[committed] openmp: Temporarily disable into_ssa when gimplifying OpenMP reduction clauses [PR99007]

[Jakub Jelinek]

Hi!

gimplify_scan_omp_clauses was already calling gimplify_expr with false as
last argument to make sure it is not an SSA_NAME, but as the testcases show,
that is not enough, SSA_NAME temporaries created during that gimplification
can be reused too and we can't allow SSA_NAMEs to be used across OpenMP
region boundaries, as we can only firstprivatize decls.

Fixed by temporarily disabling into_ssa.

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

2021-02-10  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/99007
	* gimplify.c (gimplify_scan_omp_clauses): For MEM_REF on reductions,
	temporarily disable gimplify_ctxp->into_ssa around gimplify_expr
	calls.

	* g++.dg/gomp/pr99007.C: New test.
	* gcc.dg/gomp/pr99007-1.c: New test.
	* gcc.dg/gomp/pr99007-2.c: New test.
	* gcc.dg/gomp/pr99007-3.c: New test.

--- gcc/gimplify.c.jj	2021-01-26 08:57:46.473172059 +0100
+++ gcc/gimplify.c	2021-02-09 17:15:29.391887803 +0100
@@ -8781,13 +8781,17 @@ gimplify_scan_omp_clauses (tree *list_p,
 	  if (TREE_CODE (decl) == MEM_REF)
 	    {
 	      tree type = TREE_TYPE (decl);
+	      bool saved_into_ssa = gimplify_ctxp->into_ssa;
+	      gimplify_ctxp->into_ssa = false;
 	      if (gimplify_expr (&TYPE_MAX_VALUE (TYPE_DOMAIN (type)), pre_p,
 				 NULL, is_gimple_val, fb_rvalue, false)
 		  == GS_ERROR)
 		{
+		  gimplify_ctxp->into_ssa = saved_into_ssa;
 		  remove = true;
 		  break;
 		}
+	      gimplify_ctxp->into_ssa = saved_into_ssa;
 	      tree v = TYPE_MAX_VALUE (TYPE_DOMAIN (type));
 	      if (DECL_P (v))
 		{
@@ -8797,13 +8801,16 @@ gimplify_scan_omp_clauses (tree *list_p,
 	      decl = TREE_OPERAND (decl, 0);
 	      if (TREE_CODE (decl) == POINTER_PLUS_EXPR)
 		{
+		  gimplify_ctxp->into_ssa = false;
 		  if (gimplify_expr (&TREE_OPERAND (decl, 1), pre_p,
 				     NULL, is_gimple_val, fb_rvalue, false)
 		      == GS_ERROR)
 		    {
+		      gimplify_ctxp->into_ssa = saved_into_ssa;
 		      remove = true;
 		      break;
 		    }
+		  gimplify_ctxp->into_ssa = saved_into_ssa;
 		  v = TREE_OPERAND (decl, 1);
 		  if (DECL_P (v))
 		    {
--- gcc/testsuite/g++.dg/gomp/pr99007.C.jj	2021-02-09 17:20:36.487454483 +0100
+++ gcc/testsuite/g++.dg/gomp/pr99007.C	2021-02-09 17:26:08.779739476 +0100
@@ -0,0 +1,18 @@
+// PR middle-end/99007
+// { dg-additional-options "-Wno-div-by-zero" }
+
+template <typename T>
+void
+bar (T *)
+{
+  T s[0/0];
+  #pragma omp teams distribute parallel for reduction(+:s) allocate(s)
+  for (int i = 0; i < 8; i++)
+    ;
+}
+
+void
+foo (long *a)
+{
+  bar (a);
+}
--- gcc/testsuite/gcc.dg/gomp/pr99007-1.c.jj	2021-02-09 17:22:57.456878452 +0100
+++ gcc/testsuite/gcc.dg/gomp/pr99007-1.c	2021-02-09 17:22:38.101094856 +0100
@@ -0,0 +1,13 @@
+/* PR middle-end/99007 */
+
+void
+bar (int n)
+{
+  int i;
+  long s[n];
+  for (i = 0; i < n; i++)
+    s[i] = 0;
+  #pragma omp teams distribute parallel for reduction(+:s) allocate(s)
+  for (i = 0; i < 8; i++)
+    s[3]++;
+}
--- gcc/testsuite/gcc.dg/gomp/pr99007-2.c.jj	2021-02-09 17:23:00.449844997 +0100
+++ gcc/testsuite/gcc.dg/gomp/pr99007-2.c	2021-02-09 17:22:44.682021286 +0100
@@ -0,0 +1,15 @@
+/* PR middle-end/99007 */
+
+int
+bar (int n)
+{
+  int s[n];
+  int i, j;
+  for (i = 0; i < n; i++)
+    s[i] = 0;
+  #pragma omp teams distribute parallel for reduction(+:s) private (j)
+  for (i = 0; i < 8; i++)
+    for (j = 0; j < n; j++)
+      s[j] += i;
+  return s[0] + s[n - 1];
+}
--- gcc/testsuite/gcc.dg/gomp/pr99007-3.c.jj	2021-02-09 17:23:03.315812951 +0100
+++ gcc/testsuite/gcc.dg/gomp/pr99007-3.c	2021-02-09 17:22:52.281936308 +0100
@@ -0,0 +1,16 @@
+/* PR middle-end/99007 */
+
+int
+bar (int n)
+{
+  int s[n];
+  int i, j;
+  for (i = 0; i < n; i++)
+    s[i] = 0;
+  #pragma omp parallel reduction(+:s) num_threads(2)
+  #pragma omp parallel for reduction(+:s) private (j)
+  for (i = 0; i < 8; i++)
+    for (j = 0; j < n; j++)
+      s[j] += i;
+  return s[0] + s[n - 1];
+}

	Jakub