microptimize callFunc() by only calling getFunctionName() when necessary

even though getFunctionName() is fast it showed up in the profiler because it get's called very often,
but most of the time the actual value is not used.

src/runtime/objmodel.cpp

@@ -3232,9 +3232,10 @@ enum class KeywordDest {
     POSITIONAL,
     KWARGS,
 };
+template <typename FuncNameCB>
 static KeywordDest placeKeyword(const ParamNames* param_names, llvm::SmallVector<bool, 8>& params_filled,
                                 BoxedString* kw_name, Box* kw_val, Box*& oarg1, Box*& oarg2, Box*& oarg3, Box** oargs,
-                                BoxedDict* okwargs, const char* func_name) {
+                                BoxedDict* okwargs, FuncNameCB func_name_cb) {
     assert(kw_val);
     assert(gc::isValidGCObject(kw_val));
     assert(kw_name);
@@ -3243,7 +3244,7 @@ static KeywordDest placeKeyword(const ParamNames* param_names, llvm::SmallVector
     for (int j = 0; j < param_names->args.size(); j++) {
         if (param_names->args[j] == kw_name->s() && kw_name->size() > 0) {
             if (params_filled[j]) {
-                raiseExcHelper(TypeError, "%.200s() got multiple values for keyword argument '%s'", func_name,
+                raiseExcHelper(TypeError, "%.200s() got multiple values for keyword argument '%s'", func_name_cb(),
                                kw_name->c_str());
             }
 
@@ -3257,13 +3258,13 @@ static KeywordDest placeKeyword(const ParamNames* param_names, llvm::SmallVector
     if (okwargs) {
         Box*& v = okwargs->d[kw_name];
         if (v) {
-            raiseExcHelper(TypeError, "%.200s() got multiple values for keyword argument '%s'", func_name,
+            raiseExcHelper(TypeError, "%.200s() got multiple values for keyword argument '%s'", func_name_cb(),
                            kw_name->c_str());
         }
         v = kw_val;
         return KeywordDest::KWARGS;
     } else {
-        raiseExcHelper(TypeError, "%.200s() got an unexpected keyword argument '%s'", func_name, kw_name->c_str());
+        raiseExcHelper(TypeError, "%.200s() got an unexpected keyword argument '%s'", func_name_cb(), kw_name->c_str());
     }
 }
 
@@ -3305,10 +3306,11 @@ ArgPassSpec bindObjIntoArgs(Box* bind_obj, RewriterVar* r_bind_obj, _CallRewrite
     return ArgPassSpec(argspec.num_args + 1, argspec.num_keywords, argspec.has_starargs, argspec.has_kwargs);
 }
 
-void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_names, const char* func_name,
-                        Box** defaults, _CallRewriteArgsBase* rewrite_args, bool& rewrite_success, ArgPassSpec argspec,
-                        Box*& oarg1, Box*& oarg2, Box*& oarg3, Box** args, Box** oargs,
-                        const std::vector<BoxedString*>* keyword_names) {
+template <typename FuncNameCB>
+void rearrangeArgumentsInternal(ParamReceiveSpec paramspec, const ParamNames* param_names, FuncNameCB func_name_cb,
+                                Box** defaults, _CallRewriteArgsBase* rewrite_args, bool& rewrite_success,
+                                ArgPassSpec argspec, Box*& oarg1, Box*& oarg2, Box*& oarg3, Box** args, Box** oargs,
+                                const std::vector<BoxedString*>* keyword_names) {
     /*
      * Procedure:
      * - First match up positional arguments; any extra go to varargs.  error if too many.
@@ -3531,7 +3533,7 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
         Box* ovarargs = BoxedTuple::create(unused_positional.size(), unused_positional.data());
         getArg(varargs_idx, oarg1, oarg2, oarg3, oargs) = ovarargs;
     } else if (unused_positional.size()) {
-        raiseExcHelper(TypeError, "%s() takes at most %d argument%s (%ld given)", func_name, paramspec.num_args,
+        raiseExcHelper(TypeError, "%s() takes at most %d argument%s (%ld given)", func_name_cb(), paramspec.num_args,
                        (paramspec.num_args == 1 ? "" : "s"), argspec.num_args + argspec.num_keywords + varargs_size);
     }
 
@@ -3575,7 +3577,7 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
     };
 
     if ((!param_names || !param_names->takes_param_names) && argspec.num_keywords && !paramspec.takes_kwargs) {
-        raiseExcHelper(TypeError, "%s() doesn't take keyword arguments", func_name);
+        raiseExcHelper(TypeError, "%s() doesn't take keyword arguments", func_name_cb());
     }
 
     if (argspec.num_keywords) {
@@ -3595,7 +3597,7 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
             }
 
             auto dest = placeKeyword(param_names, params_filled, (*keyword_names)[i], kw_val, oarg1, oarg2, oarg3,
-                                     oargs, okwargs, func_name);
+                                     oargs, okwargs, func_name_cb);
             assert(!rewrite_args);
         }
     }
@@ -3622,27 +3624,28 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
             okwargs = get_okwargs();
 
             if (!okwargs && (!param_names || !param_names->takes_param_names))
-                raiseExcHelper(TypeError, "%s() doesn't take keyword arguments", func_name);
+                raiseExcHelper(TypeError, "%s() doesn't take keyword arguments", func_name_cb());
         }
 
         for (const auto& p : *d_kwargs) {
             auto k = coerceUnicodeToStr<CXX>(p.first);
 
             if (k->cls != str_cls)
-                raiseExcHelper(TypeError, "%s() keywords must be strings", func_name);
+                raiseExcHelper(TypeError, "%s() keywords must be strings", func_name_cb());
 
             BoxedString* s = static_cast<BoxedString*>(k);
 
             if (param_names && param_names->takes_param_names) {
                 assert(!rewrite_args && "would need to make sure that this didn't need to go into r_kwargs");
-                placeKeyword(param_names, params_filled, s, p.second, oarg1, oarg2, oarg3, oargs, okwargs, func_name);
+                placeKeyword(param_names, params_filled, s, p.second, oarg1, oarg2, oarg3, oargs, okwargs,
+                             func_name_cb);
             } else {
                 assert(!rewrite_args && "would need to make sure that this didn't need to go into r_kwargs");
                 assert(okwargs);
 
                 Box*& v = okwargs->d[p.first];
                 if (v) {
-                    raiseExcHelper(TypeError, "%s() got multiple values for keyword argument '%s'", func_name,
+                    raiseExcHelper(TypeError, "%s() got multiple values for keyword argument '%s'", func_name_cb(),
                                    s->data());
                 }
                 v = p.second;
@@ -3656,7 +3659,7 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
     for (int i = 0; i < paramspec.num_args - paramspec.num_defaults; i++) {
         if (params_filled[i])
             continue;
-        raiseExcHelper(TypeError, "%s() takes exactly %d arguments (%ld given)", func_name, paramspec.num_args,
+        raiseExcHelper(TypeError, "%s() takes exactly %d arguments (%ld given)", func_name_cb(), paramspec.num_args,
                        argspec.num_args + argspec.num_keywords + varargs_size);
     }
 
@@ -3686,6 +3689,15 @@ void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_name
     }
 }
 
+void rearrangeArguments(ParamReceiveSpec paramspec, const ParamNames* param_names, const char* func_name,
+                        Box** defaults, _CallRewriteArgsBase* rewrite_args, bool& rewrite_success, ArgPassSpec argspec,
+                        Box*& oarg1, Box*& oarg2, Box*& oarg3, Box** args, Box** oargs,
+                        const std::vector<BoxedString*>* keyword_names) {
+    auto func = [func_name]() { return func_name; };
+    return rearrangeArgumentsInternal(paramspec, param_names, func, defaults, rewrite_args, rewrite_success, argspec,
+                                      oarg1, oarg2, oarg3, args, oargs, keyword_names);
+}
+
 static StatCounter slowpath_callfunc("slowpath_callfunc");
 template <ExceptionStyle S>
 Box* callFunc(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2,
@@ -3727,9 +3739,10 @@ Box* callFunc(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args, ArgPassSpe
     }
 
     try {
-        rearrangeArguments(paramspec, &f->param_names, getFunctionName(f).data(),
-                           paramspec.num_defaults ? func->defaults->elts : NULL, rewrite_args, rewrite_success, argspec,
-                           arg1, arg2, arg3, args, oargs, keyword_names);
+        auto func_name_cb = [f]() { return getFunctionName(f).data(); };
+        rearrangeArgumentsInternal(paramspec, &f->param_names, func_name_cb,
+                                   paramspec.num_defaults ? func->defaults->elts : NULL, rewrite_args, rewrite_success,
+                                   argspec, arg1, arg2, arg3, args, oargs, keyword_names);
     } catch (ExcInfo e) {
         if (S == CAPI) {
             setCAPIException(e);