https://github.com/Saieiei updated https://github.com/llvm/llvm-project/pull/167879
>From dc87da3f106c3e16f17144674bdfd237e288b010 Mon Sep 17 00:00:00 2001 From: Sairudra More <[email protected]> Date: Thu, 13 Nov 2025 07:46:56 -0600 Subject: [PATCH] [OpenMP] Fix firstprivate pointer handling in target regions Firstprivate pointers in OpenMP target regions were not being lowered correctly, causing the runtime to perform unnecessary present table lookups instead of passing pointer values directly. This patch adds the OMP_MAP_LITERAL flag for firstprivate pointers, enabling the runtime to pass pointer values directly without lookups. The fix handles both explicit firstprivate clauses and implicit firstprivate semantics from defaultmap clauses. Key changes: - Track defaultmap(firstprivate:...) clauses in MappableExprsHandler - Add isEffectivelyFirstprivate() to check both explicit and implicit firstprivate semantics - Apply OMP_MAP_LITERAL flag to firstprivate pointers in generateDefaultMapInfo() Map type values: - 288 = OMP_MAP_TARGET_PARAM | OMP_MAP_LITERAL (explicit firstprivate) - 800 = OMP_MAP_TARGET_PARAM | OMP_MAP_LITERAL | OMP_MAP_IS_PTR (implicit firstprivate from defaultmap) Before: Pointers got 544 (TARGET_PARAM | IS_PTR) causing runtime lookups After: Pointers get 288 or 800 (includes LITERAL) for direct pass --- clang/lib/CodeGen/CGOpenMPRuntime.cpp | 80 +++++++-- .../target_firstprivate_pointer_codegen.cpp | 169 ++++++++++++++++++ 2 files changed, 237 insertions(+), 12 deletions(-) create mode 100644 clang/test/OpenMP/target_firstprivate_pointer_codegen.cpp diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp index 1224fa681cdc0..a00ee4cd743e9 100644 --- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp +++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp @@ -7210,6 +7210,9 @@ class MappableExprsHandler { /// firstprivate, false otherwise. llvm::DenseMap<CanonicalDeclPtr<const VarDecl>, bool> FirstPrivateDecls; + /// Set of defaultmap clause kinds that use firstprivate behavior. + llvm::DenseSet<OpenMPDefaultmapClauseKind> DefaultmapFirstprivateKinds; + /// Map between device pointer declarations and their expression components. /// The key value for declarations in 'this' is null. llvm::DenseMap< @@ -8988,6 +8991,12 @@ class MappableExprsHandler { FirstPrivateDecls.try_emplace(VD, /*Implicit=*/true); } } + // Extract defaultmap clause information. + for (const auto *C : Dir.getClausesOfKind<OMPDefaultmapClause>()) { + if (C->getDefaultmapModifier() == OMPC_DEFAULTMAP_MODIFIER_firstprivate) { + DefaultmapFirstprivateKinds.insert(C->getDefaultmapKind()); + } + } // Extract device pointer clause information. for (const auto *C : Dir.getClausesOfKind<OMPIsDevicePtrClause>()) for (auto L : C->component_lists()) @@ -9565,6 +9574,38 @@ class MappableExprsHandler { } } + /// Check if a variable should be treated as firstprivate due to explicit + /// firstprivate clause or defaultmap(firstprivate:...). + bool isEffectivelyFirstprivate(const VarDecl *VD, QualType Type) const { + // Check explicit firstprivate clauses + if (FirstPrivateDecls.count(VD)) + return true; + + // Check defaultmap(firstprivate:scalar) for scalar types + if (DefaultmapFirstprivateKinds.count(OMPC_DEFAULTMAP_scalar)) { + if (Type->isScalarType()) + return true; + } + + // Check defaultmap(firstprivate:pointer) for pointer types + if (DefaultmapFirstprivateKinds.count(OMPC_DEFAULTMAP_pointer)) { + if (Type->isAnyPointerType()) + return true; + } + + // Check defaultmap(firstprivate:aggregate) for aggregate types + if (DefaultmapFirstprivateKinds.count(OMPC_DEFAULTMAP_aggregate)) { + if (Type->isAggregateType()) + return true; + } + + // Check defaultmap(firstprivate:all) for all types + if (DefaultmapFirstprivateKinds.count(OMPC_DEFAULTMAP_all)) + return true; + + return false; + } + /// Generate the default map information for a given capture \a CI, /// record field declaration \a RI and captured value \a CV. void generateDefaultMapInfo(const CapturedStmt::Capture &CI, @@ -9592,6 +9633,9 @@ class MappableExprsHandler { CombinedInfo.DevicePtrDecls.push_back(nullptr); CombinedInfo.DevicePointers.push_back(DeviceInfoTy::None); CombinedInfo.Pointers.push_back(CV); + bool isFirstprivate = + isEffectivelyFirstprivate(VD, RI.getType().getNonReferenceType()); + if (!RI.getType()->isAnyPointerType()) { // We have to signal to the runtime captures passed by value that are // not pointers. @@ -9599,6 +9643,13 @@ class MappableExprsHandler { OpenMPOffloadMappingFlags::OMP_MAP_LITERAL); CombinedInfo.Sizes.push_back(CGF.Builder.CreateIntCast( CGF.getTypeSize(RI.getType()), CGF.Int64Ty, /*isSigned=*/true)); + } else if (isFirstprivate) { + // Firstprivate pointers should be passed by value (as literals) + // without performing a present table lookup at runtime. + CombinedInfo.Types.push_back( + OpenMPOffloadMappingFlags::OMP_MAP_LITERAL); + // Use zero size for pointer literals (just passing the pointer value) + CombinedInfo.Sizes.push_back(llvm::Constant::getNullValue(CGF.Int64Ty)); } else { // Pointers are implicitly mapped with a zero size and no flags // (other than first map that is added for all implicit maps). @@ -9612,26 +9663,31 @@ class MappableExprsHandler { assert(CI.capturesVariable() && "Expected captured reference."); const auto *PtrTy = cast<ReferenceType>(RI.getType().getTypePtr()); QualType ElementType = PtrTy->getPointeeType(); - CombinedInfo.Sizes.push_back(CGF.Builder.CreateIntCast( - CGF.getTypeSize(ElementType), CGF.Int64Ty, /*isSigned=*/true)); - // The default map type for a scalar/complex type is 'to' because by - // default the value doesn't have to be retrieved. For an aggregate - // type, the default is 'tofrom'. - CombinedInfo.Types.push_back(getMapModifiersForPrivateClauses(CI)); const VarDecl *VD = CI.getCapturedVar(); - auto I = FirstPrivateDecls.find(VD); + bool isFirstprivate = isEffectivelyFirstprivate(VD, ElementType); CombinedInfo.Exprs.push_back(VD->getCanonicalDecl()); CombinedInfo.BasePointers.push_back(CV); CombinedInfo.DevicePtrDecls.push_back(nullptr); CombinedInfo.DevicePointers.push_back(DeviceInfoTy::None); - if (I != FirstPrivateDecls.end() && ElementType->isAnyPointerType()) { - Address PtrAddr = CGF.EmitLoadOfReference(CGF.MakeAddrLValue( - CV, ElementType, CGF.getContext().getDeclAlign(VD), - AlignmentSource::Decl)); - CombinedInfo.Pointers.push_back(PtrAddr.emitRawPointer(CGF)); + + // For firstprivate pointers, pass by value instead of dereferencing + if (isFirstprivate && ElementType->isAnyPointerType()) { + // Treat as a literal value (pass the pointer value itself) + CombinedInfo.Pointers.push_back(CV); + // Use zero size for pointer literals + CombinedInfo.Sizes.push_back(llvm::Constant::getNullValue(CGF.Int64Ty)); + CombinedInfo.Types.push_back( + OpenMPOffloadMappingFlags::OMP_MAP_LITERAL); } else { + CombinedInfo.Sizes.push_back(CGF.Builder.CreateIntCast( + CGF.getTypeSize(ElementType), CGF.Int64Ty, /*isSigned=*/true)); + // The default map type for a scalar/complex type is 'to' because by + // default the value doesn't have to be retrieved. For an aggregate + // type, the default is 'tofrom'. + CombinedInfo.Types.push_back(getMapModifiersForPrivateClauses(CI)); CombinedInfo.Pointers.push_back(CV); } + auto I = FirstPrivateDecls.find(VD); if (I != FirstPrivateDecls.end()) IsImplicit = I->getSecond(); } diff --git a/clang/test/OpenMP/target_firstprivate_pointer_codegen.cpp b/clang/test/OpenMP/target_firstprivate_pointer_codegen.cpp new file mode 100644 index 0000000000000..326bc812d7d33 --- /dev/null +++ b/clang/test/OpenMP/target_firstprivate_pointer_codegen.cpp @@ -0,0 +1,169 @@ +// RUN: %clang_cc1 -verify -fopenmp -fopenmp-targets=powerpc64le-ibm-linux-gnu -x c++ -triple powerpc64le-unknown-unknown -emit-llvm %s -o - | FileCheck %s +// RUN: %clang_cc1 -fopenmp -fopenmp-targets=powerpc64le-ibm-linux-gnu -x c++ -std=c++11 -triple powerpc64le-unknown-unknown -emit-pch -o %t %s +// RUN: %clang_cc1 -fopenmp -fopenmp-targets=powerpc64le-ibm-linux-gnu -x c++ -triple powerpc64le-unknown-unknown -std=c++11 -include-pch %t -verify %s -emit-llvm -o - | FileCheck %s +// expected-no-diagnostics + +#ifndef HEADER +#define HEADER + +/// ======================================================================== +/// Test: Firstprivate pointer handling in OpenMP target regions +/// ======================================================================== +/// +/// This test verifies that pointers with firstprivate semantics get the +/// OMP_MAP_LITERAL flag, enabling the runtime to pass pointer values directly +/// without performing present table lookups. +/// +/// Map type values: +/// 288 = OMP_MAP_TARGET_PARAM (32) + OMP_MAP_LITERAL (256) +/// Used for explicit firstprivate(ptr) +/// +/// 800 = OMP_MAP_TARGET_PARAM (32) + OMP_MAP_LITERAL (256) + OMP_MAP_IS_PTR (512) +/// Used for implicit firstprivate pointers (e.g., from defaultmap clauses) +/// Note: 512 is OMP_MAP_IS_PTR, not IMPLICIT. Implicitness is tracked separately. +/// +/// 544 = OMP_MAP_TARGET_PARAM (32) + OMP_MAP_IS_PTR (512) +/// Incorrect behavior - missing LITERAL flag, causes runtime present table lookup +/// + +///========================================================================== +/// Test 1: Explicit firstprivate(pointer) → map type 288 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{[^.]*}} = private unnamed_addr constant [1 x i64] [i64 288] +// CHECK-DAG: @.offload_sizes{{[^.]*}} = private unnamed_addr constant [1 x i64] zeroinitializer + +void test1_explicit_firstprivate() { + double *ptr = nullptr; + + // Explicit firstprivate should generate map type 288 + // (TARGET_PARAM | LITERAL, no IS_PTR flag for explicit clauses) + #pragma omp target firstprivate(ptr) + { + if (ptr) ptr[0] = 1.0; + } +} + +///========================================================================== +/// Test 2: defaultmap(firstprivate:pointer) → map type 800 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 800] +// CHECK-DAG: @.offload_sizes{{.*}} = private unnamed_addr constant [1 x i64] zeroinitializer + +void test2_defaultmap_firstprivate_pointer() { + double *ptr = nullptr; + + // defaultmap(firstprivate:pointer) creates implicit firstprivate + // Should generate map type 800 (TARGET_PARAM | LITERAL | IS_PTR) + #pragma omp target defaultmap(firstprivate:pointer) + { + if (ptr) ptr[0] = 2.0; + } +} + +///========================================================================== +/// Test 3: defaultmap(firstprivate:scalar) with double → map type 800 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 800] + +void test3_defaultmap_scalar_double() { + double d = 3.0; + + // OpenMP's "scalar" category excludes pointers but includes arithmetic types + // Double gets implicit firstprivate → map type 800 + #pragma omp target defaultmap(firstprivate:scalar) + { + d += 1.0; + } +} + +///========================================================================== +/// Test 4: Pointer with defaultmap(firstprivate:scalar) → map type 800 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 800] +// CHECK-DAG: @.offload_sizes{{.*}} = private unnamed_addr constant [1 x i64] zeroinitializer + +void test4_pointer_with_scalar_defaultmap() { + double *ptr = nullptr; + + // Note: defaultmap(firstprivate:scalar) does NOT apply to pointers (scalar excludes pointers). + // However, the pointer still gets 800 because in OpenMP 5.0+, pointers without explicit + // data-sharing attributes are implicitly firstprivate and lowered as IS_PTR|LITERAL|TARGET_PARAM. + // This is the default pointer behavior, NOT due to the scalar defaultmap. + #pragma omp target defaultmap(firstprivate:scalar) + { + if (ptr) ptr[0] = 4.0; + } +} + +///========================================================================== +/// Test 5: Multiple pointers with explicit firstprivate → all get 288 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [3 x i64] [i64 288, i64 288, i64 288] +// CHECK-DAG: @.offload_sizes{{.*}} = private unnamed_addr constant [3 x i64] zeroinitializer + +void test5_multiple_firstprivate() { + int *a = nullptr; + float *b = nullptr; + double *c = nullptr; + + // All explicit firstprivate pointers get map type 288 + #pragma omp target firstprivate(a, b, c) + { + if (a) a[0] = 6; + if (b) b[0] = 7.0f; + if (c) c[0] = 8.0; + } +} + +///========================================================================== +/// Test 6: Pointer to const with firstprivate → map type 288 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 288] +// CHECK-DAG: @.offload_sizes{{.*}} = private unnamed_addr constant [1 x i64] zeroinitializer + +void test6_const_pointer() { + const double *const_ptr = nullptr; + + // Const pointer with explicit firstprivate → 288 + #pragma omp target firstprivate(const_ptr) + { + if (const_ptr) { + double val = const_ptr[0]; + (void)val; + } + } +} + +///========================================================================== +/// Test 7: Pointer-to-pointer with firstprivate → map type 288 +///========================================================================== + +// CHECK-DAG: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 288] +// CHECK-DAG: @.offload_sizes{{.*}} = private unnamed_addr constant [1 x i64] zeroinitializer + +void test7_pointer_to_pointer() { + int **pp = nullptr; + + // Pointer-to-pointer with explicit firstprivate → 288 + #pragma omp target firstprivate(pp) + { + if (pp && *pp) (*pp)[0] = 9; + } +} + +///========================================================================== +/// Verification: The key fix is that firstprivate pointers now include +/// the LITERAL flag (256), which tells the runtime to pass the pointer +/// value directly instead of performing a present table lookup. +/// +/// Before fix: Pointers got 544 (TARGET_PARAM | IS_PTR) → runtime lookup +/// After fix: Pointers get 288 or 800 (includes LITERAL) → direct pass +///========================================================================== + +#endif // HEADER _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
