feat: optimize __tact_randomized and __tact_child_contract_codes

dev-docs/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Code generation
+
+- Optimized optional global variables initialization: PR [#3327](https://github.com/tact-lang/tact/pull/3327)
+
 ### Docs
 
 - Described off-chain calls and mention exit code 11 for getters: PR [#3314](https://github.com/tact-lang/tact/pull/3314)

src/benchmarks/wallet-v5/gas.json

@@ -149,6 +149,16 @@
         "internalTransfer": "5724",
         "extensionTransfer": "4656"
       }
+    },
+    {
+      "label": "1.6.13 with optimized optional globals",
+      "pr": "https://github.com/tact-lang/tact/pull/3327",
+      "gas": {
+        "externalTransfer": "4965",
+        "addExtension": "5628",
+        "internalTransfer": "5722",
+        "extensionTransfer": "4654"
+      }
     }
   ]
 }

src/generator/writeProgram.ts

@@ -16,6 +16,7 @@ import {
     writeSerializer,
 } from "@/generator/writers/writeSerialization";
 import { writeStdlib } from "@/generator/writers/writeStdlib";
+import { enabledOptimizedChildCode } from "@/config/features";
 import { writeAccessors } from "@/generator/writers/writeAccessors";
 import type { ContractABI } from "@ton/core";
 import { writeFunction } from "@/generator/writers/writeFunction";
@@ -116,8 +117,18 @@ export async function writeProgram(
         globalVariables.push("global slice __tact_context_sender;");
     }
 
-    globalVariables.push("global cell __tact_child_contract_codes;");
-    globalVariables.push("global int __tact_randomized;");
+    const needsChildCodes =
+        contract.dependsOn.length > 0 && !enabledOptimizedChildCode(ctx);
+    if (needsChildCodes) {
+        globalVariables.push("global cell __tact_child_contract_codes;");
+    }
+
+    const needsRandom = functions.some(
+        (f) => f.name === "__tact_prepare_random",
+    );
+    if (needsRandom) {
+        globalVariables.push("global int __tact_randomized;");
+    }
 
     if (contract.globalVariables.has("inMsg")) {
         globalVariables.push("global slice __tact_in_msg;");