[llvm] Set the name of the LLVM function of the real function to its …

…name (#6495)

Issue: #602

### Brief Summary

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

taichi/codegen/llvm/codegen_llvm.cpp

@@ -22,15 +22,16 @@ namespace taichi::lang {
 // TODO(k-ye): Hide FunctionCreationGuard inside cpp file
 FunctionCreationGuard::FunctionCreationGuard(
     TaskCodeGenLLVM *mb,
-    std::vector<llvm::Type *> arguments)
+    std::vector<llvm::Type *> arguments,
+    const std::string &func_name)
     : mb(mb) {
   // Create the loop body function
   auto body_function_type = llvm::FunctionType::get(
       llvm::Type::getVoidTy(*mb->llvm_context), arguments, false);
 
   body = llvm::Function::Create(body_function_type,
-                                llvm::Function::InternalLinkage,
-                                "function_body", mb->module.get());
+                                llvm::Function::InternalLinkage, func_name,
+                                mb->module.get());
   old_func = mb->func;
   // emit into loop body function
   mb->func = body;
@@ -2668,8 +2669,9 @@ void TaskCodeGenLLVM::eliminate_unused_functions() {
 }
 
 FunctionCreationGuard TaskCodeGenLLVM::get_function_creation_guard(
-    std::vector<llvm::Type *> argument_types) {
-  return FunctionCreationGuard(this, argument_types);
+    std::vector<llvm::Type *> argument_types,
+    const std::string &func_name) {
+  return FunctionCreationGuard(this, argument_types, func_name);
 }
 
 void TaskCodeGenLLVM::initialize_context() {
@@ -2804,7 +2806,8 @@ void TaskCodeGenLLVM::visit(ReferenceStmt *stmt) {
 void TaskCodeGenLLVM::visit(FuncCallStmt *stmt) {
   if (!func_map.count(stmt->func)) {
     auto guard = get_function_creation_guard(
-        {llvm::PointerType::get(get_runtime_type("RuntimeContext"), 0)});
+        {llvm::PointerType::get(get_runtime_type("RuntimeContext"), 0)},
+        stmt->func->get_name());
     func_map.insert({stmt->func, guard.body});
     stmt->func->ir->accept(this);
   }

taichi/codegen/llvm/codegen_llvm.h

@@ -25,7 +25,8 @@ class FunctionCreationGuard {
   llvm::IRBuilder<>::InsertPoint ip;
 
   FunctionCreationGuard(TaskCodeGenLLVM *mb,
-                        std::vector<llvm::Type *> arguments);
+                        std::vector<llvm::Type *> arguments,
+                        const std::string &func_name);
 
   ~FunctionCreationGuard();
 };
@@ -316,7 +317,8 @@ class TaskCodeGenLLVM : public IRVisitor, public LLVMModuleBuilder {
   void finalize_offloaded_task_function();
 
   FunctionCreationGuard get_function_creation_guard(
-      std::vector<llvm::Type *> argument_types);
+      std::vector<llvm::Type *> argument_types,
+      const std::string &func_name = "function_body");
 
   std::tuple<llvm::Value *, llvm::Value *> get_range_for_bounds(
       OffloadedStmt *stmt);