https://gcc.gnu.org/g:57aec9c418f837bf427d8317bebdc0f825cbb043
commit 57aec9c418f837bf427d8317bebdc0f825cbb043
Author: Szabolcs Nagy <szabolcs.n...@arm.com>
Date: Tue May 9 16:00:01 2023 +0100
aarch64: Add GCS instructions
Add instructions for the Guarded Control Stack extension.
GCSSS1 and GCSSS2 are modelled as a single GCSSS unspec, because they
are always used together in the compiler.
Before GCSPOPM and GCSSS2 an extra "mov xn, 0" is added to clear the
output register, this is needed to get reasonable result when GCS is
disabled, when the instructions are NOPs. Since the instructions are
expecetd to be used behind runtime feature checks, this is mainly
relevant if GCS can be disabled asynchronously.
The output of GCSPOPM is usually not needed, so a separate gcspopm_xzr
was added to model that. Did not do the same for GCSSS as it is a less
common operation.
The used mnemonics do not depend on updated assembler since these
instructions can be used without new -march setting behind a runtime
check.
Reading the GCSPR is modelled as unspec_volatile so it does not get
reordered wrt the other instructions changing the GCSPR.
TODO:
- Do we care about async disable?
- Do we need GCSSS_xzr? (to avoid the mov x,0)
gcc/ChangeLog:
* config/aarch64/aarch64.md (aarch64_load_gcspr): New.
(aarch64_gcspopm): New.
(aarch64_gcspopm_xzr): New.
(aarch64_gcsss): New.
Diff:
---
gcc/config/aarch64/aarch64.md | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index a20462303b5..8defd6e0582 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -379,6 +379,9 @@
UNSPECV_BTI_J ; Represent BTI j.
UNSPECV_BTI_JC ; Represent BTI jc.
UNSPECV_CHKFEAT ; Represent CHKFEAT X16.
+ UNSPECV_GCSPR ; Represent MRS Xn, GCSPR_EL0
+ UNSPECV_GCSPOPM ; Represent GCSPOPM.
+ UNSPECV_GCSSS ; Represent GCSSS1 and GCSSS2.
UNSPECV_TSTART ; Represent transaction start.
UNSPECV_TCOMMIT ; Represent transaction commit.
UNSPECV_TCANCEL ; Represent transaction cancel.
@@ -8267,6 +8270,38 @@
"hint\\t40 // chkfeat x16"
)
+;; Guarded Control Stack (GCS) instructions
+(define_insn "aarch64_load_gcspr"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (unspec_volatile:DI [(const_int 0)] UNSPECV_GCSPR))]
+ ""
+ "mrs\\t%0, s3_3_c2_c5_1 // gcspr_el0"
+ [(set_attr "type" "mrs")]
+)
+
+(define_insn "aarch64_gcspopm"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (unspec_volatile:DI [(const_int 0)] UNSPECV_GCSPOPM))]
+ ""
+ "mov\\t%0, 0\;sysl\\t%0, #3, c7, c7, #1 // gcspopm"
+ [(set_attr "length" "8")]
+)
+
+(define_insn "aarch64_gcspopm_xzr"
+ [(unspec_volatile [(const_int 0)] UNSPECV_GCSPOPM)]
+ ""
+ "sysl\\txzr, #3, c7, c7, #1 // gcspopm"
+)
+
+(define_insn "aarch64_gcsss"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (unspec_volatile:DI [(match_operand:DI 1 "register_operand" "r")]
+ UNSPECV_GCSSS))]
+ ""
+ "sys\\t#3, c7, c7, #2, %1 // gcsss1\;mov\\t%0, 0\;sysl\\t%0, #3, c7, c7, #3
// gcsss2"
+ [(set_attr "length" "12")]
+)
+
;; AdvSIMD Stuff
(include "aarch64-simd.md")
