[2/2] middle-end ifcvt: Sort PHI arguments not only occurrences but also complexity [PR109154]

  Hi All,

This patch builds on the previous patch by fixing another issue with the
way ifcvt currently picks which branches to test.

The issue with the current implementation is while it sorts for
occurrences of the argument, it doesn't check for complexity of the arguments.

As an example:

  <bb 15> [local count: 528603100]:
  ...
  if (distbb_75 >= 0.0)
    goto <bb 17>; [59.00%]
  else
    goto <bb 16>; [41.00%]

  <bb 16> [local count: 216727269]:
  ...
  goto <bb 19>; [100.00%]

  <bb 17> [local count: 311875831]:
  ...
  if (distbb_75 < iftmp.0_98)
    goto <bb 18>; [20.00%]
  else
    goto <bb 19>; [80.00%]

  <bb 18> [local count: 62375167]:
  ...

  <bb 19> [local count: 528603100]:
  # prephitmp_175 = PHI <_173(18), 0.0(17), _174(16)>

All tree arguments to the PHI have the same number of occurrences, namely 1,
however it makes a big difference which comparison we test first.

Sorting only on occurrences we'll pick the compares coming from BB 18 and BB 17,
This means we end up generating 4 comparisons, while 2 would have been enough.

By keeping track of the "complexity" of the COND in each BB, (i.e. the number
of comparisons needed to traverse from the start [BB 15] to end [BB 19]) and
using a key tuple of <occurrences, complexity> we end up selecting the compare
from BB 16 and BB 18 first.  BB 16 only requires 1 compare, and BB 18, after we
test BB 16 also only requires one additional compare.  This change paired with
the one previous above results in the optimal 2 compares.

For deep nesting, i.e. for

...
  _79 = vr_15 > 20;
  _80 = _68 & _79;
  _82 = vr_15 <= 20;
  _83 = _68 & _82;
  _84 = vr_15 < -20;
  _85 = _73 & _84;
  _87 = vr_15 >= -20;
  _88 = _73 & _87;
  _ifc__111 = _55 ? 10 : 12;
  _ifc__112 = _70 ? 7 : _ifc__111;
  _ifc__113 = _85 ? 8 : _ifc__112;
  _ifc__114 = _88 ? 9 : _ifc__113;
  _ifc__115 = _45 ? 1 : _ifc__114;
  _ifc__116 = _63 ? 3 : _ifc__115;
  _ifc__117 = _65 ? 4 : _ifc__116;
  _ifc__118 = _83 ? 6 : _ifc__117;
  _ifc__119 = _60 ? 2 : _ifc__118;
  _ifc__120 = _43 ? 13 : _ifc__119;
  _ifc__121 = _75 ? 11 : _ifc__120;
  vw_1 = _80 ? 5 : _ifc__121;

Most of the comparisons are still needed because the chain of
occurrences to not negate eachother. i.e. _80 is _73 & vr_15 >= -20 and
_85 is _73 & vr_15 < -20.  clearly given _73 needs to be true in both branches,
the only additional test needed is on vr_15, where the one test is the negation
of the other.  So we don't need to do the comparison of _73 twice.

The changes in the patch reduces the overall number of compares by one, but has
a bigger effect on the dependency chain.

Previously we would generate 5 instructions chain:

	cmple   p7.s, p4/z, z29.s, z30.s
	cmpne   p7.s, p7/z, z29.s, #0
	cmple   p6.s, p7/z, z31.s, z30.s
	cmpge   p6.s, p6/z, z27.s, z25.s
	cmplt   p15.s, p6/z, z28.s, z21.s

as the longest chain.  With this patch we generate 3:

	cmple   p7.s, p3/z, z27.s, z30.s
	cmpne   p7.s, p7/z, z27.s, #0
	cmpgt   p7.s, p7/z, z31.s, z30.s

and I don't think (x <= y) && (x != 0) && (z > y) can be reduced further.

Bootstrapped and Regtested on aarch64-none-linux-gnu and no issues.

Not sure how to write a non-fragile testcase for this as the
conditionals chosen depends on threading etc. Any Suggestions?

Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

	PR tree-optimization/109154
	* tree-if-conv.cc (INCLUDE_ALGORITHM): Include.
	(struct bb_predicate): Add no_predicate_stmts.
	(set_bb_predicate): Increase predicate count.
	(set_bb_predicate_gimplified_stmts): Conditionally initialize
	no_predicate_stmts.
	(get_bb_num_predicate_stmts): New.
	(init_bb_predicate): Initialzie no_predicate_stmts.
	(release_bb_predicate): Cleanup no_predicate_stmts.
	(insert_gimplified_predicates): Preserve no_predicate_stmts.

--- inline copy of patch -- 
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 16b36dd8b0226f796c1a3fc6d45a9059385e812b..0ed50d99c46f99a4d1ea0e827ee2b2a3f494b2da 100644




--
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 16b36dd8b0226f796c1a3fc6d45a9059385e812b..0ed50d99c46f99a4d1ea0e827ee2b2a3f494b2da 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -80,6 +80,7 @@ along with GCC; see the file COPYING3.  If not see
      <L18>:;
 */
 
+#define INCLUDE_ALGORITHM
 #include "config.h"
 #include "system.h"
 #include "coretypes.h"
@@ -231,6 +232,10 @@ struct bb_predicate {
      recorded here, in order to avoid the duplication of computations
      that occur in previous conditions.  See PR44483.  */
   gimple_seq predicate_gimplified_stmts;
+
+  /* Records the number of statements recorded into
+     PREDICATE_GIMPLIFIED_STMTS.   */
+  unsigned no_predicate_stmts;
 };
 
 /* Returns true when the basic block BB has a predicate.  */
@@ -254,10 +259,16 @@ bb_predicate (basic_block bb)
 static inline void
 set_bb_predicate (basic_block bb, tree cond)
 {
+  auto aux = (struct bb_predicate *) bb->aux;
   gcc_assert ((TREE_CODE (cond) == TRUTH_NOT_EXPR
 	       && is_gimple_val (TREE_OPERAND (cond, 0)))
 	      || is_gimple_val (cond));
-  ((struct bb_predicate *) bb->aux)->predicate = cond;
+  aux->predicate = cond;
+  aux->no_predicate_stmts++;
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file, "Recording block %d value %d\n", bb->index,
+	     aux->no_predicate_stmts);
 }
 
 /* Returns the sequence of statements of the gimplification of the
@@ -270,12 +281,16 @@ bb_predicate_gimplified_stmts (basic_block bb)
 }
 
 /* Sets the sequence of statements STMTS of the gimplification of the
-   predicate for basic block BB.  */
+   predicate for basic block BB.  If PRESERVE_COUNTS then don't clear the predicate
+   counts.  */
 
 static inline void
-set_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
+set_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts,
+				   bool preserve_counts)
 {
   ((struct bb_predicate *) bb->aux)->predicate_gimplified_stmts = stmts;
+  if (stmts == NULL && !preserve_counts)
+    ((struct bb_predicate *) bb->aux)->no_predicate_stmts = 0;
 }
 
 /* Adds the sequence of statements STMTS to the sequence of statements
@@ -296,18 +311,28 @@ add_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
       gimple *stmt = gsi_stmt (gsi);
       delink_stmt_imm_use (stmt);
       gimple_set_modified (stmt, true);
+      ((struct bb_predicate *) bb->aux)->no_predicate_stmts++;
     }
   gimple_seq_add_seq_without_update
     (&(((struct bb_predicate *) bb->aux)->predicate_gimplified_stmts), stmts);
 }
 
+/* Return the number of statements the predicate of the basic block consists
+   of.  */
+
+static inline unsigned
+get_bb_num_predicate_stmts (basic_block bb)
+{
+  return ((struct bb_predicate *) bb->aux)->no_predicate_stmts;
+}
+
 /* Initializes to TRUE the predicate of basic block BB.  */
 
 static inline void
 init_bb_predicate (basic_block bb)
 {
   bb->aux = XNEW (struct bb_predicate);
-  set_bb_predicate_gimplified_stmts (bb, NULL);
+  set_bb_predicate_gimplified_stmts (bb, NULL, false);
   set_bb_predicate (bb, boolean_true_node);
 }
 
@@ -327,7 +352,7 @@ release_bb_predicate (basic_block bb)
 
       /* Discard them.  */
       gimple_seq_discard (stmts);
-      set_bb_predicate_gimplified_stmts (bb, NULL);
+      set_bb_predicate_gimplified_stmts (bb, NULL, false);
     }
 }
 
@@ -2041,7 +2066,6 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
   tree rhs, res, arg0, arg1, op0, op1, scev;
   tree cond;
   unsigned int index0;
-  unsigned int max, args_len;
   edge e;
   basic_block bb;
   unsigned int i;
@@ -2145,7 +2169,6 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
   bool swap = false;
   hash_map<tree_operand_hash, auto_vec<int> > phi_arg_map;
   unsigned int num_args = gimple_phi_num_args (phi);
-  int max_ind = -1;
   /* Vector of different PHI argument values.  */
   auto_vec<tree> args (num_args);
 
@@ -2160,28 +2183,38 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
       phi_arg_map.get_or_insert (arg).safe_push (i);
     }
 
-  /* Determine element with max number of occurrences.  */
-  max_ind = -1;
-  max = 1;
-  args_len = args.length ();
-  for (i = 0; i < args_len; i++)
+  /* Determine element with max number of occurrences and complexity.  Looking at only
+     number of occurrences as a measure for complexity isn't enough as all usages can
+     be unique but the comparisons to reach the PHI node differ per branch.  */
+  typedef std::pair <tree, std::pair <unsigned, unsigned>> ArgEntry;
+  auto_vec<ArgEntry> argsKV;
+  for (i = 0; i < args.length (); i++)
     {
-      unsigned int len;
-      if ((len = phi_arg_map.get (args[i])->length ()) > max)
+      unsigned int len = 0;
+      for (int index : phi_arg_map.get (args[i]))
 	{
-	  max_ind = (int) i;
-	  max = len;
+	  edge e = gimple_phi_arg_edge (phi, index);
+	  len += get_bb_num_predicate_stmts (e->src);
 	}
+
+      unsigned occur = phi_arg_map.get (args[i])->length ();
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Ranking %d as len=%d, idx=%d\n", i, len, occur);
+      argsKV.safe_push ({ args[i], { len, occur }});
     }
 
-  /* Put element with max number of occurences to the end of ARGS.  */
-  if (max_ind != -1 && max_ind + 1 != (int) args_len)
-    std::swap (args[args_len - 1], args[max_ind]);
+  /* Sort elements based on rankings ARGS.  */
+  std::sort(argsKV.begin(), argsKV.end(), [](ArgEntry &left, ArgEntry &right) {
+    return left.second < right.second;
+  });
+
+  for (i = 0; i < args.length (); i++)
+    args[i] = argsKV[i].first;
 
   /* Handle one special case when number of arguments with different values
      is equal 2 and one argument has the only occurrence.  Such PHI can be
      handled as if would have only 2 arguments.  */
-  if (args_len == 2 && phi_arg_map.get (args[0])->length () == 1)
+  if (args.length () == 2 && phi_arg_map.get (args[0])->length () == 1)
     {
       vec<int> *indexes;
       indexes = phi_arg_map.get (args[0]);
@@ -2317,7 +2350,7 @@ insert_gimplified_predicates (loop_p loop)
 	    }
 
 	  /* Once the sequence is code generated, set it to NULL.  */
-	  set_bb_predicate_gimplified_stmts (bb, NULL);
+	  set_bb_predicate_gimplified_stmts (bb, NULL, true);
 	}
     }
 }
  

On Fri, 7 Jul 2023, Tamar Christina wrote:

> Hi All,
> 
> This patch builds on the previous patch by fixing another issue with the
> way ifcvt currently picks which branches to test.
> 
> The issue with the current implementation is while it sorts for
> occurrences of the argument, it doesn't check for complexity of the arguments.
> 
> As an example:
> 
>   <bb 15> [local count: 528603100]:
>   ...
>   if (distbb_75 >= 0.0)
>     goto <bb 17>; [59.00%]
>   else
>     goto <bb 16>; [41.00%]
> 
>   <bb 16> [local count: 216727269]:
>   ...
>   goto <bb 19>; [100.00%]
> 
>   <bb 17> [local count: 311875831]:
>   ...
>   if (distbb_75 < iftmp.0_98)
>     goto <bb 18>; [20.00%]
>   else
>     goto <bb 19>; [80.00%]
> 
>   <bb 18> [local count: 62375167]:
>   ...
> 
>   <bb 19> [local count: 528603100]:
>   # prephitmp_175 = PHI <_173(18), 0.0(17), _174(16)>
> 
> All tree arguments to the PHI have the same number of occurrences, namely 1,
> however it makes a big difference which comparison we test first.
> 
> Sorting only on occurrences we'll pick the compares coming from BB 18 and BB 17,
> This means we end up generating 4 comparisons, while 2 would have been enough.
> 
> By keeping track of the "complexity" of the COND in each BB, (i.e. the number
> of comparisons needed to traverse from the start [BB 15] to end [BB 19]) and
> using a key tuple of <occurrences, complexity> we end up selecting the compare
> from BB 16 and BB 18 first.  BB 16 only requires 1 compare, and BB 18, after we
> test BB 16 also only requires one additional compare.  This change paired with
> the one previous above results in the optimal 2 compares.
> 
> For deep nesting, i.e. for
> 
> ...
>   _79 = vr_15 > 20;
>   _80 = _68 & _79;
>   _82 = vr_15 <= 20;
>   _83 = _68 & _82;
>   _84 = vr_15 < -20;
>   _85 = _73 & _84;
>   _87 = vr_15 >= -20;
>   _88 = _73 & _87;
>   _ifc__111 = _55 ? 10 : 12;
>   _ifc__112 = _70 ? 7 : _ifc__111;
>   _ifc__113 = _85 ? 8 : _ifc__112;
>   _ifc__114 = _88 ? 9 : _ifc__113;
>   _ifc__115 = _45 ? 1 : _ifc__114;
>   _ifc__116 = _63 ? 3 : _ifc__115;
>   _ifc__117 = _65 ? 4 : _ifc__116;
>   _ifc__118 = _83 ? 6 : _ifc__117;
>   _ifc__119 = _60 ? 2 : _ifc__118;
>   _ifc__120 = _43 ? 13 : _ifc__119;
>   _ifc__121 = _75 ? 11 : _ifc__120;
>   vw_1 = _80 ? 5 : _ifc__121;
> 
> Most of the comparisons are still needed because the chain of
> occurrences to not negate eachother. i.e. _80 is _73 & vr_15 >= -20 and
> _85 is _73 & vr_15 < -20.  clearly given _73 needs to be true in both branches,
> the only additional test needed is on vr_15, where the one test is the negation
> of the other.  So we don't need to do the comparison of _73 twice.
> 
> The changes in the patch reduces the overall number of compares by one, but has
> a bigger effect on the dependency chain.
> 
> Previously we would generate 5 instructions chain:
> 
> 	cmple   p7.s, p4/z, z29.s, z30.s
> 	cmpne   p7.s, p7/z, z29.s, #0
> 	cmple   p6.s, p7/z, z31.s, z30.s
> 	cmpge   p6.s, p6/z, z27.s, z25.s
> 	cmplt   p15.s, p6/z, z28.s, z21.s
> 
> as the longest chain.  With this patch we generate 3:
> 
> 	cmple   p7.s, p3/z, z27.s, z30.s
> 	cmpne   p7.s, p7/z, z27.s, #0
> 	cmpgt   p7.s, p7/z, z31.s, z30.s
> 
> and I don't think (x <= y) && (x != 0) && (z > y) can be reduced further.
> 
> Bootstrapped and Regtested on aarch64-none-linux-gnu and no issues.
> 
> Not sure how to write a non-fragile testcase for this as the
> conditionals chosen depends on threading etc. Any Suggestions?
> 
> Ok for master?

OK.

Likewise for the testcase - GIMPLE one starting at fix_loops.

> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/109154
> 	* tree-if-conv.cc (INCLUDE_ALGORITHM): Include.
> 	(struct bb_predicate): Add no_predicate_stmts.
> 	(set_bb_predicate): Increase predicate count.
> 	(set_bb_predicate_gimplified_stmts): Conditionally initialize
> 	no_predicate_stmts.
> 	(get_bb_num_predicate_stmts): New.
> 	(init_bb_predicate): Initialzie no_predicate_stmts.
> 	(release_bb_predicate): Cleanup no_predicate_stmts.
> 	(insert_gimplified_predicates): Preserve no_predicate_stmts.
> 
> --- inline copy of patch -- 
> diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
> index 16b36dd8b0226f796c1a3fc6d45a9059385e812b..0ed50d99c46f99a4d1ea0e827ee2b2a3f494b2da 100644
> --- a/gcc/tree-if-conv.cc
> +++ b/gcc/tree-if-conv.cc
> @@ -80,6 +80,7 @@ along with GCC; see the file COPYING3.  If not see
>       <L18>:;
>  */
>  
> +#define INCLUDE_ALGORITHM
>  #include "config.h"
>  #include "system.h"
>  #include "coretypes.h"
> @@ -231,6 +232,10 @@ struct bb_predicate {
>       recorded here, in order to avoid the duplication of computations
>       that occur in previous conditions.  See PR44483.  */
>    gimple_seq predicate_gimplified_stmts;
> +
> +  /* Records the number of statements recorded into
> +     PREDICATE_GIMPLIFIED_STMTS.   */
> +  unsigned no_predicate_stmts;
>  };
>  
>  /* Returns true when the basic block BB has a predicate.  */
> @@ -254,10 +259,16 @@ bb_predicate (basic_block bb)
>  static inline void
>  set_bb_predicate (basic_block bb, tree cond)
>  {
> +  auto aux = (struct bb_predicate *) bb->aux;
>    gcc_assert ((TREE_CODE (cond) == TRUTH_NOT_EXPR
>  	       && is_gimple_val (TREE_OPERAND (cond, 0)))
>  	      || is_gimple_val (cond));
> -  ((struct bb_predicate *) bb->aux)->predicate = cond;
> +  aux->predicate = cond;
> +  aux->no_predicate_stmts++;
> +
> +  if (dump_file && (dump_flags & TDF_DETAILS))
> +    fprintf (dump_file, "Recording block %d value %d\n", bb->index,
> +	     aux->no_predicate_stmts);
>  }
>  
>  /* Returns the sequence of statements of the gimplification of the
> @@ -270,12 +281,16 @@ bb_predicate_gimplified_stmts (basic_block bb)
>  }
>  
>  /* Sets the sequence of statements STMTS of the gimplification of the
> -   predicate for basic block BB.  */
> +   predicate for basic block BB.  If PRESERVE_COUNTS then don't clear the predicate
> +   counts.  */
>  
>  static inline void
> -set_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
> +set_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts,
> +				   bool preserve_counts)
>  {
>    ((struct bb_predicate *) bb->aux)->predicate_gimplified_stmts = stmts;
> +  if (stmts == NULL && !preserve_counts)
> +    ((struct bb_predicate *) bb->aux)->no_predicate_stmts = 0;
>  }
>  
>  /* Adds the sequence of statements STMTS to the sequence of statements
> @@ -296,18 +311,28 @@ add_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
>        gimple *stmt = gsi_stmt (gsi);
>        delink_stmt_imm_use (stmt);
>        gimple_set_modified (stmt, true);
> +      ((struct bb_predicate *) bb->aux)->no_predicate_stmts++;
>      }
>    gimple_seq_add_seq_without_update
>      (&(((struct bb_predicate *) bb->aux)->predicate_gimplified_stmts), stmts);
>  }
>  
> +/* Return the number of statements the predicate of the basic block consists
> +   of.  */
> +
> +static inline unsigned
> +get_bb_num_predicate_stmts (basic_block bb)
> +{
> +  return ((struct bb_predicate *) bb->aux)->no_predicate_stmts;
> +}
> +
>  /* Initializes to TRUE the predicate of basic block BB.  */
>  
>  static inline void
>  init_bb_predicate (basic_block bb)
>  {
>    bb->aux = XNEW (struct bb_predicate);
> -  set_bb_predicate_gimplified_stmts (bb, NULL);
> +  set_bb_predicate_gimplified_stmts (bb, NULL, false);
>    set_bb_predicate (bb, boolean_true_node);
>  }
>  
> @@ -327,7 +352,7 @@ release_bb_predicate (basic_block bb)
>  
>        /* Discard them.  */
>        gimple_seq_discard (stmts);
> -      set_bb_predicate_gimplified_stmts (bb, NULL);
> +      set_bb_predicate_gimplified_stmts (bb, NULL, false);
>      }
>  }
>  
> @@ -2041,7 +2066,6 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
>    tree rhs, res, arg0, arg1, op0, op1, scev;
>    tree cond;
>    unsigned int index0;
> -  unsigned int max, args_len;
>    edge e;
>    basic_block bb;
>    unsigned int i;
> @@ -2145,7 +2169,6 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
>    bool swap = false;
>    hash_map<tree_operand_hash, auto_vec<int> > phi_arg_map;
>    unsigned int num_args = gimple_phi_num_args (phi);
> -  int max_ind = -1;
>    /* Vector of different PHI argument values.  */
>    auto_vec<tree> args (num_args);
>  
> @@ -2160,28 +2183,38 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
>        phi_arg_map.get_or_insert (arg).safe_push (i);
>      }
>  
> -  /* Determine element with max number of occurrences.  */
> -  max_ind = -1;
> -  max = 1;
> -  args_len = args.length ();
> -  for (i = 0; i < args_len; i++)
> +  /* Determine element with max number of occurrences and complexity.  Looking at only
> +     number of occurrences as a measure for complexity isn't enough as all usages can
> +     be unique but the comparisons to reach the PHI node differ per branch.  */
> +  typedef std::pair <tree, std::pair <unsigned, unsigned>> ArgEntry;
> +  auto_vec<ArgEntry> argsKV;
> +  for (i = 0; i < args.length (); i++)
>      {
> -      unsigned int len;
> -      if ((len = phi_arg_map.get (args[i])->length ()) > max)
> +      unsigned int len = 0;
> +      for (int index : phi_arg_map.get (args[i]))
>  	{
> -	  max_ind = (int) i;
> -	  max = len;
> +	  edge e = gimple_phi_arg_edge (phi, index);
> +	  len += get_bb_num_predicate_stmts (e->src);
>  	}
> +
> +      unsigned occur = phi_arg_map.get (args[i])->length ();
> +      if (dump_file && (dump_flags & TDF_DETAILS))
> +	fprintf (dump_file, "Ranking %d as len=%d, idx=%d\n", i, len, occur);
> +      argsKV.safe_push ({ args[i], { len, occur }});
>      }
>  
> -  /* Put element with max number of occurences to the end of ARGS.  */
> -  if (max_ind != -1 && max_ind + 1 != (int) args_len)
> -    std::swap (args[args_len - 1], args[max_ind]);
> +  /* Sort elements based on rankings ARGS.  */
> +  std::sort(argsKV.begin(), argsKV.end(), [](ArgEntry &left, ArgEntry &right) {
> +    return left.second < right.second;
> +  });
> +
> +  for (i = 0; i < args.length (); i++)
> +    args[i] = argsKV[i].first;
>  
>    /* Handle one special case when number of arguments with different values
>       is equal 2 and one argument has the only occurrence.  Such PHI can be
>       handled as if would have only 2 arguments.  */
> -  if (args_len == 2 && phi_arg_map.get (args[0])->length () == 1)
> +  if (args.length () == 2 && phi_arg_map.get (args[0])->length () == 1)
>      {
>        vec<int> *indexes;
>        indexes = phi_arg_map.get (args[0]);
> @@ -2317,7 +2350,7 @@ insert_gimplified_predicates (loop_p loop)
>  	    }
>  
>  	  /* Once the sequence is code generated, set it to NULL.  */
> -	  set_bb_predicate_gimplified_stmts (bb, NULL);
> +	  set_bb_predicate_gimplified_stmts (bb, NULL, true);
>  	}
>      }
>  }
> 
> 
> 
> 
>