https://github.com/ro-i created https://github.com/llvm/llvm-project/pull/191627
Fixes https://github.com/llvm/llvm-project/issues/191549. Assisted-by: claude-4.6-opus ------------------------------- Note: I'm currently not very familiar with this portion of the code, so while the fix is tiny, I'm not sure it's the right approach. I just wanted to check the reason for the bug and since it seemed not that troublesome to fix/review, I thought that I might still go ahead and create this patch. >From ff8463a83568ecee8caecee6be2d1236c84694b4 Mon Sep 17 00:00:00 2001 From: Robert Imschweiler <[email protected]> Date: Sat, 11 Apr 2026 07:19:06 -0500 Subject: [PATCH] [OpenMP] Fix nondependent inscan variables in templated functions Fixes https://github.com/llvm/llvm-project/issues/191549. Assisted-by: claude-4.6-opus --- clang/lib/Sema/SemaOpenMP.cpp | 4 + .../scan_inscan_template_nondependent.cpp | 63 ++++++++++++++++ .../for/omp_scan_inscan_template.cpp | 73 +++++++++++++++++++ 3 files changed, 140 insertions(+) create mode 100644 clang/test/OpenMP/scan_inscan_template_nondependent.cpp create mode 100644 openmp/runtime/test/worksharing/for/omp_scan_inscan_template.cpp diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp index 73cbc7a428661..cdeca15872a95 100644 --- a/clang/lib/Sema/SemaOpenMP.cpp +++ b/clang/lib/Sema/SemaOpenMP.cpp @@ -20498,6 +20498,10 @@ static bool actOnOMPReductionKindClause( (DeclareReductionRef.isUnset() || isa<UnresolvedLookupExpr>(DeclareReductionRef.get()))) { RD.push(RefExpr, DeclareReductionRef.get()); + // Handle non-dependent inscan reduction variables in dependent contexts. + if (RD.RedModifier == OMPC_REDUCTION_inscan) + Stack->addDSA(D, RefExpr->IgnoreParens(), OMPC_reduction, nullptr, + RD.RedModifier, ASE || OASE); continue; } if (BOK == BO_Comma && DeclareReductionRef.isUnset()) { diff --git a/clang/test/OpenMP/scan_inscan_template_nondependent.cpp b/clang/test/OpenMP/scan_inscan_template_nondependent.cpp new file mode 100644 index 0000000000000..b56c1b3f50a8c --- /dev/null +++ b/clang/test/OpenMP/scan_inscan_template_nondependent.cpp @@ -0,0 +1,63 @@ +// RUN: %clang_cc1 -verify -fopenmp -std=c++17 %s +// RUN: %clang_cc1 -verify -fopenmp-simd -std=c++17 %s +// expected-no-diagnostics + +// Regression test for https://github.com/llvm/llvm-project/issues/191549 +// Inscan reductions with non-dependent types in function templates were +// incorrectly rejected because the DSA stack was not populated in +// dependent contexts. + +template <typename T> +void exclusive_in_template() { + int a[100], b[100]; + int sum = 0; + #pragma omp parallel for reduction(inscan, +: sum) + for (int i = 0; i < 100; i++) { + a[i] = sum; + #pragma omp scan exclusive(sum) + sum += b[i]; + } +} + +template <typename T> +void inclusive_in_template() { + int a[100], b[100]; + int sum = 0; + #pragma omp parallel for reduction(inscan, +: sum) + for (int i = 0; i < 100; i++) { + sum += b[i]; + #pragma omp scan inclusive(sum) + a[i] = sum; + } +} + +template <typename T> +void for_simd_inscan_in_template() { + int a[100], b[100]; + int sum = 0; + #pragma omp parallel for simd reduction(inscan, +: sum) + for (int i = 0; i < 100; i++) { + a[i] = sum; + #pragma omp scan exclusive(sum) + sum += b[i]; + } +} + +template <typename T> +void simd_inscan_in_template() { + int a[100], b[100]; + int sum = 0; + #pragma omp simd reduction(inscan, +: sum) + for (int i = 0; i < 100; i++) { + a[i] = sum; + #pragma omp scan exclusive(sum) + sum += b[i]; + } +} + +void instantiate() { + exclusive_in_template<int>(); + inclusive_in_template<int>(); + for_simd_inscan_in_template<int>(); + simd_inscan_in_template<int>(); +} diff --git a/openmp/runtime/test/worksharing/for/omp_scan_inscan_template.cpp b/openmp/runtime/test/worksharing/for/omp_scan_inscan_template.cpp new file mode 100644 index 0000000000000..685a18967b58b --- /dev/null +++ b/openmp/runtime/test/worksharing/for/omp_scan_inscan_template.cpp @@ -0,0 +1,73 @@ +// RUN: %libomp-cxx-compile-and-run | FileCheck %s + +// Regression test for https://github.com/llvm/llvm-project/issues/191549 +// Inscan reductions with non-dependent types inside function templates were +// rejected by Clang because the DSA stack was not populated in dependent +// contexts. This test verifies runtime correctness of both exclusive and +// inclusive scans in template functions. + +#include <cstdlib> +#include <numeric> +#include <stdio.h> + +#define N 100 + +template <typename T> bool test_exclusive(T *a, const T *b) { + int sum = 0; +#pragma omp parallel for reduction(inscan, + : sum) + for (int i = 0; i < N; i++) { + a[i] = sum; +#pragma omp scan exclusive(sum) + sum += b[i]; + } + + for (int i = 0, prefix = 0; i < N; i++) { + if (a[i] != prefix) + return false; + prefix += b[i]; + } + return true; +} + +template <typename T> bool test_inclusive(T *a, const T *b) { + int sum = 0; +#pragma omp parallel for reduction(inscan, + : sum) + for (int i = 0; i < N; i++) { + sum += b[i]; +#pragma omp scan inclusive(sum) + a[i] = sum; + } + + for (int i = 0, prefix = 0; i < N; i++) { + prefix += b[i]; + if (a[i] != prefix) + return false; + } + return true; +} + +int main() { + bool success = true; + + int a[N], b[N]; + std::iota(b, b + N, 1); + + if (test_exclusive<int>(a, b)) { + printf("exclusive: PASS\n"); + } else { + printf("exclusive: FAIL\n"); + success = false; + } + + if (test_inclusive<int>(a, b)) { + printf("inclusive: PASS\n"); + } else { + printf("inclusive: FAIL\n"); + success = false; + } + + return success ? EXIT_SUCCESS : EXIT_FAILURE; +} + +// CHECK: exclusive: PASS +// CHECK: inclusive: PASS _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
