On Fri, Oct 21, 2022 at 9:47 AM Richard Henderson
<richard.hender...@linaro.org> wrote:
>
> There was a typo using opc_addi instead of opc_add with the
> two registers. While we're at it, simplify the gating test
> to al == bl to improve dynamic scheduling even when the
> output register does not overlap the inputs.
>
> Reported-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
Thanks!
Applied to riscv-to-apply.next
Alistair
> ---
> Supersedes: 20221020104154.4276-4-zhiwei_...@linux.alibaba.com
> ("[RFC PATCH 3/3] tcg/riscv: Remove a wrong optimization for addsub2")
> ---
> tcg/riscv/tcg-target.c.inc | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
> index 81a83e45b1..1cdaf7b57b 100644
> --- a/tcg/riscv/tcg-target.c.inc
> +++ b/tcg/riscv/tcg-target.c.inc
> @@ -687,9 +687,15 @@ static void tcg_out_addsub2(TCGContext *s,
> if (cbl) {
> tcg_out_opc_imm(s, opc_addi, rl, al, bl);
> tcg_out_opc_imm(s, OPC_SLTIU, TCG_REG_TMP0, rl, bl);
> - } else if (rl == al && rl == bl) {
> + } else if (al == bl) {
> + /*
> + * If the input regs overlap, this is a simple doubling
> + * and carry-out is the input msb. This special case is
> + * required when the output reg overlaps the input,
> + * but we might as well use it always.
> + */
> tcg_out_opc_imm(s, OPC_SLTI, TCG_REG_TMP0, al, 0);
> - tcg_out_opc_reg(s, opc_addi, rl, al, bl);
> + tcg_out_opc_reg(s, opc_add, rl, al, al);
> } else {
> tcg_out_opc_reg(s, opc_add, rl, al, bl);
> tcg_out_opc_reg(s, OPC_SLTU, TCG_REG_TMP0,
> --
> 2.34.1
>
>
