Re: [Qemu-devel] [RFC PATCH 2/6] target/ppc: introduce get_avr64() and set_avr64() helpers for VMX register access

[Richard Henderson <richard.henderson@linaro.org>]

On 12/7/18 2:56 AM, Mark Cave-Ayland wrote:
> +    avr = tcg_temp_new_i64();                                                 \
>      EA = tcg_temp_new();                                                      \
>      gen_addr_reg_index(ctx, EA);                                              \
>      tcg_gen_andi_tl(EA, EA, ~0xf);                                            \
>      /* We only need to swap high and low halves. gen_qemu_ld64_i64 does       \
>         necessary 64-bit byteswap already. */                                  \
>      if (ctx->le_mode) {                                                       \
> -        gen_qemu_ld64_i64(ctx, cpu_avrl[rD(ctx->opcode)], EA);                \
> +        gen_qemu_ld64_i64(ctx, avr, EA);                                      \
> +        set_avr64(rD(ctx->opcode), avr, false);                               \
>          tcg_gen_addi_tl(EA, EA, 8);                                           \
> -        gen_qemu_ld64_i64(ctx, cpu_avrh[rD(ctx->opcode)], EA);                \
> +        gen_qemu_ld64_i64(ctx, avr, EA);                                      \
> +        set_avr64(rD(ctx->opcode), avr, true);  

An accurate conversion, but I'm going to call this an existing bug:

The writeback to both avr{l,h} should be delayed until all exceptions have been
raised.  Thus you should perform the two gen_qemu_ld64_i64 into two temporaries
and only then write them both back via set_avr64.

Otherwise,
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~