[PATCHv2 1/2] opcodes: add new sub-mnemonic disassembler style

[Andrew Burgess <aburgess@redhat.com>]

When adding libopcodes disassembler styling support for AArch64, it
feels like the results would be improved by having a new sub-mnemonic
style.  This will be used in cases like:

  add    w16, w7, w1, uxtb #2
                      ^^^^----- Here

And:

  cinc   w0, w1, ne
                 ^^----- Here

This commit just adds the new style, and prepares objdump to handle
the style.  A later commit will add AArch64 styling, and will actually
make use of the style.

As this style is currently unused, there should be no user visible
changes after this commit.
---
 binutils/objdump.c | 2 ++
 include/dis-asm.h  | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/binutils/objdump.c b/binutils/objdump.c
index 67824053527..4076587151c 100644
--- a/binutils/objdump.c
+++ b/binutils/objdump.c
@@ -2167,6 +2167,7 @@ objdump_color_for_disassembler_style (enum disassembler_style style)
 	{
 	case dis_style_symbol: color = 32; break;
         case dis_style_assembler_directive:
+	case dis_style_sub_mnemonic:
 	case dis_style_mnemonic: color = 33; break;
 	case dis_style_register: color = 34; break;
 	case dis_style_address:
@@ -2185,6 +2186,7 @@ objdump_color_for_disassembler_style (enum disassembler_style style)
 	{
 	case dis_style_symbol: color = 40; break;
         case dis_style_assembler_directive:
+	case dis_style_sub_mnemonic:
 	case dis_style_mnemonic: color = 142; break;
 	case dis_style_register: color = 27; break;
 	case dis_style_address:
diff --git a/include/dis-asm.h b/include/dis-asm.h
index 4f91df12498..f1a83dc84e5 100644
--- a/include/dis-asm.h
+++ b/include/dis-asm.h
@@ -62,6 +62,13 @@ enum disassembler_style
      instructions.  */
   dis_style_mnemonic,
 
+  /* Some architectures include additional mnemonic like fields within the
+     instruction operands, e.g. on aarch64 'add w16, w7, w1, lsl #2' where
+     the 'lsl' is an additional piece of text that describes how the
+     instruction should behave.  This sub-mnemonic style can be used for
+     these pieces of text.  */
+  dis_style_sub_mnemonic,
+
   /* For things that aren't real machine instructions, but rather
      assembler directives, e.g. .byte, etc.  */
   dis_style_assembler_directive,
-- 
2.25.4