Merge commit '490e23032baaece71f2ec09fa1805064b150fbc2' [#247]

1 files changed, 203 insertions, 2180 deletions

diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index 84eadd1..02e88d5 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -1,5 +1,5 @@
 /* Predicate aware uninitialized variable warning.
-   Copyright (C) 2001-2021 Free Software Foundation, Inc.
+   Copyright (C) 2001-2022 Free Software Foundation, Inc.
    Contributed by Xinliang David Li <davidxl@google.com>
 
 This file is part of GCC.
@@ -39,6 +39,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "calls.h"
 #include "gimple-range.h"
 
+#include "gimple-predicate-analysis.h"
+
 /* This implements the pass that does predicate aware warning on uses of
    possibly uninitialized variables.  The pass first collects the set of
    possibly uninitialized SSA names.  For each such name, it walks through
@@ -49,19 +51,11 @@ along with GCC; see the file COPYING3.  If not see
    default definitions or by checking if the predicate set that guards the
    defining paths is a superset of the use predicate.  */
 
-/* Max PHI args we can handle in pass.  */
-const unsigned max_phi_args = 32;
-
 /* Pointer set of potentially undefined ssa names, i.e.,
    ssa names that are defined by phi with operands that
    are not defined or potentially undefined.  */
 static hash_set<tree> *possibly_undefined_names = 0;
 
-/* Bit mask handling macros.  */
-#define MASK_SET_BIT(mask, pos) mask |= (1 << pos)
-#define MASK_TEST_BIT(mask, pos) (mask & (1 << pos))
-#define MASK_EMPTY(mask) (mask == 0)
-
 /* Returns the first bit position (starting from LSB)
    in mask that is non zero.  Returns -1 if the mask is empty.  */
 static int
@@ -138,8 +132,8 @@ uninit_undefined_value_p (tree t)
    or UNKNOWN_LOCATION otherwise.  */
 
 static void
-warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid,
-	     gimple *context, location_t phi_arg_loc = UNKNOWN_LOCATION)
+warn_uninit (opt_code opt, tree t, tree var, gimple *context,
+	     location_t phi_arg_loc = UNKNOWN_LOCATION)
 {
   /* Bail if the value isn't provably uninitialized.  */
   if (!has_undefined_value_p (t))
@@ -188,24 +182,70 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid,
     }
 
   /* Anonymous SSA_NAMEs shouldn't be uninitialized, but ssa_undefined_value_p
-     can return true if the def stmt of an anonymous SSA_NAME is COMPLEX_EXPR
-     created for conversion from scalar to complex.  Use the underlying var of
-     the COMPLEX_EXPRs real part in that case.  See PR71581.  */
+     can return true if the def stmt of an anonymous SSA_NAME is
+     1. A COMPLEX_EXPR created for conversion from scalar to complex.  Use the
+     underlying var of the COMPLEX_EXPRs real part in that case.  See PR71581.
+
+     Or
+
+     2. A call to .DEFERRED_INIT internal function. Since the original variable
+     has been eliminated by optimziation, we need to get the variable name,
+     and variable declaration location from this call.  We recorded variable
+     name into VAR_NAME_STR, and will get location info and record warning
+     suppressed info to VAR_DEF_STMT, which is the .DEFERRED_INIT call.  */
+
+  const char *var_name_str = NULL;
+  gimple *var_def_stmt = NULL;
+
   if (!var && !SSA_NAME_VAR (t))
     {
-      gimple *def_stmt = SSA_NAME_DEF_STMT (t);
-      if (is_gimple_assign (def_stmt)
-	  && gimple_assign_rhs_code (def_stmt) == COMPLEX_EXPR)
+      var_def_stmt = SSA_NAME_DEF_STMT (t);
+
+      if (is_gimple_assign (var_def_stmt)
+	  && gimple_assign_rhs_code (var_def_stmt) == COMPLEX_EXPR)
 	{
-	  tree v = gimple_assign_rhs1 (def_stmt);
+	  tree v = gimple_assign_rhs1 (var_def_stmt);
 	  if (TREE_CODE (v) == SSA_NAME
 	      && has_undefined_value_p (v)
-	      && zerop (gimple_assign_rhs2 (def_stmt)))
+	      && zerop (gimple_assign_rhs2 (var_def_stmt)))
 	    var = SSA_NAME_VAR (v);
 	}
+
+      if (gimple_call_internal_p (var_def_stmt, IFN_DEFERRED_INIT))
+	{
+	  /* Ignore the call to .DEFERRED_INIT that define the original
+	     var itself as the following case:
+		temp = .DEFERRED_INIT (4, 2, “alt_reloc");
+		alt_reloc = temp;
+	     In order to avoid generating warning for the fake usage
+	     at alt_reloc = temp.
+	  */
+	  tree lhs_var = NULL_TREE;
+	  tree lhs_var_name = NULL_TREE;
+	  const char *lhs_var_name_str = NULL;
+
+	  /* Get the variable name from the 3rd argument of call.  */
+	  tree var_name = gimple_call_arg (var_def_stmt, 2);
+	  var_name = TREE_OPERAND (TREE_OPERAND (var_name, 0), 0);
+	  var_name_str = TREE_STRING_POINTER (var_name);
+
+	  if (is_gimple_assign (context))
+	    {
+	      if (TREE_CODE (gimple_assign_lhs (context)) == VAR_DECL)
+		lhs_var = gimple_assign_lhs (context);
+	      else if (TREE_CODE (gimple_assign_lhs (context)) == SSA_NAME)
+		lhs_var = SSA_NAME_VAR (gimple_assign_lhs (context));
+	    }
+	  if (lhs_var
+	      && (lhs_var_name = DECL_NAME (lhs_var))
+	      && (lhs_var_name_str = IDENTIFIER_POINTER (lhs_var_name))
+	      && (strcmp (lhs_var_name_str, var_name_str) == 0))
+	    return;
+	  gcc_assert (var_name_str && var_def_stmt);
+	}
     }
 
-  if (var == NULL_TREE)
+  if (var == NULL_TREE && var_name_str == NULL)
     return;
 
   /* Avoid warning if we've already done so or if the warning has been
@@ -213,36 +253,66 @@ warn_uninit (opt_code opt, tree t, tree var, const char *gmsgid,
   if (((warning_suppressed_p (context, OPT_Wuninitialized)
 	|| (gimple_assign_single_p (context)
 	    && get_no_uninit_warning (gimple_assign_rhs1 (context)))))
-      || get_no_uninit_warning (var))
+      || (var && get_no_uninit_warning (var))
+      || (var_name_str
+	  && warning_suppressed_p (var_def_stmt, OPT_Wuninitialized)))
     return;
 
   /* Use either the location of the read statement or that of the PHI
      argument, or that of the uninitialized variable, in that order,
      whichever is valid.  */
-  location_t location;
+  location_t location = UNKNOWN_LOCATION;
   if (gimple_has_location (context))
     location = gimple_location (context);
   else if (phi_arg_loc != UNKNOWN_LOCATION)
     location = phi_arg_loc;
-  else
+  else if (var)
     location = DECL_SOURCE_LOCATION (var);
+  else if (var_name_str)
+    location = gimple_location (var_def_stmt);
+
   location = linemap_resolve_location (line_table, location,
 				       LRK_SPELLING_LOCATION, NULL);
 
   auto_diagnostic_group d;
-  if (!warning_at (location, opt, gmsgid, var))
-    return;
+  gcc_assert (opt == OPT_Wuninitialized || opt == OPT_Wmaybe_uninitialized);
+  if (var)
+    {
+      if ((opt == OPT_Wuninitialized
+	   && !warning_at (location, opt, "%qD is used uninitialized", var))
+	  || (opt == OPT_Wmaybe_uninitialized
+	      && !warning_at (location, opt, "%qD may be used uninitialized",
+			      var)))
+      return;
+    }
+  else if (var_name_str)
+    {
+      if ((opt == OPT_Wuninitialized
+	   && !warning_at (location, opt, "%qs is used uninitialized",
+			   var_name_str))
+	  || (opt == OPT_Wmaybe_uninitialized
+	      && !warning_at (location, opt, "%qs may be used uninitialized",
+			      var_name_str)))
+      return;
+    }
 
   /* Avoid subsequent warnings for reads of the same variable again.  */
-  suppress_warning (var, opt);
+  if (var)
+    suppress_warning (var, opt);
+  else if (var_name_str)
+    suppress_warning (var_def_stmt, opt);
 
   /* Issue a note pointing to the read variable unless the warning
      is at the same location.  */
-  location_t var_loc = DECL_SOURCE_LOCATION (var);
+  location_t var_loc = var ? DECL_SOURCE_LOCATION (var)
+			: gimple_location (var_def_stmt);
   if (location == var_loc)
     return;
 
-  inform (var_loc, "%qD was declared here", var);
+  if (var)
+    inform (var_loc, "%qD was declared here", var);
+  else if (var_name_str)
+    inform (var_loc, "%qs was declared here", var_name_str);
 }
 
 struct check_defs_data
@@ -386,26 +456,41 @@ check_defs (ao_ref *ref, tree vdef, void *data_)
   if (gimple_call_internal_p (def_stmt, IFN_DEFERRED_INIT))
     return false;
 
+  /* For address taken variable, a temporary variable is added between
+     the variable and the call to .DEFERRED_INIT function as:
+      _1 = .DEFERRED_INIT (4, 2, &"i1"[0]);
+      i1 = _1;
+     Ignore this vdef as well.  */
+  if (is_gimple_assign (def_stmt)
+      && gimple_assign_rhs_code (def_stmt) == SSA_NAME)
+    {
+      tree tmp_var = gimple_assign_rhs1 (def_stmt);
+      if (gimple_call_internal_p (SSA_NAME_DEF_STMT (tmp_var),
+				  IFN_DEFERRED_INIT))
+	return false;
+    }
+
   /* The ASAN_MARK intrinsic doesn't modify the variable.  */
   if (is_gimple_call (def_stmt))
     {
+      /* The ASAN_MARK intrinsic doesn't modify the variable.  */
       if (gimple_call_internal_p (def_stmt)
 	  && gimple_call_internal_fn (def_stmt) == IFN_ASAN_MARK)
-       return false;
+	return false;
 
       if (tree fndecl = gimple_call_fndecl (def_stmt))
-       {
-	 /* Some sanitizer calls pass integer arguments to built-ins
-	    that expect pointers.  Avoid using gimple_call_builtin_p()
-	    which fails for such calls.  */
-	 if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
-	   {
-	     built_in_function fncode = DECL_FUNCTION_CODE (fndecl);
-	     if (fncode > BEGIN_SANITIZER_BUILTINS
-		 && fncode < END_SANITIZER_BUILTINS)
-	       return false;
-	   }
-       }
+	{
+	  /* Some sanitizer calls pass integer arguments to built-ins
+	     that expect pointets. Avoid using gimple_call_builtin_p()
+	     which fails for such calls.  */
+	  if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
+	    {
+	      built_in_function fncode = DECL_FUNCTION_CODE (fndecl);
+	      if (fncode > BEGIN_SANITIZER_BUILTINS
+		  && fncode < END_SANITIZER_BUILTINS)
+		return false;
+	    }
+	}
     }
 
   /* End of VLA scope is not a kill.  */
@@ -749,7 +834,8 @@ maybe_warn_pass_by_reference (gcall *stmt, wlimits &wlims)
 	wlims.always_executed = false;
 
       /* Ignore args we are not going to read from.  */
-      if (gimple_call_arg_flags (stmt, argno - 1) & (EAF_UNUSED | EAF_NOREAD))
+      if (gimple_call_arg_flags (stmt, argno - 1)
+	  & (EAF_UNUSED | EAF_NO_DIRECT_READ))
 	continue;
 
       tree arg = gimple_call_arg (stmt, argno - 1);
@@ -881,8 +967,8 @@ warn_uninit_phi_uses (basic_block bb)
 	  use_stmt = NULL;
 	}
       if (use_stmt)
-	warn_uninit (OPT_Wuninitialized, def, SSA_NAME_VAR (def),
-		     "%qD is used uninitialized", use_stmt);
+	warn_uninit (OPT_Wuninitialized, def,
+		     SSA_NAME_VAR (def), use_stmt);
     }
 }
 
@@ -935,11 +1021,11 @@ warn_uninitialized_vars (bool wmaybe_uninit)
 		}
 	      tree use = USE_FROM_PTR (use_p);
 	      if (wlims.always_executed)
-		warn_uninit (OPT_Wuninitialized, use, SSA_NAME_VAR (use),
-			     "%qD is used uninitialized", stmt);
+		warn_uninit (OPT_Wuninitialized, use,
+			     SSA_NAME_VAR (use), stmt);
 	      else if (wmaybe_uninit)
-		warn_uninit (OPT_Wmaybe_uninitialized, use, SSA_NAME_VAR (use),
-			     "%qD may be used uninitialized", stmt);
+		warn_uninit (OPT_Wmaybe_uninitialized, use,
+			     SSA_NAME_VAR (use), stmt);
 	    }
 
 	  /* For limiting the alias walk below we count all
@@ -998,8 +1084,8 @@ can_skip_redundant_opnd (tree opnd, gimple *phi)
   return true;
 }
 
-/* Returns a bit mask holding the positions of arguments in PHI
-   that have empty (or possibly empty) definitions.  */
+/* Return a bitset holding the positions of arguments in PHI with empty
+   (or possibly empty) definitions.  */
 
 static unsigned
 compute_uninit_opnds_pos (gphi *phi)
@@ -1008,7 +1094,7 @@ compute_uninit_opnds_pos (gphi *phi)
 
   unsigned n = gimple_phi_num_args (phi);
   /* Bail out for phi with too many args.  */
-  if (n > max_phi_args)
+  if (n > predicate::func_t::max_phi_args)
     return 0;
 
   for (unsigned i = 0; i < n; ++i)
@@ -1031,2111 +1117,32 @@ compute_uninit_opnds_pos (gphi *phi)
   return uninit_opnds;
 }
 
-/* Find the immediate postdominator of the specified basic block BLOCK.  */
-
-static inline basic_block
-find_pdom (basic_block block)
-{
-  if (block == EXIT_BLOCK_PTR_FOR_FN (cfun))
-    return EXIT_BLOCK_PTR_FOR_FN (cfun);
-  else
-    {
-      basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block);
-      if (!bb)
-	return EXIT_BLOCK_PTR_FOR_FN (cfun);
-      return bb;
-    }
-}
-
-/* Find the immediate dominator of the specified basic block BLOCK.  */
-
-static inline basic_block
-find_dom (basic_block block)
-{
-  if (block == ENTRY_BLOCK_PTR_FOR_FN (cfun))
-    return ENTRY_BLOCK_PTR_FOR_FN (cfun);
-  else
-    {
-      basic_block bb = get_immediate_dominator (CDI_DOMINATORS, block);
-      if (!bb)
-	return ENTRY_BLOCK_PTR_FOR_FN (cfun);
-      return bb;
-    }
-}
-
-/* Returns true if BB1 is postdominating BB2 and BB1 is
-   not a loop exit bb.  The loop exit bb check is simple and does
-   not cover all cases.  */
-
-static bool
-is_non_loop_exit_postdominating (basic_block bb1, basic_block bb2)
-{
-  if (!dominated_by_p (CDI_POST_DOMINATORS, bb2, bb1))
-    return false;
-
-  if (single_pred_p (bb1) && !single_succ_p (bb2))
-    return false;
-
-  return true;
-}
-
-/* Find the closest postdominator of a specified BB, which is control
-   equivalent to BB.  */
-
-static inline basic_block
-find_control_equiv_block (basic_block bb)
-{
-  basic_block pdom = find_pdom (bb);
-
-  /* Skip the postdominating bb that is also loop exit.  */
-  if (!is_non_loop_exit_postdominating (pdom, bb))
-    return NULL;
-
-  if (dominated_by_p (CDI_DOMINATORS, pdom, bb))
-    return pdom;
-
-  return NULL;
-}
-
-#define MAX_NUM_CHAINS 8
-#define MAX_CHAIN_LEN 5
-#define MAX_POSTDOM_CHECK 8
-#define MAX_SWITCH_CASES 40
+/* Function object type used to determine whether an expression
+   is of interest to the predicate analyzer.  */
 
-/* Computes the control dependence chains (paths of edges)
-   for DEP_BB up to the dominating basic block BB (the head node of a
-   chain should be dominated by it).  CD_CHAINS is pointer to an
-   array holding the result chains.  CUR_CD_CHAIN is the current
-   chain being computed.  *NUM_CHAINS is total number of chains.  The
-   function returns true if the information is successfully computed,
-   return false if there is no control dependence or not computed.  */
-
-static bool
-compute_control_dep_chain (basic_block bb, basic_block dep_bb,
-			   vec<edge> *cd_chains,
-			   size_t *num_chains,
-			   vec<edge> *cur_cd_chain,
-			   int *num_calls)
+struct uninit_undef_val_t: public predicate::func_t
 {
-  edge_iterator ei;
-  edge e;
-  size_t i;
-  bool found_cd_chain = false;
-  size_t cur_chain_len = 0;
-
-  if (*num_calls > param_uninit_control_dep_attempts)
-    return false;
-  ++*num_calls;
-
-  /* Could use a set instead.  */
-  cur_chain_len = cur_cd_chain->length ();
-  if (cur_chain_len > MAX_CHAIN_LEN)
-    return false;
-
-  for (i = 0; i < cur_chain_len; i++)
-    {
-      edge e = (*cur_cd_chain)[i];
-      /* Cycle detected.  */
-      if (e->src == bb)
-	return false;
-    }
-
-  FOR_EACH_EDGE (e, ei, bb->succs)
-    {
-      basic_block cd_bb;
-      int post_dom_check = 0;
-      if (e->flags & (EDGE_FAKE | EDGE_ABNORMAL))
-	continue;
-
-      cd_bb = e->dest;
-      cur_cd_chain->safe_push (e);
-      while (!is_non_loop_exit_postdominating (cd_bb, bb))
-	{
-	  if (cd_bb == dep_bb)
-	    {
-	      /* Found a direct control dependence.  */
-	      if (*num_chains < MAX_NUM_CHAINS)
-		{
-		  cd_chains[*num_chains] = cur_cd_chain->copy ();
-		  (*num_chains)++;
-		}
-	      found_cd_chain = true;
-	      /* Check path from next edge.  */
-	      break;
-	    }
-
-	  /* Now check if DEP_BB is indirectly control dependent on BB.  */
-	  if (compute_control_dep_chain (cd_bb, dep_bb, cd_chains, num_chains,
-					 cur_cd_chain, num_calls))
-	    {
-	      found_cd_chain = true;
-	      break;
-	    }
-
-	  cd_bb = find_pdom (cd_bb);
-	  post_dom_check++;
-	  if (cd_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
-	      || post_dom_check > MAX_POSTDOM_CHECK)
-	    break;
-	}
-      cur_cd_chain->pop ();
-      gcc_assert (cur_cd_chain->length () == cur_chain_len);
-    }
-  gcc_assert (cur_cd_chain->length () == cur_chain_len);
-
-  return found_cd_chain;
-}
-
-/* The type to represent a simple predicate.  */
-
-struct pred_info
-{
-  tree pred_lhs;
-  tree pred_rhs;
-  enum tree_code cond_code;
-  bool invert;
+  virtual bool operator()(tree) override;
+  virtual unsigned phi_arg_set (gphi *) override;
 };
 
-/* The type to represent a sequence of predicates grouped
-  with .AND. operation.  */
-
-typedef vec<pred_info, va_heap, vl_ptr> pred_chain;
-
-/* The type to represent a sequence of pred_chains grouped
-  with .OR. operation.  */
-
-typedef vec<pred_chain, va_heap, vl_ptr> pred_chain_union;
-
-/* Converts the chains of control dependence edges into a set of
-   predicates.  A control dependence chain is represented by a vector
-   edges.  DEP_CHAINS points to an array of dependence chains.
-   NUM_CHAINS is the size of the chain array.  One edge in a dependence
-   chain is mapped to predicate expression represented by pred_info
-   type.  One dependence chain is converted to a composite predicate that
-   is the result of AND operation of pred_info mapped to each edge.
-   A composite predicate is presented by a vector of pred_info.  On
-   return, *PREDS points to the resulting array of composite predicates.
-   *NUM_PREDS is the number of composite predictes.  */
-
-static bool
-convert_control_dep_chain_into_preds (vec<edge> *dep_chains,
-				      size_t num_chains,
-				      pred_chain_union *preds)
-{
-  bool has_valid_pred = false;
-  size_t i, j;
-  if (num_chains == 0 || num_chains >= MAX_NUM_CHAINS)
-    return false;
-
-  /* Now convert the control dep chain into a set
-     of predicates.  */
-  preds->reserve (num_chains);
-
-  for (i = 0; i < num_chains; i++)
-    {
-      vec<edge> one_cd_chain = dep_chains[i];
-
-      has_valid_pred = false;
-      pred_chain t_chain = vNULL;
-      for (j = 0; j < one_cd_chain.length (); j++)
-	{
-	  gimple *cond_stmt;
-	  gimple_stmt_iterator gsi;
-	  basic_block guard_bb;
-	  pred_info one_pred;
-	  edge e;
-
-	  e = one_cd_chain[j];
-	  guard_bb = e->src;
-	  gsi = gsi_last_bb (guard_bb);
-	  /* Ignore empty forwarder blocks.  */
-	  if (empty_block_p (guard_bb) && single_succ_p (guard_bb))
-	    continue;
-	  /* An empty basic block here is likely a PHI, and is not one
-	     of the cases we handle below.  */
-	  if (gsi_end_p (gsi))
-	    {
-	      has_valid_pred = false;
-	      break;
-	    }
-	  cond_stmt = gsi_stmt (gsi);
-	  if (is_gimple_call (cond_stmt) && EDGE_COUNT (e->src->succs) >= 2)
-	    /* Ignore EH edge.  Can add assertion on the other edge's flag.  */
-	    continue;
-	  /* Skip if there is essentially one succesor.  */
-	  if (EDGE_COUNT (e->src->succs) == 2)
-	    {
-	      edge e1;
-	      edge_iterator ei1;
-	      bool skip = false;
-
-	      FOR_EACH_EDGE (e1, ei1, e->src->succs)
-		{
-		  if (EDGE_COUNT (e1->dest->succs) == 0)
-		    {
-		      skip = true;
-		      break;
-		    }
-		}
-	      if (skip)
-		continue;
-	    }
-	  if (gimple_code (cond_stmt) == GIMPLE_COND)
-	    {
-	      one_pred.pred_lhs = gimple_cond_lhs (cond_stmt);
-	      one_pred.pred_rhs = gimple_cond_rhs (cond_stmt);
-	      one_pred.cond_code = gimple_cond_code (cond_stmt);
-	      one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE);
-	      t_chain.safe_push (one_pred);
-	      has_valid_pred = true;
-	    }
-	  else if (gswitch *gs = dyn_cast<gswitch *> (cond_stmt))
-	    {
-	      /* Avoid quadratic behavior.  */
-	      if (gimple_switch_num_labels (gs) > MAX_SWITCH_CASES)
-		{
-		  has_valid_pred = false;
-		  break;
-		}
-	      /* Find the case label.  */
-	      tree l = NULL_TREE;
-	      unsigned idx;
-	      for (idx = 0; idx < gimple_switch_num_labels (gs); ++idx)
-		{
-		  tree tl = gimple_switch_label (gs, idx);
-		  if (e->dest == label_to_block (cfun, CASE_LABEL (tl)))
-		    {
-		      if (!l)
-			l = tl;
-		      else
-			{
-			  l = NULL_TREE;
-			  break;
-			}
-		    }
-		}
-	      /* If more than one label reaches this block or the case
-		 label doesn't have a single value (like the default one)
-		 fail.  */
-	      if (!l
-		  || !CASE_LOW (l)
-		  || (CASE_HIGH (l)
-		      && !operand_equal_p (CASE_LOW (l), CASE_HIGH (l), 0)))
-		{
-		  has_valid_pred = false;
-		  break;
-		}
-	      one_pred.pred_lhs = gimple_switch_index (gs);
-	      one_pred.pred_rhs = CASE_LOW (l);
-	      one_pred.cond_code = EQ_EXPR;
-	      one_pred.invert = false;
-	      t_chain.safe_push (one_pred);
-	      has_valid_pred = true;
-	    }
-	  else
-	    {
-	      has_valid_pred = false;
-	      break;
-	    }
-	}
-
-      if (!has_valid_pred)
-	break;
-      else
-	preds->safe_push (t_chain);
-    }
-  return has_valid_pred;
-}
-
-/* Computes all control dependence chains for USE_BB.  The control
-   dependence chains are then converted to an array of composite
-   predicates pointed to by PREDS.  PHI_BB is the basic block of
-   the phi whose result is used in USE_BB.  */
-
-static bool
-find_predicates (pred_chain_union *preds,
-		 basic_block phi_bb,
-		 basic_block use_bb)
-{
-  size_t num_chains = 0, i;
-  int num_calls = 0;
-  vec<edge> dep_chains[MAX_NUM_CHAINS];
-  auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain;
-  bool has_valid_pred = false;
-  basic_block cd_root = 0;
-
-  /* First find the closest bb that is control equivalent to PHI_BB
-     that also dominates USE_BB.  */
-  cd_root = phi_bb;
-  while (dominated_by_p (CDI_DOMINATORS, use_bb, cd_root))
-    {
-      basic_block ctrl_eq_bb = find_control_equiv_block (cd_root);
-      if (ctrl_eq_bb && dominated_by_p (CDI_DOMINATORS, use_bb, ctrl_eq_bb))
-	cd_root = ctrl_eq_bb;
-      else
-	break;
-    }
-
-  compute_control_dep_chain (cd_root, use_bb, dep_chains, &num_chains,
-			     &cur_chain, &num_calls);
-
-  has_valid_pred
-    = convert_control_dep_chain_into_preds (dep_chains, num_chains, preds);
-  for (i = 0; i < num_chains; i++)
-    dep_chains[i].release ();
-  return has_valid_pred;
-}
-
-/* Computes the set of incoming edges of PHI that have non empty
-   definitions of a phi chain.  The collection will be done
-   recursively on operands that are defined by phis.  CD_ROOT
-   is the control dependence root.  *EDGES holds the result, and
-   VISITED_PHIS is a pointer set for detecting cycles.  */
-
-static void
-collect_phi_def_edges (gphi *phi, basic_block cd_root,
-		       auto_vec<edge> *edges,
-		       hash_set<gimple *> *visited_phis)
-{
-  size_t i, n;
-  edge opnd_edge;
-  tree opnd;
-
-  if (visited_phis->add (phi))
-    return;
-
-  n = gimple_phi_num_args (phi);
-  for (i = 0; i < n; i++)
-    {
-      opnd_edge = gimple_phi_arg_edge (phi, i);
-      opnd = gimple_phi_arg_def (phi, i);
-
-      if (TREE_CODE (opnd) != SSA_NAME)
-	{
-	  if (dump_file && (dump_flags & TDF_DETAILS))
-	    {
-	      fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int) i);
-	      print_gimple_stmt (dump_file, phi, 0);
-	    }
-	  edges->safe_push (opnd_edge);
-	}
-      else
-	{
-	  gimple *def = SSA_NAME_DEF_STMT (opnd);
-
-	  if (gimple_code (def) == GIMPLE_PHI
-	      && dominated_by_p (CDI_DOMINATORS, gimple_bb (def), cd_root))
-	    collect_phi_def_edges (as_a<gphi *> (def), cd_root, edges,
-				   visited_phis);
-	  else if (!uninit_undefined_value_p (opnd))
-	    {
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-		  fprintf (dump_file, "\n[CHECK] Found def edge %d in ",
-			   (int) i);
-		  print_gimple_stmt (dump_file, phi, 0);
-		}
-	      edges->safe_push (opnd_edge);
-	    }
-	}
-    }
-}
-
-/* For each use edge of PHI, computes all control dependence chains.
-   The control dependence chains are then converted to an array of
-   composite predicates pointed to by PREDS.  */
-
-static bool
-find_def_preds (pred_chain_union *preds, gphi *phi)
-{
-  size_t num_chains = 0, i, n;
-  vec<edge> dep_chains[MAX_NUM_CHAINS];
-  auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain;
-  auto_vec<edge> def_edges;
-  bool has_valid_pred = false;
-  basic_block phi_bb, cd_root = 0;
-
-  phi_bb = gimple_bb (phi);
-  /* First find the closest dominating bb to be
-     the control dependence root.  */
-  cd_root = find_dom (phi_bb);
-  if (!cd_root)
-    return false;
-
-  hash_set<gimple *> visited_phis;
-  collect_phi_def_edges (phi, cd_root, &def_edges, &visited_phis);
-
-  n = def_edges.length ();
-  if (n == 0)
-    return false;
-
-  for (i = 0; i < n; i++)
-    {
-      size_t prev_nc, j;
-      int num_calls = 0;
-      edge opnd_edge;
-
-      opnd_edge = def_edges[i];
-      prev_nc = num_chains;
-      compute_control_dep_chain (cd_root, opnd_edge->src, dep_chains,
-				 &num_chains, &cur_chain, &num_calls);
-
-      /* Now update the newly added chains with
-	 the phi operand edge:  */
-      if (EDGE_COUNT (opnd_edge->src->succs) > 1)
-	{
-	  if (prev_nc == num_chains && num_chains < MAX_NUM_CHAINS)
-	    dep_chains[num_chains++] = vNULL;
-	  for (j = prev_nc; j < num_chains; j++)
-	    dep_chains[j].safe_push (opnd_edge);
-	}
-    }
-
-  has_valid_pred
-    = convert_control_dep_chain_into_preds (dep_chains, num_chains, preds);
-  for (i = 0; i < num_chains; i++)
-    dep_chains[i].release ();
-  return has_valid_pred;
-}
-
-/* Dump a pred_info.  */
-
-static void
-dump_pred_info (pred_info one_pred)
-{
-  if (one_pred.invert)
-    fprintf (dump_file, " (.NOT.) ");
-  print_generic_expr (dump_file, one_pred.pred_lhs);
-  fprintf (dump_file, " %s ", op_symbol_code (one_pred.cond_code));
-  print_generic_expr (dump_file, one_pred.pred_rhs);
-}
-
-/* Dump a pred_chain.  */
-
-static void
-dump_pred_chain (pred_chain one_pred_chain)
-{
-  size_t np = one_pred_chain.length ();
-  for (size_t j = 0; j < np; j++)
-    {
-      dump_pred_info (one_pred_chain[j]);
-      if (j < np - 1)
-	fprintf (dump_file, " (.AND.) ");
-      else
-	fprintf (dump_file, "\n");
-    }
-}
-
-/* Dumps the predicates (PREDS) for USESTMT.  */
-
-static void
-dump_predicates (gimple *usestmt, pred_chain_union preds, const char *msg)
-{
-  fprintf (dump_file, "%s", msg);
-  if (usestmt)
-    {
-      print_gimple_stmt (dump_file, usestmt, 0);
-      fprintf (dump_file, "is guarded by :\n\n");
-    }
-  size_t num_preds = preds.length ();
-  for (size_t i = 0; i < num_preds; i++)
-    {
-      dump_pred_chain (preds[i]);
-      if (i < num_preds - 1)
-	fprintf (dump_file, "(.OR.)\n");
-      else
-	fprintf (dump_file, "\n\n");
-    }
-}
-
-/* Destroys the predicate set *PREDS.  */
-
-static void
-destroy_predicate_vecs (pred_chain_union *preds)
-{
-  size_t i;
-
-  size_t n = preds->length ();
-  for (i = 0; i < n; i++)
-    (*preds)[i].release ();
-  preds->release ();
-}
-
-/* Computes the 'normalized' conditional code with operand
-   swapping and condition inversion.  */
-
-static enum tree_code
-get_cmp_code (enum tree_code orig_cmp_code, bool swap_cond, bool invert)
-{
-  enum tree_code tc = orig_cmp_code;
-
-  if (swap_cond)
-    tc = swap_tree_comparison (orig_cmp_code);
-  if (invert)
-    tc = invert_tree_comparison (tc, false);
-
-  switch (tc)
-    {
-    case LT_EXPR:
-    case LE_EXPR:
-    case GT_EXPR:
-    case GE_EXPR:
-    case EQ_EXPR:
-    case NE_EXPR:
-      break;
-    default:
-      return ERROR_MARK;
-    }
-  return tc;
-}
-
-/* Returns whether VAL CMPC BOUNDARY is true.  */
-
-static bool
-is_value_included_in (tree val, tree boundary, enum tree_code cmpc)
-{
-  bool inverted = false;
-  bool result;
-
-  /* Only handle integer constant here.  */
-  if (TREE_CODE (val) != INTEGER_CST || TREE_CODE (boundary) != INTEGER_CST)
-    return true;
-
-  if (cmpc == GE_EXPR || cmpc == GT_EXPR || cmpc == NE_EXPR)
-    {
-      cmpc = invert_tree_comparison (cmpc, false);
-      inverted = true;
-    }
-
-  if (cmpc == EQ_EXPR)
-    result = tree_int_cst_equal (val, boundary);
-  else if (cmpc == LT_EXPR)
-    result = tree_int_cst_lt (val, boundary);
-  else
-    {
-      gcc_assert (cmpc == LE_EXPR);
-      result = tree_int_cst_le (val, boundary);
-    }
-
-  if (inverted)
-    result ^= 1;
-
-  return result;
-}
-
-/* Returns whether VAL satisfies (x CMPC BOUNDARY) predicate.  CMPC can be
-   either one of the range comparison codes ({GE,LT,EQ,NE}_EXPR and the like),
-   or BIT_AND_EXPR.  EXACT_P is only meaningful for the latter.  It modifies the
-   question from whether VAL & BOUNDARY != 0 to whether VAL & BOUNDARY == VAL.
-   For other values of CMPC, EXACT_P is ignored.  */
-
-static bool
-value_sat_pred_p (tree val, tree boundary, enum tree_code cmpc,
-		  bool exact_p = false)
-{
-  if (cmpc != BIT_AND_EXPR)
-    return is_value_included_in (val, boundary, cmpc);
-
-  wide_int andw = wi::to_wide (val) & wi::to_wide (boundary);
-  if (exact_p)
-    return andw == wi::to_wide (val);
-  else
-    return andw.to_uhwi ();
-}
-
-/* Returns true if PRED is common among all the predicate
-   chains (PREDS) (and therefore can be factored out).  */
-
-static bool
-find_matching_predicate_in_rest_chains (pred_info pred, pred_chain_union preds)
-{
-  size_t i, j, n;
-
-  /* Trival case.  */
-  if (preds.length () == 1)
-    return true;
-
-  for (i = 1; i < preds.length (); i++)
-    {
-      bool found = false;
-      pred_chain one_chain = preds[i];
-      n = one_chain.length ();
-      for (j = 0; j < n; j++)
-	{
-	  pred_info pred2 = one_chain[j];
-	  /* Can relax the condition comparison to not
-	     use address comparison.  However, the most common
-	     case is that multiple control dependent paths share
-	     a common path prefix, so address comparison should
-	     be ok.  */
-
-	  if (operand_equal_p (pred2.pred_lhs, pred.pred_lhs, 0)
-	      && operand_equal_p (pred2.pred_rhs, pred.pred_rhs, 0)
-	      && pred2.invert == pred.invert)
-	    {
-	      found = true;
-	      break;
-	    }
-	}
-      if (!found)
-	return false;
-    }
-  return true;
-}
-
-/* Forward declaration.  */
-static bool is_use_properly_guarded (gimple *use_stmt,
-				     basic_block use_bb,
-				     gphi *phi,
-				     unsigned uninit_opnds,
-				     pred_chain_union *def_preds,
-				     hash_set<gphi *> *visited_phis);
-
-/* Returns true if all uninitialized opnds are pruned.  Returns false
-   otherwise.  PHI is the phi node with uninitialized operands,
-   UNINIT_OPNDS is the bitmap of the uninitialize operand positions,
-   FLAG_DEF is the statement defining the flag guarding the use of the
-   PHI output, BOUNDARY_CST is the const value used in the predicate
-   associated with the flag, CMP_CODE is the comparison code used in
-   the predicate, VISITED_PHIS is the pointer set of phis visited, and
-   VISITED_FLAG_PHIS is the pointer to the pointer set of flag definitions
-   that are also phis.
-
-   Example scenario:
-
-   BB1:
-   flag_1 = phi <0, 1>			// (1)
-   var_1  = phi <undef, some_val>
-
-
-   BB2:
-   flag_2 = phi <0,   flag_1, flag_1>   // (2)
-   var_2  = phi <undef, var_1, var_1>
-   if (flag_2 == 1)
-      goto BB3;
-
-   BB3:
-   use of var_2				// (3)
-
-   Because some flag arg in (1) is not constant, if we do not look into the
-   flag phis recursively, it is conservatively treated as unknown and var_1
-   is thought to be flowed into use at (3).  Since var_1 is potentially
-   uninitialized a false warning will be emitted.
-   Checking recursively into (1), the compiler can find out that only some_val
-   (which is defined) can flow into (3) which is OK.  */
+/* Return true if the argument is an expression of interest.  */
 
-static bool
-prune_uninit_phi_opnds (gphi *phi, unsigned uninit_opnds, gphi *flag_def,
-			tree boundary_cst, enum tree_code cmp_code,
-			hash_set<gphi *> *visited_phis,
-			bitmap *visited_flag_phis)
+bool
+uninit_undef_val_t::operator()(tree val)
 {
-  unsigned i;
-
-  for (i = 0; i < MIN (max_phi_args, gimple_phi_num_args (flag_def)); i++)
-    {
-      tree flag_arg;
-
-      if (!MASK_TEST_BIT (uninit_opnds, i))
-	continue;
-
-      flag_arg = gimple_phi_arg_def (flag_def, i);
-      if (!is_gimple_constant (flag_arg))
-	{
-	  gphi *flag_arg_def, *phi_arg_def;
-	  tree phi_arg;
-	  unsigned uninit_opnds_arg_phi;
-
-	  if (TREE_CODE (flag_arg) != SSA_NAME)
-	    return false;
-	  flag_arg_def = dyn_cast<gphi *> (SSA_NAME_DEF_STMT (flag_arg));
-	  if (!flag_arg_def)
-	    return false;
-
-	  phi_arg = gimple_phi_arg_def (phi, i);
-	  if (TREE_CODE (phi_arg) != SSA_NAME)
-	    return false;
-
-	  phi_arg_def = dyn_cast<gphi *> (SSA_NAME_DEF_STMT (phi_arg));
-	  if (!phi_arg_def)
-	    return false;
-
-	  if (gimple_bb (phi_arg_def) != gimple_bb (flag_arg_def))
-	    return false;
-
-	  if (!*visited_flag_phis)
-	    *visited_flag_phis = BITMAP_ALLOC (NULL);
-
-	  tree phi_result = gimple_phi_result (flag_arg_def);
-	  if (bitmap_bit_p (*visited_flag_phis, SSA_NAME_VERSION (phi_result)))
-	    return false;
-
-	  bitmap_set_bit (*visited_flag_phis,
-			  SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)));
-
-	  /* Now recursively prune the uninitialized phi args.  */
-	  uninit_opnds_arg_phi = compute_uninit_opnds_pos (phi_arg_def);
-	  if (!prune_uninit_phi_opnds
-	      (phi_arg_def, uninit_opnds_arg_phi, flag_arg_def, boundary_cst,
-	       cmp_code, visited_phis, visited_flag_phis))
-	    return false;
-
-	  phi_result = gimple_phi_result (flag_arg_def);
-	  bitmap_clear_bit (*visited_flag_phis, SSA_NAME_VERSION (phi_result));
-	  continue;
-	}
-
-      /* Now check if the constant is in the guarded range.  */
-      if (is_value_included_in (flag_arg, boundary_cst, cmp_code))
-	{
-	  tree opnd;
-	  gimple *opnd_def;
-
-	  /* Now that we know that this undefined edge is not
-	     pruned.  If the operand is defined by another phi,
-	     we can further prune the incoming edges of that
-	     phi by checking the predicates of this operands.  */
-
-	  opnd = gimple_phi_arg_def (phi, i);
-	  opnd_def = SSA_NAME_DEF_STMT (opnd);
-	  if (gphi *opnd_def_phi = dyn_cast <gphi *> (opnd_def))
-	    {
-	      edge opnd_edge;
-	      unsigned uninit_opnds2 = compute_uninit_opnds_pos (opnd_def_phi);
-	      if (!MASK_EMPTY (uninit_opnds2))
-		{
-		  pred_chain_union def_preds = vNULL;
-		  bool ok;
-		  opnd_edge = gimple_phi_arg_edge (phi, i);
-		  ok = is_use_properly_guarded (phi,
-						opnd_edge->src,
-						opnd_def_phi,
-						uninit_opnds2,
-						&def_preds,
-						visited_phis);
-		  destroy_predicate_vecs (&def_preds);
-		  if (!ok)
-		    return false;
-		}
-	    }
-	  else
-	    return false;
-	}
-    }
-
-  return true;
-}
-
-/* A helper function finds predicate which will be examined against uninit
-   paths.  If there is no "flag_var cmp const" form predicate, the function
-   tries to find predicate of form like "flag_var cmp flag_var" with value
-   range info.  PHI is the phi node whose incoming (undefined) paths need to
-   be examined.  On success, the function returns the comparsion code, sets
-   defintion gimple of the flag_var to FLAG_DEF, sets boundary_cst to
-   BOUNDARY_CST.  On fail, the function returns ERROR_MARK.  */
-
-static enum tree_code
-find_var_cmp_const (pred_chain_union preds, gphi *phi, gimple **flag_def,
-		    tree *boundary_cst)
-{
-  enum tree_code vrinfo_code = ERROR_MARK, code;
-  gimple *vrinfo_def = NULL;
-  tree vrinfo_cst = NULL, cond_lhs, cond_rhs;
-
-  gcc_assert (preds.length () > 0);
-  pred_chain the_pred_chain = preds[0];
-  for (unsigned i = 0; i < the_pred_chain.length (); i++)
-    {
-      bool use_vrinfo_p = false;
-      pred_info the_pred = the_pred_chain[i];
-      cond_lhs = the_pred.pred_lhs;
-      cond_rhs = the_pred.pred_rhs;
-      if (cond_lhs == NULL_TREE || cond_rhs == NULL_TREE)
-	continue;
-
-      code = get_cmp_code (the_pred.cond_code, false, the_pred.invert);
-      if (code == ERROR_MARK)
-	continue;
-
-      if (TREE_CODE (cond_lhs) == SSA_NAME && is_gimple_constant (cond_rhs))
-	;
-      else if (TREE_CODE (cond_rhs) == SSA_NAME
-	       && is_gimple_constant (cond_lhs))
-	{
-	  std::swap (cond_lhs, cond_rhs);
-	  if ((code = get_cmp_code (code, true, false)) == ERROR_MARK)
-	    continue;
-	}
-      /* Check if we can take advantage of "flag_var comp flag_var" predicate
-	 with value range info.  Note only first of such case is handled.  */
-      else if (vrinfo_code == ERROR_MARK
-	       && TREE_CODE (cond_lhs) == SSA_NAME
-	       && TREE_CODE (cond_rhs) == SSA_NAME)
-	{
-	  gimple* lhs_def = SSA_NAME_DEF_STMT (cond_lhs);
-	  if (!lhs_def || gimple_code (lhs_def) != GIMPLE_PHI
-	      || gimple_bb (lhs_def) != gimple_bb (phi))
-	    {
-	      std::swap (cond_lhs, cond_rhs);
-	      if ((code = get_cmp_code (code, true, false)) == ERROR_MARK)
-		continue;
-	    }
-
-	  /* Check value range info of rhs, do following transforms:
-	       flag_var < [min, max]  ->  flag_var < max
-	       flag_var > [min, max]  ->  flag_var > min
-
-	     We can also transform LE_EXPR/GE_EXPR to LT_EXPR/GT_EXPR:
-	       flag_var <= [min, max] ->  flag_var < [min, max+1]
-	       flag_var >= [min, max] ->  flag_var > [min-1, max]
-	     if no overflow/wrap.  */
-	  tree type = TREE_TYPE (cond_lhs);
-	  value_range r;
-	  if (!INTEGRAL_TYPE_P (type)
-	      || !get_range_query (cfun)->range_of_expr (r, cond_rhs)
-	      || r.kind () != VR_RANGE)
-	    continue;
-	  wide_int min = r.lower_bound ();
-	  wide_int max = r.upper_bound ();
-	  if (code == LE_EXPR
-	      && max != wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
-	    {
-	      code = LT_EXPR;
-	      max = max + 1;
-	    }
-	  if (code == GE_EXPR
-	      && min != wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
-	    {
-	      code = GT_EXPR;
-	      min = min - 1;
-	    }
-	  if (code == LT_EXPR)
-	    cond_rhs = wide_int_to_tree (type, max);
-	  else if (code == GT_EXPR)
-	    cond_rhs = wide_int_to_tree (type, min);
-	  else
-	    continue;
-
-	  use_vrinfo_p = true;
-	}
-      else
-	continue;
-
-      if ((*flag_def = SSA_NAME_DEF_STMT (cond_lhs)) == NULL)
-	continue;
-
-      if (gimple_code (*flag_def) != GIMPLE_PHI
-	  || gimple_bb (*flag_def) != gimple_bb (phi)
-	  || !find_matching_predicate_in_rest_chains (the_pred, preds))
-	continue;
-
-      /* Return if any "flag_var comp const" predicate is found.  */
-      if (!use_vrinfo_p)
-	{
-	  *boundary_cst = cond_rhs;
-	  return code;
-	}
-      /* Record if any "flag_var comp flag_var[vinfo]" predicate is found.  */
-      else if (vrinfo_code == ERROR_MARK)
-	{
-	  vrinfo_code = code;
-	  vrinfo_def = *flag_def;
-	  vrinfo_cst = cond_rhs;
-	}
-    }
-  /* Return the "flag_var cmp flag_var[vinfo]" predicate we found.  */
-  if (vrinfo_code != ERROR_MARK)
-    {
-      *flag_def = vrinfo_def;
-      *boundary_cst = vrinfo_cst;
-    }
-  return vrinfo_code;
-}
-
-/* A helper function that determines if the predicate set
-   of the use is not overlapping with that of the uninit paths.
-   The most common senario of guarded use is in Example 1:
-     Example 1:
-	   if (some_cond)
-	   {
-	      x = ...;
-	      flag = true;
-	   }
-
-	    ... some code ...
-
-	   if (flag)
-	      use (x);
-
-     The real world examples are usually more complicated, but similar
-     and usually result from inlining:
-
-	 bool init_func (int * x)
-	 {
-	     if (some_cond)
-		return false;
-	     *x  =  ..
-	     return true;
-	 }
-
-	 void foo (..)
-	 {
-	     int x;
-
-	     if (!init_func (&x))
-		return;
-
-	     .. some_code ...
-	     use (x);
-	 }
-
-     Another possible use scenario is in the following trivial example:
-
-     Example 2:
-	  if (n > 0)
-	     x = 1;
-	  ...
-	  if (n > 0)
-	    {
-	      if (m < 2)
-		 .. = x;
-	    }
-
-     Predicate analysis needs to compute the composite predicate:
-
-       1) 'x' use predicate: (n > 0) .AND. (m < 2)
-       2) 'x' default value  (non-def) predicate: .NOT. (n > 0)
-       (the predicate chain for phi operand defs can be computed
-       starting from a bb that is control equivalent to the phi's
-       bb and is dominating the operand def.)
-
-       and check overlapping:
-	  (n > 0) .AND. (m < 2) .AND. (.NOT. (n > 0))
-	<==> false
-
-     This implementation provides framework that can handle
-     scenarios.  (Note that many simple cases are handled properly
-     without the predicate analysis -- this is due to jump threading
-     transformation which eliminates the merge point thus makes
-     path sensitive analysis unnecessary.)
-
-     PHI is the phi node whose incoming (undefined) paths need to be
-     pruned, and UNINIT_OPNDS is the bitmap holding uninit operand
-     positions.  VISITED_PHIS is the pointer set of phi stmts being
-     checked.  */
-
-static bool
-use_pred_not_overlap_with_undef_path_pred (pred_chain_union preds,
-					   gphi *phi, unsigned uninit_opnds,
-					   hash_set<gphi *> *visited_phis)
-{
-  gimple *flag_def = 0;
-  tree boundary_cst = 0;
-  enum tree_code cmp_code;
-  bitmap visited_flag_phis = NULL;
-  bool all_pruned = false;
-
-  /* Find within the common prefix of multiple predicate chains
-     a predicate that is a comparison of a flag variable against
-     a constant.  */
-  cmp_code = find_var_cmp_const (preds, phi, &flag_def, &boundary_cst);
-  if (cmp_code == ERROR_MARK)
-    return false;
-
-  /* Now check all the uninit incoming edge has a constant flag value
-     that is in conflict with the use guard/predicate.  */
-  all_pruned = prune_uninit_phi_opnds
-    (phi, uninit_opnds, as_a<gphi *> (flag_def), boundary_cst, cmp_code,
-     visited_phis, &visited_flag_phis);
-
-  if (visited_flag_phis)
-    BITMAP_FREE (visited_flag_phis);
-
-  return all_pruned;
-}
-
-/* The helper function returns true if two predicates X1 and X2
-   are equivalent.  It assumes the expressions have already
-   properly re-associated.  */
-
-static inline bool
-pred_equal_p (pred_info x1, pred_info x2)
-{
-  enum tree_code c1, c2;
-  if (!operand_equal_p (x1.pred_lhs, x2.pred_lhs, 0)
-      || !operand_equal_p (x1.pred_rhs, x2.pred_rhs, 0))
-    return false;
-
-  c1 = x1.cond_code;
-  if (x1.invert != x2.invert
-      && TREE_CODE_CLASS (x2.cond_code) == tcc_comparison)
-    c2 = invert_tree_comparison (x2.cond_code, false);
-  else
-    c2 = x2.cond_code;
-
-  return c1 == c2;
-}
-
-/* Returns true if the predication is testing !=.  */
-
-static inline bool
-is_neq_relop_p (pred_info pred)
-{
-
-  return ((pred.cond_code == NE_EXPR && !pred.invert)
-	  || (pred.cond_code == EQ_EXPR && pred.invert));
-}
-
-/* Returns true if pred is of the form X != 0.  */
-
-static inline bool
-is_neq_zero_form_p (pred_info pred)
-{
-  if (!is_neq_relop_p (pred) || !integer_zerop (pred.pred_rhs)
-      || TREE_CODE (pred.pred_lhs) != SSA_NAME)
-    return false;
-  return true;
-}
-
-/* The helper function returns true if two predicates X1
-   is equivalent to X2 != 0.  */
-
-static inline bool
-pred_expr_equal_p (pred_info x1, tree x2)
-{
-  if (!is_neq_zero_form_p (x1))
-    return false;
-
-  return operand_equal_p (x1.pred_lhs, x2, 0);
-}
-
-/* Returns true of the domain of single predicate expression
-   EXPR1 is a subset of that of EXPR2.  Returns false if it
-   cannot be proved.  */
-
-static bool
-is_pred_expr_subset_of (pred_info expr1, pred_info expr2)
-{
-  enum tree_code code1, code2;
-
-  if (pred_equal_p (expr1, expr2))
-    return true;
-
-  if ((TREE_CODE (expr1.pred_rhs) != INTEGER_CST)
-      || (TREE_CODE (expr2.pred_rhs) != INTEGER_CST))
-    return false;
-
-  if (!operand_equal_p (expr1.pred_lhs, expr2.pred_lhs, 0))
-    return false;
-
-  code1 = expr1.cond_code;
-  if (expr1.invert)
-    code1 = invert_tree_comparison (code1, false);
-  code2 = expr2.cond_code;
-  if (expr2.invert)
-    code2 = invert_tree_comparison (code2, false);
-
-  if (code2 == NE_EXPR && code1 == NE_EXPR)
-    return false;
-
-  if (code2 == NE_EXPR)
-    return !value_sat_pred_p (expr2.pred_rhs, expr1.pred_rhs, code1);
-
-  if (code1 == EQ_EXPR)
-    return value_sat_pred_p (expr1.pred_rhs, expr2.pred_rhs, code2);
-
-  if (code1 == code2)
-    return value_sat_pred_p (expr1.pred_rhs, expr2.pred_rhs, code2,
-			     code1 == BIT_AND_EXPR);
+  if (TREE_CODE (val) == SSA_NAME)
+    return uninit_undefined_value_p (val);
 
   return false;
 }
 
-/* Returns true if the domain of PRED1 is a subset
-   of that of PRED2.  Returns false if it cannot be proved so.  */
+/* Return a bitset of PHI arguments of interest.  */
 
-static bool
-is_pred_chain_subset_of (pred_chain pred1, pred_chain pred2)
+unsigned
+uninit_undef_val_t::phi_arg_set (gphi *phi)
 {
-  size_t np1, np2, i1, i2;
-
-  np1 = pred1.length ();
-  np2 = pred2.length ();
-
-  for (i2 = 0; i2 < np2; i2++)
-    {
-      bool found = false;
-      pred_info info2 = pred2[i2];
-      for (i1 = 0; i1 < np1; i1++)
-	{
-	  pred_info info1 = pred1[i1];
-	  if (is_pred_expr_subset_of (info1, info2))
-	    {
-	      found = true;
-	      break;
-	    }
-	}
-      if (!found)
-	return false;
-    }
-  return true;
-}
-
-/* Returns true if the domain defined by
-   one pred chain ONE_PRED is a subset of the domain
-   of *PREDS.  It returns false if ONE_PRED's domain is
-   not a subset of any of the sub-domains of PREDS
-   (corresponding to each individual chains in it), even
-   though it may be still be a subset of whole domain
-   of PREDS which is the union (ORed) of all its subdomains.
-   In other words, the result is conservative.  */
-
-static bool
-is_included_in (pred_chain one_pred, pred_chain_union preds)
-{
-  size_t i;
-  size_t n = preds.length ();
-
-  for (i = 0; i < n; i++)
-    {
-      if (is_pred_chain_subset_of (one_pred, preds[i]))
-	return true;
-    }
-
-  return false;
-}
-
-/* Compares two predicate sets PREDS1 and PREDS2 and returns
-   true if the domain defined by PREDS1 is a superset
-   of PREDS2's domain.  N1 and N2 are array sizes of PREDS1 and
-   PREDS2 respectively.  The implementation chooses not to build
-   generic trees (and relying on the folding capability of the
-   compiler), but instead performs brute force comparison of
-   individual predicate chains (won't be a compile time problem
-   as the chains are pretty short).  When the function returns
-   false, it does not necessarily mean *PREDS1 is not a superset
-   of *PREDS2, but mean it may not be so since the analysis cannot
-   prove it.  In such cases, false warnings may still be
-   emitted.  */
-
-static bool
-is_superset_of (pred_chain_union preds1, pred_chain_union preds2)
-{
-  size_t i, n2;
-  pred_chain one_pred_chain = vNULL;
-
-  n2 = preds2.length ();
-
-  for (i = 0; i < n2; i++)
-    {
-      one_pred_chain = preds2[i];
-      if (!is_included_in (one_pred_chain, preds1))
-	return false;
-    }
-
-  return true;
-}
-
-/* Returns true if X1 is the negate of X2.  */
-
-static inline bool
-pred_neg_p (pred_info x1, pred_info x2)
-{
-  enum tree_code c1, c2;
-  if (!operand_equal_p (x1.pred_lhs, x2.pred_lhs, 0)
-      || !operand_equal_p (x1.pred_rhs, x2.pred_rhs, 0))
-    return false;
-
-  c1 = x1.cond_code;
-  if (x1.invert == x2.invert)
-    c2 = invert_tree_comparison (x2.cond_code, false);
-  else
-    c2 = x2.cond_code;
-
-  return c1 == c2;
-}
-
-/* 1) ((x IOR y) != 0) AND (x != 0) is equivalent to (x != 0);
-   2) (X AND Y) OR (!X AND Y) is equivalent to Y;
-   3) X OR (!X AND Y) is equivalent to (X OR Y);
-   4) ((x IAND y) != 0) || (x != 0 AND y != 0)) is equivalent to
-      (x != 0 AND y != 0)
-   5) (X AND Y) OR (!X AND Z) OR (!Y AND Z) is equivalent to
-      (X AND Y) OR Z
-
-   PREDS is the predicate chains, and N is the number of chains.  */
-
-/* Helper function to implement rule 1 above.  ONE_CHAIN is
-   the AND predication to be simplified.  */
-
-static void
-simplify_pred (pred_chain *one_chain)
-{
-  size_t i, j, n;
-  bool simplified = false;
-  pred_chain s_chain = vNULL;
-
-  n = one_chain->length ();
-
-  for (i = 0; i < n; i++)
-    {
-      pred_info *a_pred = &(*one_chain)[i];
-
-      if (!a_pred->pred_lhs)
-	continue;
-      if (!is_neq_zero_form_p (*a_pred))
-	continue;
-
-      gimple *def_stmt = SSA_NAME_DEF_STMT (a_pred->pred_lhs);
-      if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
-	continue;
-      if (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)
-	{
-	  for (j = 0; j < n; j++)
-	    {
-	      pred_info *b_pred = &(*one_chain)[j];
-
-	      if (!b_pred->pred_lhs)
-		continue;
-	      if (!is_neq_zero_form_p (*b_pred))
-		continue;
-
-	      if (pred_expr_equal_p (*b_pred, gimple_assign_rhs1 (def_stmt))
-		  || pred_expr_equal_p (*b_pred, gimple_assign_rhs2 (def_stmt)))
-		{
-		  /* Mark a_pred for removal.  */
-		  a_pred->pred_lhs = NULL;
-		  a_pred->pred_rhs = NULL;
-		  simplified = true;
-		  break;
-		}
-	    }
-	}
-    }
-
-  if (!simplified)
-    return;
-
-  for (i = 0; i < n; i++)
-    {
-      pred_info *a_pred = &(*one_chain)[i];
-      if (!a_pred->pred_lhs)
-	continue;
-      s_chain.safe_push (*a_pred);
-    }
-
-  one_chain->release ();
-  *one_chain = s_chain;
-}
-
-/* The helper function implements the rule 2 for the
-   OR predicate PREDS.
-
-   2) (X AND Y) OR (!X AND Y) is equivalent to Y.  */
-
-static bool
-simplify_preds_2 (pred_chain_union *preds)
-{
-  size_t i, j, n;
-  bool simplified = false;
-  pred_chain_union s_preds = vNULL;
-
-  /* (X AND Y) OR (!X AND Y) is equivalent to Y.
-     (X AND Y) OR (X AND !Y) is equivalent to X.  */
-
-  n = preds->length ();
-  for (i = 0; i < n; i++)
-    {
-      pred_info x, y;
-      pred_chain *a_chain = &(*preds)[i];
-
-      if (a_chain->length () != 2)
-	continue;
-
-      x = (*a_chain)[0];
-      y = (*a_chain)[1];
-
-      for (j = 0; j < n; j++)
-	{
-	  pred_chain *b_chain;
-	  pred_info x2, y2;
-
-	  if (j == i)
-	    continue;
-
-	  b_chain = &(*preds)[j];
-	  if (b_chain->length () != 2)
-	    continue;
-
-	  x2 = (*b_chain)[0];
-	  y2 = (*b_chain)[1];
-
-	  if (pred_equal_p (x, x2) && pred_neg_p (y, y2))
-	    {
-	      /* Kill a_chain.  */
-	      a_chain->release ();
-	      b_chain->release ();
-	      b_chain->safe_push (x);
-	      simplified = true;
-	      break;
-	    }
-	  if (pred_neg_p (x, x2) && pred_equal_p (y, y2))
-	    {
-	      /* Kill a_chain.  */
-	      a_chain->release ();
-	      b_chain->release ();
-	      b_chain->safe_push (y);
-	      simplified = true;
-	      break;
-	    }
-	}
-    }
-  /* Now clean up the chain.  */
-  if (simplified)
-    {
-      for (i = 0; i < n; i++)
-	{
-	  if ((*preds)[i].is_empty ())
-	    continue;
-	  s_preds.safe_push ((*preds)[i]);
-	}
-      preds->release ();
-      (*preds) = s_preds;
-      s_preds = vNULL;
-    }
-
-  return simplified;
-}
-
-/* The helper function implements the rule 2 for the
-   OR predicate PREDS.
-
-   3) x OR (!x AND y) is equivalent to x OR y.  */
-
-static bool
-simplify_preds_3 (pred_chain_union *preds)
-{
-  size_t i, j, n;
-  bool simplified = false;
-
-  /* Now iteratively simplify X OR (!X AND Z ..)
-       into X OR (Z ...).  */
-
-  n = preds->length ();
-  if (n < 2)
-    return false;
-
-  for (i = 0; i < n; i++)
-    {
-      pred_info x;
-      pred_chain *a_chain = &(*preds)[i];
-
-      if (a_chain->length () != 1)
-	continue;
-
-      x = (*a_chain)[0];
-
-      for (j = 0; j < n; j++)
-	{
-	  pred_chain *b_chain;
-	  pred_info x2;
-	  size_t k;
-
-	  if (j == i)
-	    continue;
-
-	  b_chain = &(*preds)[j];
-	  if (b_chain->length () < 2)
-	    continue;
-
-	  for (k = 0; k < b_chain->length (); k++)
-	    {
-	      x2 = (*b_chain)[k];
-	      if (pred_neg_p (x, x2))
-		{
-		  b_chain->unordered_remove (k);
-		  simplified = true;
-		  break;
-		}
-	    }
-	}
-    }
-  return simplified;
-}
-
-/* The helper function implements the rule 4 for the
-   OR predicate PREDS.
-
-   2) ((x AND y) != 0) OR (x != 0 AND y != 0) is equivalent to
-       (x != 0 ANd y != 0).   */
-
-static bool
-simplify_preds_4 (pred_chain_union *preds)
-{
-  size_t i, j, n;
-  bool simplified = false;
-  pred_chain_union s_preds = vNULL;
-  gimple *def_stmt;
-
-  n = preds->length ();
-  for (i = 0; i < n; i++)
-    {
-      pred_info z;
-      pred_chain *a_chain = &(*preds)[i];
-
-      if (a_chain->length () != 1)
-	continue;
-
-      z = (*a_chain)[0];
-
-      if (!is_neq_zero_form_p (z))
-	continue;
-
-      def_stmt = SSA_NAME_DEF_STMT (z.pred_lhs);
-      if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
-	continue;
-
-      if (gimple_assign_rhs_code (def_stmt) != BIT_AND_EXPR)
-	continue;
-
-      for (j = 0; j < n; j++)
-	{
-	  pred_chain *b_chain;
-	  pred_info x2, y2;
-
-	  if (j == i)
-	    continue;
-
-	  b_chain = &(*preds)[j];
-	  if (b_chain->length () != 2)
-	    continue;
-
-	  x2 = (*b_chain)[0];
-	  y2 = (*b_chain)[1];
-	  if (!is_neq_zero_form_p (x2) || !is_neq_zero_form_p (y2))
-	    continue;
-
-	  if ((pred_expr_equal_p (x2, gimple_assign_rhs1 (def_stmt))
-	       && pred_expr_equal_p (y2, gimple_assign_rhs2 (def_stmt)))
-	      || (pred_expr_equal_p (x2, gimple_assign_rhs2 (def_stmt))
-		  && pred_expr_equal_p (y2, gimple_assign_rhs1 (def_stmt))))
-	    {
-	      /* Kill a_chain.  */
-	      a_chain->release ();
-	      simplified = true;
-	      break;
-	    }
-	}
-    }
-  /* Now clean up the chain.  */
-  if (simplified)
-    {
-      for (i = 0; i < n; i++)
-	{
-	  if ((*preds)[i].is_empty ())
-	    continue;
-	  s_preds.safe_push ((*preds)[i]);
-	}
-
-      preds->release ();
-      (*preds) = s_preds;
-      s_preds = vNULL;
-    }
-
-  return simplified;
-}
-
-/* This function simplifies predicates in PREDS.  */
-
-static void
-simplify_preds (pred_chain_union *preds, gimple *use_or_def, bool is_use)
-{
-  size_t i, n;
-  bool changed = false;
-
-  if (dump_file && dump_flags & TDF_DETAILS)
-    {
-      fprintf (dump_file, "[BEFORE SIMPLICATION -- ");
-      dump_predicates (use_or_def, *preds, is_use ? "[USE]:\n" : "[DEF]:\n");
-    }
-
-  for (i = 0; i < preds->length (); i++)
-    simplify_pred (&(*preds)[i]);
-
-  n = preds->length ();
-  if (n < 2)
-    return;
-
-  do
-    {
-      changed = false;
-      if (simplify_preds_2 (preds))
-	changed = true;
-
-      /* Now iteratively simplify X OR (!X AND Z ..)
-       into X OR (Z ...).  */
-      if (simplify_preds_3 (preds))
-	changed = true;
-
-      if (simplify_preds_4 (preds))
-	changed = true;
-    }
-  while (changed);
-
-  return;
-}
-
-/* This is a helper function which attempts to normalize predicate chains
-  by following UD chains.  It basically builds up a big tree of either IOR
-  operations or AND operations, and convert the IOR tree into a
-  pred_chain_union or BIT_AND tree into a pred_chain.
-  Example:
-
-  _3 = _2 RELOP1 _1;
-  _6 = _5 RELOP2 _4;
-  _9 = _8 RELOP3 _7;
-  _10 = _3 | _6;
-  _12 = _9 | _0;
-  _t = _10 | _12;
-
- then _t != 0 will be normalized into a pred_chain_union
-
-   (_2 RELOP1 _1) OR (_5 RELOP2 _4) OR (_8 RELOP3 _7) OR (_0 != 0)
-
- Similarly given,
-
-  _3 = _2 RELOP1 _1;
-  _6 = _5 RELOP2 _4;
-  _9 = _8 RELOP3 _7;
-  _10 = _3 & _6;
-  _12 = _9 & _0;
-
- then _t != 0 will be normalized into a pred_chain:
-   (_2 RELOP1 _1) AND (_5 RELOP2 _4) AND (_8 RELOP3 _7) AND (_0 != 0)
-
-  */
-
-/* This is a helper function that stores a PRED into NORM_PREDS.  */
-
-inline static void
-push_pred (pred_chain_union *norm_preds, pred_info pred)
-{
-  pred_chain pred_chain = vNULL;
-  pred_chain.safe_push (pred);
-  norm_preds->safe_push (pred_chain);
-}
-
-/* A helper function that creates a predicate of the form
-   OP != 0 and push it WORK_LIST.  */
-
-inline static void
-push_to_worklist (tree op, vec<pred_info, va_heap, vl_ptr> *work_list,
-		  hash_set<tree> *mark_set)
-{
-  if (mark_set->contains (op))
-    return;
-  mark_set->add (op);
-
-  pred_info arg_pred;
-  arg_pred.pred_lhs = op;
-  arg_pred.pred_rhs = integer_zero_node;
-  arg_pred.cond_code = NE_EXPR;
-  arg_pred.invert = false;
-  work_list->safe_push (arg_pred);
-}
-
-/* A helper that generates a pred_info from a gimple assignment
-   CMP_ASSIGN with comparison rhs.  */
-
-static pred_info
-get_pred_info_from_cmp (gimple *cmp_assign)
-{
-  pred_info n_pred;
-  n_pred.pred_lhs = gimple_assign_rhs1 (cmp_assign);
-  n_pred.pred_rhs = gimple_assign_rhs2 (cmp_assign);
-  n_pred.cond_code = gimple_assign_rhs_code (cmp_assign);
-  n_pred.invert = false;
-  return n_pred;
-}
-
-/* Returns true if the PHI is a degenerated phi with
-   all args with the same value (relop).  In that case, *PRED
-   will be updated to that value.  */
-
-static bool
-is_degenerated_phi (gimple *phi, pred_info *pred_p)
-{
-  int i, n;
-  tree op0;
-  gimple *def0;
-  pred_info pred0;
-
-  n = gimple_phi_num_args (phi);
-  op0 = gimple_phi_arg_def (phi, 0);
-
-  if (TREE_CODE (op0) != SSA_NAME)
-    return false;
-
-  def0 = SSA_NAME_DEF_STMT (op0);
-  if (gimple_code (def0) != GIMPLE_ASSIGN)
-    return false;
-  if (TREE_CODE_CLASS (gimple_assign_rhs_code (def0)) != tcc_comparison)
-    return false;
-  pred0 = get_pred_info_from_cmp (def0);
-
-  for (i = 1; i < n; ++i)
-    {
-      gimple *def;
-      pred_info pred;
-      tree op = gimple_phi_arg_def (phi, i);
-
-      if (TREE_CODE (op) != SSA_NAME)
-	return false;
-
-      def = SSA_NAME_DEF_STMT (op);
-      if (gimple_code (def) != GIMPLE_ASSIGN)
-	return false;
-      if (TREE_CODE_CLASS (gimple_assign_rhs_code (def)) != tcc_comparison)
-	return false;
-      pred = get_pred_info_from_cmp (def);
-      if (!pred_equal_p (pred, pred0))
-	return false;
-    }
-
-  *pred_p = pred0;
-  return true;
-}
-
-/* Normalize one predicate PRED
-   1) if PRED can no longer be normlized, put it into NORM_PREDS.
-   2) otherwise if PRED is of the form x != 0, follow x's definition
-      and put normalized predicates into WORK_LIST.  */
-
-static void
-normalize_one_pred_1 (pred_chain_union *norm_preds,
-		      pred_chain *norm_chain,
-		      pred_info pred,
-		      enum tree_code and_or_code,
-		      vec<pred_info, va_heap, vl_ptr> *work_list,
-		      hash_set<tree> *mark_set)
-{
-  if (!is_neq_zero_form_p (pred))
-    {
-      if (and_or_code == BIT_IOR_EXPR)
-	push_pred (norm_preds, pred);
-      else
-	norm_chain->safe_push (pred);
-      return;
-    }
-
-  gimple *def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
-
-  if (gimple_code (def_stmt) == GIMPLE_PHI
-      && is_degenerated_phi (def_stmt, &pred))
-    work_list->safe_push (pred);
-  else if (gimple_code (def_stmt) == GIMPLE_PHI && and_or_code == BIT_IOR_EXPR)
-    {
-      int i, n;
-      n = gimple_phi_num_args (def_stmt);
-
-      /* If we see non zero constant, we should punt.  The predicate
-       * should be one guarding the phi edge.  */
-      for (i = 0; i < n; ++i)
-	{
-	  tree op = gimple_phi_arg_def (def_stmt, i);
-	  if (TREE_CODE (op) == INTEGER_CST && !integer_zerop (op))
-	    {
-	      push_pred (norm_preds, pred);
-	      return;
-	    }
-	}
-
-      for (i = 0; i < n; ++i)
-	{
-	  tree op = gimple_phi_arg_def (def_stmt, i);
-	  if (integer_zerop (op))
-	    continue;
-
-	  push_to_worklist (op, work_list, mark_set);
-	}
-    }
-  else if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
-    {
-      if (and_or_code == BIT_IOR_EXPR)
-	push_pred (norm_preds, pred);
-      else
-	norm_chain->safe_push (pred);
-    }
-  else if (gimple_assign_rhs_code (def_stmt) == and_or_code)
-    {
-      /* Avoid splitting up bit manipulations like x & 3 or y | 1.  */
-      if (is_gimple_min_invariant (gimple_assign_rhs2 (def_stmt)))
-	{
-	  /* But treat x & 3 as condition.  */
-	  if (and_or_code == BIT_AND_EXPR)
-	    {
-	      pred_info n_pred;
-	      n_pred.pred_lhs = gimple_assign_rhs1 (def_stmt);
-	      n_pred.pred_rhs = gimple_assign_rhs2 (def_stmt);
-	      n_pred.cond_code = and_or_code;
-	      n_pred.invert = false;
-	      norm_chain->safe_push (n_pred);
-	    }
-	}
-      else
-	{
-	  push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set);
-	  push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set);
-	}
-    }
-  else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt))
-	   == tcc_comparison)
-    {
-      pred_info n_pred = get_pred_info_from_cmp (def_stmt);
-      if (and_or_code == BIT_IOR_EXPR)
-	push_pred (norm_preds, n_pred);
-      else
-	norm_chain->safe_push (n_pred);
-    }
-  else
-    {
-      if (and_or_code == BIT_IOR_EXPR)
-	push_pred (norm_preds, pred);
-      else
-	norm_chain->safe_push (pred);
-    }
-}
-
-/* Normalize PRED and store the normalized predicates into NORM_PREDS.  */
-
-static void
-normalize_one_pred (pred_chain_union *norm_preds, pred_info pred)
-{
-  vec<pred_info, va_heap, vl_ptr> work_list = vNULL;
-  enum tree_code and_or_code = ERROR_MARK;
-  pred_chain norm_chain = vNULL;
-
-  if (!is_neq_zero_form_p (pred))
-    {
-      push_pred (norm_preds, pred);
-      return;
-    }
-
-  gimple *def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs);
-  if (gimple_code (def_stmt) == GIMPLE_ASSIGN)
-    and_or_code = gimple_assign_rhs_code (def_stmt);
-  if (and_or_code != BIT_IOR_EXPR && and_or_code != BIT_AND_EXPR)
-    {
-      if (TREE_CODE_CLASS (and_or_code) == tcc_comparison)
-	{
-	  pred_info n_pred = get_pred_info_from_cmp (def_stmt);
-	  push_pred (norm_preds, n_pred);
-	}
-      else
-	push_pred (norm_preds, pred);
-      return;
-    }
-
-  work_list.safe_push (pred);
-  hash_set<tree> mark_set;
-
-  while (!work_list.is_empty ())
-    {
-      pred_info a_pred = work_list.pop ();
-      normalize_one_pred_1 (norm_preds, &norm_chain, a_pred, and_or_code,
-			    &work_list, &mark_set);
-    }
-  if (and_or_code == BIT_AND_EXPR)
-    norm_preds->safe_push (norm_chain);
-
-  work_list.release ();
-}
-
-static void
-normalize_one_pred_chain (pred_chain_union *norm_preds, pred_chain one_chain)
-{
-  vec<pred_info, va_heap, vl_ptr> work_list = vNULL;
-  hash_set<tree> mark_set;
-  pred_chain norm_chain = vNULL;
-  size_t i;
-
-  for (i = 0; i < one_chain.length (); i++)
-    {
-      work_list.safe_push (one_chain[i]);
-      mark_set.add (one_chain[i].pred_lhs);
-    }
-
-  while (!work_list.is_empty ())
-    {
-      pred_info a_pred = work_list.pop ();
-      normalize_one_pred_1 (0, &norm_chain, a_pred, BIT_AND_EXPR, &work_list,
-			    &mark_set);
-    }
-
-  norm_preds->safe_push (norm_chain);
-  work_list.release ();
-}
-
-/* Normalize predicate chains PREDS and returns the normalized one.  */
-
-static pred_chain_union
-normalize_preds (pred_chain_union preds, gimple *use_or_def, bool is_use)
-{
-  pred_chain_union norm_preds = vNULL;
-  size_t n = preds.length ();
-  size_t i;
-
-  if (dump_file && dump_flags & TDF_DETAILS)
-    {
-      fprintf (dump_file, "[BEFORE NORMALIZATION --");
-      dump_predicates (use_or_def, preds, is_use ? "[USE]:\n" : "[DEF]:\n");
-    }
-
-  for (i = 0; i < n; i++)
-    {
-      if (preds[i].length () != 1)
-	normalize_one_pred_chain (&norm_preds, preds[i]);
-      else
-	{
-	  normalize_one_pred (&norm_preds, preds[i][0]);
-	  preds[i].release ();
-	}
-    }
-
-  if (dump_file)
-    {
-      fprintf (dump_file, "[AFTER NORMALIZATION -- ");
-      dump_predicates (use_or_def, norm_preds,
-		       is_use ? "[USE]:\n" : "[DEF]:\n");
-    }
-
-  destroy_predicate_vecs (&preds);
-  return norm_preds;
-}
-
-/* Return TRUE if PREDICATE can be invalidated by any individual
-   predicate in USE_GUARD.  */
-
-static bool
-can_one_predicate_be_invalidated_p (pred_info predicate,
-				    pred_chain use_guard)
-{
-  if (dump_file && dump_flags & TDF_DETAILS)
-    {
-      fprintf (dump_file, "Testing if this predicate: ");
-      dump_pred_info (predicate);
-      fprintf (dump_file, "\n...can be invalidated by a USE guard of: ");
-      dump_pred_chain (use_guard);
-    }
-  for (size_t i = 0; i < use_guard.length (); ++i)
-    {
-      /* NOTE: This is a very simple check, and only understands an
-	 exact opposite.  So, [i == 0] is currently only invalidated
-	 by [.NOT. i == 0] or [i != 0].  Ideally we should also
-	 invalidate with say [i > 5] or [i == 8].  There is certainly
-	 room for improvement here.  */
-      if (pred_neg_p (predicate, use_guard[i]))
-	{
-	  if (dump_file && dump_flags & TDF_DETAILS)
-	    {
-	      fprintf (dump_file, "  Predicate was invalidated by: ");
-	      dump_pred_info (use_guard[i]);
-	      fputc ('\n', dump_file);
-	    }
-	  return true;
-	}
-    }
-  return false;
-}
-
-/* Return TRUE if all predicates in UNINIT_PRED are invalidated by
-   USE_GUARD being true.  */
-
-static bool
-can_chain_union_be_invalidated_p (pred_chain_union uninit_pred,
-				  pred_chain use_guard)
-{
-  if (uninit_pred.is_empty ())
-    return false;
-  if (dump_file && dump_flags & TDF_DETAILS)
-    dump_predicates (NULL, uninit_pred,
-		     "Testing if anything here can be invalidated: ");
-  for (size_t i = 0; i < uninit_pred.length (); ++i)
-    {
-      pred_chain c = uninit_pred[i];
-      size_t j;
-      for (j = 0; j < c.length (); ++j)
-	if (can_one_predicate_be_invalidated_p (c[j], use_guard))
-	  break;
-
-      /* If we were unable to invalidate any predicate in C, then there
-	 is a viable path from entry to the PHI where the PHI takes
-	 an uninitialized value and continues to a use of the PHI.  */
-      if (j == c.length ())
-	return false;
-    }
-  return true;
-}
-
-/* Return TRUE if none of the uninitialized operands in UNINT_OPNDS
-   can actually happen if we arrived at a use for PHI.
-
-   PHI_USE_GUARDS are the guard conditions for the use of the PHI.  */
-
-static bool
-uninit_uses_cannot_happen (gphi *phi, unsigned uninit_opnds,
-			   pred_chain_union phi_use_guards)
-{
-  unsigned phi_args = gimple_phi_num_args (phi);
-  if (phi_args > max_phi_args)
-    return false;
-
-  /* PHI_USE_GUARDS are OR'ed together.  If we have more than one
-     possible guard, there's no way of knowing which guard was true.
-     Since we need to be absolutely sure that the uninitialized
-     operands will be invalidated, bail.  */
-  if (phi_use_guards.length () != 1)
-    return false;
-
-  /* Look for the control dependencies of all the uninitialized
-     operands and build guard predicates describing them.  */
-  pred_chain_union uninit_preds;
-  bool ret = true;
-  for (unsigned i = 0; i < phi_args; ++i)
-    {
-      if (!MASK_TEST_BIT (uninit_opnds, i))
-	continue;
-
-      edge e = gimple_phi_arg_edge (phi, i);
-      vec<edge> dep_chains[MAX_NUM_CHAINS];
-      auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain;
-      size_t num_chains = 0;
-      int num_calls = 0;
-
-      /* Build the control dependency chain for uninit operand `i'...  */
-      uninit_preds = vNULL;
-      if (!compute_control_dep_chain (ENTRY_BLOCK_PTR_FOR_FN (cfun),
-				      e->src, dep_chains, &num_chains,
-				      &cur_chain, &num_calls))
-	{
-	  ret = false;
-	  break;
-	}
-      /* ...and convert it into a set of predicates.  */
-      bool has_valid_preds
-	= convert_control_dep_chain_into_preds (dep_chains, num_chains,
-						&uninit_preds);
-      for (size_t j = 0; j < num_chains; ++j)
-	dep_chains[j].release ();
-      if (!has_valid_preds)
-	{
-	  ret = false;
-	  break;
-	}
-      simplify_preds (&uninit_preds, NULL, false);
-      uninit_preds = normalize_preds (uninit_preds, NULL, false);
-
-      /* Can the guard for this uninitialized operand be invalidated
-	 by the PHI use?  */
-      if (!can_chain_union_be_invalidated_p (uninit_preds, phi_use_guards[0]))
-	{
-	  ret = false;
-	  break;
-	}
-    }
-  destroy_predicate_vecs (&uninit_preds);
-  return ret;
-}
-
-/* Computes the predicates that guard the use and checks
-   if the incoming paths that have empty (or possibly
-   empty) definition can be pruned/filtered.  The function returns
-   true if it can be determined that the use of PHI's def in
-   USE_STMT is guarded with a predicate set not overlapping with
-   predicate sets of all runtime paths that do not have a definition.
-
-   Returns false if it is not or it cannot be determined.  USE_BB is
-   the bb of the use (for phi operand use, the bb is not the bb of
-   the phi stmt, but the src bb of the operand edge).
-
-   UNINIT_OPNDS is a bit vector.  If an operand of PHI is uninitialized, the
-   corresponding bit in the vector is 1.  VISITED_PHIS is a pointer
-   set of phis being visited.
-
-   *DEF_PREDS contains the (memoized) defining predicate chains of PHI.
-   If *DEF_PREDS is the empty vector, the defining predicate chains of
-   PHI will be computed and stored into *DEF_PREDS as needed.
-
-   VISITED_PHIS is a pointer set of phis being visited.  */
-
-static bool
-is_use_properly_guarded (gimple *use_stmt,
-			 basic_block use_bb,
-			 gphi *phi,
-			 unsigned uninit_opnds,
-			 pred_chain_union *def_preds,
-			 hash_set<gphi *> *visited_phis)
-{
-  basic_block phi_bb;
-  pred_chain_union preds = vNULL;
-  bool has_valid_preds = false;
-  bool is_properly_guarded = false;
-
-  if (visited_phis->add (phi))
-    return false;
-
-  phi_bb = gimple_bb (phi);
-
-  if (is_non_loop_exit_postdominating (use_bb, phi_bb))
-    return false;
-
-  has_valid_preds = find_predicates (&preds, phi_bb, use_bb);
-
-  if (!has_valid_preds)
-    {
-      destroy_predicate_vecs (&preds);
-      return false;
-    }
-
-  /* Try to prune the dead incoming phi edges.  */
-  is_properly_guarded
-    = use_pred_not_overlap_with_undef_path_pred (preds, phi, uninit_opnds,
-						 visited_phis);
-
-  /* We might be able to prove that if the control dependencies
-     for UNINIT_OPNDS are true, that the control dependencies for
-     USE_STMT can never be true.  */
-  if (!is_properly_guarded)
-    is_properly_guarded |= uninit_uses_cannot_happen (phi, uninit_opnds,
-						      preds);
-
-  if (is_properly_guarded)
-    {
-      destroy_predicate_vecs (&preds);
-      return true;
-    }
-
-  if (def_preds->is_empty ())
-    {
-      has_valid_preds = find_def_preds (def_preds, phi);
-
-      if (!has_valid_preds)
-	{
-	  destroy_predicate_vecs (&preds);
-	  return false;
-	}
-
-      simplify_preds (def_preds, phi, false);
-      *def_preds = normalize_preds (*def_preds, phi, false);
-    }
-
-  simplify_preds (&preds, use_stmt, true);
-  preds = normalize_preds (preds, use_stmt, true);
-
-  is_properly_guarded = is_superset_of (*def_preds, preds);
-
-  destroy_predicate_vecs (&preds);
-  return is_properly_guarded;
+  return compute_uninit_opnds_pos (phi);
 }
 
 /* Searches through all uses of a potentially
@@ -3149,48 +1156,42 @@ is_use_properly_guarded (gimple *use_stmt,
 
 static gimple *
 find_uninit_use (gphi *phi, unsigned uninit_opnds,
-		 vec<gphi *> *worklist,
-		 hash_set<gphi *> *added_to_worklist)
+		 vec<gphi *> *worklist, hash_set<gphi *> *added_to_worklist)
 {
-  tree phi_result;
+  /* The Boolean predicate guarding the PHI definition.  Initialized
+     lazily from PHI in the first call to is_use_guarded() and cached
+     for subsequent iterations.  */
+  uninit_undef_val_t eval;
+  predicate def_preds (eval);
+
   use_operand_p use_p;
-  gimple *use_stmt;
   imm_use_iterator iter;
-  pred_chain_union def_preds = vNULL;
-  gimple *ret = NULL;
-
-  phi_result = gimple_phi_result (phi);
-
+  tree phi_result = gimple_phi_result (phi);
   FOR_EACH_IMM_USE_FAST (use_p, iter, phi_result)
     {
-      basic_block use_bb;
-
-      use_stmt = USE_STMT (use_p);
+      gimple *use_stmt = USE_STMT (use_p);
       if (is_gimple_debug (use_stmt))
 	continue;
 
+      basic_block use_bb;
       if (gphi *use_phi = dyn_cast<gphi *> (use_stmt))
 	use_bb = gimple_phi_arg_edge (use_phi,
 				      PHI_ARG_INDEX_FROM_USE (use_p))->src;
       else
 	use_bb = gimple_bb (use_stmt);
 
-      hash_set<gphi *> visited_phis;
-      if (is_use_properly_guarded (use_stmt, use_bb, phi, uninit_opnds,
-				   &def_preds, &visited_phis))
+      if (def_preds.is_use_guarded (use_stmt, use_bb, phi, uninit_opnds))
 	continue;
 
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{
-	  fprintf (dump_file, "[CHECK]: Found unguarded use: ");
+	  fprintf (dump_file, "Found unguarded use in bb %u: ",
+		   use_bb->index);
 	  print_gimple_stmt (dump_file, use_stmt, 0);
 	}
       /* Found one real use, return.  */
       if (gimple_code (use_stmt) != GIMPLE_PHI)
-	{
-	  ret = use_stmt;
-	  break;
-	}
+	return use_stmt;
 
       /* Found a phi use that is not guarded,
 	 add the phi to the worklist.  */
@@ -3207,8 +1208,7 @@ find_uninit_use (gphi *phi, unsigned uninit_opnds,
 	}
     }
 
-  destroy_predicate_vecs (&def_preds);
-  return ret;
+  return NULL;
 }
 
 /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions
@@ -3233,28 +1233,46 @@ warn_uninitialized_phi (gphi *phi, vec<gphi *> *worklist,
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
-      fprintf (dump_file, "[CHECK]: examining phi: ");
+      fprintf (dump_file, "Examining phi: ");
       print_gimple_stmt (dump_file, phi, 0);
     }
 
-  /* Now check if we have any use of the value without proper guard.  */
   gimple *uninit_use_stmt = find_uninit_use (phi, uninit_opnds,
 					     worklist, added_to_worklist);
 
-  /* All uses are properly guarded.  */
+  /* All uses are properly guarded but a new PHI may have been added
+     to WORKLIST.  */
   if (!uninit_use_stmt)
     return;
 
-  int phiarg_index = MASK_FIRST_SET_BIT (uninit_opnds);
+  unsigned phiarg_index = MASK_FIRST_SET_BIT (uninit_opnds);
   tree uninit_op = gimple_phi_arg_def (phi, phiarg_index);
   if (SSA_NAME_VAR (uninit_op) == NULL_TREE)
     return;
 
-  location_t phi_arg_loc = gimple_phi_arg_location (phi, phiarg_index);
+  location_t loc = UNKNOWN_LOCATION;
+  if (gimple_phi_arg_has_location (phi, phiarg_index))
+    loc = gimple_phi_arg_location (phi, phiarg_index);
+  else
+    {
+      tree arg_def = gimple_phi_arg_def (phi, phiarg_index);
+      if (TREE_CODE (arg_def) == SSA_NAME)
+	{
+	  gimple *def_stmt = SSA_NAME_DEF_STMT (arg_def);
+	  if (gphi *arg_phi = dyn_cast<gphi *> (def_stmt))
+	    {
+	      unsigned uop = compute_uninit_opnds_pos (arg_phi);
+	      unsigned idx = MASK_FIRST_SET_BIT (uop);
+	      if (idx < gimple_phi_num_args (arg_phi)
+		  && gimple_phi_arg_has_location (arg_phi, idx))
+		loc = gimple_phi_arg_location (arg_phi, idx);
+	    }
+	}
+    }
+
   warn_uninit (OPT_Wmaybe_uninitialized, uninit_op,
 	       SSA_NAME_VAR (uninit_op),
-	       "%qD may be used uninitialized in this function",
-	       uninit_use_stmt, phi_arg_loc);
+	       uninit_use_stmt, loc);
 }
 
 static bool
@@ -3292,8 +1310,8 @@ public:
 
 }; // class pass_late_warn_uninitialized
 
-unsigned int
-pass_late_warn_uninitialized::execute (function *fun)
+static void
+execute_late_warn_uninitialized (function *fun)
 {
   basic_block bb;
   gphi_iterator gsi;
@@ -3316,15 +1334,13 @@ pass_late_warn_uninitialized::execute (function *fun)
     for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
       {
 	gphi *phi = gsi.phi ();
-	size_t n, i;
-
-	n = gimple_phi_num_args (phi);
 
 	/* Don't look at virtual operands.  */
 	if (virtual_operand_p (gimple_phi_result (phi)))
 	  continue;
 
-	for (i = 0; i < n; ++i)
+	unsigned n = gimple_phi_num_args (phi);
+	for (unsigned i = 0; i < n; ++i)
 	  {
 	    tree op = gimple_phi_arg_def (phi, i);
 	    if (TREE_CODE (op) == SSA_NAME && uninit_undefined_value_p (op))
@@ -3333,7 +1349,8 @@ pass_late_warn_uninitialized::execute (function *fun)
 		added_to_worklist.add (phi);
 		if (dump_file && (dump_flags & TDF_DETAILS))
 		  {
-		    fprintf (dump_file, "[WORKLIST]: add to initial list: ");
+		    fprintf (dump_file, "[WORKLIST]: add to initial list "
+			     "for operand %u of: ", i);
 		    print_gimple_stmt (dump_file, phi, 0);
 		  }
 		break;
@@ -3353,6 +1370,12 @@ pass_late_warn_uninitialized::execute (function *fun)
   possibly_undefined_names = NULL;
   free_dominance_info (CDI_POST_DOMINATORS);
   timevar_pop (TV_TREE_UNINIT);
+}
+
+unsigned int
+pass_late_warn_uninitialized::execute (function *fun)
+{
+  execute_late_warn_uninitialized (fun);
   return 0;
 }