From 00c1666e053982c8a9cff86eee080b3806ad5d95 Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Thu, 27 Aug 2026 11:40:53 -0700
Subject: [PATCH] AArch64: SYSL writes its Rt operand, it does not read it

SYSL was generated with CS_AC_READ on Rt, but Rt is the destination.
"SYSL <Xt>, #<op1>, <Cn>, <Cm>{, #<op2>}" is the system instruction
WITH RESULT, and the Arm ARM names Xt "the 64-bit name of the
general-purpose destination register", encoded in the Rt field.

Before:

  sysl x0, #0, c0, c0, #0
    operands[0].type: REG = x0
    operands[0].access: READ
  Registers read: x0

After:

  sysl x0, #0, c0, c0, #0
    operands[0].type: REG = x0
    operands[0].access: WRITE
  Registers modified: x0

A consumer tracking register liveness saw a use where there is a
definition, which is the unsafe direction: a value written into Xt
looked like it was still needed.

SYS (without the L) is the opposite direction -- its Xt is a source,
and it takes it as the last operand -- and is already CS_AC_READ; it is
untouched.
---
 arch/AArch64/AArch64GenCSMappingInsnOp.inc |  2 +-
 tests/details/aarch64.yaml                 | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/AArch64/AArch64GenCSMappingInsnOp.inc b/arch/AArch64/AArch64GenCSMappingInsnOp.inc
index 1c03340534..0f3556bc68 100644
--- a/arch/AArch64/AArch64GenCSMappingInsnOp.inc
+++ b/arch/AArch64/AArch64GenCSMappingInsnOp.inc
@@ -46762,7 +46762,7 @@
 }},
 { /* AARCH64_SYSLxt (7060) - AARCH64_INS_SYSL - sysl	$Rt, $op1, $Cn, $Cm, $op2 */
 {
-  { CS_OP_REG, CS_AC_READ, { CS_DATA_TYPE_i64, CS_DATA_TYPE_LAST } }, /* Rt */
+  { CS_OP_REG, CS_AC_WRITE, { CS_DATA_TYPE_i64, CS_DATA_TYPE_LAST } }, /* Rt */
   { CS_OP_IMM, CS_AC_READ, { CS_DATA_TYPE_i64, CS_DATA_TYPE_LAST } }, /* op1 */
   { CS_OP_IMM, CS_AC_READ, { CS_DATA_TYPE_i32, CS_DATA_TYPE_LAST } }, /* Cn */
   { CS_OP_IMM, CS_AC_READ, { CS_DATA_TYPE_i32, CS_DATA_TYPE_LAST } }, /* Cm */
diff --git a/tests/details/aarch64.yaml b/tests/details/aarch64.yaml
index 4b0086dcda..f11791ca03 100644
--- a/tests/details/aarch64.yaml
+++ b/tests/details/aarch64.yaml
@@ -1800,3 +1800,15 @@ test_cases:
               mem_disp: 1
               access: CS_AC_WRITE
           regs_read: [ b10, x8 ]
+  -
+    input:
+      bytes: [0x00,0x00,0x28,0xd5]
+      arch: "CS_ARCH_AARCH64"
+      options: [ CS_OPT_DETAIL ]
+      address: 0x0
+    expected:
+      insns:
+      -
+        asm_text: "sysl	x0, #0, c0, c0, #0"
+        details:
+          regs_write: [ x0 ]