_defined_conversion(source_type: Type, target_type: Type) -> Symbols.Function? => | |
| 233 | _conversion_lookup.find(source_type, target_type); | |
| 234 | ||
| 235 | _build_conversion_call(value: Value, function: Symbols.Function, target_type: Type) -> Value is | |
| 236 | let arguments = Collections.LIST[Value](); | |
| 237 | arguments.add(value); | |
| 238 | ||
| 239 | let call: Value = | |
| 240 | Call.STATIC( | |
| 241 | function, | |
| 242 | _value_boxer.box_arguments(arguments, function.arguments), | |
| 243 | function.return_type, | |
| 244 | null | |
| 245 | ); | |
| 246 | ||
| 247 | if !target_type.is_optional then | |
| 248 | return call; | |
| 249 | fi | |
| 250 | ||
| 251 | return _guard_against_conversion_failure(call, target_type); | |
| 252 | si | |
| 253 | ||
| 254 | // A user-defined conversion is arbitrary code and can throw; | |
| 255 | // `cast T?(...)` promises never to, for the two failure kinds | |
| 256 | // the C# conversion-operator guidelines specify. Any other | |
| 257 | // exception is a bug and propagates. | |
| 258 | _guard_against_conversion_failure(call: Value, target_type: Type) -> Value is | |
| 259 | let block = _block_context.enter_block(target_type); | |
| 260 | let brancher = _brancher.get_for(block); | |
| 261 | ||
| 262 | let result = TEMP(block, "user_convert", target_type); | |
| 263 | ||
| 264 | let done = IR.LABEL(); | |
| 265 | ||
| 266 | block.add(".try {{"); | |
| 267 | result.store(_value_boxer.box_if_needed(call, target_type)); | |
| 268 | brancher.leave(done); | |
| 269 | block.add("}}"); | |
| 270 | ||
| 271 | block.add("catch class ['System.Runtime']System.InvalidCastException {{"); | |
| 272 | block.add("pop"); | |
| 273 | result.store(IR.Values.DEFAULT(target_type)); | |
| 274 | brancher.leave(done); | |
| 275 | block.add("}}"); | |
| 276 | ||
| 277 | block.add("catch class ['System.Runtime']System.OverflowException {{"); | |
| 278 | block.add("pop"); | |
| 279 | result.store(IR.Values.DEFAULT(target_type)); | |
| 280 | brancher.leave(done); | |
| 281 | block.add("}}"); | |
| 282 | ||
| 283 | brancher.label(done); | |
| 284 | block.add(result.load()); | |
| 285 | ||
| 286 | _block_context.leave_block(); | |
| 287 | ||
| 288 | return block; | |
| 289 | si | |
| 290 | ||
| 291 | _conditionally_unbox( | |
| 292 | value: IR.Values.Value, | |
| 293 | target_type: Types.Type | |
| 294 | ) -> IR.Values.Value | |
| 295 | is | |
| 296 | // value is the result of a cast instruction ('isinsnt'). we now need | |
| 297 | // to check if the result is not null before we attempt to unbox, or | |
| 298 | // if the result is null, we return the value type's default value instead | |
| 299 | ||
| 300 | let block = _block_context.enter_block(target_type); | |
| 301 | let brancher = _brancher.get_for(block); | |
| 302 | ||
| 303 | let temp = TYPE_WRAPPER(_innate_symbol_lookup.get_object_type(), value).get_temp_copier(block, "cast"); | |
| 304 | ||
| 305 | let want_default_value = IR.LABEL(); | |
| 306 | let done = IR.LABEL(); | |
| 307 | ||
| 308 | // is the `isinst` result null? | |
| 309 | brancher.branch(BRANCH.Z, temp(), want_default_value); | |
| 310 | ||
| 311 | // `isinst` result is not null, so safe to unbox: | |
| 312 | block.add( | |
| 313 | UNBOX( | |
| 314 | TYPE_WRAPPER(target_type, temp()) | |
| 315 | ) | |
| 316 | ); | |
| 317 | ||
| 318 | brancher.branch(done); | |
| 319 | ||
| 320 | brancher.label(want_default_value); | |
| 321 | ||
| 322 | // 'isinst' result is null, so attempting unbox would throw | |
| 323 | // NullReferenceException. return default value instead: | |
| 324 | block.add(IR.Values.DEFAULT(target_type)); | |
| 325 | ||
| 326 | brancher.label(done); | |
| 327 | ||
| 328 | _block_context.leave_block(); | |
| 329 | ||
| 330 | return block; | |
| 331 | si | |
| 332 | si | |
| 333 | si |