From 9d50112acfc01f85fe0fb6d88b329e6122e817b3 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 2 Jul 2020 11:03:33 +0200 Subject: [PATCH] openmp: Diagnose non-rectangular loops with invalid steps THe OpenMP 5 standard requires that if some loop in OpenMP loop nest refers to some outer loop's iterator variable, then the subtraction of the multiplication factors for the outer iterator multiplied by the outer increment modulo the inner increment is 0. For loops with non-constants in any of these we can't diagnose it, it would be a task for something like -fsanitize=openmp, but if all these are constant, we can diagnose it. 2020-07-02 Jakub Jelinek * omp-expand.c (expand_omp_for): Diagnose non-rectangular loops with invalid steps - ((m2 - m1) * incr_outer) % incr must be 0 in valid OpenMP non-rectangular loops. Use XALLOCAVEC. * c-c++-common/gomp/loop-7.c: New test. --- gcc/omp-expand.c | 48 ++++++++++++++++++++++-- gcc/testsuite/c-c++-common/gomp/loop-7.c | 24 ++++++++++++ 2 files changed, 68 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/gomp/loop-7.c diff --git a/gcc/omp-expand.c b/gcc/omp-expand.c index 0f07e51f7e8..b1349d8f088 100644 --- a/gcc/omp-expand.c +++ b/gcc/omp-expand.c @@ -7122,15 +7122,55 @@ expand_omp_for (struct omp_region *region, gimple *inner_stmt) struct omp_for_data fd; struct omp_for_data_loop *loops; - loops - = (struct omp_for_data_loop *) - alloca (gimple_omp_for_collapse (last_stmt (region->entry)) - * sizeof (struct omp_for_data_loop)); + loops = XALLOCAVEC (struct omp_for_data_loop, + gimple_omp_for_collapse (last_stmt (region->entry))); omp_extract_for_data (as_a (last_stmt (region->entry)), &fd, loops); region->sched_kind = fd.sched_kind; region->sched_modifiers = fd.sched_modifiers; region->has_lastprivate_conditional = fd.lastprivate_conditional != 0; + if (fd.non_rect && !gimple_omp_for_combined_into_p (fd.for_stmt)) + { + for (int i = fd.first_nonrect; i <= fd.last_nonrect; i++) + if ((loops[i].m1 || loops[i].m2) + && (loops[i].m1 == NULL_TREE + || TREE_CODE (loops[i].m1) == INTEGER_CST) + && (loops[i].m2 == NULL_TREE + || TREE_CODE (loops[i].m2) == INTEGER_CST) + && TREE_CODE (loops[i].step) == INTEGER_CST + && TREE_CODE (loops[i - loops[i].outer].step) == INTEGER_CST) + { + tree t; + tree itype = TREE_TYPE (loops[i].v); + if (loops[i].m1 && loops[i].m2) + t = fold_build2 (MINUS_EXPR, itype, loops[i].m2, loops[i].m1); + else if (loops[i].m1) + t = fold_build1 (NEGATE_EXPR, itype, loops[i].m1); + else + t = loops[i].m2; + t = fold_build2 (MULT_EXPR, itype, t, + fold_convert (itype, + loops[i - loops[i].outer].step)); + if (TYPE_UNSIGNED (itype) && loops[i].cond_code == GT_EXPR) + t = fold_build2 (TRUNC_MOD_EXPR, itype, + fold_build1 (NEGATE_EXPR, itype, t), + fold_build1 (NEGATE_EXPR, itype, + fold_convert (itype, + loops[i].step))); + else + t = fold_build2 (TRUNC_MOD_EXPR, itype, t, + fold_convert (itype, loops[i].step)); + if (integer_nonzerop (t)) + error_at (gimple_location (fd.for_stmt), + "invalid OpenMP non-rectangular loop step; " + "%<(%E - %E) * %E%> is not a multiple of loop %d " + "step %qE", + loops[i].m2 ? loops[i].m2 : integer_zero_node, + loops[i].m1 ? loops[i].m1 : integer_zero_node, + loops[i - loops[i].outer].step, i + 1, + loops[i].step); + } + } gcc_assert (EDGE_COUNT (region->entry->succs) == 2); BRANCH_EDGE (region->entry)->flags &= ~EDGE_ABNORMAL; diff --git a/gcc/testsuite/c-c++-common/gomp/loop-7.c b/gcc/testsuite/c-c++-common/gomp/loop-7.c new file mode 100644 index 00000000000..4c8f27e76a5 --- /dev/null +++ b/gcc/testsuite/c-c++-common/gomp/loop-7.c @@ -0,0 +1,24 @@ +void +foo (void) +{ + #pragma omp for collapse(2) /* { dg-error "invalid OpenMP non-rectangular loop step" } */ + for (int i = 0; i < 6; i++) + for (int j = 4 * i; j < 7 * i; j += 2) + ; + #pragma omp for collapse(2) /* { dg-error "invalid OpenMP non-rectangular loop step" } */ + for (int i = 0; i < 32; i += 7) + for (int j = 3 * i; j < 7 * i; j += 30) + ; + #pragma omp for collapse(2) + for (int i = 0; i < 6; i++) + for (int j = 4 * i; j < 6 * i; j += 2) + ; + #pragma omp for collapse(2) + for (int i = 0; i < 6; i += 2) + for (int j = 4 * i; j < 7 * i; j += 2) + ; + #pragma omp for collapse(2) + for (int i = 0; i < 6; i += 5) + for (int j = 4 * i; j < 7 * i; j += 15) + ; +}