This patch adds a target-independent aligned_register_operand
predicate, for use with register constraints that use filters
to impose an alignment. The definition deliberately jetisons
some of the historical baggage in general_operand.
gcc/
* common.md (aligned_register_operand): New predicate.
---
gcc/common.md | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/gcc/common.md b/gcc/common.md
index 51ecd79786b..91a72bd7731 100644
--- a/gcc/common.md
+++ b/gcc/common.md
@@ -17,6 +17,34 @@
;; along with GCC; see the file COPYING3. If not see
;; <http://www.gnu.org/licenses/>. */
+;; This predicate is intended to be paired with register constraints that use
+;; register filters to impose an alignment. Operands that are aligned via
+;; TARGET_HARD_REGNO_MODE_OK should use normal register_operands instead.
+(define_predicate "aligned_register_operand"
+ (match_code "reg,subreg")
+{
+ /* Require the offset in a non-paradoxical subreg to be naturally aligned.
+ For example, if we have a subreg of something that is double the size of
+ this operand, the offset must select the first or second half of it. */
+ if (SUBREG_P (op)
+ && multiple_p (SUBREG_BYTE (op), GET_MODE_SIZE (GET_MODE (op))))
+ op = SUBREG_REG (op);
+ if (!REG_P (op))
+ return false;
+
+ if (HARD_REGISTER_P (op))
+ {
+ if (!in_hard_reg_set_p (operand_reg_set, GET_MODE (op), REGNO (op)))
+ return false;
+
+ /* Reject hard registers that would need reloading, so that the reload
+ is visible to IRA and to pre-RA optimizers. */
+ if (REGNO (op) % REG_NREGS (op) != 0)
+ return false;
+ }
+ return true;
+})
+
(define_register_constraint "r" "GENERAL_REGS"
"Matches any general register.")
--
2.25.1
