The pattern `a rrotate (32-b)` should be optimized to `a lrotate b`.
The same is also true for `a lrotate (32-b)`. It can be optimized to
`a rrotate b`.
This patch adds following patterns:
a rrotate (32-b) -> a lrotate b
a lrotate (32-b) -> a rrotate b
PR tree-optimization/109906
gcc/ChangeLog:
* match.pd (a rrotate (32-b) -> a lrotate b): New pattern
(a lrotate (32-b) -> a rrotate b): New pattern
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr109906.c: New test.
---
gcc/match.pd | 10 ++++++
gcc/testsuite/gcc.dg/tree-ssa/pr109906.c | 40 ++++++++++++++++++++++++
2 files changed, 50 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109906.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 5566c0e4c41..77cb3f8060a 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4759,6 +4759,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
build_int_cst (TREE_TYPE (@1),
element_precision (type)), @1); }))
+/* a rrotate (32-b) -> a lrotate b */
+/* a lrotate (32-b) -> a rrotate b */
+(for rotate (lrotate rrotate)
+ (simplify
+ (rotate @0 (minus INTEGER_CST@1 @2))
+ (if (TYPE_PRECISION (TREE_TYPE (@0)) == wi::to_wide (@1))
+ (if (rotate == RROTATE_EXPR)
+ (lrotate @0 @2)
+ (rrotate @0 @2)))))
+
/* Turn (a OP c1) OP c2 into a OP (c1+c2). */
(for op (lrotate rrotate rshift lshift)
(simplify
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr109906.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr109906.c
new file mode 100644
index 00000000000..fe576d7ce3a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr109906.c
@@ -0,0 +1,40 @@
+/* PR tree-optimization/109906 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized-raw" } */
+
+/* Implementation of rotate right operation */
+static inline
+unsigned rrotate(unsigned x, int t)
+{
+ if (t >= 32) __builtin_unreachable();
+ unsigned tl = x >> (t);
+ unsigned th = x << (32-t);
+ return tl | th;
+}
+
+/* Here rotate left is achieved by doing rotate right by (32 - x) */
+unsigned rotateleft(unsigned t, int x)
+{
+ return rrotate (t, 32-x);
+}
+
+/* Implementation of rotate left operation */
+static inline
+unsigned lrotate(unsigned x, int t)
+{
+ if (t >= 32) __builtin_unreachable();
+ unsigned tl = x << (t);
+ unsigned th = x >> (32-t);
+ return tl | th;
+}
+
+/* Here rotate right is achieved by doing rotate left by (32 - x) */
+unsigned rotateright(unsigned t, int x)
+{
+ return lrotate (t, 32-x);
+}
+
+/* Shouldn't have instruction for (32 - x). */
+/* { dg-final { scan-tree-dump-not "minus_expr" "optimized" } } */
+/* { dg-final { scan-tree-dump "rrotate_expr" "optimized" } } */
+/* { dg-final { scan-tree-dump "lrotate_expr" "optimized" } } */
--
2.17.1
