match.pd: Optimize (x < 0) != (y < 0) into (x ^ y) < 0 [PR94718]

The following patch (on top of the two other PR94718 patches) performs the
actual optimization requested in the PR.

2020-05-04  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94718
	* match.pd ((X < 0) != (Y < 0) into (X ^ Y) < 0): New simplification.

	* gcc.dg/tree-ssa/pr94718-4.c: New test.
	* gcc.dg/tree-ssa/pr94718-5.c: New test.

5 files changed, 153 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 036a403..fae7ece 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,9 @@
 2020-05-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/94718
+	* match.pd ((X < 0) != (Y < 0) into (X ^ Y) < 0): New simplification.
+
+	PR tree-optimization/94718
 	* match.pd (bitop (convert @0) (convert? @1)): For GIMPLE, if we can,
 	replace two nop conversions on bit_{and,ior,xor} argument
 	and result with just one conversion on the result or another argument.
diff --git a/gcc/match.pd b/gcc/match.pd
index 929be14..9c1e239 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4358,6 +4358,30 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (cmp (bit_and:cs @0 @2) (bit_and:cs @1 @2))
   (cmp (bit_and (bit_xor @0 @1) @2) { build_zero_cst (TREE_TYPE (@2)); })))
 
+/* (X < 0) != (Y < 0) into (X ^ Y) < 0.
+   (X >= 0) != (Y >= 0) into (X ^ Y) < 0.
+   (X < 0) == (Y < 0) into (X ^ Y) >= 0.
+   (X >= 0) == (Y >= 0) into (X ^ Y) >= 0.  */
+(for cmp (eq ne)
+     ncmp (ge lt)
+ (for sgncmp (ge lt)
+  (simplify
+   (cmp (sgncmp @0 integer_zerop@2) (sgncmp @1 integer_zerop))
+   (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	&& !TYPE_UNSIGNED (TREE_TYPE (@0))
+	&& types_match (@0, @1))
+    (ncmp (bit_xor @0 @1) @2)))))
+/* (X < 0) == (Y >= 0) into (X ^ Y) < 0.
+   (X < 0) != (Y >= 0) into (X ^ Y) >= 0.  */
+(for cmp (eq ne)
+     ncmp (lt ge)
+ (simplify
+  (cmp:c (lt @0 integer_zerop@2) (ge @1 integer_zerop))
+   (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	&& !TYPE_UNSIGNED (TREE_TYPE (@0))
+	&& types_match (@0, @1))
+    (ncmp (bit_xor @0 @1) @2))))
+
 /* If we have (A & C) == C where C is a power of 2, convert this into
    (A & C) != 0.  Similarly for NE_EXPR.  */
 (for cmp (eq ne)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 09979b5..2fedff3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,10 @@
 2020-05-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/94718
+	* gcc.dg/tree-ssa/pr94718-4.c: New test.
+	* gcc.dg/tree-ssa/pr94718-5.c: New test.
+
+	PR tree-optimization/94718
 	* gcc.dg/tree-ssa/pr94718-3.c: New test.
 
 	PR tree-optimization/94718
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94718-4.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-4.c
new file mode 100644
index 0000000..8b9c109
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-4.c
@@ -0,0 +1,61 @@
+/* PR tree-optimization/94718 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-ipa-icf -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "= \[xy]_\[0-9]+\\\(D\\\) \\^ \[xy]_\[0-9]+\\\(D\\\);" 8 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "\[0-9]+ < 0;" 8 "optimized" } } */
+
+int
+f1 (int x, int y)
+{
+  return (x < 0) != (y < 0);
+}
+
+int
+f2 (int x, int y)
+{
+  return (x >= 0) != (y >= 0);
+}
+
+int
+f3 (int x, int y)
+{
+  return (x < 0) == (y >= 0);
+}
+
+int
+f4 (int x, int y)
+{
+  return (x >= 0) == (y < 0);
+}
+
+int
+f5 (int x, int y)
+{
+  int s = (x < 0);
+  int t = (y < 0);
+  return s != t;
+}
+
+int
+f6 (int x, int y)
+{
+  int s = (x >= 0);
+  int t = (y >= 0);
+  return s != t;
+}
+
+int
+f7 (int x, int y)
+{
+  int s = (x < 0);
+  int t = (y >= 0);
+  return s == t;
+}
+
+int
+f8 (int x, int y)
+{
+  int s = (x >= 0);
+  int t = (y < 0);
+  return s == t;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94718-5.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-5.c
new file mode 100644
index 0000000..4bd3732
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94718-5.c
@@ -0,0 +1,61 @@
+/* PR tree-optimization/94718 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-ipa-icf -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "= \[xy]_\[0-9]+\\\(D\\\) \\^ \[xy]_\[0-9]+\\\(D\\\);" 8 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "\[0-9]+ >= 0;" 8 "optimized" } } */
+
+int
+f1 (int x, int y)
+{
+  return (x < 0) == (y < 0);
+}
+
+int
+f2 (int x, int y)
+{
+  return (x >= 0) == (y >= 0);
+}
+
+int
+f3 (int x, int y)
+{
+  return (x < 0) != (y >= 0);
+}
+
+int
+f4 (int x, int y)
+{
+  return (x >= 0) != (y < 0);
+}
+
+int
+f5 (int x, int y)
+{
+  int s = (x < 0);
+  int t = (y < 0);
+  return s == t;
+}
+
+int
+f6 (int x, int y)
+{
+  int s = (x >= 0);
+  int t = (y >= 0);
+  return s == t;
+}
+
+int
+f7 (int x, int y)
+{
+  int s = (x < 0);
+  int t = (y >= 0);
+  return s != t;
+}
+
+int
+f8 (int x, int y)
+{
+  int s = (x >= 0);
+  int t = (y < 0);
+  return s != t;
+}