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

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.  Additionally
it limits two_value_replacement optimization to the late phiopt like
conditional_replacement.

2020-12-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/96232
	* tree-ssa-phiopt.c (two_value_replacement): Optimize even boolean lhs
	cases as long as arg0 has wider precision and conditional_replacement
	doesn't handle that case.
	(tree_ssa_phiopt_worker): Don't call two_value_replacement during
	early phiopt.

	* gcc.dg/tree-ssa/pr96232-2.c: New test.
	* gcc.dg/tree-ssa/pr88676-2.c: Check phiopt2 dump rather than phiopt1.

3 files changed, 39 insertions, 6 deletions

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr88676-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr88676-2.c
index 0e61636..ea88407 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr88676-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr88676-2.c
@@ -1,7 +1,7 @@
 /* PR tree-optimization/88676 */
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-phiopt1" } */
-/* { dg-final { scan-tree-dump-not " = PHI <" "phiopt1" { target le } } } */
+/* { dg-options "-O2 -fdump-tree-phiopt2" } */
+/* { dg-final { scan-tree-dump-not " = PHI <" "phiopt2" { target le } } } */
 
 struct foo1 {
   int i:1;
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr96232-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr96232-2.c
new file mode 100644
index 0000000..9f51820
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr96232-2.c
@@ -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;
+}
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index e2758b2..21b88c0 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -337,7 +337,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 	    }
 
 	  /* Do the replacement of conditional if it can be done.  */
-	  if (two_value_replacement (bb, bb1, e2, phi, arg0, arg1))
+	  if (!early_p && two_value_replacement (bb, bb1, e2, phi, arg0, arg1))
 	    cfgchanged = true;
 	  else if (!early_p
 		   && conditional_replacement (bb, bb1, e1, e2, phi,
@@ -635,7 +635,6 @@ two_value_replacement (basic_block cond_bb, basic_block middle_bb,
 
   if (TREE_CODE (lhs) != SSA_NAME
       || !INTEGRAL_TYPE_P (TREE_TYPE (lhs))
-      || TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE
       || TREE_CODE (rhs) != INTEGER_CST)
     return false;
 
@@ -648,9 +647,25 @@ two_value_replacement (basic_block cond_bb, basic_block middle_bb,
       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;