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[OpenMP][IRBuilder] Handle target ... nowait when codegen targets host #124720

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Merged
merged 1 commit into from
Jan 28, 2025
Merged

[OpenMP][IRBuilder] Handle target ... nowait when codegen targets host #124720

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14 changes: 9 additions & 5 deletions llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7258,10 +7258,12 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::emitTargetTask(
// If `HasNoWait == true`, we call @__kmpc_omp_target_task_alloc to provide
// the DeviceID to the deferred task and also since
// @__kmpc_omp_target_task_alloc creates an untied/async task.
bool NeedsTargetTask = HasNoWait && DeviceID;
Function *TaskAllocFn =
!HasNoWait ? getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task_alloc)
: getOrCreateRuntimeFunctionPtr(
OMPRTL___kmpc_omp_target_task_alloc);
!NeedsTargetTask
? getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task_alloc)
: getOrCreateRuntimeFunctionPtr(
OMPRTL___kmpc_omp_target_task_alloc);

// Arguments - `loc_ref` (Ident) and `gtid` (ThreadID)
// call.
Expand Down Expand Up @@ -7310,8 +7312,10 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::emitTargetTask(
/*sizeof_task=*/TaskSize, /*sizeof_shared=*/SharedsSize,
/*task_func=*/ProxyFn};

if (HasNoWait)
if (NeedsTargetTask) {
assert(DeviceID && "Expected non-empty device ID.");
TaskAllocArgs.push_back(DeviceID);
}

TaskData = Builder.CreateCall(TaskAllocFn, TaskAllocArgs);

Expand All @@ -7333,7 +7337,7 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::emitTargetTask(
// ---------------------------------------------------------------
// The above means that the lack of a nowait on the target construct
// translates to '#pragma omp task if(0)'
if (!HasNoWait) {
if (!NeedsTargetTask) {
if (DepArray) {
Function *TaskWaitFn =
getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_wait_deps);
Expand Down
29 changes: 29 additions & 0 deletions mlir/test/Target/LLVMIR/omptarget-nowait-host-only.mlir
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@@ -0,0 +1,29 @@
// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s

// Tests `target ... nowait` when code gen targets the host rather than a
// device.

module attributes {omp.is_target_device = false} {
llvm.func @omp_target_nowait_() {
%0 = llvm.mlir.constant(1 : i64) : i64
%1 = llvm.alloca %0 x f32 {bindc_name = "x"} : (i64) -> !llvm.ptr
%3 = omp.map.info var_ptr(%1 : !llvm.ptr, f32) map_clauses(tofrom) capture(ByRef) -> !llvm.ptr {name = "x"}
omp.target nowait map_entries(%3 -> %arg0 : !llvm.ptr) {
%4 = llvm.mlir.constant(5.000000e+00 : f32) : f32
llvm.store %4, %arg0 : f32, !llvm.ptr
omp.terminator
}
llvm.return
}
}

// CHECK: define void @omp_target_nowait_()
// CHECK-NOT: define {{.*}} @
// CHECK-NOT: call ptr @__kmpc_omp_target_task_alloc({{.*}})
// Verify that we directly emit a call to the "target" region's body from the
// parent function of the the `omp.target` op.
// CHECK: call void @__omp_offloading_[[DEV:.*]]_[[FIL:.*]]_omp_target_nowait__l[[LINE:.*]](ptr {{.*}})
// CHECK-NEXT: ret void

// CHECK: define internal void @__omp_offloading_[[DEV]]_[[FIL]]_omp_target_nowait__l[[LINE]](ptr %[[ADDR_X:.*]])
// CHECK: store float 5{{.*}}, ptr %[[ADDR_X]], align 4
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