[PATCH][lto/66752] Fix missed FSM jump thread

PR lto/66752
	* tree-ssa-threadedge.c (simplify_conrol_stmt_condition): If we are
	unable to find X NE 0 in the tables, return X as the simplified
	condition.
	(fsm_find_control_statement_thread_paths): If nodes in NEXT_PATH are
	in VISISTED_BBS, then return failure.  Else add nodes from NEXT_PATH
	to VISISTED_BBS.
	* tree-ssa-threadupdate.c (duplicate_thread_path): Fix up edge flags
	after removing the control flow statement and unnecessary edges.

	PR lto/66752
	* gcc.dg/tree-ssa/pr66752-2.c: New test.
	* gcc.dg/torture/pr66752-1.c: New test
	* g++.dg/torture/pr66752-2.C: New test.

From-SVN: r227307

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2015-08-28  Jeff Law  <law@redhat.com>
+
+	PR lto/66752
+	* tree-ssa-threadedge.c (simplify_conrol_stmt_condition): If we are
+	unable to find X NE 0 in the tables, return X as the simplified
+	condition.
+	(fsm_find_control_statement_thread_paths): If nodes in NEXT_PATH are
+	in VISISTED_BBS, then return failure.  Else add nodes from NEXT_PATH
+	to VISISTED_BBS.
+	* tree-ssa-threadupdate.c (duplicate_thread_path): Fix up edge flags
+	after removing the control flow statement and unnecessary edges.
+
 2015-08-28  Alan Lawrence  <alan.lawrence@arm.com>
 
 	Revert:

gcc/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2015-08-28  Jeff Law  <law@redhat.com>
+
+	PR lto/66752
+	* gcc.dg/tree-ssa/pr66752-2.c: New test.
+	* gcc.dg/torture/pr66752-1.c: New test
+	* g++.dg/torture/pr66752-2.C: New test.
+
 2015-08-28  Alan Lawrence  <alan.lawrence@arm.com>
 	Revert:
 	2015-08-27  Alan Lawrence  <alan.lawrence@arm.com>

gcc/testsuite/g++.dg/torture/pr66752-2.C

@@ -0,0 +1,60 @@
+/* { dg-do compile } */
+extern "C"
+{
+  typedef struct _IO_FILE FILE;
+  extern int fprintf (FILE * __restrict __stream,
+		      const char *__restrict __format, ...);
+}
+typedef union tree_node *tree;
+class ipa_polymorphic_call_context
+{
+};
+class ipcp_value_base
+{
+};
+template < typename valtype > class ipcp_value:public ipcp_value_base
+{
+public:valtype value;
+  ipcp_value *next;
+};
+
+template < typename valtype > class ipcp_lattice
+{
+public:ipcp_value < valtype > *values;
+  void print (FILE * f, bool dump_sources, bool dump_benefits);
+};
+
+class ipcp_param_lattices
+{
+public:ipcp_lattice < tree > itself;
+  ipcp_lattice < ipa_polymorphic_call_context > ctxlat;
+};
+template < typename valtype > void ipcp_lattice < valtype >::print (FILE * f,
+								    bool
+								    dump_sources,
+								    bool
+								    dump_benefits)
+{
+  ipcp_value < valtype > *val;
+  bool prev = false;
+  for (val = values; val; val = val->next)
+    {
+      if (dump_benefits && prev)
+	fprintf (f, "               ");
+      else if (!dump_benefits && prev)
+	fprintf (f, ", ");
+      else
+	prev = true;
+      if (dump_sources)
+	fprintf (f, "]");
+      if (dump_benefits)
+	fprintf (f, "shit");
+    }
+}
+
+void
+print_all_lattices (FILE * f, bool dump_sources, bool dump_benefits)
+{
+  struct ipcp_param_lattices *plats;
+  plats->ctxlat.print (f, dump_sources, dump_benefits);
+}

gcc/testsuite/gcc.dg/torture/pr66752-1.c

@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+
+typedef unsigned int size_t;
+struct fde_vector
+{
+  size_t count;
+  const struct dwarf_fde *array[];
+};
+struct object;
+typedef struct dwarf_fde fde;
+typedef int (*fde_compare_t) (struct object *, const fde *, const fde *);
+void
+fde_merge (struct object *ob, fde_compare_t fde_compare,
+	   struct fde_vector *v1, struct fde_vector *v2)
+{
+  size_t i1, i2;
+  const fde *fde2;
+  do
+    {
+      i2--;
+      while (i1 > 0 && fde_compare (ob, v1->array[i1 - 1], fde2) > 0)
+	{
+	  i1--;
+	}
+    }
+  while (i2 > 0);
+}

gcc/testsuite/gcc.dg/tree-ssa/pr66752-3.c

@@ -0,0 +1,39 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dom1-details -fdump-tree-optimized" } */
+
+extern int status, pt;
+extern int count;
+void
+foo (int N, int c, int b, int *a)
+{
+  int i, flag;
+  i = b -1;
+  flag = 1;
+  if (status && i < N && a[i] == b) {
+    N--;
+    flag = 0;
+   if (pt)
+     count++;
+  }
+  else    
+    for (i = -1, flag = 1; ++i < N && flag;)
+      if (a[i] == b)
+        {
+          --N;
+          flag = 0;
+          if (i < N)
+            a[i] = a[N];
+           else
+            a[i] = 0;
+          if (pt)
+            count++;
+        }
+ if(status && flag)
+   pt--;
+}
+
+/* There are 3 FSM jump threading opportunities.  */
+/* { dg-final { scan-tree-dump-times "FSM" 3 "dom1"} } */
+
+/* There should be no assignments or references to FLAG.  */
+/* { dg-final { scan-tree-dump-not "flag" "optimized"} } */

gcc/tree-ssa-threadedge.c

@@ -553,6 +553,24 @@ simplify_control_stmt_condition (edge e,
           || !is_gimple_min_invariant (cached_lhs))
         cached_lhs = (*simplify) (dummy_cond, stmt);
 
+      /* If we were just testing that an integral type was != 0, and that
+	 failed, just return the first operand.  This gives the FSM code a
+	 chance to optimize the path.  */
+      if (cached_lhs == NULL
+	  && cond_code == NE_EXPR)
+	{
+	  /* Recover the original operands.  They may have been simplified
+	     using context sensitive equivalences.  Those context sensitive
+	     equivalences may not be valid on paths found by the FSM optimizer.  */
+	  tree op0 = gimple_cond_lhs (stmt);
+	  tree op1 = gimple_cond_rhs (stmt);
+
+	  if (INTEGRAL_TYPE_P (TREE_TYPE (op0))
+	      && TREE_CODE (op0) == SSA_NAME
+	      && integer_zerop (op1))
+	    return op0;
+	}
+
       return cached_lhs;
     }
 
@@ -974,6 +992,21 @@ fsm_find_control_statement_thread_paths (tree expr,
 	  return;
 	}
 
+      /* Make sure we haven't already visited any of the nodes in
+	 NEXT_PATH.  Don't add them here to avoid pollution.  */
+      for (unsigned int i = 0; i < next_path->length () - 1; i++)
+	{
+	  if (visited_bbs->contains ((*next_path)[i]))
+	    {
+	      vec_free (next_path);
+	      return;
+	    }
+	}
+
+      /* Now add the nodes to VISISTED_BBS.  */
+      for (unsigned int i = 0; i < next_path->length () - 1; i++)
+	visited_bbs->add ((*next_path)[i]);
+
       /* Append all the nodes from NEXT_PATH to PATH.  */
       vec_safe_splice (path, next_path);
       next_path_length = next_path->length ();

gcc/tree-ssa-threadupdate.c

@@ -2493,6 +2493,12 @@ duplicate_thread_path (edge entry, edge exit,
 
   /* Remove the last branch in the jump thread path.  */
   remove_ctrl_stmt_and_useless_edges (region_copy[n_region - 1], exit->dest);
+
+  /* And fixup the flags on the single remaining edge.  */
+  edge fix_e = find_edge (region_copy[n_region - 1], exit->dest);
+  fix_e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL);
+  fix_e->flags |= EDGE_FALLTHRU;
+
   edge e = make_edge (region_copy[n_region - 1], exit->dest, EDGE_FALLTHRU);
 
   if (e) {