Re: [PATCH v2 01/21] Hexagon (target/hexagon) TCG generation cleanup

[Richard Henderson]

On 3/31/21 8:53 PM, Taylor Simpson wrote:
> Simplify TCG generation of hex_reg_written
>
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
> ---
>   target/hexagon/genptr.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
> index 7481f4c..87f5d92 100644
> --- a/target/hexagon/genptr.c
> +++ b/target/hexagon/genptr.c
> @@ -35,7 +35,6 @@ static inline TCGv gen_read_preg(TCGv pred, uint8_t num)
>   
>   static inline void gen_log_predicated_reg_write(int rnum, TCGv val, int slot)
>   {
> -    TCGv one = tcg_const_tl(1);
>       TCGv zero = tcg_const_tl(0);
>       TCGv slot_mask = tcg_temp_new();
>   
> @@ -43,12 +42,17 @@ static inline void gen_log_predicated_reg_write(int rnum, TCGv val, int slot)
>       tcg_gen_movcond_tl(TCG_COND_EQ, hex_new_value[rnum], slot_mask, zero,
>                              val, hex_new_value[rnum]);
>   #if HEX_DEBUG
> -    /* Do this so HELPER(debug_commit_end) will know */
> -    tcg_gen_movcond_tl(TCG_COND_EQ, hex_reg_written[rnum], slot_mask, zero,
> -                       one, hex_reg_written[rnum]);
> +    /*
> +     * Do this so HELPER(debug_commit_end) will know
> +     *
> +     * Note that slot_mask indicates the value is not written
> +     * (i.e., slot was cancelled), so we create a true/false value before
> +     * or'ing with hex_reg_written[rnum].
> +     */
> +    tcg_gen_setcond_tl(TCG_COND_EQ, slot_mask, slot_mask, zero);
> +    tcg_gen_or_tl(hex_reg_written[rnum], hex_reg_written[rnum], slot_mask);
>   #endif

Having looked forward at patch 5, it appears this could be further improved by 
examining ctx->regs_written.


r~