Hi,
At present, the corresponding optimization function has not been
verified through test cases redundant-bitmap-2.C on RV. Part of the
reason is that SHIFT_COUNT_TRUNCATED is defined as 0, which does not
meet the condition.
Could you provide some relevant test cases to verify the optimization
effect of this supplementary order on architectures such as RV or x86?
This patch adds a new simplification rule to `simplify-rtx.cc` that
handles a common bit manipulation pattern involving a single-bit set
and clear followed by XOR.
The transformation targets RTL of the form:
(xor (and (rotate (~1) A) B) (ashift 1 A))
which is semantically equivalent to:
B | (1 << A)
- v3 log:
Update RTL format, remove commas.
Only apply on SHIFT_COUNT_TRUNCATED target.
check '!side_effects_p' on XEXP (op1, 1).
gcc/ChangeLog:
* simplify-rtx.cc (simplify_context::simplify_binary_operation_1): Handle
more logical simplifications.
---
gcc/simplify-rtx.cc | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index b34fd2f4b9e..cbe61b49bf6 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -4063,6 +4063,20 @@ simplify_context::simplify_binary_operation_1
(rtx_code code,
&& rtx_equal_p (XEXP (XEXP (op0, 0), 0), op1))
return simplify_gen_binary (IOR, mode, XEXP (op0, 1), op1);
+ /* Convert (xor (and (rotate (~1) A) B) (ashift 1 A))
+ into B | (1 << A). */
+ if (SHIFT_COUNT_TRUNCATED
+ && GET_CODE (op0) == AND
+ && GET_CODE (XEXP (op0, 0)) == ROTATE
+ && CONST_INT_P (XEXP (XEXP (op0, 0), 0))
+ && INTVAL (XEXP (XEXP (op0, 0), 0)) == -2
+ && GET_CODE (op1) == ASHIFT
+ && CONST_INT_P (XEXP (op1, 0))
+ && INTVAL (XEXP (op1, 0)) == 1
+ && rtx_equal_p (XEXP (XEXP (op0, 0), 1), XEXP (op1, 1))
+ && !side_effects_p (XEXP (op1, 1)))
+ return simplify_gen_binary (IOR, mode, XEXP (op0, 1), op1);
+
tem = simplify_with_subreg_not (code, mode, op0, op1);
if (tem)
return tem;
--
2.43.0
