SaveState: Only rehash functions in code a load changed

Every load hashed all known functions again, for the replacement hooks:
2.4-6 ms, about half the load. Functions in module code the load left as
it was keep their hash, so only the rest is hashed now (0.5-1 ms). The
code is compared on every load for this, not only with a JIT.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/HLE/sceKernelModule.cpp

@@ -534,6 +534,13 @@ static void __KernelModuleInit() {
 	eventModuleLoadDone = CoreTiming::RegisterEvent("LoadModuleDone", &__KernelLoadModuleDone);
 }
 
+// Set for the next load by the savestate code: code the load left as it was.
+static std::vector<std::pair<u32, u32>> g_unchangedCodeOnLoad;
+
+void __KernelModuleSetUnchangedCodeOnLoad(std::vector<std::pair<u32, u32>> unchanged) {
+	g_unchangedCodeOnLoad = std::move(unchanged);
+}
+
 std::vector<std::pair<u32, u32>> __KernelModuleCodeRanges() {
 	std::vector<std::pair<u32, u32>> ranges;
 	u32 error;
@@ -615,7 +622,9 @@ void __KernelModuleDoState(PointerWrap &p) {
 		}
 		// The functions were found in memory from before the load, where other code may have been
 		// (an overlay module, say.) Hash them from what's there now, so a hook only goes where it matches.
-		MIPSAnalyst::RehashFunctions();
+		// Only what the load may have changed: hashing it all again takes milliseconds.
+		MIPSAnalyst::RehashFunctions(g_unchangedCodeOnLoad);
+		g_unchangedCodeOnLoad.clear();
 		if (g_Config.bFuncReplacements) {
 			MIPSAnalyst::ReplaceFunctions();
 		}