arm: Add cfi expression support for ra_auth_code

This patch extends assembler support for the use of register names to
allow for pseudo-registers, e.g. ra_auth_code register.
This is done particularly with CFI directives in mind, allowing for
expressions of the type:

    .cfi_register ra_auth_code, 12

gas/Changelog:

	* config/tc-arm.c (tc_arm_regname_to_dw2regnum): Add
	REG_TYPE_PSEUDO handling.
	* testsuite/gas/arm/cfi-pacbti-m-readelf.d: New.
	* testsuite/gas/arm/cfi-pacbti-m.s: New.

3 files changed, 57 insertions, 0 deletions

diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index f1dc4eb..6cdc2db 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -27958,6 +27958,10 @@ tc_arm_regname_to_dw2regnum (char *regname)
   if (reg != FAIL)
     return reg + 256;
 
+  reg = arm_reg_parse (&regname, REG_TYPE_PSEUDO);
+  if (reg != FAIL)
+    return reg;
+
   return FAIL;
 }
 
diff --git a/gas/testsuite/gas/arm/cfi-pacbti-m-readelf.d b/gas/testsuite/gas/arm/cfi-pacbti-m-readelf.d
new file mode 100644
index 0000000..997ea75
--- /dev/null
+++ b/gas/testsuite/gas/arm/cfi-pacbti-m-readelf.d
@@ -0,0 +1,31 @@
+#readelf: -wf
+#source: cfi-pacbti-m.s
+#name: Call Frame information for Armv8.1-M.Mainline PACBTI extension
+# This test is only valid on ELF based ports.
+#notarget: *-*-pe *-*-wince
+# VxWorks needs a special variant of this file.
+#skip: *-*-vxworks*
+
+Contents of the .eh_frame section:
+
+
+00000000 00000010 00000000 CIE
+  Version:               1
+  Augmentation:          "zR"
+  Code alignment factor: 2
+  Data alignment factor: -4
+  Return address column: 14
+  Augmentation data:     1b
+  DW_CFA_def_cfa: r13 ofs 0
+
+00000014 00000020 00000018 FDE cie=00000000 pc=00000000..0000000c
+  DW_CFA_advance_loc: 4 to 00000004
+  DW_CFA_register: r143 in r12
+  DW_CFA_advance_loc: 4 to 00000008
+  DW_CFA_def_cfa_offset: 8
+  DW_CFA_offset: r14 at cfa-8
+  DW_CFA_offset: r12 at cfa-4
+  DW_CFA_advance_loc: 4 to 0000000c
+  DW_CFA_restore_extended: r143
+  DW_CFA_restore: r14
+  DW_CFA_def_cfa_offset: 0
diff --git a/gas/testsuite/gas/arm/cfi-pacbti-m.s b/gas/testsuite/gas/arm/cfi-pacbti-m.s
new file mode 100644
index 0000000..515400d
--- /dev/null
+++ b/gas/testsuite/gas/arm/cfi-pacbti-m.s
@@ -0,0 +1,22 @@
+    .arch armv8.1-m.main
+    .arch_extension pacbti
+    .eabi_attribute Tag_PAC_extension, 2
+    .eabi_attribute Tag_BTI_extension, 2
+    .eabi_attribute Tag_BTI_use, 1
+    .eabi_attribute Tag_PACRET_use, 1
+    .syntax unified
+    .text
+    .thumb
+.Lstart:
+    .cfi_startproc
+    pacbti ip, lr, sp
+    .cfi_register ra_auth_code, ip
+    push {ip, lr}
+    .cfi_def_cfa_offset 8
+    .cfi_offset lr, -8
+    .cfi_offset ip, -4
+    pop {ip, lr}
+    .cfi_restore 143
+    .cfi_restore 14
+    .cfi_def_cfa_offset 0
+    .cfi_endproc