Re: [Qemu-devel] [PATCH 8/8] tcg/optimize: Add more identity simplifications

[Aurelien Jarno]

On Fri, Jan 31, 2014 at 08:47:03AM -0600, Richard Henderson wrote:
> Recognize 0 operand to andc, and -1 operands to and, orc, eqv.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  tcg/optimize.c | 39 ++++++++++++++++++++++++---------------
>  1 file changed, 24 insertions(+), 15 deletions(-)
> 
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index a703f8c..8d7100e 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -716,7 +716,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, 
> uint16_t *tcg_opc_ptr,
>              break;
>          }
>  
> -        /* Simplify expression for "op r, a, 0 => mov r, a" cases */
> +        /* Simplify expression for "op r, a, const => mov r, a" cases */
>          switch (op) {
>          CASE_OP_32_64(add):
>          CASE_OP_32_64(sub):
> @@ -727,23 +727,32 @@ static TCGArg *tcg_constant_folding(TCGContext *s, 
> uint16_t *tcg_opc_ptr,
>          CASE_OP_32_64(rotr):
>          CASE_OP_32_64(or):
>          CASE_OP_32_64(xor):
> -            if (temps[args[1]].state == TCG_TEMP_CONST) {
> -                /* Proceed with possible constant folding. */
> -                break;
> -            }
> -            if (temps[args[2]].state == TCG_TEMP_CONST
> +        CASE_OP_32_64(andc):
> +            if (temps[args[1]].state != TCG_TEMP_CONST
> +                && temps[args[2]].state == TCG_TEMP_CONST
>                  && temps[args[2]].val == 0) {
> -                if (temps_are_copies(args[0], args[1])) {
> -                    s->gen_opc_buf[op_index] = INDEX_op_nop;
> -                } else {
> -                    s->gen_opc_buf[op_index] = op_to_mov(op);
> -                    tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
> -                    gen_args += 2;
> -                }
> -                args += 3;
> -                continue;
> +                goto do_mov3;
>              }
>              break;
> +        CASE_OP_32_64(and):
> +        CASE_OP_32_64(orc):
> +        CASE_OP_32_64(eqv):
> +            if (temps[args[1]].state != TCG_TEMP_CONST
> +                && temps[args[2]].state == TCG_TEMP_CONST
> +                && temps[args[2]].val == -1) {
> +                goto do_mov3;
> +            }
> +            break;
> +        do_mov3:
> +            if (temps_are_copies(args[0], args[1])) {
> +                s->gen_opc_buf[op_index] = INDEX_op_nop;
> +            } else {
> +                s->gen_opc_buf[op_index] = op_to_mov(op);
> +                tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
> +                gen_args += 2;
> +            }
> +            args += 3;
> +            continue;
>          default:
>              break;
>          }

Reviewed-by: Aurelien Jarno <address@hidden>

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net