[committed] Fix gimplification ICE with local VLA inside of simd body (PR middle-end/78884)

[Jakub Jelinek]

Hi!

This fixes an ICE in the gimplifier, for VLAs we really can't call
omp_add_variable with GOVD_PRIVATE before the DECL_EXPR is actually
gimplified.
Furthermore, there is really no hope in actually vectorizing such loops and
when we make it just GOVD_LOCAL, we shouldn't mark the loop as loop->safelen
> 1.

Bootstrapped/regtested on x86_64-linux and i686-linux, committed so far to
trunk.

2019-07-04  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/78884
        * gimplify.c (struct gimplify_omp_ctx): Add add_safelen1 member.
        (gimplify_bind_expr): If seeing TREE_ADDRESSABLE VLA inside of simd
        loop body, set ctx->add_safelen1 instead of making it GOVD_PRIVATE.
        (gimplify_adjust_omp_clauses): Add safelen (1) clause if
        ctx->add_safelen1 is set.

        * gcc.dg/gomp/pr78884.c: New test.

--- gcc/gimplify.c.jj   2019-07-03 06:55:33.562493081 +0200
+++ gcc/gimplify.c      2019-07-04 21:23:32.295352338 +0200
@@ -221,6 +221,7 @@ struct gimplify_omp_ctx
   bool combined_loop;
   bool distribute;
   bool target_firstprivatize_array_bases;
+  bool add_safelen1;
   int defaultmap[4];
 };
 
@@ -1331,12 +1332,17 @@ gimplify_bind_expr (tree *expr_p, gimple
                  || splay_tree_lookup (ctx->variables,
                                        (splay_tree_key) t) == NULL)
                {
+                 int flag = GOVD_LOCAL;
                  if (ctx->region_type == ORT_SIMD
                      && TREE_ADDRESSABLE (t)
                      && !TREE_STATIC (t))
-                   omp_add_variable (ctx, t, GOVD_PRIVATE | GOVD_SEEN);
-                 else
-                   omp_add_variable (ctx, t, GOVD_LOCAL | GOVD_SEEN);
+                   {
+                     if (TREE_CODE (DECL_SIZE_UNIT (t)) != INTEGER_CST)
+                       ctx->add_safelen1 = true;
+                     else
+                       flag = GOVD_PRIVATE;
+                   }
+                 omp_add_variable (ctx, t, flag | GOVD_SEEN);
                }
              /* Static locals inside of target construct or offloaded
                 routines need to be "omp declare target".  */
@@ -9801,6 +9807,18 @@ gimplify_adjust_omp_clauses (gimple_seq
        }
     }
 
+  if (ctx->add_safelen1)
+    {
+      /* If there are VLAs in the body of simd loop, prevent
+        vectorization.  */
+      gcc_assert (ctx->region_type == ORT_SIMD);
+      c = build_omp_clause (UNKNOWN_LOCATION, OMP_CLAUSE_SAFELEN);
+      OMP_CLAUSE_SAFELEN_EXPR (c) = integer_one_node;
+      OMP_CLAUSE_CHAIN (c) = *list_p;
+      *list_p = c;
+      list_p = &OMP_CLAUSE_CHAIN (c);
+    }
+
   if (ctx->region_type == ORT_WORKSHARE
       && ctx->outer_context
       && ctx->outer_context->region_type == ORT_COMBINED_PARALLEL)
--- gcc/testsuite/gcc.dg/gomp/pr78884.c.jj      2019-07-04 21:25:36.142391446 
+0200
+++ gcc/testsuite/gcc.dg/gomp/pr78884.c 2019-07-04 21:25:06.370862824 +0200
@@ -0,0 +1,16 @@
+/* PR middle-end/78884 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fopenmp" } */
+
+void bar (int *);
+
+void
+foo (int n)
+{
+#pragma omp simd
+  for (int i = 0; i < 1024; i++)
+    {
+      int vla[n];
+      bar (vla);
+    }
+}

        Jakub