From: Richard Henderson <richard.henderson@linaro.org>
To: Song Gao <gaosong@loongson.cn>, qemu-devel@nongnu.org
Cc: c@jia.je, philmd@redhat.com, git@xen0n.name, maobibo@loongson.cn
Subject: Re: [PATCH] tcg: Fixes set const_args[i] wrong value when instructions imm is 0
Date: Thu, 1 Feb 2024 07:16:12 +1000 [thread overview]
Message-ID: <70186760-61be-4b44-8c0f-eb6acb4587f2@linaro.org> (raw)
In-Reply-To: <20240131072740.2569850-1-gaosong@loongson.cn>
On 1/31/24 17:27, Song Gao wrote:
> It seems that tcg_reg_alloc_op() set const_args[i] wrong value
> when instructions imm is 0. The LoongArch tcg_out_vec_op() cmp_vec
> use the wrong const_args[2].
> e.g
> The wrong const_args[2] is 0.
> IN: vslti.w v5, v4, 0x0 OUT: vslt.w v1, v1, v0
>
> The right const_args[2] is 1.
> IN: vslti.w v5, v4, 0x0 OUT: vslti.w v1, v1, 0x0
>
> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/2136
> Signed-off-by: Song Gao <gaosong@loongson.cn>
> ---
> tcg/tcg.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index e2c38f6d11..5b290123bc 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -4808,7 +4808,7 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op)
> arg_ct = &def->args_ct[i];
> ts = arg_temp(arg);
>
> - if (ts->val_type == TEMP_VAL_CONST
> + if ((ts->val_type == TEMP_VAL_CONST || ts->kind == TEMP_CONST)
> && tcg_target_const_match(ts->val, ts->type, arg_ct->ct, TCGOP_VECE(op))) {
> /* constant is OK for instruction */
> const_args[i] = 1;
This is wrong.
I strongly suspect that the TEMP_CONST value 0 has been loaded into a register for use in
another operation, and the register allocator sees that it is still there.
r~
next prev parent reply other threads:[~2024-01-31 21:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-31 7:27 [PATCH] tcg: Fixes set const_args[i] wrong value when instructions imm is 0 Song Gao
2024-01-31 21:16 ` Richard Henderson [this message]
2024-02-01 1:17 ` gaosong
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