Hi!
The following patch (on top of the two other PR94718 patches) performs the
actual optimization requested in the PR.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for stage1?
2020-04-30 Jakub Jelinek <ja...@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.
--- gcc/match.pd.jj 2020-04-30 12:43:10.473982154 +0200
+++ gcc/match.pd 2020-04-30 13:10:11.305134082 +0200
@@ -4358,6 +4358,28 @@ (define_operator_list COND_TERNARY
(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)))))
+(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)
--- gcc/testsuite/gcc.dg/tree-ssa/pr94718-4.c.jj 2020-04-30
12:56:00.552606387 +0200
+++ gcc/testsuite/gcc.dg/tree-ssa/pr94718-4.c 2020-04-30 13:12:57.320699373
+0200
@@ -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;
+}
--- gcc/testsuite/gcc.dg/tree-ssa/pr94718-5.c.jj 2020-04-30
13:01:44.893558240 +0200
+++ gcc/testsuite/gcc.dg/tree-ssa/pr94718-5.c 2020-04-30 13:14:00.434768470
+0200
@@ -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;
+}
Jakub
