[OpenMP 5.0] Codegen support for user-defined mappers.

This patch implements the code generation for OpenMP 5.0 declare mapper
(user-defined mapper) constructs. For each declare mapper, a mapper
function is generated. These mapper functions will be called by the
runtime and/or other mapper functions to achieve user defined mapping.

The design slides can be found at
https://github.com/lingda-li/public-sharing/blob/master/mapper_runtime_design.pptx

Re-commit after revert in r367773 because r367755 changed the LLVM-IR
output such that a CHECK line failed.

Patch by Lingda Li <[email protected]>

Differential Revision: https://reviews.llvm.org/D59474

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@367905 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/GlobalDecl.h

@@ -59,6 +59,7 @@ class GlobalDecl {
   GlobalDecl(const CapturedDecl *D) { Init(D); }
   GlobalDecl(const ObjCMethodDecl *D) { Init(D); }
   GlobalDecl(const OMPDeclareReductionDecl *D) { Init(D); }
+  GlobalDecl(const OMPDeclareMapperDecl *D) { Init(D); }
   GlobalDecl(const CXXConstructorDecl *D, CXXCtorType Type) : Value(D, Type) {}
   GlobalDecl(const CXXDestructorDecl *D, CXXDtorType Type) : Value(D, Type) {}
   GlobalDecl(const VarDecl *D, DynamicInitKind StubKind)

lib/AST/ASTContext.cpp

@@ -9860,7 +9860,7 @@ bool ASTContext::DeclMustBeEmitted(const Decl *D) {
     return !D->getDeclContext()->isDependentContext();
   else if (isa<OMPAllocateDecl>(D))
     return !D->getDeclContext()->isDependentContext();
-  else if (isa<OMPDeclareReductionDecl>(D))
+  else if (isa<OMPDeclareReductionDecl>(D) || isa<OMPDeclareMapperDecl>(D))
     return !D->getDeclContext()->isDependentContext();
   else if (isa<ImportDecl>(D))
     return true;

lib/CodeGen/CGDecl.cpp

@@ -2530,10 +2530,11 @@ void CodeGenModule::EmitOMPDeclareReduction(const OMPDeclareReductionDecl *D,
 }
 
 void CodeGenModule::EmitOMPDeclareMapper(const OMPDeclareMapperDecl *D,
-                                            CodeGenFunction *CGF) {
-  if (!LangOpts.OpenMP || (!LangOpts.EmitAllDecls && !D->isUsed()))
+                                         CodeGenFunction *CGF) {
+  if (!LangOpts.OpenMP || LangOpts.OpenMPSimd ||
+      (!LangOpts.EmitAllDecls && !D->isUsed()))
     return;
-  // FIXME: need to implement mapper code generation
+  getOpenMPRuntime().emitUserDefinedMapper(D, CGF);
 }
 
 void CodeGenModule::EmitOMPRequiresDecl(const OMPRequiresDecl *D) {

lib/CodeGen/CGOpenMPRuntime.h

@@ -345,6 +345,14 @@ class CGOpenMPRuntime {
                          SmallVector<const OMPDeclareReductionDecl *, 4>>
       FunctionUDRMapTy;
   FunctionUDRMapTy FunctionUDRMap;
+  /// Map from the user-defined mapper declaration to its corresponding
+  /// functions.
+  llvm::DenseMap<const OMPDeclareMapperDecl *, llvm::Function *> UDMMap;
+  /// Map of functions and their local user-defined mappers.
+  using FunctionUDMMapTy =
+      llvm::DenseMap<llvm::Function *,
+                     SmallVector<const OMPDeclareMapperDecl *, 4>>;
+  FunctionUDMMapTy FunctionUDMMap;
   /// Type kmp_critical_name, originally defined as typedef kmp_int32
   /// kmp_critical_name[8];
   llvm::ArrayType *KmpCriticalNameTy;
@@ -738,6 +746,14 @@ class CGOpenMPRuntime {
                                 llvm::Value *Ctor, llvm::Value *CopyCtor,
                                 llvm::Value *Dtor, SourceLocation Loc);
 
+  /// Emit the array initialization or deletion portion for user-defined mapper
+  /// code generation.
+  void emitUDMapperArrayInitOrDel(CodeGenFunction &MapperCGF,
+                                  llvm::Value *Handle, llvm::Value *BasePtr,
+                                  llvm::Value *Ptr, llvm::Value *Size,
+                                  llvm::Value *MapType, CharUnits ElementSize,
+                                  llvm::BasicBlock *ExitBB, bool IsInit);
+
   struct TaskResultTy {
     llvm::Value *NewTask = nullptr;
     llvm::Function *TaskEntry = nullptr;
@@ -798,6 +814,10 @@ class CGOpenMPRuntime {
   virtual std::pair<llvm::Function *, llvm::Function *>
   getUserDefinedReduction(const OMPDeclareReductionDecl *D);
 
+  /// Emit the function for the user defined mapper construct.
+  void emitUserDefinedMapper(const OMPDeclareMapperDecl *D,
+                             CodeGenFunction *CGF = nullptr);
+
   /// Emits outlined function for the specified OpenMP parallel directive
   /// \a D. This outlined function has type void(*)(kmp_int32 *ThreadID,
   /// kmp_int32 BoundID, struct context_vars*).

lib/CodeGen/ModuleBuilder.cpp

@@ -232,6 +232,9 @@ namespace {
           if (auto *DRD = dyn_cast<OMPDeclareReductionDecl>(Member)) {
             if (Ctx->DeclMustBeEmitted(DRD))
               Builder->EmitGlobal(DRD);
+          } else if (auto *DMD = dyn_cast<OMPDeclareMapperDecl>(Member)) {
+            if (Ctx->DeclMustBeEmitted(DMD))
+              Builder->EmitGlobal(DMD);
           }
         }
       }