OpenMP: Add helper function for convergent runtime calls

[arsenm]

Summary

Most of the functions emitted here should probably be convergent, but
only barriers are currently marked. Introduce this helper before
adding convergent to more functions.

[JonChesterfield]

LGTM.

[ABataev]

Tests?

clang/lib/CodeGen/CodeGenModule.h

1040

Add a comment with the name of parameter for true argument.

[arsenm]

Add comments

[arsenm]

In D69494#1722853, @ABataev wrote:

Tests?

In D69494#1722853, @ABataev wrote:

Tests?

This is NFC and doesn't change any behavior. The test for the convergent attribute is already handled in nvptx_parallel_codegen.cpp

[ABataev]

In D69494#1722867, @arsenm wrote:

In D69494#1722853, @ABataev wrote:

Tests?

In D69494#1722853, @ABataev wrote:

Tests?

This is NFC and doesn't change any behavior. The test for the convergent attribute is already handled in nvptx_parallel_codegen.cpp

Nope, you're narking some calls withe the new attribute. It is not NFC in this case.

[arsenm]

In D69494#1722868, @ABataev wrote:

In D69494#1722867, @arsenm wrote:

In D69494#1722853, @ABataev wrote:

Tests?

In D69494#1722853, @ABataev wrote:

Tests?

This is NFC and doesn't change any behavior. The test for the convergent attribute is already handled in nvptx_parallel_codegen.cpp

Nope, you're narking some calls withe the new attribute. It is not NFC in this case.

More precisely, this is marking the function declarations with the attribute. These were already marked with the attribute. This just moves it into the helper function. D69495 adds new instances of the attribute

[ABataev]

Ah, yes, missed this. Then just add a comment.

[arsenm]

r40ab8ae9fb70f1550815bf0f867148b5101a4f66

clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp

RTLFn =
         CGM.CreateRuntimeFunction(FnTy, "__kmpc_restore_team_static_memory");
     break;
   }
   case OMPRTL__kmpc_barrier: {
     // Build void __kmpc_barrier(ident_t *loc, kmp_int32 global_tid);
     llvm::Type *TypeParams[] = {getIdentTyPointerTy(), CGM.Int32Ty};
     auto *FnTy =
         llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
-    RTLFn = CGM.CreateRuntimeFunction(FnTy, /*Name*/ "__kmpc_barrier");
-    cast<llvm::Function>(RTLFn.getCallee())
-        ->addFnAttr(llvm::Attribute::Convergent);
+    RTLFn =
+        CGM.CreateConvergentRuntimeFunction(FnTy, /*Name*/ "__kmpc_barrier");
     break;
   }
   case OMPRTL__kmpc_barrier_simple_spmd: {
     // Build void __kmpc_barrier_simple_spmd(ident_t *loc, kmp_int32
     // global_tid);
     llvm::Type *TypeParams[] = {getIdentTyPointerTy(), CGM.Int32Ty};
     auto *FnTy =
         llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
-    RTLFn =
-        CGM.CreateRuntimeFunction(FnTy, /*Name*/ "__kmpc_barrier_simple_spmd");
-    cast<llvm::Function>(RTLFn.getCallee())
-        ->addFnAttr(llvm::Attribute::Convergent);
+    RTLFn = CGM.CreateConvergentRuntimeFunction(
+        FnTy, /*Name*/ "__kmpc_barrier_simple_spmd");
     break;
   }
   case OMPRTL_NVPTX__kmpc_warp_active_thread_mask: {
     // Build int32_t __kmpc_warp_active_thread_mask(void);
     auto *FnTy =
         llvm::FunctionType::get(CGM.Int32Ty, llvm::None, /*isVarArg=*/false);
     RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_warp_active_thread_mask");
     break;

clang/lib/CodeGen/CodeGenModule.h

public:
 
   /// Add a destructor and object to add to the C++ global destructor function.
   void AddCXXDtorEntry(llvm::FunctionCallee DtorFn, llvm::Constant *Object) {
     CXXGlobalDtors.emplace_back(DtorFn.getFunctionType(), DtorFn.getCallee(),
                                 Object);
   }
 
   /// Create or return a runtime function declaration with the specified type
-  /// and name.
+  /// and name. If \p AssumeConvergent is true, the call will have the
+  /// convergent attribute added.
   llvm::FunctionCallee
   CreateRuntimeFunction(llvm::FunctionType *Ty, StringRef Name,
                         llvm::AttributeList ExtraAttrs = llvm::AttributeList(),
-                        bool Local = false);
+                        bool Local = false, bool AssumeConvergent = false);
+
+  /// Create or return a runtime function declaration with the specified type
+  /// and name. This will automatically add the convergent attribute to the
+  /// function declaration.
+  llvm::FunctionCallee CreateConvergentRuntimeFunction(
+      llvm::FunctionType *Ty, StringRef Name,
+      llvm::AttributeList ExtraAttrs = llvm::AttributeList(),
+      bool Local = false) {
+    return CreateRuntimeFunction(Ty, Name, ExtraAttrs, Local, true);
+  }
 
   /// Create a new runtime global variable with the specified type and name.
   llvm::Constant *CreateRuntimeVariable(llvm::Type *Ty,
                                         StringRef Name);
 
   ///@name Custom Blocks Runtime Interfaces
   ///@{
 

clang/lib/CodeGen/CodeGenModule.cpp

GetRuntimeFunctionDecl(ASTContext &C, StringRef Name) {
 
   return nullptr;
 }
 
 /// CreateRuntimeFunction - Create a new runtime function with the specified
 /// type and name.
 llvm::FunctionCallee
 CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy, StringRef Name,
-                                     llvm::AttributeList ExtraAttrs,
-                                     bool Local) {
+                                     llvm::AttributeList ExtraAttrs, bool Local,
+                                     bool AssumeConvergent) {
+  if (AssumeConvergent) {
+    ExtraAttrs =
+        ExtraAttrs.addAttribute(VMContext, llvm::AttributeList::FunctionIndex,
+                                llvm::Attribute::Convergent);
+  }
+
   llvm::Constant *C =
       GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(), /*ForVTable=*/false,
                               /*DontDefer=*/false, /*IsThunk=*/false,
                               ExtraAttrs);
 
   if (auto *F = dyn_cast<llvm::Function>(C)) {
     if (F->empty()) {
       F->setCallingConv(getRuntimeCC());