Re: [Qemu-devel] [PATCH 1/2] target/mips: Fix decoding mechanism of R5900 MFLO1, MFHI1, MTLO1 and MTHI1

[Maciej W. Rozycki]

On Sun, 4 Nov 2018, Fredrik Noring wrote:

> It appears the correct function is tcg_gen_mov_tl because the TX79 manual
> says
> 
>       MFHI:  GPR[rd]63..0 <- HI63..0
>       MFLO:  GPR[rd]63..0 <- LO63..0
>       MTHI:  HI63..0 <- GPR[rs]63..0
>       MTLO:  LO63..0 <- GPR[rs]63..0
>       MFHI1: GPR[rd]63..0 <- HI127..64
>       MFLO1: GPR[rd]63..0 <- LO127..64
>       MTHI1: HI127..64 <- GPR[rs]63..0
>       MTLO1: LO127..64 <- GPR[rs]63..0
> 
> so the GPR is copied to/from in full in all cases. This is slightly
> different to how acc = 1 is handled in gen_HILO.

 However `gen_HILO' looks wrong to me as it'll truncate the values of 
$acc3-$acc1 with the 64-bit DSP ASE.

  Maciej