[OpenMP] Fix declare target link implementation

Summary:
This patch fixes the case where variables in different compilation units or the same compilation unit are under the declare target link clause AND have the same name.
This also fixes the name clash error that occurs when unified memory is activated.
The changes in this patch include:
- Pointers to internal variables are given unique names.
- Externally visible variables are given the same name as before.
- All pointer variables (external or internal) are weakly linked.

Reviewers: ABataev, jdoerfert, caomhin

Reviewed By: ABataev

Subscribers: lebedev.ri, guansong, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64592

llvm-svn: 367613

1 files changed, 40 insertions, 32 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index 27e7175da84..2674e3a229e 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -2552,6 +2552,32 @@ CGOpenMPRuntime::createDispatchNextFunction(unsigned IVSize, bool IVSigned) {
   return CGM.CreateRuntimeFunction(FnTy, Name);
 }
 
+/// Obtain information that uniquely identifies a target entry. This
+/// consists of the file and device IDs as well as line number associated with
+/// the relevant entry source location.
+static void getTargetEntryUniqueInfo(ASTContext &C, SourceLocation Loc,
+                                     unsigned &DeviceID, unsigned &FileID,
+                                     unsigned &LineNum) {
+  SourceManager &SM = C.getSourceManager();
+
+  // The loc should be always valid and have a file ID (the user cannot use
+  // #pragma directives in macros)
+
+  assert(Loc.isValid() && "Source location is expected to be always valid.");
+
+  PresumedLoc PLoc = SM.getPresumedLoc(Loc);
+  assert(PLoc.isValid() && "Source location is expected to be always valid.");
+
+  llvm::sys::fs::UniqueID ID;
+  if (auto EC = llvm::sys::fs::getUniqueID(PLoc.getFilename(), ID))
+    SM.getDiagnostics().Report(diag::err_cannot_open_file)
+        << PLoc.getFilename() << EC.message();
+
+  DeviceID = ID.getDevice();
+  FileID = ID.getFile();
+  LineNum = PLoc.getLine();
+}
+
 Address CGOpenMPRuntime::getAddrOfDeclareTargetVar(const VarDecl *VD) {
   if (CGM.getLangOpts().OpenMPSimd)
     return Address::invalid();
@@ -2563,19 +2589,27 @@ Address CGOpenMPRuntime::getAddrOfDeclareTargetVar(const VarDecl *VD) {
     SmallString<64> PtrName;
     {
       llvm::raw_svector_ostream OS(PtrName);
-      OS << CGM.getMangledName(GlobalDecl(VD)) << "_decl_tgt_ref_ptr";
+      OS << CGM.getMangledName(GlobalDecl(VD));
+      if (!VD->isExternallyVisible()) {
+        unsigned DeviceID, FileID, Line;
+        getTargetEntryUniqueInfo(CGM.getContext(),
+                                 VD->getCanonicalDecl()->getBeginLoc(),
+                                 DeviceID, FileID, Line);
+        OS << llvm::format("_%x", FileID);
+      }
+      OS << "_decl_tgt_ref_ptr";
     }
     llvm::Value *Ptr = CGM.getModule().getNamedValue(PtrName);
     if (!Ptr) {
       QualType PtrTy = CGM.getContext().getPointerType(VD->getType());
       Ptr = getOrCreateInternalVariable(CGM.getTypes().ConvertTypeForMem(PtrTy),
                                         PtrName);
-      if (!CGM.getLangOpts().OpenMPIsDevice) {
-        auto *GV = cast<llvm::GlobalVariable>(Ptr);
-        GV->setLinkage(llvm::GlobalValue::ExternalLinkage);
+
+      auto *GV = cast<llvm::GlobalVariable>(Ptr);
+      GV->setLinkage(llvm::GlobalValue::WeakAnyLinkage);
+
+      if (!CGM.getLangOpts().OpenMPIsDevice)
         GV->setInitializer(CGM.GetAddrOfGlobal(VD));
-      }
-      CGM.addUsedGlobal(cast<llvm::GlobalValue>(Ptr));
       registerTargetGlobalVariable(VD, cast<llvm::Constant>(Ptr));
     }
     return Address(Ptr, CGM.getContext().getDeclAlign(VD));
@@ -2749,32 +2783,6 @@ llvm::Function *CGOpenMPRuntime::emitThreadPrivateVarDefinition(
   return nullptr;
 }
 
-/// Obtain information that uniquely identifies a target entry. This
-/// consists of the file and device IDs as well as line number associated with
-/// the relevant entry source location.
-static void getTargetEntryUniqueInfo(ASTContext &C, SourceLocation Loc,
-                                     unsigned &DeviceID, unsigned &FileID,
-                                     unsigned &LineNum) {
-  SourceManager &SM = C.getSourceManager();
-
-  // The loc should be always valid and have a file ID (the user cannot use
-  // #pragma directives in macros)
-
-  assert(Loc.isValid() && "Source location is expected to be always valid.");
-
-  PresumedLoc PLoc = SM.getPresumedLoc(Loc);
-  assert(PLoc.isValid() && "Source location is expected to be always valid.");
-
-  llvm::sys::fs::UniqueID ID;
-  if (auto EC = llvm::sys::fs::getUniqueID(PLoc.getFilename(), ID))
-    SM.getDiagnostics().Report(diag::err_cannot_open_file)
-        << PLoc.getFilename() << EC.message();
-
-  DeviceID = ID.getDevice();
-  FileID = ID.getFile();
-  LineNum = PLoc.getLine();
-}
-
 bool CGOpenMPRuntime::emitDeclareTargetVarDefinition(const VarDecl *VD,
                                                      llvm::GlobalVariable *Addr,
                                                      bool PerformInit) {