re PR tree-optimization/82129 (ICE in compute_antic, at tree-ssa-pre.c:2447)

2017-10-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/82129
	* tree-ssa-pre.c (bitmap_set_and): Remove.
	(compute_antic_aux): Compute ANTIC_OUT intersection in a way
	canonicalizing expressions in the set to those with lowest
	ID rather than taking that from the first edge.

	* gcc.dg/torture/pr82129.c: New testcase.

From-SVN: r253998

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6caddb8..28052db 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2017-10-23  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/82129
+       * tree-ssa-pre.c (bitmap_set_and): Remove.
+       (compute_antic_aux): Compute ANTIC_OUT intersection in a way
+       canonicalizing expressions in the set to those with lowest
+       ID rather than taking that from the first edge.
+
 2017-10-23  Richard Sandiford  <richard.sandiford@linaro.org>
 
        * combine.c (rtx_equal_for_field_assignment_p): Use

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f14930b..9ca1131 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-10-23  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/82129
+       * gcc.dg/torture/pr82129.c: New testcase.
+
 2017-10-22  Uros Bizjak  <ubizjak@gmail.com>
 
        PR target/52451

diff --git a/gcc/testsuite/gcc.dg/torture/pr82129.c b/gcc/testsuite/gcc.dg/torture/pr82129.c
new file mode 100644 (file)
index 0000000..b116149
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr82129.c
@@ -0,0 +1,52 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-ftree-pre" } */
+
+int pj;
+
+void
+g4 (unsigned long int *bc, unsigned long int *h5)
+{
+  if (pj != 0)
+    {
+      int ib = 0;
+
+      while (bc != 0)
+       {
+m6:
+         for (pj = 0; pj < 2; ++pj)
+           pj = 0;
+
+         while (pj != 0)
+           {
+             for (;;)
+               {
+               }
+
+             while (ib != 0)
+               {
+                 unsigned long int tv = *bc;
+                 unsigned long int n7;
+
+                 *bc = 1;
+                 while (*bc != 0)
+                   {
+                   }
+
+ut:
+                 if (pj == 0)
+                   n7 = *h5 > 0;
+                 else
+                   {
+                     *h5 = tv;
+                     n7 = *h5;
+                   }
+                 ib += n7;
+               }
+           }
+       }
+
+      goto ut;
+    }
+
+  goto m6;
+}

diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 5eb47a9..4861a4c 100644 (file)
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -537,7 +537,6 @@ static pre_expr bitmap_find_leader (bitmap_set_t, unsigned int);
 static void bitmap_value_insert_into_set (bitmap_set_t, pre_expr);
 static void bitmap_value_replace_in_set (bitmap_set_t, pre_expr);
 static void bitmap_set_copy (bitmap_set_t, bitmap_set_t);
-static void bitmap_set_and (bitmap_set_t, bitmap_set_t);
 static bool bitmap_set_contains_value (bitmap_set_t, unsigned int);
 static void bitmap_insert_into_set (bitmap_set_t, pre_expr);
 static bitmap_set_t bitmap_set_new (void);
@@ -800,36 +799,6 @@ sorted_array_from_bitmap_set (bitmap_set_t set)
   return result;
 }
 
-/* Perform bitmapped set operation DEST &= ORIG.  */
-
-static void
-bitmap_set_and (bitmap_set_t dest, bitmap_set_t orig)
-{
-  bitmap_iterator bi;
-  unsigned int i;
-
-  if (dest != orig)
-    {
-      bitmap_and_into (&dest->values, &orig->values);
-
-      unsigned int to_clear = -1U;
-      FOR_EACH_EXPR_ID_IN_SET (dest, i, bi)
-       {
-         if (to_clear != -1U)
-           {
-             bitmap_clear_bit (&dest->expressions, to_clear);
-             to_clear = -1U;
-           }
-         pre_expr expr = expression_for_id (i);
-         unsigned int value_id = get_expr_value_id (expr);
-         if (!bitmap_bit_p (&dest->values, value_id))
-           to_clear = i;
-       }
-      if (to_clear != -1U)
-       bitmap_clear_bit (&dest->expressions, to_clear);
-    }
-}
-
 /* Subtract all expressions contained in ORIG from DEST.  */
 
 static bitmap_set_t
@@ -2182,17 +2151,54 @@ compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
 
       phi_translate_set (ANTIC_OUT, ANTIC_IN (first), block, first);
 
+      /* If we have multiple successors we need to intersect the ANTIC_OUT
+         sets.  For values that's a simple intersection but for
+        expressions it is a union.  Given we want to have a single
+        expression per value in our sets we have to canonicalize.
+        Avoid randomness and running into cycles like for PR82129 and
+        canonicalize the expression we choose to the one with the
+        lowest id.  This requires we actually compute the union first.  */
       FOR_EACH_VEC_ELT (worklist, i, bprime)
        {
          if (!gimple_seq_empty_p (phi_nodes (bprime)))
            {
              bitmap_set_t tmp = bitmap_set_new ();
              phi_translate_set (tmp, ANTIC_IN (bprime), block, bprime);
-             bitmap_set_and (ANTIC_OUT, tmp);
+             bitmap_and_into (&ANTIC_OUT->values, &tmp->values);
+             bitmap_ior_into (&ANTIC_OUT->expressions, &tmp->expressions);
              bitmap_set_free (tmp);
            }
          else
-           bitmap_set_and (ANTIC_OUT, ANTIC_IN (bprime));
+           {
+             bitmap_and_into (&ANTIC_OUT->values, &ANTIC_IN (bprime)->values);
+             bitmap_ior_into (&ANTIC_OUT->expressions,
+                              &ANTIC_IN (bprime)->expressions);
+           }
+       }
+      if (! worklist.is_empty ())
+       {
+         /* Prune expressions not in the value set, canonicalizing to
+            expression with lowest ID.  */
+         bitmap_iterator bi;
+         unsigned int i;
+         unsigned int to_clear = -1U;
+         bitmap seen_value = BITMAP_ALLOC (NULL);
+         FOR_EACH_EXPR_ID_IN_SET (ANTIC_OUT, i, bi)
+           {
+             if (to_clear != -1U)
+               {
+                 bitmap_clear_bit (&ANTIC_OUT->expressions, to_clear);
+                 to_clear = -1U;
+               }
+             pre_expr expr = expression_for_id (i);
+             unsigned int value_id = get_expr_value_id (expr);
+             if (!bitmap_bit_p (&ANTIC_OUT->values, value_id)
+                 || !bitmap_set_bit (seen_value, value_id))
+               to_clear = i;
+           }
+         if (to_clear != -1U)
+           bitmap_clear_bit (&ANTIC_OUT->expressions, to_clear);
+         BITMAP_FREE (seen_value);
        }
     }