Re: [PATCH] openmp: fix UBSAN error at gcc/fortran/openmp.c:4737

[Tobias Burnus]

On 8/17/20 11:15 AM, Martin Liška wrote:

I'm suggesting one more clean up that uses static assert
instead of a run-time check.

I concur that compile-time checks are nicer.
LGTM – it should be able catch this kind of mistakes.

Tobias

Thoughts?
Martin

0001-opnemp-add-static-assert-for-clause_names.patch

 From c9aee2c44d5cf7e417d381988b2f4900e9ea8b05 Mon Sep 17 00:00:00 2001
From: Martin Liska<mli...@suse.cz>
Date: Mon, 17 Aug 2020 11:14:13 +0200
Subject: [PATCH] opnemp: add static assert for clause_names.

gcc/fortran/ChangeLog:

      * openmp.c (resolve_omp_clauses): Add static assert
      for OMP_LIST_NUM and size of clause_names array.
      Remove check that is always true.
---
  gcc/fortran/openmp.c | 8 ++------
  1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/gcc/fortran/openmp.c b/gcc/fortran/openmp.c
index 60d8e5573c2..4d33a450a33 100644
--- a/gcc/fortran/openmp.c
+++ b/gcc/fortran/openmp.c
@@ -4371,6 +4371,7 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses 
*omp_clauses,
      "TO", "FROM", "REDUCTION", "DEVICE_RESIDENT", "LINK", "USE_DEVICE",
      "CACHE", "IS_DEVICE_PTR", "USE_DEVICE_PTR", "USE_DEVICE_ADDR",
      "NONTEMPORAL" };
+  STATIC_ASSERT (ARRAY_SIZE (clause_names) == OMP_LIST_NUM);

    if (omp_clauses == NULL)
      return;
@@ -4732,12 +4733,7 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses 
*omp_clauses,
    for (list = 0; list < OMP_LIST_NUM; list++)
      if ((n = omp_clauses->lists[list]) != NULL)
        {
-     const char *name;
-
-     if (list < OMP_LIST_NUM)
-       name = clause_names[list];
-     else
-       gcc_unreachable ();
+     const char *name = clause_names[list];

      switch (list)
        {
-- 2.28.0

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