Add fixture for double negation optimisation

Author: rkalis

packages/cashc/test/generation/fixtures.ts

@@ -2010,4 +2010,53 @@ export const fixtures: Fixture[] = [
       fingerprint: '3ab69a954ec4bf9ceeb58eceb8ead206195032edf6627155eb82f528403c94dd',
     },
   },
+  {
+    fn: 'double_negation.cash',
+    artifact: {
+      contractName: 'DoubleNegation',
+      constructorInputs: [{ name: 'flag', type: 'bool' }],
+      abi: [{ name: 'spend', inputs: [{ name: 'target', type: 'int' }] }],
+      bytecode:
+        // require(!!flag) - OP_NOT OP_NOT OP_VERIFY is optimised to OP_VERIFY
+        'OP_DUP OP_VERIFY '
+        // int i = 0; bool done = false;
+        + 'OP_0 OP_0 '
+        // do { i = i + 1;
+        + 'OP_BEGIN OP_OVER OP_1ADD OP_ROT OP_DROP OP_SWAP '
+        // done = i >= target;
+        + 'OP_OVER OP_4 OP_PICK OP_GREATERTHANOREQUAL OP_NIP '
+        // } while (!done) - OP_NOT OP_NOT OP_UNTIL is optimised to OP_UNTIL
+        + 'OP_DUP OP_UNTIL '
+        // if (!!flag) - OP_NOT OP_NOT OP_IF becomes OP_NOT OP_NOTIF, which is optimised to OP_IF
+        + 'OP_ROT OP_IF '
+        // require(i == target); }
+        + 'OP_OVER OP_3 OP_PICK OP_NUMEQUALVERIFY OP_ENDIF '
+        // require(i > 0)
+        + 'OP_SWAP OP_0 OP_GREATERTHAN '
+        // clean up i and done
+        + 'OP_NIP OP_NIP',
+      debug: {
+        bytecode: '7669000065788b7b757c785479a27776667b637853799d687c00a07777',
+        sourceMap: '4:18:4:22;:8::24:1;6:16:6:17:0;7:20:7:25;9:8:13:24;10:16:10:17;:::21:1;:12::22;;;11:19:11:20:0;:24::30;;:19:::1;:12::31;13:18:13:22:0;9:8::24:1;16:14:16:18:0;:12:18:9;17:20:17:21;:25::31;;:12::33:1;16:20:18:9;20:16:20:17:0;:20::21;:8::23:1;2:31:21:5;',
+        logs: [],
+        requires: [
+          { ip: 2, line: 4 },
+          { ip: 23, line: 17 },
+          { ip: 28, line: 20 },
+        ],
+        sourceTags: '27:28:sc',
+      },
+      source: fs.readFileSync(new URL('../valid-contract-files/double_negation.cash', import.meta.url), { encoding: 'utf-8' }),
+      compiler: {
+        name: 'cashc',
+        version,
+        options: {
+          enforceFunctionParameterTypes: true,
+          enforceLocktimeGuard: true,
+        },
+      },
+      updatedAt: '',
+      fingerprint: 'ed0b5bc35f0130fa04d1fce813fbd7c183bb5346006d10c0808f0d9872712ded',
+    },
+  },
 ];

packages/cashc/test/valid-contract-files/double_negation.cash

@@ -0,0 +1,22 @@
+contract DoubleNegation(bool flag) {
+    function spend(int target) {
+        // OP_NOT OP_NOT OP_VERIFY => OP_VERIFY
+        require(!!flag);
+
+        int i = 0;
+        bool done = false;
+
+        do {
+            i = i + 1;
+            done = i >= target;
+        // OP_NOT OP_NOT OP_UNTIL => OP_UNTIL
+        } while (!done);
+
+        // OP_NOT OP_NOT OP_IF => OP_NOT OP_NOTIF => OP_IF
+        if (!!flag) {
+            require(i == target);
+        }
+
+        require(i > 0);
+    }
+}