[PATCH] phiopt: Handle bool in two_value_replacement [PR796232]

[Jakub Jelinek <jakub@redhat.com>]

Hi!

The following patch improves code generation on the included testcase by
enabling two_value_replacement on booleans.  It does that only for arg0/arg1
values that conditional_replacement doesn't handle, and only does it if not
in the early phiopt pass, because conditional_replacement isn't done early
either.
I must say I'm not sure about that, in PR87105 / PR87608 you've added the
early phiopt pass and specifically excluded conditional_replacement and a
few others from being optimized early, but then 3 months later I've added
two_value_replacement and didn't restrict it to !early_p.  Shall we instead
do two_value_replacement only in late phiopt?

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2020-12-05  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/96232
	* tree-ssa-phiopt.c (two_value_replacement): Add early_p argument.
	If false, optimize even boolean lhs cases as long as arg0 has wider
	precision and conditional_replacement doesn't handle that case.

	* gcc.dg/tree-ssa/pr96232-2.c: New test.

--- gcc/tree-ssa-phiopt.c.jj	2020-12-04 17:27:53.472837921 +0100
+++ gcc/tree-ssa-phiopt.c	2020-12-04 17:54:56.070689584 +0100
@@ -51,7 +51,7 @@ along with GCC; see the file COPYING3.
 
 static unsigned int tree_ssa_phiopt_worker (bool, bool, bool);
 static bool two_value_replacement (basic_block, basic_block, edge, gphi *,
-				   tree, tree);
+				   tree, tree, 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,
@@ -337,7 +337,7 @@ tree_ssa_phiopt_worker (bool do_store_el
 	    }
 
 	  /* Do the replacement of conditional if it can be done.  */
-	  if (two_value_replacement (bb, bb1, e2, phi, arg0, arg1))
+	  if (two_value_replacement (bb, bb1, e2, phi, arg0, arg1, early_p))
 	    cfgchanged = true;
 	  else if (!early_p
 		   && conditional_replacement (bb, bb1, e1, e2, phi,
@@ -614,7 +614,7 @@ factor_out_conditional_conversion (edge
 
 static bool
 two_value_replacement (basic_block cond_bb, basic_block middle_bb,
-		       edge e1, gphi *phi, tree arg0, tree arg1)
+		       edge e1, gphi *phi, tree arg0, tree arg1, bool early_p)
 {
   /* Only look for adjacent integer constants.  */
   if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))
@@ -635,7 +635,7 @@ two_value_replacement (basic_block cond_
 
   if (TREE_CODE (lhs) != SSA_NAME
       || !INTEGRAL_TYPE_P (TREE_TYPE (lhs))
-      || TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE
+      || (early_p && TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE)
       || TREE_CODE (rhs) != INTEGER_CST)
     return false;
 
@@ -648,9 +648,25 @@ two_value_replacement (basic_block cond_
       return false;
     }
 
+  /* Defer boolean x ? 0 : {1,-1} or x ? {1,-1} : 0 to
+     conditional_replacement.  */
+  if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE
+      && (integer_zerop (arg0)
+	  || integer_zerop (arg1)
+	  || TREE_CODE (TREE_TYPE (arg0)) == BOOLEAN_TYPE
+	  || (TYPE_PRECISION (TREE_TYPE (arg0))
+	      <= TYPE_PRECISION (TREE_TYPE (lhs)))))
+    return false;
+
   wide_int min, max;
-  if (get_range_info (lhs, &min, &max) != VR_RANGE
-      || min + 1 != max
+  if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE)
+    {
+      min = wi::to_wide (boolean_false_node);
+      max = wi::to_wide (boolean_true_node);
+    }
+  else if (get_range_info (lhs, &min, &max) != VR_RANGE)
+    return false;
+  if (min + 1 != max
       || (wi::to_wide (rhs) != min
 	  && wi::to_wide (rhs) != max))
     return false;
--- gcc/testsuite/gcc.dg/tree-ssa/pr96232-2.c.jj	2020-12-04 17:56:22.180730234 +0100
+++ gcc/testsuite/gcc.dg/tree-ssa/pr96232-2.c	2020-12-04 17:57:27.973997239 +0100
@@ -0,0 +1,18 @@
+/* PR tree-optimization/96232 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump " 38 - " "optimized" } } */
+/* { dg-final { scan-tree-dump " \\+ 97;" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "PHI <" "optimized" } } */
+
+int
+foo (_Bool x)
+{
+  return x ? 37 : 38;
+}
+
+int
+bar (_Bool x)
+{
+  return x ? 98 : 97;
+}

	Jakub