[Mlir-commits] [mlir] [WIP][OpenMP][MLIR] Lowering task_reduction clause for pass-by-value vars to LLVMIR (PR #125218)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Fri Jan 31 05:21:29 PST 2025
https://github.com/NimishMishra created https://github.com/llvm/llvm-project/pull/125218
None
>From ae5fdaa9e3263f4602b4baa12a018c461302cbbd Mon Sep 17 00:00:00 2001
From: Nimish Mishra <neelam.nimish at gmail.com>
Date: Tue, 28 Jan 2025 16:25:51 +0530
Subject: [PATCH] [OpenMP][MLIR] Lowering task_reduction clause for
pass-by-value vars to LLVMIR
---
.../mlir/Dialect/OpenMP/OpenMPClauses.td | 5 +
.../OpenMP/OpenMPToLLVMIRTranslation.cpp | 233 +++++++++++++++++-
.../Target/LLVMIR/openmp-task-reduction.mlir | 79 ++++++
mlir/test/Target/LLVMIR/openmp-todo.mlir | 28 ---
4 files changed, 307 insertions(+), 38 deletions(-)
create mode 100644 mlir/test/Target/LLVMIR/openmp-task-reduction.mlir
diff --git a/mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td b/mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td
index a8d97a36df79ee..d7986bc074639a 100644
--- a/mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td
+++ b/mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td
@@ -1321,6 +1321,11 @@ class OpenMP_TaskReductionClauseSkip<
unsigned numTaskReductionBlockArgs() {
return getTaskReductionVars().size();
}
+
+ /// Returns the number of reduction variables.
+ unsigned getNumReductionVars() { return getReductionVars().size(); }
+
+ auto getReductionSyms() { return getTaskReductionSyms(); }
}];
let description = [{
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index eb873fd1b7f6fe..386d695ef0228a 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -245,11 +245,6 @@ static LogicalResult checkImplementationStatus(Operation &op) {
op.getReductionMod().value() != omp::ReductionModifier::defaultmod)
result = todo("reduction with modifier");
};
- auto checkTaskReduction = [&todo](auto op, LogicalResult &result) {
- if (!op.getTaskReductionVars().empty() || op.getTaskReductionByref() ||
- op.getTaskReductionSyms())
- result = todo("task_reduction");
- };
auto checkUntied = [&todo](auto op, LogicalResult &result) {
if (op.getUntied())
result = todo("untied");
@@ -276,10 +271,7 @@ static LogicalResult checkImplementationStatus(Operation &op) {
checkAllocate(op, result);
checkInReduction(op, result);
})
- .Case([&](omp::TaskgroupOp op) {
- checkAllocate(op, result);
- checkTaskReduction(op, result);
- })
+ .Case([&](omp::TaskgroupOp op) { checkAllocate(op, result); })
.Case([&](omp::TaskwaitOp op) {
checkDepend(op, result);
checkNowait(op, result);
@@ -1817,6 +1809,212 @@ convertOmpTaskOp(omp::TaskOp taskOp, llvm::IRBuilderBase &builder,
return success();
}
+template <typename OP>
+llvm::Value *createTaskReductionFunction(
+ llvm::IRBuilderBase &builder, const std::string &name, llvm::Type *redTy,
+ LLVM::ModuleTranslation &moduleTranslation,
+ SmallVectorImpl<omp::DeclareReductionOp> &reductionDecls, Region ®ion,
+ OP &op, unsigned Cnt, llvm::ArrayRef<bool> &isByRef,
+ SmallVectorImpl<llvm::Value *> &privateReductionVariables,
+ DenseMap<Value, llvm::Value *> &reductionVariableMap) {
+
+ llvm::LLVMContext &Context = builder.getContext();
+ // TODO: by-ref reduction variables are yet to be handled.
+ llvm::Type *OpaquePtrTy = llvm::PointerType::get(Context, 0);
+ if (region.empty() && name == "red_fini")
+ // Finalization is optional for reductions.
+ return llvm::Constant::getNullValue(OpaquePtrTy);
+ llvm::FunctionType *funcType =
+ llvm::FunctionType::get(OpaquePtrTy, {OpaquePtrTy, OpaquePtrTy}, false);
+ llvm::Function *function =
+ llvm::Function::Create(funcType, llvm::Function::ExternalLinkage, name,
+ builder.GetInsertBlock()->getModule());
+ function->setDoesNotRecurse();
+ llvm::BasicBlock *entry =
+ llvm::BasicBlock::Create(Context, "entry", function);
+ llvm::IRBuilder<> bbBuilder(entry);
+
+ llvm::Value *arg0 = function->getArg(0);
+ llvm::Value *arg1 = function->getArg(1);
+
+ if (name == "red_init") {
+ function->addParamAttr(0, llvm::Attribute::NoAlias);
+ function->addParamAttr(1, llvm::Attribute::NoAlias);
+ mapInitializationArgs(op, moduleTranslation, reductionDecls,
+ reductionVariableMap, Cnt);
+ } else if (name == "red_comb") {
+ llvm::Value *arg0L = bbBuilder.CreateLoad(redTy, arg0);
+ llvm::Value *arg1L = bbBuilder.CreateLoad(redTy, arg1);
+ moduleTranslation.mapValue(region.front().getArgument(0), arg0L);
+ moduleTranslation.mapValue(region.front().getArgument(1), arg1L);
+ }
+ if (region.empty() || isByRef[Cnt]) {
+ // Emit en empty function body in case of empty region or pass-by-reference
+ // vars
+ // TODO: Add support for translating pass-by-reference vars.
+ bbBuilder.CreateRet(arg0); // Return from the function
+ return function;
+ }
+
+ SmallVector<llvm::Value *, 1> phis;
+ if (failed(inlineConvertOmpRegions(region, "", bbBuilder, moduleTranslation,
+ &phis)))
+ return nullptr;
+ assert(
+ phis.size() == 1 &&
+ "expected one value to be yielded from the reduction declaration region");
+ bbBuilder.CreateStore(phis[0], arg0);
+ bbBuilder.CreateRet(arg0); // Return from the function
+ return function;
+}
+
+void emitTaskRedInitCall(
+ llvm::IRBuilderBase &builder, LLVM::ModuleTranslation &moduleTranslation,
+ const llvm::OpenMPIRBuilder::LocationDescription &ompLoc, int arraySize,
+ llvm::Value *ArrayAlloca) {
+
+ llvm::LLVMContext &Context = builder.getContext();
+ uint32_t SrcLocStrSize;
+ llvm::Constant *SrcLocStr =
+ moduleTranslation.getOpenMPBuilder()->getOrCreateSrcLocStr(ompLoc,
+ SrcLocStrSize);
+ llvm::Value *Ident = moduleTranslation.getOpenMPBuilder()->getOrCreateIdent(
+ SrcLocStr, SrcLocStrSize);
+ llvm::Value *ThreadID =
+ moduleTranslation.getOpenMPBuilder()->getOrCreateThreadID(Ident);
+ llvm::Constant *ConstInt =
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(Context), arraySize);
+
+ llvm::Function *TaskRedInitFn =
+ moduleTranslation.getOpenMPBuilder()->getOrCreateRuntimeFunctionPtr(
+ llvm::omp::OMPRTL___kmpc_taskred_init);
+ builder.CreateCall(TaskRedInitFn, {ThreadID, ConstInt, ArrayAlloca});
+}
+
+template <typename OP>
+static LogicalResult allocAndInitializeTaskReductionVars(
+ OP op, ArrayRef<BlockArgument> reductionArgs, llvm::IRBuilderBase &builder,
+ LLVM::ModuleTranslation &moduleTranslation,
+ llvm::OpenMPIRBuilder::InsertPointTy &allocaIP,
+ SmallVectorImpl<omp::DeclareReductionOp> &reductionDecls,
+ SmallVectorImpl<llvm::Value *> &privateReductionVariables,
+ DenseMap<Value, llvm::Value *> &reductionVariableMap,
+ llvm::ArrayRef<bool> isByRef) {
+
+ if (op.getNumReductionVars() == 0)
+ return success();
+
+ llvm::OpenMPIRBuilder::LocationDescription ompLoc(builder);
+ llvm::LLVMContext &Context = builder.getContext();
+ SmallVector<DeferredStore> deferredStores;
+
+ // Save the current insertion point
+ auto oldIP = builder.saveIP();
+
+ // Set insertion point after the allocations
+ builder.SetInsertPoint(allocaIP.getBlock()->getTerminator());
+
+ // Define the kmp_taskred_input_t structure
+ llvm::StructType *kmp_taskred_input_t =
+ llvm::StructType::create(Context, "kmp_taskred_input_t");
+ llvm::Type *OpaquePtrTy = llvm::PointerType::get(Context, 0); // void*
+ llvm::Type *SizeTy = builder.getInt64Ty(); // size_t (assumed to be i64)
+ llvm::Type *FlagsTy = llvm::Type::getInt32Ty(Context); // flags (i32)
+
+ // Structure members
+ std::vector<llvm::Type *> structMembers = {
+ OpaquePtrTy, // reduce_shar (void*)
+ OpaquePtrTy, // reduce_orig (void*)
+ SizeTy, // reduce_size (size_t)
+ OpaquePtrTy, // reduce_init (void*)
+ OpaquePtrTy, // reduce_fini (void*)
+ OpaquePtrTy, // reduce_comb (void*)
+ FlagsTy // flags (i32)
+ };
+
+ kmp_taskred_input_t->setBody(structMembers);
+ int arraySize = op.getNumReductionVars();
+ llvm::ArrayType *ArrayTy =
+ llvm::ArrayType::get(kmp_taskred_input_t, arraySize);
+
+ // Allocate the array for kmp_taskred_input_t
+ llvm::AllocaInst *ArrayAlloca =
+ builder.CreateAlloca(ArrayTy, nullptr, "kmp_taskred_array");
+
+ // Restore the insertion point
+ builder.restoreIP(oldIP);
+ llvm::DataLayout DL = builder.GetInsertBlock()->getModule()->getDataLayout();
+
+ for (int Cnt = 0; Cnt < arraySize; ++Cnt) {
+ llvm::Value *shared =
+ moduleTranslation.lookupValue(op.getReductionVars()[Cnt]);
+ // Create a GEP to access the reduction element
+ llvm::Value *StructPtr = builder.CreateGEP(
+ ArrayTy, ArrayAlloca, {builder.getInt32(0), builder.getInt32(Cnt)},
+ "red_element");
+
+ llvm::Value *FieldPtrReduceShar = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 0, "reduce_shar");
+ builder.CreateStore(shared, FieldPtrReduceShar);
+
+ llvm::Value *FieldPtrReduceOrig = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 1, "reduce_orig");
+ builder.CreateStore(shared, FieldPtrReduceOrig);
+
+ // Store size of the reduction variable
+ llvm::Value *FieldPtrReduceSize = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 2, "reduce_size");
+ llvm::Type *redTy;
+ if (auto *alloca = dyn_cast<llvm::AllocaInst>(shared)) {
+ redTy = alloca->getAllocatedType();
+ uint64_t sizeInBytes = DL.getTypeAllocSize(redTy);
+
+ llvm::ConstantInt *sizeConst =
+ llvm::ConstantInt::get(llvm::Type::getInt64Ty(Context), sizeInBytes);
+ builder.CreateStore(sizeConst, FieldPtrReduceSize);
+ } else {
+ llvm_unreachable("Non alloca instruction found.");
+ }
+
+ // Initialize reduction variable
+ llvm::Value *FieldPtrReduceInit = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 3, "reduce_init");
+ llvm::Value *initFunction = createTaskReductionFunction(
+ builder, "red_init", redTy, moduleTranslation, reductionDecls,
+ reductionDecls[Cnt].getInitializerRegion(), op, Cnt, isByRef,
+ privateReductionVariables, reductionVariableMap);
+ builder.CreateStore(initFunction, FieldPtrReduceInit);
+
+ // Create finish and combine functions
+ llvm::Value *FieldPtrReduceFini = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 4, "reduce_fini");
+ llvm::Value *finiFunction = createTaskReductionFunction(
+ builder, "red_fini", redTy, moduleTranslation, reductionDecls,
+ reductionDecls[Cnt].getCleanupRegion(), op, Cnt, isByRef,
+ privateReductionVariables, reductionVariableMap);
+ builder.CreateStore(finiFunction, FieldPtrReduceFini);
+
+ llvm::Value *FieldPtrReduceComb = builder.CreateStructGEP(
+ kmp_taskred_input_t, StructPtr, 5, "reduce_comb");
+ llvm::Value *combFunction = createTaskReductionFunction(
+ builder, "red_comb", redTy, moduleTranslation, reductionDecls,
+ reductionDecls[Cnt].getReductionRegion(), op, Cnt, isByRef,
+ privateReductionVariables, reductionVariableMap);
+ builder.CreateStore(combFunction, FieldPtrReduceComb);
+
+ llvm::Value *FieldPtrFlags =
+ builder.CreateStructGEP(kmp_taskred_input_t, StructPtr, 6, "flags");
+ llvm::ConstantInt *flagVal =
+ llvm::ConstantInt::get(llvm::Type::getInt64Ty(Context), 0);
+ builder.CreateStore(flagVal, FieldPtrFlags);
+ }
+
+ // Emit the runtime call
+ emitTaskRedInitCall(builder, moduleTranslation, ompLoc, arraySize,
+ ArrayAlloca);
+ return success();
+}
+
/// Converts an OpenMP taskgroup construct into LLVM IR using OpenMPIRBuilder.
static LogicalResult
convertOmpTaskgroupOp(omp::TaskgroupOp tgOp, llvm::IRBuilderBase &builder,
@@ -1825,8 +2023,23 @@ convertOmpTaskgroupOp(omp::TaskgroupOp tgOp, llvm::IRBuilderBase &builder,
if (failed(checkImplementationStatus(*tgOp)))
return failure();
+ llvm::ArrayRef<bool> isByRef = getIsByRef(tgOp.getTaskReductionByref());
+ assert(isByRef.size() == tgOp.getNumReductionVars());
+ SmallVector<omp::DeclareReductionOp> reductionDecls;
+ collectReductionDecls(tgOp, reductionDecls);
+ SmallVector<llvm::Value *> privateReductionVariables(
+ tgOp.getNumReductionVars());
+ DenseMap<Value, llvm::Value *> reductionVariableMap;
+ MutableArrayRef<BlockArgument> reductionArgs =
+ tgOp.getRegion().getArguments();
+ LogicalResult bodyGenStatus = success();
auto bodyCB = [&](InsertPointTy allocaIP, InsertPointTy codegenIP) {
builder.restoreIP(codegenIP);
+ if (failed(allocAndInitializeTaskReductionVars(
+ tgOp, reductionArgs, builder, moduleTranslation, allocaIP,
+ reductionDecls, privateReductionVariables, reductionVariableMap,
+ isByRef)))
+ bodyGenStatus = failure();
return convertOmpOpRegions(tgOp.getRegion(), "omp.taskgroup.region",
builder, moduleTranslation)
.takeError();
@@ -1842,7 +2055,7 @@ convertOmpTaskgroupOp(omp::TaskgroupOp tgOp, llvm::IRBuilderBase &builder,
return failure();
builder.restoreIP(*afterIP);
- return success();
+ return bodyGenStatus;
}
static LogicalResult
diff --git a/mlir/test/Target/LLVMIR/openmp-task-reduction.mlir b/mlir/test/Target/LLVMIR/openmp-task-reduction.mlir
new file mode 100644
index 00000000000000..1d4d22d5413c61
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/openmp-task-reduction.mlir
@@ -0,0 +1,79 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+omp.declare_reduction @add_reduction_i32 : i32 init {
+^bb0(%arg0: i32):
+ %0 = llvm.mlir.constant(0 : i32) : i32
+ omp.yield(%0 : i32)
+} combiner {
+^bb0(%arg0: i32, %arg1: i32):
+ %0 = llvm.add %arg0, %arg1 : i32
+ omp.yield(%0 : i32)
+}
+llvm.func @_QPtest_task_reduciton() {
+ %0 = llvm.mlir.constant(1 : i64) : i64
+ %1 = llvm.alloca %0 x i32 {bindc_name = "x"} : (i64) -> !llvm.ptr
+ omp.taskgroup task_reduction(@add_reduction_i32 %1 -> %arg0 : !llvm.ptr) {
+ %2 = llvm.load %1 : !llvm.ptr -> i32
+ %3 = llvm.mlir.constant(1 : i32) : i32
+ %4 = llvm.add %2, %3 : i32
+ llvm.store %4, %1 : i32, !llvm.ptr
+ omp.terminator
+ }
+ llvm.return
+}
+
+//CHECK-LABEL: define void @_QPtest_task_reduciton() {
+//CHECK: %[[VAL1:.*]] = alloca i32, i64 1, align 4
+//CHECK: %[[RED_ARRY:.*]] = alloca [1 x %kmp_taskred_input_t], align 8
+//CHECK: br label %entry
+
+//CHECK: entry:
+//CHECK: %[[TID:.*]] = call i32 @__kmpc_global_thread_num(ptr @{{.*}})
+//CHECK: call void @__kmpc_taskgroup(ptr @1, i32 %[[TID]])
+//CHECK: %[[RED_ELEMENT:.*]] = getelementptr [1 x %kmp_taskred_input_t], ptr %[[RED_ARRY]], i32 0, i32 0
+//CHECK: %[[RED_SHARED:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 0
+//CHECK: store ptr %[[VAL1]], ptr %[[RED_SHARED]], align 8
+//CHECK: %[[RED_ORIG:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 1
+//CHECK: store ptr %[[VAL1]], ptr %[[RED_ORIG]], align 8
+//CHECK: %[[RED_SIZE:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 2
+//CHECK: store i64 4, ptr %[[RED_SIZE]], align 4
+//CHECK: %[[RED_INIT:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 3
+//CHECK: store ptr @red_init, ptr %[[RED_INIT]], align 8
+//CHECK: %[[RED_FINI:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 4
+//CHECK: store ptr null, ptr %[[RED_FINI]], align 8
+//CHECK: %[[RED_COMB:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 5
+//CHECK: store ptr @red_comb, ptr %[[RED_COMB]], align 8
+//CHECK: %[[FLAGS:.*]] = getelementptr inbounds nuw %kmp_taskred_input_t, ptr %[[RED_ELEMENT]], i32 0, i32 6
+//CHECK: store i64 0, ptr %[[FLAGS]], align 4
+//CHECK: %[[TID1:.*]] = call i32 @__kmpc_global_thread_num(ptr @{{.*}})
+//CHECK: %2 = call ptr @__kmpc_taskred_init(i32 %[[TID1]], i32 1, ptr %[[RED_ARRY]])
+//CHECK: br label %omp.taskgroup.region
+
+//CHECK: omp.taskgroup.region:
+//CHECK: %[[VAL3:.*]] = load i32, ptr %[[VAL1]], align 4
+//CHECK: %4 = add i32 %[[VAL3]], 1
+//CHECK: store i32 %4, ptr %[[VAL1]], align 4
+//CHECK: br label %omp.region.cont
+
+//CHECK: omp.region.cont:
+//CHECK: br label %taskgroup.exit
+
+//CHECK: taskgroup.exit:
+//CHECK: call void @__kmpc_end_taskgroup(ptr @{{.+}}, i32 %[[TID]])
+//CHECK: ret void
+//CHECK: }
+
+//CHECK-LABEL: define ptr @red_init(ptr noalias %0, ptr noalias %1) #2 {
+//CHECK: entry:
+//CHECK: store i32 0, ptr %0, align 4
+//CHECK: ret ptr %0
+//CHECK: }
+
+//CHECK-LABEL: define ptr @red_comb(ptr %0, ptr %1) #2 {
+//CHECK: entry:
+//CHECK: %[[LD0:.*]] = load i32, ptr %0, align 4
+//CHECK: %[[LD1:.*]] = load i32, ptr %1, align 4
+//CHECK: %[[RES:.*]] = add i32 %[[LD0]], %[[LD1]]
+//CHECK: store i32 %[[RES]], ptr %0, align 4
+//CHECK: ret ptr %0
+//CHECK: }
diff --git a/mlir/test/Target/LLVMIR/openmp-todo.mlir b/mlir/test/Target/LLVMIR/openmp-todo.mlir
index 457bb87fae27ad..1e407e648fb29c 100644
--- a/mlir/test/Target/LLVMIR/openmp-todo.mlir
+++ b/mlir/test/Target/LLVMIR/openmp-todo.mlir
@@ -442,34 +442,6 @@ llvm.func @taskgroup_allocate(%x : !llvm.ptr) {
// -----
-omp.declare_reduction @add_f32 : f32
-init {
-^bb0(%arg: f32):
- %0 = llvm.mlir.constant(0.0 : f32) : f32
- omp.yield (%0 : f32)
-}
-combiner {
-^bb1(%arg0: f32, %arg1: f32):
- %1 = llvm.fadd %arg0, %arg1 : f32
- omp.yield (%1 : f32)
-}
-atomic {
-^bb2(%arg2: !llvm.ptr, %arg3: !llvm.ptr):
- %2 = llvm.load %arg3 : !llvm.ptr -> f32
- llvm.atomicrmw fadd %arg2, %2 monotonic : !llvm.ptr, f32
- omp.yield
-}
-llvm.func @taskgroup_task_reduction(%x : !llvm.ptr) {
- // expected-error at below {{not yet implemented: Unhandled clause task_reduction in omp.taskgroup operation}}
- // expected-error at below {{LLVM Translation failed for operation: omp.taskgroup}}
- omp.taskgroup task_reduction(@add_f32 %x -> %prv : !llvm.ptr) {
- omp.terminator
- }
- llvm.return
-}
-
-// -----
-
llvm.func @taskloop(%lb : i32, %ub : i32, %step : i32) {
// expected-error at below {{not yet implemented: omp.taskloop}}
// expected-error at below {{LLVM Translation failed for operation: omp.taskloop}}
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