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Date: Tue, 12 Sep 2017 17:14:29 +0300
From: Sergey Smolov <smolov@ispras.ru>
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Subject: [Qemu-devel] MIPS 'move' insn emulation
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To: QEMU Developers <qemu-devel@nongnu.org>

Hello, List!

I run MIPS assembler program on QEMU. The program is just a sample, here 
is the code:

.text
     addiu $8, $zero, 0x7
     move $9, $8
     sll $8, $8, 3
     add $8, $8, $9

The program finishes on QEMU with the following values for registers, 
and it's ok:

$8 - 0x3f
$9 - 0x7

Now I want to implement some logging features for MIPS assembler 
programs. For example, I want to write a record to log every time the 
'move' instruction writes some value to GPR register.

I've the code I probably need to modify in target/mips/translate.c:

[code]

static void gen_logic(DisasContext *ctx, uint32_t opc,
                       int rd, int rs, int rt)
{
...
} else if (rs != 0 && rt == 0) {
             tcg_gen_mov_tl(cpu_gpr[rd], cpu_gpr[rs]);
}

[/code]

I suppose that for my assembler program cpu_gpr[rs] here should contain 
0x7 value at runtime. Is it possible to extract this value somehow? I've 
tried the following constructions:

GET_TCG_I32(cpu_gpr[rs])
((CPUMIPSState *)tcg_ctx.cpu)->active_tc.gpr[rs]

but they do not provide me the correct value. Could you help me in 
solving this problem?

Thanks in advance,
  Sergey Smolov