[PATCH] Improve FSM threader to handle compiler temporaries too

	* tree-ssa-threadbackward.c (fsm_find_thread_path): Remove
	restriction that traced SSA_NAME is a user variable.

	* gcc.dg/tree-ssa/ssa-dom-thread-11.c: New test.

From-SVN: r228727

gcc/ChangeLog

+2015-10-12  Jeff Law  <law@redhat.com>
+
+	* tree-ssa-threadbackward.c (fsm_find_thread_path): Remove
+	restriction that traced SSA_NAME is a user variable.
+
 2015-10-12  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/67476

gcc/testsuite/ChangeLog

+2015-10-12  Jeff Law  <law@redhat.com>
+
+	* gcc.dg/tree-ssa/ssa-dom-thread-11.c: New test.
+
 2015-10-12  Ville Voutilainen  <ville.voutilainen@gmail.com>
 
 	PR c++/58566

gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-11.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp2-details" } */
+/* { dg-final { scan-tree-dump "FSM" "vrp2" } } */
+
+void abort (void);
+typedef struct bitmap_head_def *bitmap;
+typedef const struct bitmap_head_def *const_bitmap;
+typedef struct bitmap_obstack
+{
+  struct bitmap_obstack *next;
+  unsigned int indx;
+}
+bitmap_element;
+typedef struct bitmap_head_def
+{
+  bitmap_element *first;
+}
+bitmap_head;
+static __inline__ unsigned char
+bitmap_elt_ior (bitmap dst, bitmap_element * dst_elt,
+		bitmap_element * dst_prev, const bitmap_element * a_elt,
+		const bitmap_element * b_elt)
+{
+  ((void) (!(a_elt || b_elt) ? abort (), 0 : 0));
+}
+
+unsigned char
+bitmap_ior_and_compl (bitmap dst, const_bitmap a, const_bitmap b,
+		      const_bitmap kill)
+{
+  bitmap_element *dst_elt = dst->first;
+  const bitmap_element *a_elt = a->first;
+  const bitmap_element *b_elt = b->first;
+  const bitmap_element *kill_elt = kill->first;
+  bitmap_element *dst_prev = ((void *) 0);
+  while (a_elt || b_elt)
+    {
+      if (b_elt && kill_elt && kill_elt->indx == b_elt->indx
+	  && (!a_elt || a_elt->indx >= b_elt->indx));
+      else
+	{
+	  bitmap_elt_ior (dst, dst_elt, dst_prev, a_elt, b_elt);
+	  if (a_elt && b_elt && a_elt->indx == b_elt->indx)
+	    ;
+	  else if (a_elt && (!b_elt || a_elt->indx <= b_elt->indx))
+	    a_elt = a_elt->next;
+	}
+    }
+}

gcc/tree-ssa-threadbackward.c

@@ -70,7 +70,7 @@ fsm_find_thread_path (basic_block start_bb, basic_block end_bb,
   return false;
 }
 
-/* We trace the value of the variable EXPR back through any phi nodes looking
+/* We trace the value of the SSA_NAME EXPR back through any phi nodes looking
    for places where it gets a constant value and save the path.  Stop after
    having recorded MAX_PATHS jump threading paths.  */
 
@@ -80,11 +80,10 @@ fsm_find_control_statement_thread_paths (tree expr,
 					 vec<basic_block, va_gc> *&path,
 					 bool seen_loop_phi)
 {
-  tree var = SSA_NAME_VAR (expr);
   gimple *def_stmt = SSA_NAME_DEF_STMT (expr);
   basic_block var_bb = gimple_bb (def_stmt);
 
-  if (var == NULL || var_bb == NULL)
+  if (var_bb == NULL)
     return;
 
   /* For the moment we assume that an SSA chain only contains phi nodes, and