[wasm] Remove unused WasmCode* return

For implementing wasm GC we need to revisit all places where we hold
WasmCode*. This CL reduces these places.

R=mstarzinger@chromium.org

Bug: v8:8217
Change-Id: I869e3c1817a3b9a24ab6aa281c0688bdf890dd33
Reviewed-on: https://chromium-review.googlesource.com/c/1297951Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56942}

src/wasm/function-compiler.cc

@@ -135,7 +135,7 @@ void WasmCompilationUnit::SwitchMode(ExecutionTier new_mode) {
 }
 
 // static
-WasmCode* WasmCompilationUnit::CompileWasmFunction(
+bool WasmCompilationUnit::CompileWasmFunction(
     Isolate* isolate, NativeModule* native_module, WasmFeatures* detected,
     ErrorThrower* thrower, const WasmFunction* function, ExecutionTier mode) {
   ModuleWireBytes wire_bytes(native_module->wire_bytes());
@@ -149,9 +149,9 @@ WasmCode* WasmCompilationUnit::CompileWasmFunction(
   unit.ExecuteCompilation(&env, detected);
   if (unit.failed()) {
     unit.ReportError(thrower);
-    return nullptr;
+    return false;
   }
-  return unit.result();
+  return true;
 }
 
 void WasmCompilationUnit::SetResult(WasmCode* code) {

src/wasm/function-compiler.h

@@ -55,10 +55,10 @@ class WasmCompilationUnit final {
 
   void ReportError(ErrorThrower* thrower) const;
 
-  static WasmCode* CompileWasmFunction(
-      Isolate* isolate, NativeModule* native_module, WasmFeatures* detected,
-      ErrorThrower* thrower, const WasmFunction* function,
-      ExecutionTier = GetDefaultExecutionTier());
+  static bool CompileWasmFunction(Isolate* isolate, NativeModule* native_module,
+                                  WasmFeatures* detected, ErrorThrower* thrower,
+                                  const WasmFunction* function,
+                                  ExecutionTier = GetDefaultExecutionTier());
 
  private:
   friend class LiftoffCompilationUnit;

src/wasm/module-compiler.cc

@@ -652,9 +652,9 @@ void CompileSequentially(Isolate* isolate, NativeModule* native_module,
     if (func.imported) continue;  // Imports are compiled at instantiation time.
 
     // Compile the function.
-    WasmCode* code = WasmCompilationUnit::CompileWasmFunction(
+    bool success = WasmCompilationUnit::CompileWasmFunction(
         isolate, native_module, &detected, thrower, &func);
-    if (code == nullptr) {
+    if (!success) {
       TruncatedUserString<> name(wire_bytes.GetNameOrNull(&func, module));
       thrower->CompileError("Compilation of #%d:%.*s failed.", i, name.length(),
                             name.start());

src/wasm/wasm-engine.cc

@@ -176,10 +176,9 @@ bool WasmEngine::CompileFunction(Isolate* isolate, NativeModule* native_module,
   ErrorThrower thrower(isolate, "Manually requested tier up");
   // Note we assume that "one-off" compilations can discard detected features.
   WasmFeatures detected = kNoWasmFeatures;
-  WasmCode* ret = WasmCompilationUnit::CompileWasmFunction(
+  return WasmCompilationUnit::CompileWasmFunction(
       isolate, native_module, &detected, &thrower,
       &native_module->module()->functions[function_index], tier);
-  return ret != nullptr;
 }
 
 std::shared_ptr<NativeModule> WasmEngine::ExportNativeModule(