https://gcc.gnu.org/g:a88d6c6d777ad7c9235e2e620318f26e5347e50a
commit r15-3866-ga88d6c6d777ad7c9235e2e620318f26e5347e50a
Author: Konstantinos Eleftheriou <konstantinos.elefther...@vrull.eu>
Date: Wed Aug 7 17:54:30 2024 +0200
match: Fix A || B not optimized to true when !B implies A [PR114326]
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) cmp d || a != b --> 0 cmp d || a != b
(a ^ b) cmp c || a != b --> 0 cmp 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.
Tested-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>
Diff:
---
gcc/match.pd | 30 ++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c | 55 +++++++++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c | 55 +++++++++++++++++++++++++
3 files changed, 140 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 7150b8e78cab..d10ac7d6cd20 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3787,6 +3787,36 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (types_match (type, TREE_TYPE (@0)))
(bit_xor @0 { build_one_cst (type); } ))))))
+/* ((a ^ b) & c) cmp d || a != b --> (0 cmp d || a != b). */
+(for cmp (simple_comparison)
+ (simplify
+ (bit_ior
+ (cmp:c
+ (bit_and:c
+ (bit_xor:c @0 @1)
+ tree_expr_nonzero_p@2)
+ @3)
+ (ne:c@4 @0 @1))
+ (bit_ior
+ (cmp
+ { build_zero_cst (TREE_TYPE (@0)); }
+ @3)
+ @4)))
+
+/* (a ^ b) cmp c || a != b --> (0 cmp c || a != b). */
+(for cmp (simple_comparison)
+ (simplify
+ (bit_ior
+ (cmp:c
+ (bit_xor:c @0 @1)
+ @2)
+ (ne:c@3 @0 @1))
+ (bit_ior
+ (cmp
+ { build_zero_cst (TREE_TYPE (@0)); }
+ @2)
+ @3)))
+
/* We can't reassociate at all for saturating types. */
(if (!TYPE_SATURATING (type))
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 000000000000..e5dc98e7541d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
@@ -0,0 +1,55 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized" } */
+
+typedef unsigned long int uint64_t;
+
+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;
+}
+
+int cmp3(int d1, int d2) {
+ if (10 > (0xabcd & (d2 ^ d1)) || d2 != d1)
+ return 0;
+ return 1;
+}
+
+int cmp4(int d1, int d2) {
+ if (d2 != d1 || 10 > (0xabcd & (d2 ^ d1)))
+ return 0;
+ return 1;
+}
+
+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;
+}
+
+int cmp3_64(uint64_t d1, uint64_t d2) {
+ if (10 > (0xabcd & (d2 ^ d1)) || d2 != d1)
+ return 0;
+ return 1;
+}
+
+int cmp4_64(uint64_t d1, uint64_t d2) {
+ if (d2 != d1 || 10 > (0xabcd & (d2 ^ d1)))
+ 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 000000000000..c55cfbcc84c8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
@@ -0,0 +1,55 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-optimized" } */
+
+typedef unsigned long int uint64_t;
+
+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;
+}
+
+int cmp3(int d1, int d2) {
+ if (0xabcd > (d2 ^ d1) || d2 != d1)
+ return 0;
+ return 1;
+}
+
+int cmp4(int d1, int d2) {
+ if (d2 != d1 || 0xabcd > (d2 ^ d1))
+ return 0;
+ return 1;
+}
+
+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;
+}
+
+int cmp3_64(uint64_t d1, uint64_t d2) {
+ if (0xabcd > (d2 ^ d1) || d2 != d1)
+ return 0;
+ return 1;
+}
+
+int cmp4_64(uint64_t d1, uint64_t d2) {
+ if (d2 != d1 || 0xabcd > (d2 ^ d1))
+ 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" } } */
