[AArch64] Ensure APAS instruction passes register parameter (#121928)

In PR #112341, the `APAS` instruction was added as part of the Armv9.6-A
specification, but it didn't take the Xt register parameter. This change
fixes this.

Author: jthackray

llvm/lib/Target/AArch64/AArch64InstrFormats.td

@@ -1804,7 +1804,9 @@ class TMSystemException<bits<3> op1, string asm, list<dag> pattern>
 }
 
 class APASI : SimpleSystemI<0, (ins GPR64:$Xt), "apas", "\t$Xt">, Sched<[]> {
+  bits<5> Xt;
   let Inst{20-5} = 0b0111001110000000;
+  let Inst{4-0} = Xt;
   let DecoderNamespace = "APAS";
 }
 

llvm/test/MC/AArch64/armv9.6a-rme-gpc3.s

@@ -2,10 +2,18 @@
 // RUN: llvm-mc -triple aarch64 -show-encoding %s  | FileCheck %s
 .func:
   apas x0
+  apas x1
+  apas x2
+  apas x17
+  apas x30
   mrs x3, GPCBW_EL3
   msr GPCBW_EL3, x4
 
 # CHECK:      .func:
-# CHECK-NEXT: 	apas	x0                              // encoding: [0x1f,0x70,0x0e,0xd5]
+# CHECK-NEXT:	apas    x0                              // encoding: [0x00,0x70,0x0e,0xd5]
+# CHECK-NEXT:	apas    x1                              // encoding: [0x01,0x70,0x0e,0xd5]
+# CHECK-NEXT:	apas    x2                              // encoding: [0x02,0x70,0x0e,0xd5]
+# CHECK-NEXT:	apas    x17                             // encoding: [0x11,0x70,0x0e,0xd5]
+# CHECK-NEXT:	apas    x30                             // encoding: [0x1e,0x70,0x0e,0xd5]
 # CHECK-NEXT: 	mrs	x3, GPCBW_EL3                   // encoding: [0xa3,0x21,0x3e,0xd5]
 # CHECK-NEXT: 	msr	GPCBW_EL3, x4                   // encoding: [0xa4,0x21,0x1e,0xd5]

llvm/test/MC/Disassembler/AArch64/armv9.6a-rme-gpc3.txt

@@ -1,10 +1,18 @@
 # NOTE: Assertions have been autogenerated by utils/update_mca_test_checks.py
 # RUN: llvm-mc -triple aarch64 -disassemble %s  | FileCheck %s
 
-[0x1f,0x70,0x0e,0xd5]
+[0x00,0x70,0x0e,0xd5]
+[0x01,0x70,0x0e,0xd5]
+[0x02,0x70,0x0e,0xd5]
+[0x11,0x70,0x0e,0xd5]
+[0x1e,0x70,0x0e,0xd5]
 [0xa3,0x21,0x3e,0xd5]
 [0xa4,0x21,0x1e,0xd5]
 
-# CHECK:      	sys	#6, c7, c0, #0
+# CHECK:      	sys	#6, c7, c0, #0, x0
+# CHECK-NEXT: 	sys	#6, c7, c0, #0, x1
+# CHECK-NEXT: 	sys	#6, c7, c0, #0, x2
+# CHECK-NEXT: 	sys	#6, c7, c0, #0, x17
+# CHECK-NEXT: 	sys	#6, c7, c0, #0, x30
 # CHECK-NEXT: 	mrs	x3, GPCBW_EL3
 # CHECK-NEXT: 	msr	GPCBW_EL3, x4