Remove unused Pass::prepareToRun (#3386)

Author: tlively

src/pass.h

@@ -268,10 +268,6 @@ class Pass {
 public:
   virtual ~Pass() = default;
 
-  // Override this to perform preparation work before the pass runs.
-  // This will be called before the pass is run on a module.
-  virtual void prepareToRun(PassRunner* runner, Module* module) {}
-
   // Implement this with code to run the pass on the whole module
   virtual void run(PassRunner* runner, Module* module) {
     WASM_UNREACHABLE("unimplemented");

src/passes/pass.cpp

@@ -670,7 +670,6 @@ void PassRunner::runOnFunction(Function* func) {
 }
 
 void PassRunner::doAdd(std::unique_ptr<Pass> pass) {
-  pass->prepareToRun(this, wasm);
   passes.emplace_back(std::move(pass));
 }
 

src/wasm-module-building.h

@@ -122,15 +122,6 @@ class OptimizingIncrementalModuleBuilder {
       return;
     }
 
-    // Before parallelism, create all passes on the main thread here, to ensure
-    // prepareToRun() is called for each pass before we start to optimize
-    // functions.
-    {
-      PassRunner passRunner(wasm, passOptions);
-      addPrePasses(passRunner);
-      passRunner.addDefaultFunctionOptimizationPasses();
-    }
-
     // prepare work list
     endMarker = new Function();
     list = new std::atomic<Function*>[numFunctions];