diff mbox series

[v2] MATCH: Simplify `a rrotate (32-b) -> a lrotate b` [PR109906]

Message ID 20240918064517.3593-1-quic_eikagupt@quicinc.com
State New
Headers
Series [v2] MATCH: Simplify `a rrotate (32-b) -> a lrotate b` [PR109906] |

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Commit Message

Eikansh Gupta Sept. 18, 2024, 6:45 a.m. UTC 
  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                             |  9 ++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr109906.c | 40 ++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109906.c

Comments

Jeff Law Sept. 18, 2024, 5:30 p.m. UTC | #1 
On 9/18/24 12:45 AM, Eikansh Gupta wrote:
> 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.
Note I think the testcase is specific to 32bit int targets.  You 
probably need to use a target selector to limit it appropriately.

> /* { dg-require-effective-target int32 } */
Is probably the magic selector you want...


And you need to indicate where it was bootstrapped and regression tested.

I think the match.pd bits are fine.  So it's really just a matter of 
dotting i's and crossing t's on process and testsuite adjustment.
Jeff
diff mbox series

Patch

diff --git a/gcc/match.pd b/gcc/match.pd
index 5566c0e4c41..b67ffce9586 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4759,6 +4759,15 @@  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)
+     orotate (rrotate lrotate)
+ (simplify
+  (rotate @0 (minus INTEGER_CST@1 @2))
+   (if (TYPE_PRECISION (TREE_TYPE (@0)) == wi::to_wide (@1))
+     (orotate @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" } } */