From: kelefth <konstantinos.elefther...@vrull.eu>
In expressions like (a != b || ((a ^ b) & c) == d) and
(a != b || (a ^ b) == c), (a ^ b) is folded to false.
In the equivalent expressions (((a ^ b) & c) == d || a != b) and
((a ^ b) == c || a != b) this is not happening.
This patch adds the following simplifications in match.pd:
((a ^ b) & c) == d || a != b --> 0 == d || a != b
(a ^ b) == c || a != b --> 0 == c || a != b
PR tree-optimization/114326
gcc/ChangeLog:
* match.pd: Add two patterns to fold a ^ b to 0, when a == b.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/fold-xor-and-or.c: New test.
* gcc.dg/tree-ssa/fold-xor-or.c: New test.
Reviewed-by: Christoph Müllner <christoph.muell...@vrull.eu>
Signed-off-by: Philipp Tomsich <philipp.toms...@vrull.eu>
Signed-off-by: Konstantinos Eleftheriou <konstantinos.elefther...@vrull.eu>
---
gcc/match.pd | 30 ++++++++++++++++++
.../gcc.dg/tree-ssa/fold-xor-and-or.c | 31 +++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c | 31 +++++++++++++++++++
3 files changed, 92 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
diff --git a/gcc/match.pd b/gcc/match.pd
index be211535a49..6bab3cfbde1 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -10727,3 +10727,33 @@ and,
}
(if (full_perm_p)
(vec_perm (op@3 @0 @1) @3 @2))))))
+
+/* ((a ^ b) & c) == d || a != b --> (0 == d || a != b). */
+(for cmp (simple_comparison)
+ (simplify
+ (bit_ior
+ (cmp
+ (bit_and
+ (bit_xor @0 @1)
+ tree_expr_nonzero_p@2)
+ @3)
+ (ne@4 @0 @1))
+ (bit_ior
+ (cmp
+ { build_zero_cst (TREE_TYPE (@0)); }
+ @3)
+ @4)))
+
+/* (a ^ b) == c || a != b --> (0 == c || a != b). */
+(for cmp (simple_comparison)
+ (simplify
+ (bit_ior
+ (cmp
+ (bit_xor @0 @1)
+ @2)
+ (ne@3 @0 @1))
+ (bit_ior
+ (cmp
+ { build_zero_cst (TREE_TYPE (@0)); }
+ @2)
+ @3)))
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
new file mode 100644
index 00000000000..ec327e62f6e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized" } */
+
+int cmp1(int d1, int d2) {
+ if (((d1 ^ d2) & 0xabcd) == 0 || d1 != d2)
+ return 0;
+ return 1;
+}
+
+int cmp2(int d1, int d2) {
+ if (d1 != d2 || ((d1 ^ d2) & 0xabcd) == 0)
+ return 0;
+ return 1;
+}
+
+typedef unsigned long int uint64_t;
+
+int cmp1_64(uint64_t d1, uint64_t d2) {
+ if (((d1 ^ d2) & 0xabcd) == 0 || d1 != d2)
+ return 0;
+ return 1;
+}
+
+int cmp2_64(uint64_t d1, uint64_t d2) {
+ if (d1 != d2 || ((d1 ^ d2) & 0xabcd) == 0)
+ return 0;
+ return 1;
+}
+
+/* The if should be removed, so the condition should not exist */
+/* { dg-final { scan-tree-dump-not "d1_\[0-9\]+.D. \\^ d2_\[0-9\]+.D."
"optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
new file mode 100644
index 00000000000..f5fce847394
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized" } */
+
+int cmp1(int d1, int d2) {
+ if ((d1 ^ d2) == 0xabcd || d1 != d2)
+ return 0;
+ return 1;
+}
+
+int cmp2(int d1, int d2) {
+ if (d1 != d2 || (d1 ^ d2) == 0xabcd)
+ return 0;
+ return 1;
+}
+
+typedef unsigned long int uint64_t;
+
+int cmp1_64(uint64_t d1, uint64_t d2) {
+ if ((d1 ^ d2) == 0xabcd || d1 != d2)
+ return 0;
+ return 1;
+}
+
+int cmp2_64(uint64_t d1, uint64_t d2) {
+ if (d1 != d2 || (d1 ^ d2) == 0xabcd)
+ return 0;
+ return 1;
+}
+
+/* The if should be removed, so the condition should not exist */
+/* { dg-final { scan-tree-dump-not "d1_\[0-9\]+.D. \\^ d2_\[0-9\]+.D."
"optimized" } } */
--
2.46.0
