[OPENMP]Target region: emit const firstprivates as globals with constant

memory.

If the variable with the constant non-scalar type is firstprivatized in
the target region, the local copy is created with the data copying.
Instead, we allocate the copy in the constant memory and avoid extra
copying in the outlined target regions. This global copy is used in the
target regions without loss of the performance.

llvm-svn: 355418

1 files changed, 62 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index 49ba14c8136..64fdefd9a6f 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -2945,9 +2945,8 @@ Address CGOpenMPRuntime::emitThreadIDAddress(CodeGenFunction &CGF,
   return ThreadIDTemp;
 }
 
-llvm::Constant *
-CGOpenMPRuntime::getOrCreateInternalVariable(llvm::Type *Ty,
-                                             const llvm::Twine &Name) {
+llvm::Constant *CGOpenMPRuntime::getOrCreateInternalVariable(
+    llvm::Type *Ty, const llvm::Twine &Name, unsigned AddressSpace) {
   SmallString<256> Buffer;
   llvm::raw_svector_ostream Out(Buffer);
   Out << Name;
@@ -2962,7 +2961,8 @@ CGOpenMPRuntime::getOrCreateInternalVariable(llvm::Type *Ty,
   return Elem.second = new llvm::GlobalVariable(
              CGM.getModule(), Ty, /*IsConstant*/ false,
              llvm::GlobalValue::CommonLinkage, llvm::Constant::getNullValue(Ty),
-             Elem.first());
+             Elem.first(), /*InsertBefore=*/nullptr,
+             llvm::GlobalValue::NotThreadLocal, AddressSpace);
 }
 
 llvm::Value *CGOpenMPRuntime::getCriticalRegionLock(StringRef CriticalName) {
@@ -7285,9 +7285,14 @@ private:
     // A first private variable captured by reference will use only the
     // 'private ptr' and 'map to' flag. Return the right flags if the captured
     // declaration is known as first-private in this handler.
-    if (FirstPrivateDecls.count(Cap.getCapturedVar()))
+    if (FirstPrivateDecls.count(Cap.getCapturedVar())) {
+      if (Cap.getCapturedVar()->getType().isConstant(CGF.getContext()) &&
+          Cap.getCaptureKind() == CapturedStmt::VCK_ByRef)
+        return MappableExprsHandler::OMP_MAP_ALWAYS |
+               MappableExprsHandler::OMP_MAP_TO;
       return MappableExprsHandler::OMP_MAP_PRIVATE |
              MappableExprsHandler::OMP_MAP_TO;
+    }
     return MappableExprsHandler::OMP_MAP_TO |
            MappableExprsHandler::OMP_MAP_FROM;
   }
@@ -7914,9 +7919,6 @@ public:
       }
     } else {
       assert(CI.capturesVariable() && "Expected captured reference.");
-      CurBasePointers.push_back(CV);
-      CurPointers.push_back(CV);
-
       const auto *PtrTy = cast<ReferenceType>(RI.getType().getTypePtr());
       QualType ElementType = PtrTy->getPointeeType();
       CurSizes.push_back(CGF.getTypeSize(ElementType));
@@ -7924,6 +7926,24 @@ public:
       // default the value doesn't have to be retrieved. For an aggregate
       // type, the default is 'tofrom'.
       CurMapTypes.push_back(getMapModifiersForPrivateClauses(CI));
+      const VarDecl *VD = CI.getCapturedVar();
+      if (FirstPrivateDecls.count(VD) &&
+          VD->getType().isConstant(CGF.getContext())) {
+        llvm::Constant *Addr =
+            CGF.CGM.getOpenMPRuntime().registerTargetFirstprivateCopy(CGF, VD);
+        // Copy the value of the original variable to the new global copy.
+        CGF.Builder.CreateMemCpy(
+            CGF.MakeNaturalAlignAddrLValue(Addr, ElementType).getAddress(),
+            Address(CV, CGF.getContext().getTypeAlignInChars(ElementType)),
+            CurSizes.back(),
+            /*isVolatile=*/false);
+        // Use new global variable as the base pointers.
+        CurBasePointers.push_back(Addr);
+        CurPointers.push_back(Addr);
+      } else {
+        CurBasePointers.push_back(CV);
+        CurPointers.push_back(CV);
+      }
     }
     // Every default map produces a single argument which is a target parameter.
     CurMapTypes.back() |= OMP_MAP_TARGET_PARAM;
@@ -8725,6 +8745,40 @@ bool CGOpenMPRuntime::emitTargetGlobalVariable(GlobalDecl GD) {
   return false;
 }
 
+llvm::Constant *
+CGOpenMPRuntime::registerTargetFirstprivateCopy(CodeGenFunction &CGF,
+                                                const VarDecl *VD) {
+  assert(VD->getType().isConstant(CGM.getContext()) &&
+         "Expected constant variable.");
+  StringRef VarName;
+  llvm::Constant *Addr;
+  llvm::GlobalValue::LinkageTypes Linkage;
+  QualType Ty = VD->getType();
+  SmallString<128> Buffer;
+  {
+    unsigned DeviceID;
+    unsigned FileID;
+    unsigned Line;
+    getTargetEntryUniqueInfo(CGM.getContext(), VD->getLocation(), DeviceID,
+                             FileID, Line);
+    llvm::raw_svector_ostream OS(Buffer);
+    OS << "__omp_offloading_firstprivate_" << llvm::format("_%x", DeviceID)
+       << llvm::format("_%x_", FileID) << VD->getName() << "_l" << Line;
+    VarName = OS.str();
+  }
+  Linkage = llvm::GlobalValue::InternalLinkage;
+  Addr =
+      getOrCreateInternalVariable(CGM.getTypes().ConvertTypeForMem(Ty), VarName,
+                                  getDefaultFirstprivateAddressSpace());
+  cast<llvm::GlobalValue>(Addr)->setLinkage(Linkage);
+  CharUnits VarSize = CGM.getContext().getTypeSizeInChars(Ty);
+  CGM.addCompilerUsedGlobal(cast<llvm::GlobalValue>(Addr));
+  OffloadEntriesInfoManager.registerDeviceGlobalVarEntryInfo(
+      VarName, Addr, VarSize,
+      OffloadEntriesInfoManagerTy::OMPTargetGlobalVarEntryTo, Linkage);
+  return Addr;
+}
+
 void CGOpenMPRuntime::registerTargetGlobalVariable(const VarDecl *VD,
                                                    llvm::Constant *Addr) {
   llvm::Optional<OMPDeclareTargetDeclAttr::MapTypeTy> Res =