[OpenMP][NVPTX] Simplify codegen for orphaned parallel, NFCI.

Worker threads fork off to the compiler generated worker function
directly after entering the kernel function. Hence, there is no
need to check whether the current thread is the master if we are
outside of a parallel region (neither SPMD nor parallel_level > 0).

Differential Revision: https://reviews.llvm.org/D52732

llvm-svn: 343618

1 files changed, 7 insertions, 25 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
index 96cf6c1173b..a923232e817 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
@@ -2233,30 +2233,24 @@ void CGOpenMPRuntimeNVPTX::emitNonSPMDParallelCall(
     Work.emplace_back(WFn);
   };
 
-  auto &&LNParallelGen = [this, Loc, &SeqGen, &L0ParallelGen, &CodeGen,
-                          &ThreadIDAddr](CodeGenFunction &CGF,
-                                         PrePostActionTy &Action) {
-    RegionCodeGenTy RCG(CodeGen);
+  auto &&LNParallelGen = [this, Loc, &SeqGen, &L0ParallelGen](
+                             CodeGenFunction &CGF, PrePostActionTy &Action) {
     if (IsInParallelRegion) {
       SeqGen(CGF, Action);
     } else if (IsInTargetMasterThreadRegion) {
       L0ParallelGen(CGF, Action);
-    } else if (getExecutionMode() == CGOpenMPRuntimeNVPTX::EM_NonSPMD) {
-      RCG(CGF);
     } else {
       // Check for master and then parallelism:
       // if (__kmpc_is_spmd_exec_mode() || __kmpc_parallel_level(loc, gtid)) {
-      //  Serialized execution.
-      // } else if (master) {
-      //   Worker call.
+      //   Serialized execution.
       // } else {
-      //   Outlined function call.
+      //   Worker call.
       // }
       CGBuilderTy &Bld = CGF.Builder;
       llvm::BasicBlock *ExitBB = CGF.createBasicBlock(".exit");
       llvm::BasicBlock *SeqBB = CGF.createBasicBlock(".sequential");
       llvm::BasicBlock *ParallelCheckBB = CGF.createBasicBlock(".parcheck");
-      llvm::BasicBlock *MasterCheckBB = CGF.createBasicBlock(".mastercheck");
+      llvm::BasicBlock *MasterBB = CGF.createBasicBlock(".master");
       llvm::Value *IsSPMD = Bld.CreateIsNotNull(CGF.EmitNounwindRuntimeCall(
           createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_is_spmd_exec_mode)));
       Bld.CreateCondBr(IsSPMD, SeqBB, ParallelCheckBB);
@@ -2269,29 +2263,17 @@ void CGOpenMPRuntimeNVPTX::emitNonSPMDParallelCall(
           createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_parallel_level),
           {RTLoc, ThreadID});
       llvm::Value *Res = Bld.CreateIsNotNull(PL);
-      Bld.CreateCondBr(Res, SeqBB, MasterCheckBB);
+      Bld.CreateCondBr(Res, SeqBB, MasterBB);
       CGF.EmitBlock(SeqBB);
       SeqGen(CGF, Action);
       CGF.EmitBranch(ExitBB);
       // There is no need to emit line number for unconditional branch.
       (void)ApplyDebugLocation::CreateEmpty(CGF);
-      CGF.EmitBlock(MasterCheckBB);
-      llvm::BasicBlock *MasterThenBB = CGF.createBasicBlock("master.then");
-      llvm::BasicBlock *ElseBlock = CGF.createBasicBlock("omp_if.else");
-      llvm::Value *IsMaster =
-          Bld.CreateICmpEQ(getNVPTXThreadID(CGF), getMasterThreadID(CGF));
-      Bld.CreateCondBr(IsMaster, MasterThenBB, ElseBlock);
-      CGF.EmitBlock(MasterThenBB);
+      CGF.EmitBlock(MasterBB);
       L0ParallelGen(CGF, Action);
       CGF.EmitBranch(ExitBB);
       // There is no need to emit line number for unconditional branch.
       (void)ApplyDebugLocation::CreateEmpty(CGF);
-      CGF.EmitBlock(ElseBlock);
-      // In the worker need to use the real thread id.
-      ThreadIDAddr = emitThreadIDAddress(CGF, Loc);
-      RCG(CGF);
-      // There is no need to emit line number for unconditional branch.
-      (void)ApplyDebugLocation::CreateEmpty(CGF);
       // Emit the continuation block for code after the if.
       CGF.EmitBlock(ExitBB, /*IsFinished=*/true);
     }