target-mips: Fix seg fault for LUI when MIPS_DEBUG_DISAS==1.

The call to gen_logic_imm for OPC_LUI passes -1 for rs.  This
causes the MIPS_DEBUG statement to seg fault due to the deference
of regnames[rs].  This patch fixes that.

Signed-off-by: Eric Johnson <ericj@mips.com>
---
 target-mips/translate.c |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

On Fri, Nov 09, 2012 at 07:40:51PM -0800, Eric Johnson wrote:
> The call to gen_logic_imm for OPC_LUI passes -1 for rs.  This
> causes the MIPS_DEBUG statement to seg fault due to the deference
> of regnames[rs].  This patch fixes that.
> 
> Signed-off-by: Eric Johnson <ericj@mips.com>
> ---
>  target-mips/translate.c |   18 +++++++++++-------
>  1 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/target-mips/translate.c b/target-mips/translate.c
> index 8175da0..aba6327 100644
> --- a/target-mips/translate.c
> +++ b/target-mips/translate.c
> @@ -2013,7 +2013,6 @@ static void gen_logic_imm(CPUMIPSState *env, DisasContext *ctx, uint32_t opc,
>                            int rt, int rs, int16_t imm)
>  {
>      target_ulong uimm;
> -    const char *opn = "imm logic";
>  
>      if (rt == 0) {
>          /* If no destination, treat it as a NOP. */
> @@ -2027,29 +2026,34 @@ static void gen_logic_imm(CPUMIPSState *env, DisasContext *ctx, uint32_t opc,
>              tcg_gen_andi_tl(cpu_gpr[rt], cpu_gpr[rs], uimm);
>          else
>              tcg_gen_movi_tl(cpu_gpr[rt], 0);
> -        opn = "andi";
> +        MIPS_DEBUG("%s %s, %s, " TARGET_FMT_lx, "andi", regnames[rt],
> +            regnames[rs], uimm);
>          break;
>      case OPC_ORI:
>          if (rs != 0)
>              tcg_gen_ori_tl(cpu_gpr[rt], cpu_gpr[rs], uimm);
>          else
>              tcg_gen_movi_tl(cpu_gpr[rt], uimm);
> -        opn = "ori";
> +        MIPS_DEBUG("%s %s, %s, " TARGET_FMT_lx, "ori", regnames[rt],
> +            regnames[rs], uimm);
>          break;
>      case OPC_XORI:
>          if (likely(rs != 0))
>              tcg_gen_xori_tl(cpu_gpr[rt], cpu_gpr[rs], uimm);
>          else
>              tcg_gen_movi_tl(cpu_gpr[rt], uimm);
> -        opn = "xori";
> +        MIPS_DEBUG("%s %s, %s, " TARGET_FMT_lx, "xori", regnames[rt],
> +            regnames[rs], uimm);
>          break;
>      case OPC_LUI:
>          tcg_gen_movi_tl(cpu_gpr[rt], imm << 16);
> -        opn = "lui";
> +        MIPS_DEBUG("lui %s, " TARGET_FMT_lx, regnames[rt], uimm);
> +        break;
> +
> +    default:
> +        MIPS_DEBUG("Unknown logical immediate opcode %08x", opc);
>          break;
>      }
> -    (void)opn; /* avoid a compiler warning */
> -    MIPS_DEBUG("%s %s, %s, " TARGET_FMT_lx, opn, regnames[rt], regnames[rs], uimm);
>  }
>  
>  /* Set on less than with immediate operand */

Thanks, I applied this patch, with minor tweak: instead of using printf
%s to format the opcode name, I moved it to the string like it was
%already the case for LUI.