gas: sframe: testsuite: add testcase for .cfi_negate_ra_state

Add a new test to check that .cfi_negate_ra_state on aarch64 is handled
well (a non-empty SFrame section with valid SFrame FREs is generated).

ChangeLog:

	* testsuite/gas/cfi-sframe/cfi-sframe-aarch64-2.d: New test.
	* testsuite/gas/cfi-sframe/cfi-sframe-aarch64-2.s: Likewise.
	* testsuite/gas/cfi-sframe/cfi-sframe.exp: Adjust the list
	accordingly.

gas/testsuite/gas/cfi-sframe/cfi-sframe-aarch64-2.d

@@ -0,0 +1,20 @@
+#as: --gsframe
+#objdump: --sframe=.sframe
+#name: SFrame cfi_negate_ra_state test
+#...
+Contents of the SFrame section .sframe:
+
+  Header :
+
+    Version: SFRAME_VERSION_1
+    Flags: NONE
+    Num FDEs: 1
+    Num FREs: 2
+
+  Function Index :
+    func idx \[0\]: pc = 0x0, size = 8 bytes
+    STARTPC + CFA + FP + RA +
+#...
+    0+0004 +sp\+16 +u +u\[s\] +
+
+#pass

gas/testsuite/gas/cfi-sframe/cfi-sframe-aarch64-2.s

@@ -0,0 +1,18 @@
+## ARMv8.3 addded support a new security feature named Pointer Authentication. The
+## main idea behind this is to use the unused bits in the pointer values.
+## Each pointer is patched with a PAC before writing to memory, and is verified
+## before using it.
+## When the pointers are mangled, the unwinder needs to know so it can mask off
+## the PAC from the pointer value to recover the return address, and
+## conversely, skip doing so if the pointers are not mangled.
+##
+## .cfi_negate_ra_state CFI directive is used to convey this information.
+##
+## SFrame has support for this. This testcase ensures that the directive
+## is interpreted successfully.
+	.cfi_startproc
+	.long 0
+	.cfi_def_cfa_offset 16
+	.cfi_negate_ra_state
+	.long 0
+	.cfi_endproc

gas/testsuite/gas/cfi-sframe/cfi-sframe.exp

@@ -96,4 +96,5 @@ if { [istarget "x86_64-*-*"] && [gas_sframe_check] } then {
 # aarch64 specific tests
 if { [istarget "aarch64*-*-*"] && [gas_sframe_check] } then {
     run_dump_test "cfi-sframe-aarch64-1"
+    run_dump_test "cfi-sframe-aarch64-2"
 }