[committed] Fix OpenMP array reduction handling in orphaned workshare (PR middle-end/80853)

[Jakub Jelinek]

Hi!

For pointer based array sections, we are not requiring the pointer to be
shared in outer context and it might be not shared (e.g. function argument
or just a private pointer initialized to point to something shared etc.),
which is right, but we shouldn't require it during lowering either.

This patch fixes ICE on it.  Bootstrapped/regtested on x86_64-linux and
i686-linux, committed to trunk, queued for release branches.

2017-05-22  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/80853
        * omp-low.c (lower_reduction_clauses): Pass OMP_CLAUSE_PRIVATE
        as last argument to build_outer_var_ref for pointer bases of array
        section reductions.

        * testsuite/libgomp.c/pr80853.c: New test.

--- gcc/omp-low.c.jj    2017-04-21 08:14:29.436790613 +0200
+++ gcc/omp-low.c       2017-05-22 11:34:51.085746641 +0200
@@ -5140,15 +5140,25 @@ lower_reduction_clauses (tree clauses, g
       if (OMP_CLAUSE_CODE (c) != OMP_CLAUSE_REDUCTION)
        continue;
 
+      enum omp_clause_code ccode = OMP_CLAUSE_REDUCTION;
       orig_var = var = OMP_CLAUSE_DECL (c);
       if (TREE_CODE (var) == MEM_REF)
        {
          var = TREE_OPERAND (var, 0);
          if (TREE_CODE (var) == POINTER_PLUS_EXPR)
            var = TREE_OPERAND (var, 0);
-         if (TREE_CODE (var) == INDIRECT_REF
-             || TREE_CODE (var) == ADDR_EXPR)
+         if (TREE_CODE (var) == ADDR_EXPR)
            var = TREE_OPERAND (var, 0);
+         else
+           {
+             /* If this is a pointer or referenced based array
+                section, the var could be private in the outer
+                context e.g. on orphaned loop construct.  Pretend this
+                is private variable's outer reference.  */
+             ccode = OMP_CLAUSE_PRIVATE;
+             if (TREE_CODE (var) == INDIRECT_REF)
+               var = TREE_OPERAND (var, 0);
+           }
          orig_var = var;
          if (is_variable_sized (var))
            {
@@ -5162,7 +5172,7 @@ lower_reduction_clauses (tree clauses, g
       new_var = lookup_decl (var, ctx);
       if (var == OMP_CLAUSE_DECL (c) && omp_is_reference (var))
        new_var = build_simple_mem_ref_loc (clause_loc, new_var);
-      ref = build_outer_var_ref (var, ctx);
+      ref = build_outer_var_ref (var, ctx, ccode);
       code = OMP_CLAUSE_REDUCTION_CODE (c);
 
       /* reduction(-:var) sums up the partial results, so it acts
--- libgomp/testsuite/libgomp.c/pr80853.c.jj    2017-05-22 11:28:50.060287195 
+0200
+++ libgomp/testsuite/libgomp.c/pr80853.c       2017-05-22 11:28:29.000000000 
+0200
@@ -0,0 +1,29 @@
+/* PR middle-end/80853 */
+/* { dg-do run } */
+
+__attribute__((noinline, noclone)) void
+foo (int *p)
+{
+  #pragma omp for reduction(+:p[:4])
+  for (int i = 0; i < 64; i++)
+    {
+      p[0] += i;
+      p[1] += i / 2;
+      p[2] += 2 * i;
+      p[3] += 3 * i;
+    }
+}
+
+int
+main ()
+{
+  int p[4] = { 0, 0, 0, 0 };
+  #pragma omp parallel
+  foo (p);
+  if (p[0] != 63 * 64 / 2
+      || p[1] != 31 * 32
+      || p[2] != 63 * 64
+      || p[3] != 3 * 63 * 64 / 2)
+    __builtin_abort ();
+  return 0;
+}

        Jakub