This in this PR we have missed optimization where we miss that,
`1 >> x` and `(1 >> x) ^ 1` can't be equal. There are a few ways of
optimizing this, the easiest and simpliest is to simplify `1 >> x` into
just `x == 0` as those are equivalant (if we ignore out of range values for x).
we already have an optimization for `(1 >> X) !=/== 0` so the only difference
here is we don't need the `!=/== 0` part to do the transformation.
So this removes the `(1 >> X) !=/== 0` transformation and just adds a simplfied
`1 >> x` -> `x == 0` one.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/102705
gcc/ChangeLog:
* match.pd (`(1 >> X) != 0`): Remove pattern.
(`1 >> x`): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr105832-2.c: Update testcase.
* gcc.dg/tree-ssa/pr96669-1.c: Likewise.
* gcc.dg/tree-ssa/pr102705-1.c: New test.
* gcc.dg/tree-ssa/pr102705-2.c: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
gcc/match.pd | 16 ++++++++--------
gcc/testsuite/gcc.dg/tree-ssa/pr102705-1.c | 17 +++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/pr102705-2.c | 17 +++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/pr105832-2.c | 8 ++++----
gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c | 2 +-
5 files changed, 47 insertions(+), 13 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr102705-1.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr102705-2.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 17193087498..b6cbb851897 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4998,6 +4998,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(op @0 { build_int_cst (TREE_TYPE (@1), prec - 1); })))
(op @0 { build_int_cst (TREE_TYPE (@1), low); })))))))
+/* Fold `1 >> a` into `a == 0` for scalar integral types. */
+(simplify
+ (rshift integer_onep @2)
+ (if (INTEGRAL_TYPE_P (type))
+ (convert (eq:boolean_type_node @2 { build_zero_cst (TREE_TYPE (@2)); }))))
/* Simplify (CST << x) & 1 to 0 if CST is even or to x == 0 if it is odd. */
(simplify
@@ -5009,7 +5014,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Simplify ((C << x) & D) != 0 where C and D are power of two constants,
either to false if D is smaller (unsigned comparison) than C, or to
x == log2 (D) - log2 (C). Similarly for right shifts.
- Note for `(1 >> x)`, the & 1 has been removed so matching that seperately.
*/
+ Note `(1 >> x)`, the & 1 has been removed so but will have been
+ already folded above. */
(for cmp (ne eq)
icmp (eq ne)
(simplify
@@ -5026,13 +5032,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
int c2 = wi::clz (wi::to_wide (@2)); }
(if (c1 > c2)
{ constant_boolean_node (cmp == NE_EXPR ? false : true, type); }
- (icmp @0 { build_int_cst (TREE_TYPE (@0), c2 - c1); })))))
- /* `(1 >> X) != 0` -> `X == 0` */
- /* `(1 >> X) == 0` -> `X != 0` */
- (simplify
- (cmp (rshift integer_onep@1 @0) integer_zerop)
- (if (INTEGRAL_TYPE_P (TREE_TYPE (@1)))
- (icmp @0 { build_zero_cst (TREE_TYPE (@0)); }))))
+ (icmp @0 { build_int_cst (TREE_TYPE (@0), c2 - c1); }))))))
/* (CST1 << A) == CST2 -> A == ctz (CST2) - ctz (CST1)
(CST1 << A) != CST2 -> A != ctz (CST2) - ctz (CST1)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr102705-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr102705-1.c
new file mode 100644
index 00000000000..60b53c03472
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr102705-1.c
@@ -0,0 +1,17 @@
+/* PR tree-optimization/102705 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-original" } */
+/* { dg-final { scan-tree-dump "a == 0" "original" } } */
+/* { dg-final { scan-tree-dump "b == 0" "original" } } */
+
+int
+f1 (int a)
+{
+ return (1 >> a);
+}
+
+int
+f2 (int b)
+{
+ return ((1 >> b) & 1);
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr102705-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr102705-2.c
new file mode 100644
index 00000000000..a12606c7856
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr102705-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/102705 */
+/* { dg-final { scan-tree-dump-not "foo " "optimized" } } */
+
+
+void foo(void);
+static int b;
+static char c;
+static short a(short d, short e) { return e == 0 || d && e == 1 ? 0 : d % e; }
+int main() {
+ b = c = b >= 2 ? 0 : 1 >> b;
+ short f = a(0 >= 0 ^ c, 5);
+ if (f == c)
+ foo();
+ a(0, 9);
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr105832-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr105832-2.c
index 2d2a33e2755..ebcc76bda68 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr105832-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr105832-2.c
@@ -1,10 +1,10 @@
/* PR tree-optimization/105832 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
-/* { dg-final { scan-tree-dump "return a == 0;" "original" } } */
-/* { dg-final { scan-tree-dump "return b == 0;" "original" } } */
-/* { dg-final { scan-tree-dump "return c != 0;" "original" } } */
-/* { dg-final { scan-tree-dump "return d != 0;" "original" } } */
+/* { dg-final { scan-tree-dump "a == 0" "original" } } */
+/* { dg-final { scan-tree-dump "b == 0" "original" } } */
+/* { dg-final { scan-tree-dump "c != 0" "original" } } */
+/* { dg-final { scan-tree-dump "d != 0" "original" } } */
int
f1 (int a)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c
index 6a95a6ba8c1..56932330218 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr96669-1.c
@@ -5,7 +5,7 @@
/* { dg-final { scan-tree-dump "return 1;" "original" } } */
/* { dg-final { scan-tree-dump "return c == 3;" "original" } } */
/* { dg-final { scan-tree-dump "return d != 1;" "original" } } */
-/* { dg-final { scan-tree-dump "return e != 0;" "original" } } */
+/* { dg-final { scan-tree-dump "e != 0" "original" } } */
/* { dg-final { scan-tree-dump "return f == 1;" "original" } } */
/* { dg-final { scan-tree-dump "return 0;" "original" } } */
/* { dg-final { scan-tree-dump "return h != 1;" "original" } } */
--
2.43.0
