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[OPENMP][NVPTX]Fix critical region codegen. 

Summary:
Previously critical regions were emitted with the barrier making it a
worksharing construct though it is not. Also, it leads to incorrect
behavior in Cuda9+. Patch fixes this problem.

Reviewers: ABataev, jdoerfert

Subscribers: jholewinski, guansong, cfe-commits, grokos

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66673

llvm-svn: 369946
This commit is contained in:
Alexey Bataev 2019-08-26 19:07:48 +00:00
parent b504eb8bb5
commit 2cd7fafc11
2 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
View File

@ -107,6 +107,10 @@ enum OpenMPRTLFunctionNVPTX {
/// Call to void __kmpc_barrier_simple_spmd(ident_t *loc, kmp_int32
/// global_tid);
OMPRTL__kmpc_barrier_simple_spmd,
/// Call to int32_t __kmpc_warp_active_thread_mask(void);
OMPRTL_NVPTX__kmpc_warp_active_thread_mask,
/// Call to void __kmpc_syncwarp(int32_t Mask);
OMPRTL_NVPTX__kmpc_syncwarp,
};
/// Pre(post)-action for different OpenMP constructs specialized for NVPTX.
@ -1794,6 +1798,20 @@ CGOpenMPRuntimeNVPTX::createNVPTXRuntimeFunction(unsigned Function) {
->addFnAttr(llvm::Attribute::Convergent);
break;
}
case OMPRTL_NVPTX__kmpc_warp_active_thread_mask: {
// Build int32_t __kmpc_warp_active_thread_mask(void);
auto *FnTy =
llvm::FunctionType::get(CGM.Int32Ty, llvm::None, /*isVarArg=*/false);
RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_warp_active_thread_mask");
break;
}
case OMPRTL_NVPTX__kmpc_syncwarp: {
// Build void __kmpc_syncwarp(kmp_int32 Mask);
auto *FnTy =
llvm::FunctionType::get(CGM.VoidTy, CGM.Int32Ty, /*isVarArg=*/false);
RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_syncwarp");
break;
}
}
return RTLFn;
}
@ -2700,6 +2718,9 @@ void CGOpenMPRuntimeNVPTX::emitCriticalRegion(
llvm::BasicBlock *BodyBB = CGF.createBasicBlock("omp.critical.body");
llvm::BasicBlock *ExitBB = CGF.createBasicBlock("omp.critical.exit");
// Get the mask of active threads in the warp.
llvm::Value *Mask = CGF.EmitRuntimeCall(
createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_warp_active_thread_mask));
// Fetch team-local id of the thread.
llvm::Value *ThreadID = getNVPTXThreadID(CGF);
@ -2740,8 +2761,9 @@ void CGOpenMPRuntimeNVPTX::emitCriticalRegion(
// Block waits for all threads in current team to finish then increments the
// counter variable and returns to the loop.
CGF.EmitBlock(SyncBB);
emitBarrierCall(CGF, Loc, OMPD_unknown, /*EmitChecks=*/false,
/*ForceSimpleCall=*/true);
// Reconverge active threads in the warp.
(void)CGF.EmitRuntimeCall(
createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_syncwarp), Mask);
llvm::Value *IncCounterVal =
CGF.Builder.CreateNSWAdd(CounterVal, CGF.Builder.getInt32(1));

3
clang/test/OpenMP/nvptx_parallel_codegen.cpp
View File

@ -343,6 +343,7 @@ int bar(int n){
// CHECK-LABEL: define internal void @{{.+}}(i32* noalias %{{.+}}, i32* noalias %{{.+}}, i32* dereferenceable{{.*}})
// CHECK: [[CC:%.+]] = alloca i32,
// CHECK: [[MASK:%.+]] = call i32 @__kmpc_warp_active_thread_mask()
// CHECK: [[TID:%.+]] = call i32 @llvm.nvvm.read.ptx.sreg.tid.x()
// CHECK: [[NUM_THREADS:%.+]] = call i32 @llvm.nvvm.read.ptx.sreg.ntid.x()
// CHECK: store i32 0, i32* [[CC]],
@ -362,7 +363,7 @@ int bar(int n){
// CHECK: store i32
// CHECK: call void @__kmpc_end_critical(
// CHECK: call void @__kmpc_barrier(%struct.ident_t* @{{.+}}, i32 %{{.+}})
// CHECK: call void @__kmpc_syncwarp(i32 [[MASK]])
// CHECK: [[NEW_CC_VAL:%.+]] = add nsw i32 [[CC_VAL]], 1
// CHECK: store i32 [[NEW_CC_VAL]], i32* [[CC]],
// CHECK: br label