Commit 87c56158 authored by Patrick Flynn's avatar Patrick Flynn
Browse files

Added fix for race conditions in inner loop

parent 2da6c452

clang/lib/CodeGen/CGKokkos.cpp

+41 −10
Original line number Diff line number Diff line
@@ -199,7 +199,7 @@ CodeGenFunction::EmitKokkosParallelForInductionVar(const LambdaExpr *Lambda) { 
    const ParmVarDecl *InductionVarDecl = MD->getParamDecl(i);

    assert(InductionVarDecl && "EmitKokkosParallelFor() -- bad loop variable decl!");

    

    EmitVarDecl(*InductionVarDecl);

    //EmitVarDecl(*InductionVarDecl);

    params.push_back(InductionVarDecl);

  }
@@ -315,6 +315,7 @@ bool CodeGenFunction::EmitKokkosParallelFor(const CallExpr *CE, 
  // This is 'equivalent' to the Init statement in a traditional for loop (e.g. int i = 0). 

  const ParmVarDecl *InductionVarDecl; 

  InductionVarDecl = EmitKokkosParallelForInductionVar(Lambda).at(0);

  EmitVarDecl(*InductionVarDecl);



   // Create the sync region. 

  PushSyncRegion();
@@ -447,7 +448,8 @@ bool CodeGenFunction::EmitKokkosParallelForMD(const CallExpr *CE, std::string PF 
  std::vector<const ParmVarDecl*> params = EmitKokkosParallelForInductionVar(Lambda);

  

  // Build the inner loops, and eventually the body

  return EmitKokkosInnerLoop(CE, Lambda, nullptr, DimQueue, StartQueue, params, ForallAttrs);

  std::vector<std::pair<llvm::Value*, llvm::AllocaInst*>> TLIVarList;

  return EmitKokkosInnerLoop(CE, Lambda, nullptr, DimQueue, StartQueue, params, TLIVarList, ForallAttrs);

}



// This is in charge of building an inner loop. It works as a recursive function to allow the loops
@@ -460,6 +462,7 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
            std::vector<const Expr*> DimQueue,

            std::vector<const Expr*> StartQueue,

            std::vector<const ParmVarDecl*> params,

            std::vector<std::pair<llvm::Value*, llvm::AllocaInst*>> TLIVarList,

            ArrayRef<const Attr *> ForallAttrs) {

  // Load the data we need

  int pos = DimQueue.size();
@@ -482,10 +485,11 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
  JumpDest Sync = getJumpDestInCurrentScope("kokkos.forall.sync" + std::to_string(pos));

  llvm::BasicBlock *End = createBasicBlock("kokkos.forall.end" + std::to_string(pos));



  // Set the induction variable's starting point

  /*// Set the induction variable's starting point

  EmitBlock(InductionSet);

  EmitVarDecl(*InductionVarDecl);

  llvm::Value *LoopStart = EmitScalarExpr(SE);

  Builder.CreateStore(LoopStart, GetAddrOfLocalVar(InductionVarDecl));

  Builder.CreateStore(LoopStart, GetAddrOfLocalVar(InductionVarDecl));*/

  

  // Extract a conveince block and setup the lexical scope based on 

  // the lambda's source range.
@@ -512,6 +516,12 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
  llvm::Instruction *SRStart = EmitSyncRegionStart();

  CurSyncRegion->setSyncRegionStart(SRStart);

  

  // Set the induction variable's starting point

  EmitBlock(InductionSet);

  EmitVarDecl(*InductionVarDecl);

  llvm::Value *LoopStart = EmitScalarExpr(SE);

  Builder.CreateStore(LoopStart, GetAddrOfLocalVar(InductionVarDecl));



  // TODO: Need to check attributes for spawning strategy. 

  LoopStack.setSpawnStrategy(LoopAttributes::DAC);
@@ -558,6 +568,9 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
                           InductionVarDecl->getName() + ".detach");

  Builder.CreateAlignedStore(GInductionVal, TLInductionVar,

                             getContext().getTypeAlignInChars(RefType));

                             

  std::pair<llvm::Value*, llvm::AllocaInst*> pair(GInductionVar, TLInductionVar);

  TLIVarList.push_back(pair);

  {

    if (DimQueue.size() == 0) {

      // Create a separate cleanup scope for the body, in case it is not
@@ -566,8 +579,26 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
      RunCleanupsScope BodyScope(*this);

      EmitStmt(Lambda->getBody());

      InKokkosConstruct = false;

      

      // Modify the body to use the ''detach''-local induction variable.

      // At this point in the codegen, the body block has been emitted 

      // and we can safely replace the ''sequential`` induction variable 

      // within the detach basic block.

      llvm::BasicBlock *CurrentBlock = Builder.GetInsertBlock();

      for (int i = 0; i<TLIVarList.size(); i++) {

        auto TLVar = TLIVarList.at(i).second;

        auto GInductionVar = TLIVarList.at(i).first;

        

        for(llvm::Value::use_iterator UI = GInductionVar->use_begin(), UE = GInductionVar->use_end(); 

            UI != UE; ) {

          llvm::Use &U = *UI++;

          llvm::Instruction *I = cast<llvm::Instruction>(U.getUser());

          if (I->getParent() == CurrentBlock) 

            U.set(TLVar);

        }

      }

    } else {

      EmitKokkosInnerLoop(CE, Lambda, ConditionBlock, DimQueue, StartQueue, params, ForallAttrs);

      EmitKokkosInnerLoop(CE, Lambda, ConditionBlock, DimQueue, StartQueue, params, TLIVarList, ForallAttrs);

    }

  }
@@ -579,14 +610,14 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
  // At this point in the codegen, the body block has been emitted 

  // and we can safely replace the ''sequential`` induction variable 

  // within the detach basic block.

  llvm::BasicBlock *CurrentBlock = Builder.GetInsertBlock();

 /* llvm::BasicBlock *CurrentBlock = Builder.GetInsertBlock();

  for(llvm::Value::use_iterator UI = GInductionVar->use_begin(), UE = GInductionVar->use_end(); 

      UI != UE; ) {

    llvm::Use &U = *UI++;

    llvm::Instruction *I = cast<llvm::Instruction>(U.getUser());

    if (I->getParent() == CurrentBlock) 

      U.set(TLInductionVar);

  }

  }*/



  EmitBlock(Reattach.getBlock());

  Builder.CreateReattach(Increment, SRStart);
@@ -605,9 +636,9 @@ bool CodeGenFunction::EmitKokkosInnerLoop(const CallExpr *CE, const LambdaExpr * 
  PForScope.ForceCleanup();

  LoopStack.pop();

  

  if (TopBlock != nullptr) {

  /*if (TopBlock != nullptr) {

    EmitBranch(TopBlock);

  }

  }*/



  EmitBlock(Sync.getBlock());

  Builder.CreateSync(End, SRStart);

clang/lib/CodeGen/CodeGenFunction.h

+1 −0
Original line number Diff line number Diff line
@@ -3535,6 +3535,7 @@ public: 
            std::vector<const Expr*> DimQueue,

            std::vector<const Expr*> StartQueue,

            std::vector<const ParmVarDecl*> params,

            std::vector<std::pair<llvm::Value*, llvm::AllocaInst*>> TLIVarList,

            ArrayRef<const Attr *> ForallAttrs);

  bool EmitKokkosParallelReduce(const CallExpr *CE, ArrayRef<const Attr *> Attrs);

  bool InKokkosConstruct = false; // FIXME: Should/can we refactor this away?