opcodes/aarch64: split off creation of comment text in disassembler

The function aarch64_print_operand (aarch64-opc.c) is responsible for
converting an instruction operand into the textual representation of
that operand.

In some cases, a comment is included in the operand representation,
though this (currently) only happens for the last operand of the
instruction.

In a future commit I would like to enable the new libopcodes styling
for AArch64, this will allow objdump and GDB[1] to syntax highlight
the disassembler output, however, having operands and comments
combined in a single string like this makes such styling harder.

In this commit, I propose to extend aarch64_print_operand to take a
second buffer.  Any comments for the instruction are written into this
extra buffer.  The two callers of aarch64_print_operand are then
updated to pass an extra buffer, and print any resulting comment.

In this commit no styling is added, that will come later.  However, I
have adjusted the output slightly.  Before this commit some comments
would be separated from the instruction operands with a tab character,
while in other cases the comment was separated with two single spaces.

After this commit I use a single tab character in all cases.  This
means a few test cases needed updated.  If people would prefer me to
move everyone to use the two spaces, then just let me know.  Or maybe
there was a good reason why we used a mix of styles, I could probably
figure out a way to maintain the old output exactly if that is
critical.

Other than that, there should be no user visible changes after this
commit.

[1] GDB patches have not been merged yet, but have been posted to the
GDB mailing list:
https://sourceware.org/pipermail/gdb-patches/2022-June/190142.html

1 files changed, 11 insertions, 1 deletions

diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index e9f7ee9..779db31 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -5358,6 +5358,7 @@ print_operands (char *buf, const aarch64_opcode *opcode,
   for (i = 0; i < AARCH64_MAX_OPND_NUM; ++i)
     {
       char str[128];
+      char cmt[128];
 
       /* We regard the opcode operand info more, however we also look into
 	 the inst->operands to support the disassembling of the optional
@@ -5370,7 +5371,7 @@ print_operands (char *buf, const aarch64_opcode *opcode,
 
       /* Generate the operand string in STR.  */
       aarch64_print_operand (str, sizeof (str), 0, opcode, opnds, i, NULL, NULL,
-			     NULL, cpu_variant);
+			     NULL, cmt, sizeof (cmt), cpu_variant);
 
       /* Delimiter.  */
       if (str[0] != '\0')
@@ -5378,6 +5379,15 @@ print_operands (char *buf, const aarch64_opcode *opcode,
 
       /* Append the operand string.  */
       strcat (buf, str);
+
+      /* Append a comment.  This works because only the last operand ever
+	 adds a comment.  If that ever changes then we'll need to be
+	 smarter here.  */
+      if (cmt[0] != '\0')
+	{
+	  strcat (buf, "\t// ");
+	  strcat (buf, cmt);
+	}
     }
 }