From: Christoph Müllner <christoph.muellner@vrull.eu>
Date: Wed, 20 Jul 2022 22:26:29 +0000 (+0200)
Subject: RISC-V: Add support for literal instruction arguments
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=25236d63fdb138e24cb34aa6c513ae8de2dac7b8;p=binutils-gdb.git

RISC-V: Add support for literal instruction arguments

This patch introduces support for arbitrary literal instruction
arguments, that are not encoded in the opcode.

A typical use case for this feature would be an instruction that
applies an implicit shift by a constant value on an immediate
(that is a real operand). With this patch it is possible to make
this shift visible in the dissasembly and support such artificial
parameter as part of the asssembly code.

Co-developed-by: Lifang Xia <lifang_xia@linux.alibaba.com>
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
---

diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 00e4635de6e..d9f63b11398 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -1279,6 +1279,9 @@ validate_riscv_insn (const struct riscv_opcode *opc, int length)
 
 	    switch (*++oparg)
 	      {
+		case 'l': /* Literal.  */
+		  oparg += strcspn(oparg, ",") - 1;
+		  break;
 		case 's': /* 'XsN@S' ... N-bit signed immediate at bit S.  */
 		  goto use_imm;
 		case 'u': /* 'XuN@S' ... N-bit unsigned immediate at bit S.  */
@@ -3310,6 +3313,13 @@ riscv_ip (char *str, struct riscv_cl_insn *ip, expressionS *imm_expr,
 
 		switch (*++oparg)
 		  {
+		    case 'l': /* Literal.  */
+		      n = strcspn (++oparg, ",");
+		      if (strncmp (oparg, asarg, n))
+			as_bad (_("unexpected literal (%s)"), asarg);
+		      oparg += n - 1;
+		      asarg += n;
+		      continue;
 		    case 's': /* 'XsN@S' ... N-bit signed immediate at bit S.  */
 		      sign = true;
 		      goto parse_imm;
diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index 2594e818254..f2d399260c1 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -570,6 +570,15 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
 
 	    switch (*++oparg)
 	      {
+		case 'l': /* Literal.  */
+		  oparg++;
+		  while (*oparg && *oparg != ',')
+		    {
+		      print (info->stream, dis_style_text, "%c", *oparg);
+		      oparg++;
+		    }
+		  oparg--;
+		  break;
 		case 's': /* 'XsN@S' ... N-bit signed immediate at bit S.  */
 		  sign = true;
 		  goto print_imm;