re PR tree-optimization/71016 (Redundant sign extension with conditional __builtin_clzl)

	PR tree-optimization/71016
	* tree-ssa-phiopt.c (tree_ssa_phiopt_worker): Pass cond_stmt to
	factor_out_conditional_conversion.  Formatting fix.
	(factor_out_conditional_conversion): Add cond_stmt argument.
	If arg1 is INTEGER_CST, punt if new_arg0 is not any operand of
	cond_stmt and if arg0_def_stmt is not the only stmt in its bb.
	Formatting fix.

	* gcc.target/i386/pr71016.c: New test.
	* gcc.target/aarch64/pr71016.c: New test.
	* gcc.dg/tree-ssa/pr66726-3.c: New test.

From-SVN: r244114

1 files changed, 34 insertions, 7 deletions

diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index 259f6fe..07a226e 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -49,7 +49,8 @@ along with GCC; see the file COPYING3.  If not see
 static unsigned int tree_ssa_phiopt_worker (bool, bool);
 static bool conditional_replacement (basic_block, basic_block,
 				     edge, edge, gphi *, tree, tree);
-static gphi *factor_out_conditional_conversion (edge, edge, gphi *, tree, tree);
+static gphi *factor_out_conditional_conversion (edge, edge, gphi *, tree, tree,
+						gimple *);
 static int value_replacement (basic_block, basic_block,
 			      edge, edge, gimple *, tree, tree);
 static bool minmax_replacement (basic_block, basic_block,
@@ -233,7 +234,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads)
 	  continue;
 	}
       else if (do_hoist_loads
-		 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
+	       && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
 	{
 	  basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
 
@@ -313,7 +314,8 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads)
 	  gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE);
 
 	  gphi *newphi = factor_out_conditional_conversion (e1, e2, phi,
-							    arg0, arg1);
+							    arg0, arg1,
+							    cond_stmt);
 	  if (newphi != NULL)
 	    {
 	      phi = newphi;
@@ -402,11 +404,12 @@ replace_phi_edge_with_variable (basic_block cond_block,
 
 /* PR66726: Factor conversion out of COND_EXPR.  If the arguments of the PHI
    stmt are CONVERT_STMT, factor out the conversion and perform the conversion
-   to the result of PHI stmt.  Return the newly-created PHI, if any.  */
+   to the result of PHI stmt.  COND_STMT is the controlling predicate.
+   Return the newly-created PHI, if any.  */
 
 static gphi *
 factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
-				   tree arg0, tree arg1)
+				   tree arg0, tree arg1, gimple *cond_stmt)
 {
   gimple *arg0_def_stmt = NULL, *arg1_def_stmt = NULL, *new_stmt;
   tree new_arg0 = NULL_TREE, new_arg1 = NULL_TREE;
@@ -472,7 +475,31 @@ factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
 	  && int_fits_type_p (arg1, TREE_TYPE (new_arg0)))
 	{
 	  if (gimple_assign_cast_p (arg0_def_stmt))
-	    new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1);
+	    {
+	      /* For the INTEGER_CST case, we are just moving the
+		 conversion from one place to another, which can often
+		 hurt as the conversion moves further away from the
+		 statement that computes the value.  So, perform this
+		 only if new_arg0 is an operand of COND_STMT, or
+		 if arg0_def_stmt is the only non-debug stmt in
+		 its basic block, because then it is possible this
+		 could enable further optimizations (minmax replacement
+		 etc.).  See PR71016.  */
+	      if (new_arg0 != gimple_cond_lhs (cond_stmt)
+		  && new_arg0 != gimple_cond_rhs (cond_stmt)
+		  && gimple_bb (arg0_def_stmt) == e0->src)
+		{
+		  gsi = gsi_for_stmt (arg0_def_stmt);
+		  gsi_prev_nondebug (&gsi);
+		  if (!gsi_end_p (gsi))
+		    return NULL;
+		  gsi = gsi_for_stmt (arg0_def_stmt);
+		  gsi_next_nondebug (&gsi);
+		  if (!gsi_end_p (gsi))
+		    return NULL;
+		}
+	      new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1);
+	    }
 	  else
 	    return NULL;
 	}
@@ -524,7 +551,7 @@ factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
   /* Create the conversion stmt and insert it.  */
   if (convert_code == VIEW_CONVERT_EXPR)
     temp = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (result), temp);
-  new_stmt = gimple_build_assign (result,  convert_code, temp);
+  new_stmt = gimple_build_assign (result, convert_code, temp);
   gsi = gsi_after_labels (gimple_bb (phi));
   gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);