MATCH: change single_non_singleton_phi_for_edges for singleton phis

I noticed that single_non_singleton_phi_for_edges could
return a phi whos entry are all the same for the edge.
This happens only if there was a single phis in the first place.
Also gimple_seq_singleton_p walks the sequence to see if it the one
element in the sequence so there is removing that check actually
reduces the number of pointer walks needed.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (single_non_singleton_phi_for_edges):
	Remove the special case of gimple_seq_singleton_p.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index d1746c4b468aab08cc8ca8d5033fd3171374d042..f1e07502b02d01c5a83faa5706aff7dbe4273d21 100644 (file)
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -62,14 +62,6 @@ single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
 {
   gimple_stmt_iterator i;
   gphi *phi = NULL;
-  if (gimple_seq_singleton_p (seq))
-    {
-      phi = as_a <gphi *> (gsi_stmt (gsi_start (seq)));
-      /* Never return virtual phis.  */
-      if (virtual_operand_p (gimple_phi_result (phi)))
-       return NULL;
-      return phi;
-    }
   for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
     {
       gphi *p = as_a <gphi *> (gsi_stmt (i));