openmp: Fix placement of 2nd+ preparation statement for PHIs in simd clone lowering...

For normal stmts, preparation statements are inserted before the stmt, so if we need multiple,
they are in the correct order, but for PHIs we emit them after labels in the entry successor
bb, and we used to emit them in the reverse order that way.

2020-05-14  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/95108
	* omp-simd-clone.c (struct modify_stmt_info): Add after_stmt member.
	(ipa_simd_modify_stmt_ops): For PHIs, only add before first stmt in
	entry block if info->after_stmt is NULL, otherwise add after that stmt
	and update it after adding each stmt.
	(ipa_simd_modify_function_body): Initialize info.after_stmt.

	* gcc.dg/gomp/pr95108.c: New test.

(cherry picked from commit d0fb9ffc1b8f3b86bbdf0e915cec2136141b329b)

diff --git a/gcc/omp-simd-clone.c b/gcc/omp-simd-clone.c
index 71ff03412044406a9e3f804c64cc782a1d7d590a..09fdd6074321b219cc3679e423bc69a6ff9f4b4f 100644 (file)
--- a/gcc/omp-simd-clone.c
+++ b/gcc/omp-simd-clone.c
@@ -821,6 +821,7 @@ simd_clone_init_simd_arrays (struct cgraph_node *node,
 struct modify_stmt_info {
   ipa_param_body_adjustments *adjustments;
   gimple *stmt;
+  gimple *after_stmt;
   /* True if the parent statement was modified by
      ipa_simd_modify_stmt_ops.  */
   bool modified;
@@ -912,7 +913,10 @@ ipa_simd_modify_stmt_ops (tree *tp, int *walk_subtrees, void *data)
       gimple_stmt_iterator gsi;
       if (gimple_code (info->stmt) == GIMPLE_PHI)
        {
-         gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+         if (info->after_stmt)
+           gsi = gsi_for_stmt (info->after_stmt);
+         else
+           gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
          /* Cache SSA_NAME for next time.  */
          if (pbr
              && TREE_CODE (*orig_tp) == ADDR_EXPR
@@ -924,7 +928,12 @@ ipa_simd_modify_stmt_ops (tree *tp, int *walk_subtrees, void *data)
        }
       else
        gsi = gsi_for_stmt (info->stmt);
-      gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+      if (info->after_stmt)
+       gsi_insert_after (&gsi, stmt, GSI_SAME_STMT);
+      else
+       gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+      if (gimple_code (info->stmt) == GIMPLE_PHI)
+       info->after_stmt = stmt;
       *orig_tp = repl;
     }
   else if (!useless_type_conversion_p (TREE_TYPE (*tp), TREE_TYPE (repl)))
@@ -1015,6 +1024,7 @@ ipa_simd_modify_function_body (struct cgraph_node *node,
          gphi *phi = as_a <gphi *> (gsi_stmt (gsi));
          int i, n = gimple_phi_num_args (phi);
          info.stmt = phi;
+         info.after_stmt = NULL;
          struct walk_stmt_info wi;
          memset (&wi, 0, sizeof (wi));
          info.modified = false;
@@ -1040,6 +1050,7 @@ ipa_simd_modify_function_body (struct cgraph_node *node,
        {
          gimple *stmt = gsi_stmt (gsi);
          info.stmt = stmt;
+         info.after_stmt = NULL;
          struct walk_stmt_info wi;
 
          memset (&wi, 0, sizeof (wi));

diff --git a/gcc/testsuite/gcc.dg/gomp/pr95108.c b/gcc/testsuite/gcc.dg/gomp/pr95108.c
new file mode 100644 (file)
index 0000000..b492333
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gomp/pr95108.c
@@ -0,0 +1,18 @@
+/* PR middle-end/95108 */
+/* { dg-do compile { target vect_simd_clones } } */
+/* { dg-options "-O2 -fopenmp-simd -w" } */
+
+int *v;
+
+#pragma omp declare simd
+void
+foo (int x)
+{
+  int *a = &x + 1;
+
+  for (;;)
+    {
+      *v = *a;
+      a = v;
+    }
+}