Using post-index stg is a faster way of memory tagging/untagging.
TBD:
- Currently generated by in the aarch64 backend. Not sure if this
is the right way to do it.
- Also not clear how to weave in the generation of stzg.
ChangeLog:
* gcc/config/aarch64/aarch64.md
---
[New in RFC V2]
---
gcc/config/aarch64/aarch64.md | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 175aed3146ac..3cb773a77ad8 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -8475,6 +8475,21 @@
[(set_attr "type" "memtag")]
)
+;; STG with post-index writeback.
+(define_insn "*stg_post"
+ [(set (mem:QI (unspec:DI
+ [(plus:DI (match_operand:DI 1 "register_operand" "=rk")
+ (const_int 0))]
+ UNSPEC_TAG_SPACE))
+ (and:QI (lshiftrt:DI (match_operand:DI 0 "register_operand" "rk")
+ (const_int 56)) (const_int 15)))
+ (set (match_dup 1)
+ (plus:DI (match_dup 1) (match_operand:DI 2 "aarch64_granule16_simm9"
"i")))]
+ "TARGET_MEMTAG"
+ "stg\\t%0, [%1], #%2"
+ [(set_attr "type" "memtag")]
+)
+
;; ST2G updates allocation tags for two memory granules (i.e. 32 bytes) at
;; once, without zero initialization.
(define_insn "st2g"
--
2.43.0
