[Flang][OpenMP] Enable no-loop kernels #155818
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Enable the generation of no-loop kernels for Fortran OpenMP code. target teams distribute parallel do pragmas can be promoted to no-loop kernels if the user adds the -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription flags. If the OpenMP kernel contains reduction or num_teams clauses, it is not promoted to no-loop mode. The global OpenMP device RTL oversubscription flags no longer force no-loop code generation for Fortran.
DominikAdamski
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Meinersbur,
dhruvachak,
dpalermo,
kevinsala,
ronlieb,
shiltian and
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@llvm/pr-subscribers-offload @llvm/pr-subscribers-mlir-llvm Author: Dominik Adamski (DominikAdamski) ChangesEnable the generation of no-loop kernels for Fortran OpenMP code. target teams distribute parallel do pragmas can be promoted to no-loop kernels if the user adds the -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription flags. If the OpenMP kernel contains reduction or num_teams clauses, it is not promoted to no-loop mode. The global OpenMP device RTL oversubscription flags no longer force no-loop code generation for Fortran. Full diff: https://github.com/llvm/llvm-project/pull/155818.diff 8 Files Affected:
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index b1ae3cf6525b8..4c078a45628a9 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3824,10 +3824,23 @@ let Visibility = [ClangOption, CC1Option, FC1Option, FlangOption] in {
let Group = f_Group in {
def fopenmp_target_debug_EQ : Joined<["-"], "fopenmp-target-debug=">;
-def fopenmp_assume_teams_oversubscription : Flag<["-"], "fopenmp-assume-teams-oversubscription">;
-def fopenmp_assume_threads_oversubscription : Flag<["-"], "fopenmp-assume-threads-oversubscription">;
-def fno_openmp_assume_teams_oversubscription : Flag<["-"], "fno-openmp-assume-teams-oversubscription">;
-def fno_openmp_assume_threads_oversubscription : Flag<["-"], "fno-openmp-assume-threads-oversubscription">;
+def fopenmp_assume_teams_oversubscription : Flag<["-"], "fopenmp-assume-teams-oversubscription">,
+ HelpText<"Allow enforcement to ensure there are enough teams to cover the "
+ "loop iteration space. It may ignore environment variables. "
+ "If the fopenmp-assume-teams-oversubscription and "
+ "fopenmp-assume-threads-oversubscription flags are set, Flang may "
+ "generate more optimized OpenMP kernels for target teams distribute "
+ "parallel do pragmas.">;
+def fopenmp_assume_threads_oversubscription : Flag<["-"], "fopenmp-assume-threads-oversubscription">,
+ HelpText<"Assume threads oversubscription. If the "
+ "fopenmp-assume-teams-oversubscription and "
+ "fopenmp-assume-threads-oversubscription flags are set, Flang may "
+ "generate more optimized OpenMP kernels for target teams distribute "
+ "parallel do pragmas.">;
+def fno_openmp_assume_teams_oversubscription : Flag<["-"], "fno-openmp-assume-teams-oversubscription">,
+ HelpText<"Do not assume teams oversubscription.">;
+def fno_openmp_assume_threads_oversubscription : Flag<["-"], "fno-openmp-assume-threads-oversubscription">,
+ HelpText<"Do not assume threads oversubscription.">;
def fopenmp_assume_no_thread_state : Flag<["-"], "fopenmp-assume-no-thread-state">,
HelpText<"Assert no thread in a parallel region modifies an ICV">,
MarshallingInfoFlag<LangOpts<"OpenMPNoThreadState">>;
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h b/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
index 1050e3d8b08dd..49078e4162ebc 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
+++ b/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
@@ -1075,11 +1075,13 @@ class OpenMPIRBuilder {
/// preheader of the loop.
/// \param LoopType Information about type of loop worksharing.
/// It corresponds to type of loop workshare OpenMP pragma.
+ /// \param NoLoop If true, no-loop code is generated.
///
/// \returns Point where to insert code after the workshare construct.
InsertPointTy applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
InsertPointTy AllocaIP,
- omp::WorksharingLoopType LoopType);
+ omp::WorksharingLoopType LoopType,
+ bool NoLoop);
/// Modifies the canonical loop to be a statically-scheduled workshare loop.
///
@@ -1199,6 +1201,7 @@ class OpenMPIRBuilder {
/// present.
/// \param LoopType Information about type of loop worksharing.
/// It corresponds to type of loop workshare OpenMP pragma.
+ /// \param NoLoop If true, no-loop code is generated.
///
/// \returns Point where to insert code after the workshare construct.
LLVM_ABI InsertPointOrErrorTy applyWorkshareLoop(
@@ -1209,7 +1212,8 @@ class OpenMPIRBuilder {
bool HasMonotonicModifier = false, bool HasNonmonotonicModifier = false,
bool HasOrderedClause = false,
omp::WorksharingLoopType LoopType =
- omp::WorksharingLoopType::ForStaticLoop);
+ omp::WorksharingLoopType::ForStaticLoop,
+ bool NoLoop = false);
/// Tile a loop nest.
///
diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index c0e956840f989..bec5abb45041f 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -4955,7 +4955,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
WorksharingLoopType LoopType,
BasicBlock *InsertBlock, Value *Ident,
Value *LoopBodyArg, Value *TripCount,
- Function &LoopBodyFn) {
+ Function &LoopBodyFn, bool NoLoop) {
Type *TripCountTy = TripCount->getType();
Module &M = OMPBuilder->M;
IRBuilder<> &Builder = OMPBuilder->Builder;
@@ -4984,7 +4984,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
if (LoopType == WorksharingLoopType::DistributeForStaticLoop) {
RealArgs.push_back(ConstantInt::get(TripCountTy, 0));
}
- RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), 0));
+ RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), NoLoop));
Builder.CreateCall(RTLFn, RealArgs);
}
@@ -4992,7 +4992,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
static void workshareLoopTargetCallback(
OpenMPIRBuilder *OMPIRBuilder, CanonicalLoopInfo *CLI, Value *Ident,
Function &OutlinedFn, const SmallVector<Instruction *, 4> &ToBeDeleted,
- WorksharingLoopType LoopType) {
+ WorksharingLoopType LoopType, bool NoLoop) {
IRBuilder<> &Builder = OMPIRBuilder->Builder;
BasicBlock *Preheader = CLI->getPreheader();
Value *TripCount = CLI->getTripCount();
@@ -5039,17 +5039,16 @@ static void workshareLoopTargetCallback(
OutlinedFnCallInstruction->eraseFromParent();
createTargetLoopWorkshareCall(OMPIRBuilder, LoopType, Preheader, Ident,
- LoopBodyArg, TripCount, OutlinedFn);
+ LoopBodyArg, TripCount, OutlinedFn, NoLoop);
for (auto &ToBeDeletedItem : ToBeDeleted)
ToBeDeletedItem->eraseFromParent();
CLI->invalidate();
}
-OpenMPIRBuilder::InsertPointTy
-OpenMPIRBuilder::applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
- InsertPointTy AllocaIP,
- WorksharingLoopType LoopType) {
+OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::applyWorkshareLoopTarget(
+ DebugLoc DL, CanonicalLoopInfo *CLI, InsertPointTy AllocaIP,
+ WorksharingLoopType LoopType, bool NoLoop) {
uint32_t SrcLocStrSize;
Constant *SrcLocStr = getOrCreateSrcLocStr(DL, SrcLocStrSize);
Value *Ident = getOrCreateIdent(SrcLocStr, SrcLocStrSize);
@@ -5132,7 +5131,7 @@ OpenMPIRBuilder::applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
OI.PostOutlineCB = [=, ToBeDeletedVec =
std::move(ToBeDeleted)](Function &OutlinedFn) {
workshareLoopTargetCallback(this, CLI, Ident, OutlinedFn, ToBeDeletedVec,
- LoopType);
+ LoopType, NoLoop);
};
addOutlineInfo(std::move(OI));
return CLI->getAfterIP();
@@ -5143,9 +5142,9 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::applyWorkshareLoop(
bool NeedsBarrier, omp::ScheduleKind SchedKind, Value *ChunkSize,
bool HasSimdModifier, bool HasMonotonicModifier,
bool HasNonmonotonicModifier, bool HasOrderedClause,
- WorksharingLoopType LoopType) {
+ WorksharingLoopType LoopType, bool NoLoop) {
if (Config.isTargetDevice())
- return applyWorkshareLoopTarget(DL, CLI, AllocaIP, LoopType);
+ return applyWorkshareLoopTarget(DL, CLI, AllocaIP, LoopType, NoLoop);
OMPScheduleType EffectiveScheduleType = computeOpenMPScheduleType(
SchedKind, ChunkSize, HasSimdModifier, HasMonotonicModifier,
HasNonmonotonicModifier, HasOrderedClause);
diff --git a/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td b/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
index c080c3fac87d4..e0cd06805ab40 100644
--- a/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
+++ b/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
@@ -230,6 +230,7 @@ def TargetRegionFlagsNone : I32BitEnumAttrCaseNone<"none">;
def TargetRegionFlagsGeneric : I32BitEnumAttrCaseBit<"generic", 0>;
def TargetRegionFlagsSpmd : I32BitEnumAttrCaseBit<"spmd", 1>;
def TargetRegionFlagsTripCount : I32BitEnumAttrCaseBit<"trip_count", 2>;
+def TargetRegionFlagsNoLoop : I32BitEnumAttrCaseBit<"no_loop", 3>;
def TargetRegionFlags : OpenMP_BitEnumAttr<
"TargetRegionFlags",
@@ -237,7 +238,8 @@ def TargetRegionFlags : OpenMP_BitEnumAttr<
TargetRegionFlagsNone,
TargetRegionFlagsGeneric,
TargetRegionFlagsSpmd,
- TargetRegionFlagsTripCount
+ TargetRegionFlagsTripCount,
+ TargetRegionFlagsNoLoop
]>;
//===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
index 6e43f28e8d93d..1e10dd114b30a 100644
--- a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
+++ b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
@@ -2106,6 +2106,29 @@ Operation *TargetOp::getInnermostCapturedOmpOp() {
});
}
+/// Check if we can promote SPMD kernel to No-Loop kernel
+static bool canPromoteToNoLoop(Operation *capturedOp, TeamsOp teamsOp,
+ WsloopOp *wsLoopOp) {
+ // num_teams clause can break no-loop teams/threads assumption
+ if (teamsOp.getNumTeamsUpper())
+ return false;
+ // reduction kernels are slower in no-loop mode
+ if (teamsOp.getNumReductionVars())
+ return false;
+ if (wsLoopOp->getNumReductionVars())
+ return false;
+ // check if the user allows the promotion of kernels to no-loop mode
+ OffloadModuleInterface offloadMod =
+ capturedOp->getParentOfType<omp::OffloadModuleInterface>();
+ if (!offloadMod)
+ return false;
+ auto ompFlags = offloadMod.getFlags();
+ if (!ompFlags)
+ return false;
+ return ompFlags.getAssumeTeamsOversubscription() &&
+ ompFlags.getAssumeThreadsOversubscription();
+}
+
TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
// A non-null captured op is only valid if it resides inside of a TargetOp
// and is the result of calling getInnermostCapturedOmpOp() on it.
@@ -2134,7 +2157,8 @@ TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
// Detect target-teams-distribute-parallel-wsloop[-simd].
if (numWrappers == 2) {
- if (!isa<WsloopOp>(innermostWrapper))
+ WsloopOp *wsloopOp = dyn_cast<WsloopOp>(innermostWrapper);
+ if (!wsloopOp)
return TargetRegionFlags::generic;
innermostWrapper = std::next(innermostWrapper);
@@ -2145,12 +2169,19 @@ TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
if (!isa_and_present<ParallelOp>(parallelOp))
return TargetRegionFlags::generic;
- Operation *teamsOp = parallelOp->getParentOp();
- if (!isa_and_present<TeamsOp>(teamsOp))
+ TeamsOp teamsOp = dyn_cast<TeamsOp>(parallelOp->getParentOp());
+ if (!teamsOp)
return TargetRegionFlags::generic;
- if (teamsOp->getParentOp() == targetOp.getOperation())
- return TargetRegionFlags::spmd | TargetRegionFlags::trip_count;
+ TargetRegionFlags result;
+
+ if (teamsOp->getParentOp() == targetOp.getOperation()) {
+ TargetRegionFlags result =
+ TargetRegionFlags::spmd | TargetRegionFlags::trip_count;
+ if (canPromoteToNoLoop(capturedOp, teamsOp, wsloopOp))
+ result = result | TargetRegionFlags::no_loop;
+ return result;
+ }
}
// Detect target-teams-distribute[-simd] and target-teams-loop.
else if (isa<DistributeOp, LoopOp>(innermostWrapper)) {
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index 6694de8383534..d67d5eb741543 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -2590,13 +2590,27 @@ convertOmpWsloop(Operation &opInst, llvm::IRBuilderBase &builder,
}
builder.SetInsertPoint(*regionBlock, (*regionBlock)->begin());
+
+ bool noLoopMode = false;
+ omp::TargetOp targetOp = wsloopOp->getParentOfType<mlir::omp::TargetOp>();
+ if (targetOp) {
+ Operation *targetCapturedOp = targetOp.getInnermostCapturedOmpOp();
+ omp::TargetRegionFlags kernelFlags =
+ targetOp.getKernelExecFlags(targetCapturedOp);
+ if (omp::bitEnumContainsAll(kernelFlags,
+ omp::TargetRegionFlags::spmd |
+ omp::TargetRegionFlags::no_loop) &&
+ !omp::bitEnumContainsAny(kernelFlags, omp::TargetRegionFlags::generic))
+ noLoopMode = true;
+ }
+
llvm::OpenMPIRBuilder::InsertPointOrErrorTy wsloopIP =
ompBuilder->applyWorkshareLoop(
ompLoc.DL, loopInfo, allocaIP, loopNeedsBarrier,
convertToScheduleKind(schedule), chunk, isSimd,
scheduleMod == omp::ScheduleModifier::monotonic,
scheduleMod == omp::ScheduleModifier::nonmonotonic, isOrdered,
- workshareLoopType);
+ workshareLoopType, noLoopMode);
if (failed(handleError(wsloopIP, opInst)))
return failure();
@@ -5365,6 +5379,12 @@ initTargetDefaultAttrs(omp::TargetOp targetOp, Operation *capturedOp,
? llvm::omp::OMP_TGT_EXEC_MODE_GENERIC_SPMD
: llvm::omp::OMP_TGT_EXEC_MODE_GENERIC
: llvm::omp::OMP_TGT_EXEC_MODE_SPMD;
+ if (omp::bitEnumContainsAll(kernelFlags,
+ omp::TargetRegionFlags::spmd |
+ omp::TargetRegionFlags::no_loop) &&
+ !omp::bitEnumContainsAny(kernelFlags, omp::TargetRegionFlags::generic))
+ attrs.ExecFlags = llvm::omp::OMP_TGT_EXEC_MODE_SPMD_NO_LOOP;
+
attrs.MinTeams = minTeamsVal;
attrs.MaxTeams.front() = maxTeamsVal;
attrs.MinThreads = 1;
diff --git a/offload/DeviceRTL/src/Workshare.cpp b/offload/DeviceRTL/src/Workshare.cpp
index 59a2cc3f27aca..653104ce883d1 100644
--- a/offload/DeviceRTL/src/Workshare.cpp
+++ b/offload/DeviceRTL/src/Workshare.cpp
@@ -800,10 +800,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more threads than iterations we can indicate that to
// avoid an outer loop.
- if (config::getAssumeThreadsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumThreads >= NumIters, "Broken assumption");
@@ -851,10 +847,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more blocks than iterations we can indicate that to
// avoid an outer loop.
- if (config::getAssumeTeamsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumBlocks >= NumIters, "Broken assumption");
@@ -914,11 +906,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more threads (across all blocks) than iterations we
// can indicate that to avoid an outer loop.
- if (config::getAssumeTeamsOversubscription() &
- config::getAssumeThreadsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumBlocks * NumThreads >= NumIters, "Broken assumption");
diff --git a/offload/test/offloading/fortran/target-no-loop.f90 b/offload/test/offloading/fortran/target-no-loop.f90
new file mode 100644
index 0000000000000..dd2bf7c2196b6
--- /dev/null
+++ b/offload/test/offloading/fortran/target-no-loop.f90
@@ -0,0 +1,43 @@
+! Check if the first OpenMP GPU kernel is promoted to no-loop mode.
+! The second cannot be promoted due to the limit on the number of teams.
+! REQUIRES: flang, amdgpu
+
+! RUN: %libomptarget-compile-fortran-generic -O3 -fopenmp-assume-threads-oversubscription -fopenmp-assume-teams-oversubscription
+! RUN: env LIBOMPTARGET_INFO=16 %libomptarget-run-generic 2>&1 | %fcheck-generic
+program main
+ use omp_lib
+ implicit none
+ integer :: i
+ integer :: array(1024), errors = 0
+ array = 1
+
+ !$omp target teams distribute parallel do
+ do i = 1, 1024
+ array(i) = i
+ end do
+
+ do i = 1, 1024
+ if ( array( i) .ne. (i) ) then
+ errors = errors + 1
+ end if
+ end do
+
+ !$omp target teams distribute parallel do num_teams(3)
+ do i = 1, 1024
+ array(i) = i
+ end do
+
+ do i = 1, 1024
+ if ( array( i) .ne. (i) ) then
+ errors = errors + 1
+ end if
+ end do
+
+ print *,"number of errors: ", errors
+
+end program main
+
+! CHECK: "PluginInterface" device {{[0-9]+}} info: Launching kernel {{.*}} SPMD-No-Loop mode
+! CHECK: "PluginInterface" device {{[0-9]+}} info: Launching kernel {{.*}} SPMD mode
+! CHECK: number of errors: 0
+
|
Member
|
@llvm/pr-subscribers-flang-openmp Author: Dominik Adamski (DominikAdamski) ChangesEnable the generation of no-loop kernels for Fortran OpenMP code. target teams distribute parallel do pragmas can be promoted to no-loop kernels if the user adds the -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription flags. If the OpenMP kernel contains reduction or num_teams clauses, it is not promoted to no-loop mode. The global OpenMP device RTL oversubscription flags no longer force no-loop code generation for Fortran. Full diff: https://github.com/llvm/llvm-project/pull/155818.diff 8 Files Affected:
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index b1ae3cf6525b8..4c078a45628a9 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3824,10 +3824,23 @@ let Visibility = [ClangOption, CC1Option, FC1Option, FlangOption] in {
let Group = f_Group in {
def fopenmp_target_debug_EQ : Joined<["-"], "fopenmp-target-debug=">;
-def fopenmp_assume_teams_oversubscription : Flag<["-"], "fopenmp-assume-teams-oversubscription">;
-def fopenmp_assume_threads_oversubscription : Flag<["-"], "fopenmp-assume-threads-oversubscription">;
-def fno_openmp_assume_teams_oversubscription : Flag<["-"], "fno-openmp-assume-teams-oversubscription">;
-def fno_openmp_assume_threads_oversubscription : Flag<["-"], "fno-openmp-assume-threads-oversubscription">;
+def fopenmp_assume_teams_oversubscription : Flag<["-"], "fopenmp-assume-teams-oversubscription">,
+ HelpText<"Allow enforcement to ensure there are enough teams to cover the "
+ "loop iteration space. It may ignore environment variables. "
+ "If the fopenmp-assume-teams-oversubscription and "
+ "fopenmp-assume-threads-oversubscription flags are set, Flang may "
+ "generate more optimized OpenMP kernels for target teams distribute "
+ "parallel do pragmas.">;
+def fopenmp_assume_threads_oversubscription : Flag<["-"], "fopenmp-assume-threads-oversubscription">,
+ HelpText<"Assume threads oversubscription. If the "
+ "fopenmp-assume-teams-oversubscription and "
+ "fopenmp-assume-threads-oversubscription flags are set, Flang may "
+ "generate more optimized OpenMP kernels for target teams distribute "
+ "parallel do pragmas.">;
+def fno_openmp_assume_teams_oversubscription : Flag<["-"], "fno-openmp-assume-teams-oversubscription">,
+ HelpText<"Do not assume teams oversubscription.">;
+def fno_openmp_assume_threads_oversubscription : Flag<["-"], "fno-openmp-assume-threads-oversubscription">,
+ HelpText<"Do not assume threads oversubscription.">;
def fopenmp_assume_no_thread_state : Flag<["-"], "fopenmp-assume-no-thread-state">,
HelpText<"Assert no thread in a parallel region modifies an ICV">,
MarshallingInfoFlag<LangOpts<"OpenMPNoThreadState">>;
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h b/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
index 1050e3d8b08dd..49078e4162ebc 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
+++ b/llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
@@ -1075,11 +1075,13 @@ class OpenMPIRBuilder {
/// preheader of the loop.
/// \param LoopType Information about type of loop worksharing.
/// It corresponds to type of loop workshare OpenMP pragma.
+ /// \param NoLoop If true, no-loop code is generated.
///
/// \returns Point where to insert code after the workshare construct.
InsertPointTy applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
InsertPointTy AllocaIP,
- omp::WorksharingLoopType LoopType);
+ omp::WorksharingLoopType LoopType,
+ bool NoLoop);
/// Modifies the canonical loop to be a statically-scheduled workshare loop.
///
@@ -1199,6 +1201,7 @@ class OpenMPIRBuilder {
/// present.
/// \param LoopType Information about type of loop worksharing.
/// It corresponds to type of loop workshare OpenMP pragma.
+ /// \param NoLoop If true, no-loop code is generated.
///
/// \returns Point where to insert code after the workshare construct.
LLVM_ABI InsertPointOrErrorTy applyWorkshareLoop(
@@ -1209,7 +1212,8 @@ class OpenMPIRBuilder {
bool HasMonotonicModifier = false, bool HasNonmonotonicModifier = false,
bool HasOrderedClause = false,
omp::WorksharingLoopType LoopType =
- omp::WorksharingLoopType::ForStaticLoop);
+ omp::WorksharingLoopType::ForStaticLoop,
+ bool NoLoop = false);
/// Tile a loop nest.
///
diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index c0e956840f989..bec5abb45041f 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -4955,7 +4955,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
WorksharingLoopType LoopType,
BasicBlock *InsertBlock, Value *Ident,
Value *LoopBodyArg, Value *TripCount,
- Function &LoopBodyFn) {
+ Function &LoopBodyFn, bool NoLoop) {
Type *TripCountTy = TripCount->getType();
Module &M = OMPBuilder->M;
IRBuilder<> &Builder = OMPBuilder->Builder;
@@ -4984,7 +4984,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
if (LoopType == WorksharingLoopType::DistributeForStaticLoop) {
RealArgs.push_back(ConstantInt::get(TripCountTy, 0));
}
- RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), 0));
+ RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), NoLoop));
Builder.CreateCall(RTLFn, RealArgs);
}
@@ -4992,7 +4992,7 @@ static void createTargetLoopWorkshareCall(OpenMPIRBuilder *OMPBuilder,
static void workshareLoopTargetCallback(
OpenMPIRBuilder *OMPIRBuilder, CanonicalLoopInfo *CLI, Value *Ident,
Function &OutlinedFn, const SmallVector<Instruction *, 4> &ToBeDeleted,
- WorksharingLoopType LoopType) {
+ WorksharingLoopType LoopType, bool NoLoop) {
IRBuilder<> &Builder = OMPIRBuilder->Builder;
BasicBlock *Preheader = CLI->getPreheader();
Value *TripCount = CLI->getTripCount();
@@ -5039,17 +5039,16 @@ static void workshareLoopTargetCallback(
OutlinedFnCallInstruction->eraseFromParent();
createTargetLoopWorkshareCall(OMPIRBuilder, LoopType, Preheader, Ident,
- LoopBodyArg, TripCount, OutlinedFn);
+ LoopBodyArg, TripCount, OutlinedFn, NoLoop);
for (auto &ToBeDeletedItem : ToBeDeleted)
ToBeDeletedItem->eraseFromParent();
CLI->invalidate();
}
-OpenMPIRBuilder::InsertPointTy
-OpenMPIRBuilder::applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
- InsertPointTy AllocaIP,
- WorksharingLoopType LoopType) {
+OpenMPIRBuilder::InsertPointTy OpenMPIRBuilder::applyWorkshareLoopTarget(
+ DebugLoc DL, CanonicalLoopInfo *CLI, InsertPointTy AllocaIP,
+ WorksharingLoopType LoopType, bool NoLoop) {
uint32_t SrcLocStrSize;
Constant *SrcLocStr = getOrCreateSrcLocStr(DL, SrcLocStrSize);
Value *Ident = getOrCreateIdent(SrcLocStr, SrcLocStrSize);
@@ -5132,7 +5131,7 @@ OpenMPIRBuilder::applyWorkshareLoopTarget(DebugLoc DL, CanonicalLoopInfo *CLI,
OI.PostOutlineCB = [=, ToBeDeletedVec =
std::move(ToBeDeleted)](Function &OutlinedFn) {
workshareLoopTargetCallback(this, CLI, Ident, OutlinedFn, ToBeDeletedVec,
- LoopType);
+ LoopType, NoLoop);
};
addOutlineInfo(std::move(OI));
return CLI->getAfterIP();
@@ -5143,9 +5142,9 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::applyWorkshareLoop(
bool NeedsBarrier, omp::ScheduleKind SchedKind, Value *ChunkSize,
bool HasSimdModifier, bool HasMonotonicModifier,
bool HasNonmonotonicModifier, bool HasOrderedClause,
- WorksharingLoopType LoopType) {
+ WorksharingLoopType LoopType, bool NoLoop) {
if (Config.isTargetDevice())
- return applyWorkshareLoopTarget(DL, CLI, AllocaIP, LoopType);
+ return applyWorkshareLoopTarget(DL, CLI, AllocaIP, LoopType, NoLoop);
OMPScheduleType EffectiveScheduleType = computeOpenMPScheduleType(
SchedKind, ChunkSize, HasSimdModifier, HasMonotonicModifier,
HasNonmonotonicModifier, HasOrderedClause);
diff --git a/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td b/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
index c080c3fac87d4..e0cd06805ab40 100644
--- a/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
+++ b/mlir/include/mlir/Dialect/OpenMP/OpenMPEnums.td
@@ -230,6 +230,7 @@ def TargetRegionFlagsNone : I32BitEnumAttrCaseNone<"none">;
def TargetRegionFlagsGeneric : I32BitEnumAttrCaseBit<"generic", 0>;
def TargetRegionFlagsSpmd : I32BitEnumAttrCaseBit<"spmd", 1>;
def TargetRegionFlagsTripCount : I32BitEnumAttrCaseBit<"trip_count", 2>;
+def TargetRegionFlagsNoLoop : I32BitEnumAttrCaseBit<"no_loop", 3>;
def TargetRegionFlags : OpenMP_BitEnumAttr<
"TargetRegionFlags",
@@ -237,7 +238,8 @@ def TargetRegionFlags : OpenMP_BitEnumAttr<
TargetRegionFlagsNone,
TargetRegionFlagsGeneric,
TargetRegionFlagsSpmd,
- TargetRegionFlagsTripCount
+ TargetRegionFlagsTripCount,
+ TargetRegionFlagsNoLoop
]>;
//===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
index 6e43f28e8d93d..1e10dd114b30a 100644
--- a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
+++ b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
@@ -2106,6 +2106,29 @@ Operation *TargetOp::getInnermostCapturedOmpOp() {
});
}
+/// Check if we can promote SPMD kernel to No-Loop kernel
+static bool canPromoteToNoLoop(Operation *capturedOp, TeamsOp teamsOp,
+ WsloopOp *wsLoopOp) {
+ // num_teams clause can break no-loop teams/threads assumption
+ if (teamsOp.getNumTeamsUpper())
+ return false;
+ // reduction kernels are slower in no-loop mode
+ if (teamsOp.getNumReductionVars())
+ return false;
+ if (wsLoopOp->getNumReductionVars())
+ return false;
+ // check if the user allows the promotion of kernels to no-loop mode
+ OffloadModuleInterface offloadMod =
+ capturedOp->getParentOfType<omp::OffloadModuleInterface>();
+ if (!offloadMod)
+ return false;
+ auto ompFlags = offloadMod.getFlags();
+ if (!ompFlags)
+ return false;
+ return ompFlags.getAssumeTeamsOversubscription() &&
+ ompFlags.getAssumeThreadsOversubscription();
+}
+
TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
// A non-null captured op is only valid if it resides inside of a TargetOp
// and is the result of calling getInnermostCapturedOmpOp() on it.
@@ -2134,7 +2157,8 @@ TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
// Detect target-teams-distribute-parallel-wsloop[-simd].
if (numWrappers == 2) {
- if (!isa<WsloopOp>(innermostWrapper))
+ WsloopOp *wsloopOp = dyn_cast<WsloopOp>(innermostWrapper);
+ if (!wsloopOp)
return TargetRegionFlags::generic;
innermostWrapper = std::next(innermostWrapper);
@@ -2145,12 +2169,19 @@ TargetRegionFlags TargetOp::getKernelExecFlags(Operation *capturedOp) {
if (!isa_and_present<ParallelOp>(parallelOp))
return TargetRegionFlags::generic;
- Operation *teamsOp = parallelOp->getParentOp();
- if (!isa_and_present<TeamsOp>(teamsOp))
+ TeamsOp teamsOp = dyn_cast<TeamsOp>(parallelOp->getParentOp());
+ if (!teamsOp)
return TargetRegionFlags::generic;
- if (teamsOp->getParentOp() == targetOp.getOperation())
- return TargetRegionFlags::spmd | TargetRegionFlags::trip_count;
+ TargetRegionFlags result;
+
+ if (teamsOp->getParentOp() == targetOp.getOperation()) {
+ TargetRegionFlags result =
+ TargetRegionFlags::spmd | TargetRegionFlags::trip_count;
+ if (canPromoteToNoLoop(capturedOp, teamsOp, wsloopOp))
+ result = result | TargetRegionFlags::no_loop;
+ return result;
+ }
}
// Detect target-teams-distribute[-simd] and target-teams-loop.
else if (isa<DistributeOp, LoopOp>(innermostWrapper)) {
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index 6694de8383534..d67d5eb741543 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -2590,13 +2590,27 @@ convertOmpWsloop(Operation &opInst, llvm::IRBuilderBase &builder,
}
builder.SetInsertPoint(*regionBlock, (*regionBlock)->begin());
+
+ bool noLoopMode = false;
+ omp::TargetOp targetOp = wsloopOp->getParentOfType<mlir::omp::TargetOp>();
+ if (targetOp) {
+ Operation *targetCapturedOp = targetOp.getInnermostCapturedOmpOp();
+ omp::TargetRegionFlags kernelFlags =
+ targetOp.getKernelExecFlags(targetCapturedOp);
+ if (omp::bitEnumContainsAll(kernelFlags,
+ omp::TargetRegionFlags::spmd |
+ omp::TargetRegionFlags::no_loop) &&
+ !omp::bitEnumContainsAny(kernelFlags, omp::TargetRegionFlags::generic))
+ noLoopMode = true;
+ }
+
llvm::OpenMPIRBuilder::InsertPointOrErrorTy wsloopIP =
ompBuilder->applyWorkshareLoop(
ompLoc.DL, loopInfo, allocaIP, loopNeedsBarrier,
convertToScheduleKind(schedule), chunk, isSimd,
scheduleMod == omp::ScheduleModifier::monotonic,
scheduleMod == omp::ScheduleModifier::nonmonotonic, isOrdered,
- workshareLoopType);
+ workshareLoopType, noLoopMode);
if (failed(handleError(wsloopIP, opInst)))
return failure();
@@ -5365,6 +5379,12 @@ initTargetDefaultAttrs(omp::TargetOp targetOp, Operation *capturedOp,
? llvm::omp::OMP_TGT_EXEC_MODE_GENERIC_SPMD
: llvm::omp::OMP_TGT_EXEC_MODE_GENERIC
: llvm::omp::OMP_TGT_EXEC_MODE_SPMD;
+ if (omp::bitEnumContainsAll(kernelFlags,
+ omp::TargetRegionFlags::spmd |
+ omp::TargetRegionFlags::no_loop) &&
+ !omp::bitEnumContainsAny(kernelFlags, omp::TargetRegionFlags::generic))
+ attrs.ExecFlags = llvm::omp::OMP_TGT_EXEC_MODE_SPMD_NO_LOOP;
+
attrs.MinTeams = minTeamsVal;
attrs.MaxTeams.front() = maxTeamsVal;
attrs.MinThreads = 1;
diff --git a/offload/DeviceRTL/src/Workshare.cpp b/offload/DeviceRTL/src/Workshare.cpp
index 59a2cc3f27aca..653104ce883d1 100644
--- a/offload/DeviceRTL/src/Workshare.cpp
+++ b/offload/DeviceRTL/src/Workshare.cpp
@@ -800,10 +800,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more threads than iterations we can indicate that to
// avoid an outer loop.
- if (config::getAssumeThreadsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumThreads >= NumIters, "Broken assumption");
@@ -851,10 +847,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more blocks than iterations we can indicate that to
// avoid an outer loop.
- if (config::getAssumeTeamsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumBlocks >= NumIters, "Broken assumption");
@@ -914,11 +906,6 @@ template <typename Ty> class StaticLoopChunker {
// If we know we have more threads (across all blocks) than iterations we
// can indicate that to avoid an outer loop.
- if (config::getAssumeTeamsOversubscription() &
- config::getAssumeThreadsOversubscription()) {
- OneIterationPerThread = true;
- }
-
if (OneIterationPerThread)
ASSERT(NumBlocks * NumThreads >= NumIters, "Broken assumption");
diff --git a/offload/test/offloading/fortran/target-no-loop.f90 b/offload/test/offloading/fortran/target-no-loop.f90
new file mode 100644
index 0000000000000..dd2bf7c2196b6
--- /dev/null
+++ b/offload/test/offloading/fortran/target-no-loop.f90
@@ -0,0 +1,43 @@
+! Check if the first OpenMP GPU kernel is promoted to no-loop mode.
+! The second cannot be promoted due to the limit on the number of teams.
+! REQUIRES: flang, amdgpu
+
+! RUN: %libomptarget-compile-fortran-generic -O3 -fopenmp-assume-threads-oversubscription -fopenmp-assume-teams-oversubscription
+! RUN: env LIBOMPTARGET_INFO=16 %libomptarget-run-generic 2>&1 | %fcheck-generic
+program main
+ use omp_lib
+ implicit none
+ integer :: i
+ integer :: array(1024), errors = 0
+ array = 1
+
+ !$omp target teams distribute parallel do
+ do i = 1, 1024
+ array(i) = i
+ end do
+
+ do i = 1, 1024
+ if ( array( i) .ne. (i) ) then
+ errors = errors + 1
+ end if
+ end do
+
+ !$omp target teams distribute parallel do num_teams(3)
+ do i = 1, 1024
+ array(i) = i
+ end do
+
+ do i = 1, 1024
+ if ( array( i) .ne. (i) ) then
+ errors = errors + 1
+ end if
+ end do
+
+ print *,"number of errors: ", errors
+
+end program main
+
+! CHECK: "PluginInterface" device {{[0-9]+}} info: Launching kernel {{.*}} SPMD-No-Loop mode
+! CHECK: "PluginInterface" device {{[0-9]+}} info: Launching kernel {{.*}} SPMD mode
+! CHECK: number of errors: 0
+
|
Contributor
Author
dhruvachak
reviewed
Aug 28, 2025
| @@ -0,0 +1,43 @@ | |||
| ! Check if the first OpenMP GPU kernel is promoted to no-loop mode. | |||
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Please add more test cases showing thread_limit/num_threads clauses and envars OMP_NUM_TEAMS and OMP_TEAMS_THREAD_LIMIT. Additionally, tests with "omp teams" and "omp parallel". I know some of them are negative test cases but would be good to have.
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Done. Please see updated test.
skatrak
reviewed
Aug 29, 2025
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Thank you Dominik, I only checked your MLIR changes and have one comment.
| bool noLoopMode = false; | ||
| omp::TargetOp targetOp = wsloopOp->getParentOfType<mlir::omp::TargetOp>(); | ||
| if (targetOp) { | ||
| Operation *targetCapturedOp = targetOp.getInnermostCapturedOmpOp(); |
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Should we check here that the captured op is the omp.loop_nest wrapped by this omp.wsloop? The current implementation will set noLoopMode = true for both omp.wsloops generated by this code:
!$omp target teams distribute parallel do
do i=1,10
!$omp do
do j=1,i
end do
end doI'm not actually sure about what is the expected behavior of this, but I imagine that no-loop would just refer to the outer loop, as it's the one for which the trip count can be evaluated in the host.
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Hi Sergio,
thanks for your feedback:
Should we check here that the captured op is the omp.loop_nest wrapped by this omp.wsloop?
Yes. There is assumption in TargetRegionFlags TargetOp::getKernelExecFlags which checks if the argument is is the result of calling getInnermostCapturedOmpOp().
I'm not actually sure about what is the expected behavior of this, but I imagine that no-loop would just refer to the outer loop, as it's the one for which the trip count can be evaluated in the host.
There are 2 issues:
- Yes, your guess is right. The no-loop should refer only to the outer loop. I modified the OMPIRBuilder code to generate no-loop code only for distribute for static loop: 564410d#diff-a6c8db9d350ec59f4eb93f27f29468b01c9590426a11c9cb79e499bc96b28adc
- Currently Flang does not generate valid code for OpenMP kernel (the issue is not related to my patch):
!$omp target teams distribute parallel do
do i = 0,15
!$omp parallel do
do j = 1, 64
array(i* 64 + j) = i *64 + j
end do
!$omp end parallel do
end do
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Thank you for the clarifications, Dominik.
Yes. There is assumption in
TargetRegionFlags TargetOp::getKernelExecFlagswhich checks if the argument is is the result of callinggetInnermostCapturedOmpOp().
What I mean is adding something like this:
Operation *targetCapturedOp = targetOp.getInnermostCapturedOmpOp();
if (*loopOp == targetCapturedOp) {
omp::TargetRegionFlags kernelFlags = targetOp.getKernelExecFlags(targetCapturedOp);
...
}We need that because, if not, noLoopMode will also be set to true for every omp.wsloop nested inside of a no-loop SPMD target region, even if that loop is not the top-level SPMD one.
| }); | ||
| } | ||
|
|
||
| /// Check if we can promote SPMD kernel to No-Loop kernel |
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Suggested change
| /// Check if we can promote SPMD kernel to No-Loop kernel | |
| /// Check if we can promote SPMD kernel to No-Loop kernel. |
| /// Check if we can promote SPMD kernel to No-Loop kernel | ||
| static bool canPromoteToNoLoop(Operation *capturedOp, TeamsOp teamsOp, | ||
| WsloopOp *wsLoopOp) { | ||
| // num_teams clause can break no-loop teams/threads assumption |
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Suggested change
| // num_teams clause can break no-loop teams/threads assumption | |
| // num_teams clause can break no-loop teams/threads assumption. |
| // num_teams clause can break no-loop teams/threads assumption | ||
| if (teamsOp.getNumTeamsUpper()) | ||
| return false; | ||
| // reduction kernels are slower in no-loop mode |
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Suggested change
| // reduction kernels are slower in no-loop mode | |
| // Reduction kernels are slower in no-loop mode. |
| return false; | ||
| if (wsLoopOp->getNumReductionVars()) | ||
| return false; | ||
| // check if the user allows the promotion of kernels to no-loop mode |
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Suggested change
| // check if the user allows the promotion of kernels to no-loop mode | |
| // Check if the user allows the promotion of kernels to no-loop mode. |
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
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Meinersbur
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Sep 10, 2025
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Could you add somewhere an explanation what a "no-loop kernel" even is? Maybe in OpenMPEnums.td, but I don't know whether it is even used to create documentation like for MLIR.
Comment on lines
5007
to
5008
| } else | ||
| RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), 0)); |
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Suggested change
| } else | |
| RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), 0)); | |
| } else { | |
| RealArgs.push_back(ConstantInt::get(Builder.getInt8Ty(), 0)); | |
| } |
if/else chains should not use braced bodies for either all or none of its members
Comment on lines
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to
3850
| HelpText<"Allow enforcement to ensure there are enough teams to cover the " | ||
| "loop iteration space. It may ignore environment variables. " | ||
| "If the fopenmp-assume-teams-oversubscription and " | ||
| "fopenmp-assume-threads-oversubscription flags are set, Flang may " | ||
| "generate more optimized OpenMP kernels for target teams distribute " | ||
| "parallel do pragmas.">; | ||
| def fopenmp_assume_threads_oversubscription : Flag<["-"], "fopenmp-assume-threads-oversubscription">, | ||
| HelpText<"Assume threads oversubscription. If the " | ||
| "fopenmp-assume-teams-oversubscription and " | ||
| "fopenmp-assume-threads-oversubscription flags are set, Flang may " | ||
| "generate more optimized OpenMP kernels for target teams distribute " | ||
| "parallel do pragmas.">; |
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I find these HelpTexts more confusing than helpful. Proposal:
Allow the optimizer to discretely increase the number of teams/threads. May cause ignore environment variables that set the number of teams/threads to be ignored. The combination of -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription may allow the conversion of loops into sequential code by ensuring that each team/thread executes at most one iteration.
(please adapt as you see fit)
The name "assume_threads/teams_oversubscription" seems disconnected from this function at first, but I think it comes from allowing oversubscription, where the "subscription" is the number of available teams/threads as determined by thread_limit, num_teams, OMP_THREAD_LIMIT, etc., and threfore allowing the optimzer to oversubscribe this amount. Maybe there is a way to make the description more connected to the flag name.
Avoid "Flang" in the HelpText. It might also made available in Clang on day.
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Thanks for the feedback. I changed the description.
| @@ -0,0 +1,96 @@ | |||
| ! REQUIRES: flang, amdgpu | |||
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| ! REQUIRES: flang, amdgpu | |
| ! REQUIRES: flang |
Shouldn't this still be correct with nvidia GPUs?
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Yes, it should be correct with Nvida GPU. I fixed the test case.
Contributor
Author
Good point. I updated OpenMPEnums.td. |
Meinersbur
approved these changes
Sep 24, 2025
Comment on lines
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to
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| "These flags describe properties of the target kernel. " | ||
| "TargetRegionFlagsGeneric - denotes generic kernel. " | ||
| "TargetRegionFlagsSpmd - denotes SPMD kernel. " | ||
| "TargetRegionFlagsNoLoop - denotes kernel where " | ||
| "num_teams * num_threads >= loop_trip_count. It allows the conversion " | ||
| "of loops into sequential code by ensuring that each team/thread " | ||
| "executes at most one iteration. " | ||
| "TargetRegionFlagsTripCount - checks if the loop trip count should be " | ||
| "calculated.", [ |
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This syntx might be possible here:
Suggested change
| "These flags describe properties of the target kernel. " | |
| "TargetRegionFlagsGeneric - denotes generic kernel. " | |
| "TargetRegionFlagsSpmd - denotes SPMD kernel. " | |
| "TargetRegionFlagsNoLoop - denotes kernel where " | |
| "num_teams * num_threads >= loop_trip_count. It allows the conversion " | |
| "of loops into sequential code by ensuring that each team/thread " | |
| "executes at most one iteration. " | |
| "TargetRegionFlagsTripCount - checks if the loop trip count should be " | |
| "calculated.", [ | |
| [{ These flags describe properties of the target kernel. | |
| TargetRegionFlagsGeneric - denotes generic kernel. | |
| TargetRegionFlagsSpmd - denotes SPMD kernel. | |
| TargetRegionFlagsNoLoop - denotes kernel where | |
| num_teams * num_threads >= loop_trip_count. It allows the conversion | |
| of loops into sequential code by ensuring that each team/thread | |
| executes at most one iteration. | |
| TargetRegionFlagsTripCount - checks if the loop trip count should be | |
| calculated. }], [ |
This gets rendered has HTML (example: source render), will probably be a wall of text without line breaks. Don't know whether it is possible to use lists (markdown?)
This reverts commit 31f87cd.
Contributor
|
Apologies for the late notice. I see that one of our bots shows some of the testing here as failing Can you please have a look? Thank you! |
mahesh-attarde
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Oct 3, 2025
Enable the generation of no-loop kernels for Fortran OpenMP code. target teams distribute parallel do pragmas can be promoted to no-loop kernels if the user adds the -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription flags. If the OpenMP kernel contains reduction or num_teams clauses, it is not promoted to no-loop mode. The global OpenMP device RTL oversubscription flags no longer force no-loop code generation for Fortran.
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Enable the generation of no-loop kernels for Fortran OpenMP code. target teams distribute parallel do pragmas can be promoted to no-loop kernels if the user adds the -fopenmp-assume-teams-oversubscription and -fopenmp-assume-threads-oversubscription flags.
If the OpenMP kernel contains reduction or num_teams clauses, it is not promoted to no-loop mode.
The global OpenMP device RTL oversubscription flags no longer force no-loop code generation for Fortran.