re PR tree-optimization/91257 (Compile-time and memory-hog hog)

2019-07-30  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/91257
	* bitmap.c (bitmap_ior_and_compl_into): Open-code.

From-SVN: r273909

gcc/ChangeLog

+2019-07-30  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/91257
+	* bitmap.c (bitmap_ior_and_compl_into): Open-code.
+
 2019-07-30  Martin Liska  <mliska@suse.cz>
 
 	* doc/invoke.texi: Document new behavior.

gcc/bitmap.c

@@ -2421,16 +2421,75 @@ bitmap_ior_and_compl (bitmap dst, const_bitmap a, const_bitmap b, const_bitmap k
 bool
 bitmap_ior_and_compl_into (bitmap a, const_bitmap b, const_bitmap c)
 {
-  bitmap_head tmp;
-  bool changed;
+  bitmap_element *a_elt = a->first;
+  const bitmap_element *b_elt = b->first;
+  const bitmap_element *c_elt = c->first;
+  bitmap_element and_elt;
+  bitmap_element *a_prev = NULL;
+  bitmap_element **a_prev_pnext = &a->first;
+  bool changed = false;
+  unsigned ix;
 
   gcc_checking_assert (!a->tree_form && !b->tree_form && !c->tree_form);
 
-  bitmap_initialize (&tmp, &bitmap_default_obstack);
-  bitmap_and_compl (&tmp, b, c);
-  changed = bitmap_ior_into (a, &tmp);
-  bitmap_clear (&tmp);
+  if (a == b)
+    return false;
+  if (bitmap_empty_p (c))
+    return bitmap_ior_into (a, b);
+  else if (bitmap_empty_p (a))
+    return bitmap_and_compl (a, b, c);
+
+  and_elt.indx = -1;
+  while (b_elt)
+    {
+      /* Advance C.  */
+      while (c_elt && c_elt->indx < b_elt->indx)
+	c_elt = c_elt->next;
+
+      const bitmap_element *and_elt_ptr;
+      if (c_elt && c_elt->indx == b_elt->indx)
+	{
+	  BITMAP_WORD overall = 0;
+	  and_elt_ptr = &and_elt;
+	  and_elt.indx = b_elt->indx;
+	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
+	    {
+	      and_elt.bits[ix] = b_elt->bits[ix] & ~c_elt->bits[ix];
+	      overall |= and_elt.bits[ix];
+	    }
+	  if (!overall)
+	    {
+	      b_elt = b_elt->next;
+	      continue;
+	    }
+	}
+      else
+	and_elt_ptr = b_elt;
+
+      b_elt = b_elt->next;
 
+      /* Now find a place to insert AND_ELT.  */
+      do
+	{
+	  ix = a_elt ? a_elt->indx : and_elt_ptr->indx;
+          if (ix == and_elt_ptr->indx)
+	    changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt,
+				      and_elt_ptr, changed);
+          else if (ix > and_elt_ptr->indx)
+	    changed = bitmap_elt_copy (a, NULL, a_prev, and_elt_ptr, changed);
+
+          a_prev = *a_prev_pnext;
+          a_prev_pnext = &a_prev->next;
+          a_elt = *a_prev_pnext;
+
+          /* If A lagged behind B/C, we advanced it so loop once more.  */
+	}
+      while (ix < and_elt_ptr->indx);
+    }
+
+  gcc_checking_assert (!a->current == !a->first);
+  if (a->current)
+    a->indx = a->current->indx;
   return changed;
 }