Author: Tom Eccles Date: 2025-04-29T17:19:40+01:00 New Revision: 7b70fc74d039dbb0c3c67feb1741bb5c446d55f7
URL: https://github.com/llvm/llvm-project/commit/7b70fc74d039dbb0c3c67feb1741bb5c446d55f7 DIFF: https://github.com/llvm/llvm-project/commit/7b70fc74d039dbb0c3c67feb1741bb5c446d55f7.diff LOG: [mlir][OpenMP] Convert omp.cancel sections to LLVMIR (#137193) This is quite ugly but it is the best I could think of. The old FiniCBWrapper was way too brittle depending upon the exact block structure inside of the section, and could be confused by any control flow in the section (e.g. an if clause on cancel). The wording in the comment and variable names didn't seem to match where it was actually branching too as well. Clang's (non-OpenMPIRBuilder) lowering for cancel inside of sections branches to a block containing __kmpc_for_static_fini. This was hard to achieve here because sometimes the FiniCBWrapper has to run before the worksharing loop finalization has been crated. To get around this ordering issue I created a dummy branch to a dummy block, which is then fixed later once all of the information is available. Added: Modified: clang/lib/CodeGen/CGStmtOpenMP.cpp llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp mlir/test/Target/LLVMIR/openmp-cancel.mlir mlir/test/Target/LLVMIR/openmp-todo.mlir Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp index 156f64bb5f508..cd3ded088ee27 100644 --- a/clang/lib/CodeGen/CGStmtOpenMP.cpp +++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp @@ -4345,8 +4345,9 @@ void CodeGenFunction::EmitOMPSectionsDirective(const OMPSectionsDirective &S) { using InsertPointTy = llvm::OpenMPIRBuilder::InsertPointTy; using BodyGenCallbackTy = llvm::OpenMPIRBuilder::StorableBodyGenCallbackTy; - auto FiniCB = [this](InsertPointTy IP) { - OMPBuilderCBHelpers::FinalizeOMPRegion(*this, IP); + auto FiniCB = [](InsertPointTy IP) { + // Don't FinalizeOMPRegion because this is done inside of OMPIRBuilder for + // sections. return llvm::Error::success(); }; diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp index 5afb580190914..8dc6ea175e0dc 100644 --- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp +++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp @@ -2172,6 +2172,9 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::createSections( if (!updateToLocation(Loc)) return Loc.IP; + // FiniCBWrapper needs to create a branch to the loop finalization block, but + // this has not been created yet at some times when this callback runs. + SmallVector<BranchInst *> CancellationBranches; auto FiniCBWrapper = [&](InsertPointTy IP) { if (IP.getBlock()->end() != IP.getPoint()) return FiniCB(IP); @@ -2179,16 +2182,9 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::createSections( // will fail because that function requires the Finalization Basic Block to // have a terminator, which is already removed by EmitOMPRegionBody. // IP is currently at cancelation block. - // We need to backtrack to the condition block to fetch - // the exit block and create a branch from cancelation - // to exit block. - IRBuilder<>::InsertPointGuard IPG(Builder); - Builder.restoreIP(IP); - auto *CaseBB = IP.getBlock()->getSinglePredecessor(); - auto *CondBB = CaseBB->getSinglePredecessor()->getSinglePredecessor(); - auto *ExitBB = CondBB->getTerminator()->getSuccessor(1); - Instruction *I = Builder.CreateBr(ExitBB); - IP = InsertPointTy(I->getParent(), I->getIterator()); + BranchInst *DummyBranch = Builder.CreateBr(IP.getBlock()); + IP = InsertPointTy(DummyBranch->getParent(), DummyBranch->getIterator()); + CancellationBranches.push_back(DummyBranch); return FiniCB(IP); }; @@ -2251,6 +2247,9 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::createSections( return WsloopIP.takeError(); InsertPointTy AfterIP = *WsloopIP; + BasicBlock *LoopFini = AfterIP.getBlock()->getSinglePredecessor(); + assert(LoopFini && "Bad structure of static workshare loop finalization"); + // Apply the finalization callback in LoopAfterBB auto FiniInfo = FinalizationStack.pop_back_val(); assert(FiniInfo.DK == OMPD_sections && @@ -2264,6 +2263,12 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::createSections( AfterIP = {FiniBB, FiniBB->begin()}; } + // Now we can fix the dummy branch to point to the right place + for (BranchInst *DummyBranch : CancellationBranches) { + assert(DummyBranch->getNumSuccessors() == 1); + DummyBranch->setSuccessor(0, LoopFini); + } + return AfterIP; } diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp index 02ef0a5511ff3..16c93f902d9ec 100644 --- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp +++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp @@ -161,7 +161,8 @@ static LogicalResult checkImplementationStatus(Operation &op) { auto checkCancelDirective = [&todo](auto op, LogicalResult &result) { omp::ClauseCancellationConstructType cancelledDirective = op.getCancelDirective(); - if (cancelledDirective != omp::ClauseCancellationConstructType::Parallel) + if (cancelledDirective != omp::ClauseCancellationConstructType::Parallel && + cancelledDirective != omp::ClauseCancellationConstructType::Sections) result = todo("cancel directive construct type not yet supported"); }; auto checkDepend = [&todo](auto op, LogicalResult &result) { @@ -1688,10 +1689,11 @@ convertOmpSections(Operation &opInst, llvm::IRBuilderBase &builder, auto finiCB = [&](InsertPointTy codeGenIP) { return llvm::Error::success(); }; allocaIP = findAllocaInsertPoint(builder, moduleTranslation); + bool isCancellable = constructIsCancellable(sectionsOp); llvm::OpenMPIRBuilder::LocationDescription ompLoc(builder); llvm::OpenMPIRBuilder::InsertPointOrErrorTy afterIP = moduleTranslation.getOpenMPBuilder()->createSections( - ompLoc, allocaIP, sectionCBs, privCB, finiCB, false, + ompLoc, allocaIP, sectionCBs, privCB, finiCB, isCancellable, sectionsOp.getNowait()); if (failed(handleError(afterIP, opInst))) diff --git a/mlir/test/Target/LLVMIR/openmp-cancel.mlir b/mlir/test/Target/LLVMIR/openmp-cancel.mlir index 1f67d6ceb34af..fca16b936fc85 100644 --- a/mlir/test/Target/LLVMIR/openmp-cancel.mlir +++ b/mlir/test/Target/LLVMIR/openmp-cancel.mlir @@ -80,3 +80,79 @@ llvm.func @cancel_parallel_if(%arg0 : i1) { // CHECK: br label %[[VAL_23]] // CHECK: omp.par.exit.exitStub: ; preds = %[[VAL_31]], %[[VAL_26]] // CHECK: ret void + +llvm.func @cancel_sections_if(%cond : i1) { + omp.sections { + omp.section { + omp.cancel cancellation_construct_type(sections) if(%cond) + omp.terminator + } + omp.terminator + } + llvm.return +} +// CHECK-LABEL: define void @cancel_sections_if +// CHECK: %[[VAL_0:.*]] = alloca i32, align 4 +// CHECK: %[[VAL_1:.*]] = alloca i32, align 4 +// CHECK: %[[VAL_2:.*]] = alloca i32, align 4 +// CHECK: %[[VAL_3:.*]] = alloca i32, align 4 +// CHECK: br label %[[VAL_4:.*]] +// CHECK: entry: ; preds = %[[VAL_5:.*]] +// CHECK: br label %[[VAL_6:.*]] +// CHECK: omp_section_loop.preheader: ; preds = %[[VAL_4]] +// CHECK: store i32 0, ptr %[[VAL_1]], align 4 +// CHECK: store i32 0, ptr %[[VAL_2]], align 4 +// CHECK: store i32 1, ptr %[[VAL_3]], align 4 +// CHECK: %[[VAL_7:.*]] = call i32 @__kmpc_global_thread_num(ptr @1) +// CHECK: call void @__kmpc_for_static_init_4u(ptr @1, i32 %[[VAL_7]], i32 34, ptr %[[VAL_0]], ptr %[[VAL_1]], ptr %[[VAL_2]], ptr %[[VAL_3]], i32 1, i32 0) +// CHECK: %[[VAL_8:.*]] = load i32, ptr %[[VAL_1]], align 4 +// CHECK: %[[VAL_9:.*]] = load i32, ptr %[[VAL_2]], align 4 +// CHECK: %[[VAL_10:.*]] = sub i32 %[[VAL_9]], %[[VAL_8]] +// CHECK: %[[VAL_11:.*]] = add i32 %[[VAL_10]], 1 +// CHECK: br label %[[VAL_12:.*]] +// CHECK: omp_section_loop.header: ; preds = %[[VAL_13:.*]], %[[VAL_6]] +// CHECK: %[[VAL_14:.*]] = phi i32 [ 0, %[[VAL_6]] ], [ %[[VAL_15:.*]], %[[VAL_13]] ] +// CHECK: br label %[[VAL_16:.*]] +// CHECK: omp_section_loop.cond: ; preds = %[[VAL_12]] +// CHECK: %[[VAL_17:.*]] = icmp ult i32 %[[VAL_14]], %[[VAL_11]] +// CHECK: br i1 %[[VAL_17]], label %[[VAL_18:.*]], label %[[VAL_19:.*]] +// CHECK: omp_section_loop.body: ; preds = %[[VAL_16]] +// CHECK: %[[VAL_20:.*]] = add i32 %[[VAL_14]], %[[VAL_8]] +// CHECK: %[[VAL_21:.*]] = mul i32 %[[VAL_20]], 1 +// CHECK: %[[VAL_22:.*]] = add i32 %[[VAL_21]], 0 +// CHECK: switch i32 %[[VAL_22]], label %[[VAL_23:.*]] [ +// CHECK: i32 0, label %[[VAL_24:.*]] +// CHECK: ] +// CHECK: omp_section_loop.body.case: ; preds = %[[VAL_18]] +// CHECK: br label %[[VAL_25:.*]] +// CHECK: omp.section.region: ; preds = %[[VAL_24]] +// CHECK: br i1 %[[VAL_26:.*]], label %[[VAL_27:.*]], label %[[VAL_28:.*]] +// CHECK: 9: ; preds = %[[VAL_25]] +// CHECK: %[[VAL_29:.*]] = call i32 @__kmpc_global_thread_num(ptr @1) +// CHECK: %[[VAL_30:.*]] = call i32 @__kmpc_cancel(ptr @1, i32 %[[VAL_29]], i32 3) +// CHECK: %[[VAL_31:.*]] = icmp eq i32 %[[VAL_30]], 0 +// CHECK: br i1 %[[VAL_31]], label %[[VAL_32:.*]], label %[[VAL_33:.*]] +// CHECK: .split: ; preds = %[[VAL_27]] +// CHECK: br label %[[VAL_34:.*]] +// CHECK: 12: ; preds = %[[VAL_25]] +// CHECK: br label %[[VAL_34]] +// CHECK: 13: ; preds = %[[VAL_28]], %[[VAL_32]] +// CHECK: br label %[[VAL_35:.*]] +// CHECK: omp.region.cont: ; preds = %[[VAL_34]] +// CHECK: br label %[[VAL_23]] +// CHECK: omp_section_loop.body.sections.after: ; preds = %[[VAL_35]], %[[VAL_18]] +// CHECK: br label %[[VAL_13]] +// CHECK: omp_section_loop.inc: ; preds = %[[VAL_23]] +// CHECK: %[[VAL_15]] = add nuw i32 %[[VAL_14]], 1 +// CHECK: br label %[[VAL_12]] +// CHECK: omp_section_loop.exit: ; preds = %[[VAL_33]], %[[VAL_16]] +// CHECK: call void @__kmpc_for_static_fini(ptr @1, i32 %[[VAL_7]]) +// CHECK: %[[VAL_36:.*]] = call i32 @__kmpc_global_thread_num(ptr @1) +// CHECK: call void @__kmpc_barrier(ptr @2, i32 %[[VAL_36]]) +// CHECK: br label %[[VAL_37:.*]] +// CHECK: omp_section_loop.after: ; preds = %[[VAL_19]] +// CHECK: br label %[[VAL_38:.*]] +// CHECK: omp_section_loop.aftersections.fini: ; preds = %[[VAL_37]] +// CHECK: ret void +// CHECK: .cncl: ; preds = %[[VAL_27]] +// CHECK: br label %[[VAL_19]] diff --git a/mlir/test/Target/LLVMIR/openmp-todo.mlir b/mlir/test/Target/LLVMIR/openmp-todo.mlir index a408a5a9c8682..0cc96deacd954 100644 --- a/mlir/test/Target/LLVMIR/openmp-todo.mlir +++ b/mlir/test/Target/LLVMIR/openmp-todo.mlir @@ -42,22 +42,6 @@ llvm.func @cancel_wsloop(%lb : i32, %ub : i32, %step: i32) { // ----- -llvm.func @cancel_sections() { - // expected-error@below {{LLVM Translation failed for operation: omp.sections}} - omp.sections { - omp.section { - // expected-error@below {{not yet implemented: Unhandled clause cancel directive construct type not yet supported in omp.cancel operation}} - // expected-error@below {{LLVM Translation failed for operation: omp.cancel}} - omp.cancel cancellation_construct_type(sections) - omp.terminator - } - omp.terminator - } - llvm.return -} - -// ----- - llvm.func @cancel_taskgroup() { // expected-error@below {{LLVM Translation failed for operation: omp.taskgroup}} omp.taskgroup { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
