[OPENMP] Codegen for 'firstprivate' clause.

This patch generates some helper variables that used as private copies of the corresponding original variables inside an OpenMP 'parallel' directive. These generated variables are initialized by copy using values of the original variables (with the copy constructor, if any). For arrays, initializator is generated for single element and in the codegen procedure this initial value is automatically propagated between all elements of the private copy.
In outlined function, references to original variables are replaced by the references to these private helper variables. At the end of the initialization of the private variables an implicit barier is generated by calling __kmpc_barrier(...) runtime function to be sure that all threads were initialized using original values of the variables.
Differential Revision: http://reviews.llvm.org/D5140

llvm-svn: 219306

1 files changed, 107 insertions, 12 deletions

diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 985cc0e62ae..5efff2ccbde 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -24,6 +24,110 @@ using namespace CodeGen;
 //                              OpenMP Directive Emission
 //===----------------------------------------------------------------------===//
 
+void CodeGenFunction::EmitOMPAggregateAssign(LValue OriginalAddr,
+                                             llvm::Value *PrivateAddr,
+                                             const Expr *AssignExpr,
+                                             QualType OriginalType,
+                                             const VarDecl *VDInit) {
+  EmitBlock(createBasicBlock(".omp.assign.begin."));
+  if (!isa<CXXConstructExpr>(AssignExpr) || isTrivialInitializer(AssignExpr)) {
+    // Perform simple memcpy.
+    EmitAggregateAssign(PrivateAddr, OriginalAddr.getAddress(),
+                        AssignExpr->getType());
+  } else {
+    // Perform element-by-element initialization.
+    QualType ElementTy;
+    auto SrcBegin = OriginalAddr.getAddress();
+    auto DestBegin = PrivateAddr;
+    auto ArrayTy = OriginalType->getAsArrayTypeUnsafe();
+    auto SrcNumElements = emitArrayLength(ArrayTy, ElementTy, SrcBegin);
+    auto DestNumElements = emitArrayLength(ArrayTy, ElementTy, DestBegin);
+    auto SrcEnd = Builder.CreateGEP(SrcBegin, SrcNumElements);
+    auto DestEnd = Builder.CreateGEP(DestBegin, DestNumElements);
+    // The basic structure here is a do-while loop, because we don't
+    // need to check for the zero-element case.
+    auto BodyBB = createBasicBlock("omp.arraycpy.body");
+    auto DoneBB = createBasicBlock("omp.arraycpy.done");
+    auto IsEmpty =
+        Builder.CreateICmpEQ(DestBegin, DestEnd, "omp.arraycpy.isempty");
+    Builder.CreateCondBr(IsEmpty, DoneBB, BodyBB);
+
+    // Enter the loop body, making that address the current address.
+    auto EntryBB = Builder.GetInsertBlock();
+    EmitBlock(BodyBB);
+    auto SrcElementPast = Builder.CreatePHI(SrcBegin->getType(), 2,
+                                            "omp.arraycpy.srcElementPast");
+    SrcElementPast->addIncoming(SrcEnd, EntryBB);
+    auto DestElementPast = Builder.CreatePHI(DestBegin->getType(), 2,
+                                             "omp.arraycpy.destElementPast");
+    DestElementPast->addIncoming(DestEnd, EntryBB);
+
+    // Shift the address back by one element.
+    auto NegativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
+    auto DestElement = Builder.CreateGEP(DestElementPast, NegativeOne,
+                                         "omp.arraycpy.dest.element");
+    auto SrcElement = Builder.CreateGEP(SrcElementPast, NegativeOne,
+                                        "omp.arraycpy.src.element");
+    {
+      // Create RunCleanScope to cleanup possible temps.
+      CodeGenFunction::RunCleanupsScope Init(*this);
+      // Emit initialization for single element.
+      LocalDeclMap[VDInit] = SrcElement;
+      EmitAnyExprToMem(AssignExpr, DestElement,
+                       AssignExpr->getType().getQualifiers(),
+                       /*IsInitializer*/ false);
+      LocalDeclMap.erase(VDInit);
+    }
+
+    // Check whether we've reached the end.
+    auto Done =
+        Builder.CreateICmpEQ(DestElement, DestBegin, "omp.arraycpy.done");
+    Builder.CreateCondBr(Done, DoneBB, BodyBB);
+    DestElementPast->addIncoming(DestElement, Builder.GetInsertBlock());
+    SrcElementPast->addIncoming(SrcElement, Builder.GetInsertBlock());
+
+    // Done.
+    EmitBlock(DoneBB, true);
+  }
+  EmitBlock(createBasicBlock(".omp.assign.end."));
+}
+
+void CodeGenFunction::EmitOMPFirstprivateClause(
+    const OMPExecutableDirective &D,
+    CodeGenFunction::OuterDeclMapTy &OuterDeclMap) {
+  auto PrivateFilter = [](const OMPClause *C) -> bool {
+    return C->getClauseKind() == OMPC_firstprivate;
+  };
+  for (OMPExecutableDirective::filtered_clause_iterator<decltype(PrivateFilter)>
+           I(D.clauses(), PrivateFilter); I; ++I) {
+    auto *C = cast<OMPFirstprivateClause>(*I);
+    auto IRef = C->varlist_begin();
+    auto InitsRef = C->inits().begin();
+    for (auto IInit : C->private_copies()) {
+      auto VD = cast<VarDecl>(cast<DeclRefExpr>(IInit)->getDecl());
+      if (*InitsRef != nullptr) {
+        // Emit VarDecl with copy init for arrays.
+        auto *FD = CapturedStmtInfo->lookup(
+            cast<VarDecl>(cast<DeclRefExpr>(*IRef)->getDecl()));
+        LValue Base = MakeNaturalAlignAddrLValue(
+            CapturedStmtInfo->getContextValue(),
+            getContext().getTagDeclType(FD->getParent()));
+        auto OriginalAddr = EmitLValueForField(Base, FD);
+        auto VDInit = cast<VarDecl>(cast<DeclRefExpr>(*InitsRef)->getDecl());
+        auto Emission = EmitAutoVarAlloca(*VD);
+        // Emit initialization of aggregate firstprivate vars.
+        EmitOMPAggregateAssign(OriginalAddr, Emission.getAllocatedAddress(),
+                               VD->getInit(), (*IRef)->getType(), VDInit);
+        EmitAutoVarCleanups(Emission);
+      } else
+        // Emit VarDecl with copy init.
+        EmitDecl(*VD);
+      OuterDeclMap[cast<DeclRefExpr>(*IRef)->getDecl()] = GetAddrOfLocalVar(VD);
+      ++IRef, ++InitsRef;
+    }
+  }
+}
+
 void CodeGenFunction::EmitOMPParallelDirective(const OMPParallelDirective &S) {
   const CapturedStmt *CS = cast<CapturedStmt>(S.getAssociatedStmt());
   llvm::Value *CapturedStruct = GenerateCapturedStmtArgument(*CS);
@@ -31,22 +135,13 @@ void CodeGenFunction::EmitOMPParallelDirective(const OMPParallelDirective &S) {
   llvm::Value *OutlinedFn;
   {
     CodeGenFunction CGF(CGM, true);
-    CGCapturedStmtInfo CGInfo(*CS, CS->getCapturedRegionKind());
+    CGOpenMPRegionInfo CGInfo(S, *CS, *CS->getCapturedDecl()->param_begin());
     CGF.CapturedStmtInfo = &CGInfo;
     OutlinedFn = CGF.GenerateCapturedStmtFunction(*CS);
   }
 
-  // Build call __kmpc_fork_call(loc, 1, microtask, captured_struct/*context*/)
-  llvm::Value *Args[] = {
-      CGM.getOpenMPRuntime().EmitOpenMPUpdateLocation(*this, S.getLocStart()),
-      Builder.getInt32(1), // Number of arguments after 'microtask' argument
-      // (there is only one additional argument - 'context')
-      Builder.CreateBitCast(OutlinedFn,
-                            CGM.getOpenMPRuntime().getKmpc_MicroPointerTy()),
-      EmitCastToVoidPtr(CapturedStruct)};
-  llvm::Constant *RTLFn = CGM.getOpenMPRuntime().CreateRuntimeFunction(
-      CGOpenMPRuntime::OMPRTL__kmpc_fork_call);
-  EmitRuntimeCall(RTLFn, Args);
+  CGM.getOpenMPRuntime().EmitOMPParallelCall(*this, S.getLocStart(), OutlinedFn,
+                                             CapturedStruct);
 }
 
 void CodeGenFunction::EmitOMPLoopBody(const OMPLoopDirective &S,