Simplify "1 - bool_val" to "bool_val ^ 1"

For bool values, it is easier to deal with
xor 1 rather than having 1 - a. This is because
we are more likely to simplify the xor further in many
cases.

This is a special case for (MASK - b) where MASK
is a powerof2 - 1 and b <= MASK but only for bool
ranges ([0,1]) as that is the main case where the
difference comes into play.

Note this is enabled for gimple folding only
as the ranges are only know while doing gimple
folding and cfun is not always set when fold is called.

OK? Bootstrapped and tested on x86_64-linux-gnu with no
regressions.

gcc/ChangeLog:

	PR tree-optimization/108355
	PR tree-optimization/96921
	* match.pd: Add pattern for "1 - bool_val".

gcc/testsuite/ChangeLog:

	PR tree-optimization/108355
	PR tree-optimization/96921
	* gcc.dg/tree-ssa/bool-minus-1.c: New test.
	* gcc.dg/tree-ssa/bool-minus-2.c: New test.
	* gcc.dg/tree-ssa/pr108354-1.c: New test.

4 files changed, 83 insertions, 0 deletions

diff --git a/gcc/match.pd b/gcc/match.pd
index 821630d..e7b7003 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1732,6 +1732,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (if (!FIXED_POINT_TYPE_P (type))
  (plus @0 (negate @1))))
 
+#if GIMPLE
+/* 1 - a is a ^ 1 if a had a bool range. */
+/* This is only enabled for gimple as sometimes
+   cfun is not set for the function which contains
+   the SSA_NAME (e.g. while IPA passes are happening,
+   fold might be called).  */
+(simplify
+ (minus integer_onep@0 SSA_NAME@1)
+  (if (INTEGRAL_TYPE_P (type)
+       && ssa_name_has_boolean_range (@1))
+   (bit_xor @1 @0)))
+#endif
+
 /* Other simplifications of negation (c.f. fold_negate_expr_1).  */
 (simplify
  (negate (mult:c@0 @1 negate_expr_p@2))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c
new file mode 100644
index 0000000..e434ff9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c
@@ -0,0 +1,11 @@
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+_Bool
+foo (_Bool a)
+{
+  int c = 1 - a;
+  return c;
+}
+
+/* { dg-final { scan-tree-dump-times "1 - " 0 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "~a" 1 "optimized" } } */
+
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c
new file mode 100644
index 0000000..b77d36c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c
@@ -0,0 +1,33 @@
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+_Bool
+foo (_Bool a, _Bool b)
+{
+  int c = 1 - a;
+  int d = 1 - b;
+  int e = c & d;
+  return 1 - e;
+}
+
+_Bool
+bar (_Bool a, _Bool b)
+{
+  int c = 1 - a;
+  int d = 1 - b;
+  _Bool e = c & d;
+  return 1 - e;
+}
+
+_Bool
+baz (_Bool a, _Bool b)
+{
+  _Bool c = 1 - a;
+  _Bool d = 1 - b;
+  _Bool e = c & d;
+  return 1 - e;
+}
+
+/* { dg-final { scan-tree-dump-times "1 - " 0 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "~a" 0 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "~b" 0 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "a_\[0-9\]+.D. \\\| b_\[0-9\]+.D." 3 "optimized" } } */
+
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c
new file mode 100644
index 0000000..60d1dbc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c
@@ -0,0 +1,26 @@
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int b;
+int *c;
+int e;
+static int *f = &e;
+int g;
+void foo();
+short(a)(short h, short i) { return h - i; }
+int(d)(int h) { return h == 83647 ? 0 : -h; }
+int main() {
+  short j;
+  int *k = &e, *l = &b;
+  *f = 0 == c;
+  j = a(0 != 2, *k);
+  if (d(j ^ (0 == l || *k)) != *k)
+    ;
+  else
+    foo();
+  c = &g;
+}
+
+/* { dg-final { scan-tree-dump-times " 1 - " 0 "optimized" } } */
+/* There should be no calls to foo. */
+/* { dg-final { scan-tree-dump-times "foo " 0 "optimized" } } */
+