subg (Subtract with Tag) is an Armv8.5-A memory tagging (MTE)
instruction. It can be used to subtract an immediate value scaled by
the tag granule from the address in the source register.
gcc/ChangeLog:
* config/aarch64/aarch64.md (subg): New definition.
---
gcc/config/aarch64/aarch64.md | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 031e621c98a1..0c7aebb838cd 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -8416,6 +8416,23 @@
[(set_attr "type" "memtag")]
)
+(define_insn "subg"
+ [(set (match_operand:DI 0 "register_operand" "=rk")
+ (ior:DI
+ (and:DI (minus:DI (match_operand:DI 1 "register_operand" "rk")
+ (match_operand:DI 2 "aarch64_granule16_uimm6" "i"))
+ (const_int -1080863910568919041)) ;; 0xf0ff...
+ (ashift:DI
+ (unspec:QI
+ [(and:QI (lshiftrt:DI (match_dup 1) (const_int 56)) (const_int 15))
+ (match_operand:QI 3 "aarch64_memtag_tag_offset" "i")]
+ UNSPEC_GEN_TAG)
+ (const_int 56))))]
+ "TARGET_MEMTAG"
+ "subg\\t%0, %1, #%2, #%3"
+ [(set_attr "type" "memtag")]
+)
+
(define_insn "subp"
[(set (match_operand:DI 0 "register_operand" "=r")
(minus:DI
--
2.43.0
