Hi everyone,
this patch optimizes ~(~x | y), (~x | y) & (x | ~y) and
(~x | y) ^ (x | ~y). Thanks to Marc Glisse
for noticing that the last two weren't optimized.
I'll post the test results soon, it took three hours in
addition to timeouts and I had to terminate it.
Waiting for your comments.
gcc/
PR tree-optimization/87009
* match.pd: Improve boolean optimizations
gcc/testsuite/
PR tree-optimization/87009
* gcc.dg/pr87009.c: Add boolean optimization tests
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 263646)
+++ gcc/match.pd (working copy)
@@ -776,6 +776,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(bit_not (bit_and:cs (bit_not @0) @1))
(bit_ior @0 (bit_not @1)))
+/* ~(~a | b) --> a & ~b */
+(simplify
+ (bit_not (bit_ior:cs (bit_not @0) @1))
+ (bit_and @0 (bit_not @1)))
+
/* Simplify (~X & Y) to X ^ Y if we know that (X & ~Y) is 0. */
#if GIMPLE
(simplify
@@ -981,6 +986,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(bit_and:c (bit_ior:c @0 @1) (bit_xor:c @1 (bit_not @0)))
(bit_and @0 @1))
+/* (~x | y) & (x | ~y) -> ~(x ^ y) */
+(simplify
+ (bit_and (bit_ior:c (bit_not @0) @1) (bit_ior:c @0 (bit_not @1)))
+ (bit_not (bit_xor @0 @1)))
+
+/* (~x | y) ^ (x | ~y) -> x ^ y */
+(simplify
+ (bit_xor (bit_ior:c (bit_not @0) @1) (bit_ior:c @0 (bit_not @1)))
+ (bit_xor @0 @1))
+
/* ~x & ~y -> ~(x | y)
~x | ~y -> ~(x & y) */
(for op (bit_and bit_ior)
Index: gcc/testsuite/gcc.dg/pr87009.c
===================================================================
--- gcc/testsuite/gcc.dg/pr87009.c (nonexistent)
+++ gcc/testsuite/gcc.dg/pr87009.c (working copy)
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-original" } */
+/* { dg-final { scan-tree-dump-times " \\^ " 4 "original" } } */
+
+int f1 (int x, int s)
+{
+ return ~(~(x|s)|x)|~(~(x|s)|s);
+}
+
+int f2 (int x, int s)
+{
+ return ~(~(~x&s)&~(x&~s));
+}
+
+int f3 (int x, int s)
+{
+ return ~((x|~s)&(~x|s));
+}
+
+int f4 (int x, int s)
+{
+ return (~x|s)&(x|~s);
+}
