[OpenMP] Add OpenMP data sharing infrastructure using global memory

Summary:
This patch handles the Clang code generation phase for the OpenMP data sharing infrastructure.

TODO: add a more detailed description.

Reviewers: ABataev, carlo.bertolli, caomhin, hfinkel, Hahnfeld

Reviewed By: ABataev

Subscribers: jholewinski, guansong, cfe-commits

Differential Revision: https://reviews.llvm.org/D43660

llvm-svn: 327513

clang/lib/CodeGen/CGDecl.cpp

@@ -1068,9 +1068,17 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
     }
 
     // A normal fixed sized variable becomes an alloca in the entry block,
-    // unless it's an NRVO variable.
-
-    if (NRVO) {
+    // unless:
+    // - it's an NRVO variable.
+    // - we are compiling OpenMP and it's an OpenMP local variable.
+
+    Address OpenMPLocalAddr =
+        getLangOpts().OpenMP
+            ? CGM.getOpenMPRuntime().getAddressOfLocalVariable(*this, &D)
+            : Address::invalid();
+    if (getLangOpts().OpenMP && OpenMPLocalAddr.isValid()) {
+      address = OpenMPLocalAddr;
+    } else if (NRVO) {
       // The named return value optimization: allocate this variable in the
       // return slot, so that we can elide the copy when returning this
       // variable (C++0x [class.copy]p34).
@@ -1896,9 +1904,18 @@ void CodeGenFunction::EmitParmDecl(const VarDecl &D, ParamValue Arg,
       }
     }
   } else {
-    // Otherwise, create a temporary to hold the value.
-    DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D),
-                            D.getName() + ".addr");
+    // Check if the parameter address is controlled by OpenMP runtime.
+    Address OpenMPLocalAddr =
+        getLangOpts().OpenMP
+            ? CGM.getOpenMPRuntime().getAddressOfLocalVariable(*this, &D)
+            : Address::invalid();
+    if (getLangOpts().OpenMP && OpenMPLocalAddr.isValid()) {
+      DeclPtr = OpenMPLocalAddr;
+    } else {
+      // Otherwise, create a temporary to hold the value.
+      DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D),
+                              D.getName() + ".addr");
+    }
     DoStore = true;
   }
 

clang/lib/CodeGen/CGOpenMPRuntime.cpp

@@ -8100,6 +8100,11 @@ Address CGOpenMPRuntime::getParameterAddress(CodeGenFunction &CGF,
   return CGF.GetAddrOfLocalVar(NativeParam);
 }
 
+Address CGOpenMPRuntime::getAddressOfLocalVariable(CodeGenFunction &CGF,
+                                                   const VarDecl *VD) {
+  return Address::invalid();
+}
+
 llvm::Value *CGOpenMPSIMDRuntime::emitParallelOutlinedFunction(
     const OMPExecutableDirective &D, const VarDecl *ThreadIDVar,
     OpenMPDirectiveKind InnermostKind, const RegionCodeGenTy &CodeGen) {

clang/lib/CodeGen/CGOpenMPRuntime.h

@@ -676,7 +676,7 @@ class CGOpenMPRuntime {
 
   /// \brief Cleans up references to the objects in finished function.
   ///
-  void functionFinished(CodeGenFunction &CGF);
+  virtual void functionFinished(CodeGenFunction &CGF);
 
   /// \brief Emits code for parallel or serial call of the \a OutlinedFn with
   /// variables captured in a record which address is stored in \a
@@ -1362,6 +1362,14 @@ class CGOpenMPRuntime {
   emitOutlinedFunctionCall(CodeGenFunction &CGF, SourceLocation Loc,
                            llvm::Value *OutlinedFn,
                            ArrayRef<llvm::Value *> Args = llvm::None) const;
+
+  /// Emits OpenMP-specific function prolog.
+  /// Required for device constructs.
+  virtual void emitFunctionProlog(CodeGenFunction &CGF, const Decl *D) {}
+
+  /// Gets the OpenMP-specific address of the local variable.
+  virtual Address getAddressOfLocalVariable(CodeGenFunction &CGF,
+                                            const VarDecl *VD);
 };
 
 /// Class supports emissionof SIMD-only code.