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| 1 | namespace IR.Values is | |
| 2 | use System.Reflection.Metadata.ILOpCode | |
| 3 | use TypeTyped = Semantic.Types.Typed | |
| 4 | use Semantic.Types.Type | |
| 5 | ||
| 6 | class COMPARE_ORDER_TO_ZERO: Value, TypeTyped is | |
| 7 | value: Value | |
| 8 | actual_operation: string? | |
| 9 | type: Type | |
| 10 | ||
| 11 | is_value_type: bool => true | |
| 12 | ||
| 13 | init(value: Value, actual_operation: string?, type: Type) is | |
| 14 | super.init() | |
| 15 | ||
| 16 | self.value = value | |
| 17 | self.actual_operation = actual_operation | |
| 18 | self.type = type | |
| 19 | si | |
| 20 | ||
| 21 | // How the operator maps onto a comparison against zero: which | |
| 22 | // comparison to make, and whether its answer has to be flipped. | |
| 23 | // `>=` is `!(x < 0)` and `<=` is `!(x > 0)`, there being no | |
| 24 | // negated comparison instruction to reach for instead. `==` | |
| 25 | // reads an order value as an equality test - used by `case` | |
| 26 | // when it falls back to a scrutinee's `<>` in place of a | |
| 27 | // missing `=~` (see CASE_MATCH_OPERAND_RESOLVER). | |
| 28 | lowering: (op_code: ILOpCode, negates: bool) => | |
| 29 | if actual_operation =~ ">" then | |
| 30 | (ILOpCode.CGT, false) | |
| 31 | elif actual_operation =~ ">=" then | |
| 32 | (ILOpCode.CLT, true) | |
| 33 | elif actual_operation =~ "<" then | |
| 34 | (ILOpCode.CLT, false) | |
| 35 | elif actual_operation =~ "<=" then | |
| 36 | (ILOpCode.CGT, true) | |
| 37 | elif actual_operation =~ "==" then | |
| 38 | (ILOpCode.CEQ, false) | |
| 39 | else | |
| 40 | throw System.Exception("unexpected compare order operation: {actual_operation}") | |
| 41 | fi | |
| 42 | ||
| 43 | gen(context: IR.CONTEXT) is | |
| 44 | let (op_code, negates) = lowering | |
| 45 | ||
| 46 | Value.gen(value, context) | |
| 47 | ||
| 48 | let body = context.current_srm_body_emitter! | |
| 49 | ||
| 50 | body.ldc_i4(0) | |
| 51 | body.op(op_code) | |
| 52 | ||
| 53 | if negates then | |
| 54 | body.ldc_i4(0) | |
| 55 | body.op(ILOpCode.CEQ) | |
| 56 | fi | |
| 57 | si | |
| 58 | ||
| 59 | to_string() -> string => | |
| 60 | "compare-order-to-zero[{actual_operation}]({value})" | |
| 61 | si | |
| 62 | si |