From: Song Gao <gaosong@loongson.cn>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: peter.maydell@linaro.org, thuth@redhat.com, chenhuacai@gmail.com,
philmd@redhat.com, yangxiaojuan@loongson.cn,
qemu-devel@nongnu.org, maobibo@loongson.cn, laurent@vivier.eu,
alistair.francis@wdc.com, pbonzini@redhat.com,
alex.bennee@linaro.org
Subject: Re: [PATCH v2 13/22] target/loongarch: Add floating point arithmetic instruction translation
Date: Wed, 28 Jul 2021 09:18:26 +0800 [thread overview]
Message-ID: <8a5ea059-6ed2-8303-2fa0-a056241edf80@loongson.cn> (raw)
In-Reply-To: <179b2d4e-7b0d-43ba-9f35-84ac728029f1@linaro.org>
Hi, Richard.
On 07/28/2021 12:12 AM, Richard Henderson wrote:
> On 7/26/21 9:17 PM, Song Gao wrote:
>>> I think this should be as simple as
>>>
>>> gen_helper_fp_add_s(cpu_fpu[a->fd], cpu_env,
>>> cpu_fpu[a->fj], cpu_fpu[a->fk]);
>>>
>>> I also think that loongarch should learn from risc-v and change the architecture to "nan-box" single-precision results -- fill the high 32-bits with 1s. This is an SNaN representation for double-precision and will immediately fail when incorrectly using a single-precision value as a double-precision input.
>>>
>>> Thankfully the current architecture is backward compatible with nan-boxing.
>>>
>>
>> by this method, the trans_fadd_s is
>>
>> static bool trans_fadd_s(DisasContext *ctx, arg_fadd_s * a)
>> {
>> TCGv_i64 fp0, fp1;
>>
>> fp0 = tcg_temp_new_i64();
>> fp1 = tcg_temp_new_i64();
>>
>> check_fpu_enabled(ctx);
>> gen_load_fpr64(fp0, a->fj);
>> gen_load_fpr64(fp1, a->fk);
>> gen_helper_fp_add_s(fp0, cpu_env, fp0, fp1);
>>
>> gen_check_nanbox_s(fp0, fp0); /* from riscv */
>>
>> gen_store_fpr64(fp0, a->fd);
>>
>> tcg_temp_free_i64(fp0);
>> tcg_temp_free_i64(fp1);
>>
>> return true;
>> }
>
> A few points here:
>
> (1) You do not need gen_load_fpr64 and gen_store_fpr64 at all.
> These were from mips to deal with the varying fpu sizes.
>
> (2) If we need to call a helper, then the helper as much of
> the work a possible. Therefore the nanboxing should be
> done there. See riscv/fpu_helper.c, and the use of
> nanbox_s within that file.
>
> (3) Again, use a helper function:
>
> static bool gen_binary_fp(DisasContext *ctx, arg_fmt_fdfjfk *a,
> void (*func)(TCGv_i64, TCGv_env,
> TCGv_i64, TCGv_i64))
> {
> if (check_fpu_enabled(ctx)) {
> func(cpu_fpr[a->fd], cpu_env,
> cpu_fpr[a->fj], cpu_fpr[a->fk]);
> }
> return true;
> }
>
> TRANS(fadd_s, gen_binary_fp, gen_helper_fp_add_s)
> TRANS(fadd_d, gen_binary_fp, gen_helper_fp_add_d)
>
>> uint64_t helper_fp_add_s(CPULoongArchState *env, uint64_t fp, uint64_t fp1)
>> {
>> uint32_t fp2;
>>
>> fp2 = float32_add((uint32_t)fp, (uint32_t)fp1, &env->active_fpu.fp_status);
>> update_fcsr0(env, GETPC());
>> return (uint64_t)fp2;
>> }
>
> with return nanbox_s(fp2);
>
OK.
Again, thank you kindly help.
Thanks
Song Gao.
>
> r~
next prev parent reply other threads:[~2021-07-28 1:19 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 9:52 [PATCH v2 00/22] Add LoongArch linux-user emulation support Song Gao
2021-07-21 9:52 ` [PATCH v2 01/22] target/loongarch: Add README Song Gao
2021-07-21 9:52 ` [PATCH v2 02/22] target/loongarch: Add CSR registers definition Song Gao
2021-07-21 9:52 ` [PATCH v2 03/22] target/loongarch: Add core definition Song Gao
2021-07-22 22:43 ` Richard Henderson
2021-07-26 8:47 ` Song Gao
2021-07-26 15:32 ` Richard Henderson
2021-07-21 9:53 ` [PATCH v2 04/22] target/loongarch: Add interrupt handling support Song Gao
2021-07-22 22:47 ` Richard Henderson
2021-07-26 9:23 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 05/22] target/loongarch: Add memory management support Song Gao
2021-07-22 22:48 ` Richard Henderson
2021-07-26 9:25 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 06/22] target/loongarch: Add main translation routines Song Gao
2021-07-22 23:50 ` Richard Henderson
2021-07-26 9:39 ` Song Gao
2021-07-26 15:35 ` Richard Henderson
2021-07-21 9:53 ` [PATCH v2 07/22] target/loongarch: Add fixed point arithmetic instruction translation Song Gao
2021-07-21 17:38 ` Philippe Mathieu-Daudé
2021-07-21 17:49 ` Philippe Mathieu-Daudé
2021-07-22 7:41 ` Song Gao
2021-07-23 0:46 ` Richard Henderson
2021-07-26 11:56 ` Song Gao
2021-07-26 15:53 ` Richard Henderson
2021-07-27 1:51 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 08/22] target/loongarch: Add fixed point shift " Song Gao
2021-07-23 0:51 ` Richard Henderson
2021-07-26 11:57 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 09/22] target/loongarch: Add fixed point bit " Song Gao
2021-07-21 17:46 ` Philippe Mathieu-Daudé
2021-07-22 8:17 ` Song Gao
2021-07-23 1:29 ` Richard Henderson
2021-07-26 12:22 ` Song Gao
2021-07-26 16:39 ` Richard Henderson
2021-07-21 9:53 ` [PATCH v2 10/22] target/loongarch: Add fixed point load/store " Song Gao
2021-07-23 1:45 ` Richard Henderson
2021-07-26 12:25 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 11/22] target/loongarch: Add fixed point atomic " Song Gao
2021-07-23 1:49 ` Richard Henderson
2021-07-26 12:25 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 12/22] target/loongarch: Add fixed point extra " Song Gao
2021-07-23 5:12 ` Richard Henderson
2021-07-26 12:57 ` Song Gao
2021-07-26 16:42 ` Richard Henderson
2021-07-27 1:46 ` Song Gao
2021-08-04 7:40 ` Song Gao
2021-08-04 7:51 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 13/22] target/loongarch: Add floating point arithmetic " Song Gao
2021-07-23 5:44 ` Richard Henderson
2021-07-27 7:17 ` Song Gao
2021-07-27 16:12 ` Richard Henderson
2021-07-28 1:18 ` Song Gao [this message]
2021-07-21 9:53 ` [PATCH v2 14/22] target/loongarch: Add floating point comparison " Song Gao
2021-07-23 6:11 ` Richard Henderson
2021-07-27 7:56 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 15/22] target/loongarch: Add floating point conversion " Song Gao
2021-07-23 6:16 ` Richard Henderson
2021-07-27 7:57 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 16/22] target/loongarch: Add floating point move " Song Gao
2021-07-23 6:29 ` Richard Henderson
2021-07-27 8:06 ` Song Gao
2021-08-12 9:20 ` Song Gao
2021-08-12 19:31 ` Richard Henderson
2021-07-21 9:53 ` [PATCH v2 17/22] target/loongarch: Add floating point load/store " Song Gao
2021-07-23 6:34 ` Richard Henderson
2021-07-27 8:07 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 18/22] target/loongarch: Add branch " Song Gao
2021-07-23 6:38 ` Richard Henderson
2021-07-27 8:07 ` Song Gao
2021-07-21 9:53 ` [PATCH v2 19/22] target/loongarch: Add disassembler Song Gao
2021-07-23 6:40 ` Richard Henderson
2021-08-12 10:33 ` Philippe Mathieu-Daudé
2021-07-21 9:53 ` [PATCH v2 20/22] LoongArch Linux User Emulation Song Gao
2021-07-21 9:53 ` [PATCH v2 21/22] configs: Add loongarch linux-user config Song Gao
2021-07-23 6:43 ` Richard Henderson
2021-07-21 9:53 ` [PATCH v2 22/22] target/loongarch: Add target build suport Song Gao
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