[PATCH] Add Loongson2F specific NOP instruction

[Wu Zhangjin]

This is a patch to work around a possible cpu pipeline issue. Without this,
under extreme cases, cpu might deadlock.(e.g. some have seen this with binutils
2.18, ld dies when compiling)

The changed instruction has no real effect since it write to the 'zero'
register, but it read non-zero register which is the key to prevent issue. The
issue has been solved in latest processor batches.

2009-11-13  Wu Zhangjin  <wuzhangjin@gmail.com>

        * mips-opc.c (mips_builtin_opcodes): Add NOP instruction for
        Lemote Loongson 2F.

diff --git a/opcodes/mips-opc.c b/opcodes/mips-opc.c
index caeef72..8fab6ba 100644
--- a/opcodes/mips-opc.c
+++ b/opcodes/mips-opc.c
@@ -187,6 +187,7 @@ const struct mips_opcode mips_builtin_opcodes[] =
 /* name,    args,	match,	    mask,	pinfo,          	pinfo2,		membership */
 {"pref",    "k,o(b)",   0xcc000000, 0xfc000000, RD_b,           	0,		I4_32|G3	},
 {"prefx",   "h,t(b)",	0x4c00000f, 0xfc0007ff, RD_b|RD_t|FP_S,		0,		I4_33	},
+{"nop",     "",         0x00020021, 0xffffffff, 0,              	INSN2_ALIAS,	IL2F    }, /* addu zero,zero,v0 */
 {"nop",     "",         0x00000000, 0xffffffff, 0,              	INSN2_ALIAS,	I1      }, /* sll */
 {"ssnop",   "",         0x00000040, 0xffffffff, 0,              	INSN2_ALIAS,	I32|N55	}, /* sll */
 {"ehb",     "",         0x000000c0, 0xffffffff, 0,              	INSN2_ALIAS,	I33	}, /* sll */