Without atomic_fetch_nandsi and atomic_fetch_nanddi, __atomic_fetch_nand
is expanded to a loop containing a CAS in the body, and CAS itself is a
LL-SC loop so we have a nested loop. This is obviously not a good idea
as we just need one LL-SC loop in fact.
As ~(atom & mask) is (~mask) | (~atom), we can just invert the mask
first and the body of the LL-SC loop would be just one orn instruction.
gcc/ChangeLog:
* config/loongarch/sync.md
(atomic_fetch_nand_mask_inverted<GPR:mode>): New define_insn.
(atomic_fetch_nand<GPR:mode>): New define_expand.
---
gcc/config/loongarch/sync.md | 40 ++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/gcc/config/loongarch/sync.md b/gcc/config/loongarch/sync.md
index 60038258f29..f1ab132163c 100644
--- a/gcc/config/loongarch/sync.md
+++ b/gcc/config/loongarch/sync.md
@@ -203,6 +203,46 @@ (define_insn "atomic_fetch_<amop><mode>"
"am<amop>%A3.<size>\t%0,%z2,%1"
[(set (attr "length") (const_int 4))])
+(define_insn "atomic_fetch_nand_mask_inverted<mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=&r")
+ (match_operand:GPR 1 "memory_operand" "+ZC"))
+ (set (match_dup 1)
+ (unspec_volatile:GPR
+ [(ior:GPR (not (match_dup 1))
+ (match_operand:GPR 2 "register_operand" "r"))]
+ UNSPEC_SYNC_OLD_OP))
+ (clobber (match_scratch:GPR 3 "=&r"))]
+ ""
+ {
+ return "1:\\n\\t"
+ "ll.<d>\\t%0,%1\\n\\t"
+ "orn\\t%3,%2,%0\\n\\t"
+ "sc.<d>\\t%3,%1\\n\\t"
+ "beqz\\t%3,1b";
+ }
+ [(set (attr "length") (const_int 16))])
+
+(define_expand "atomic_fetch_nand<mode>"
+ [(match_operand:GPR 0 "register_operand")
+ (match_operand:GPR 1 "memory_operand")
+ (match_operand:GPR 2 "reg_or_0_operand")
+ (match_operand:SI 3 "const_int_operand")]
+ ""
+ {
+ /* ~(atom & mask) = (~mask) | (~atom), so we can hoist
+ (~mask) out of the ll/sc loop and use the orn instruction in the
+ ll/sc loop. */
+ rtx inverted_mask = gen_reg_rtx (<MODE>mode);
+ emit_move_insn (inverted_mask,
+ expand_simple_unop (<MODE>mode, NOT, operands[2],
+ NULL_RTX, false));
+
+ emit_insn (
+ gen_atomic_fetch_nand_mask_inverted<mode> (operands[0], operands[1],
+ inverted_mask));
+ DONE;
+ })
+
(define_insn "atomic_exchange<mode>"
[(set (match_operand:GPR 0 "register_operand" "=&r")
(unspec_volatile:GPR
--
2.48.1
