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 14/22] target/loongarch: Add floating point comparison instruction translation
Date: Tue, 27 Jul 2021 15:56:38 +0800 [thread overview]
Message-ID: <228df9da-22ef-267d-121e-b05b506879e1@loongson.cn> (raw)
In-Reply-To: <e0a368a3-3f43-f5b9-b36b-7f9919148b77@linaro.org>
Hi, Richard.
On 07/23/2021 02:11 PM, Richard Henderson wrote:
> On 7/20/21 11:53 PM, Song Gao wrote:
>> +void helper_movreg2cf_i32(CPULoongArchState *env, uint32_t cd, uint32_t src)
>> +{
>> + env->active_fpu.cf[cd & 0x7] = src & 0x1;
>> +}
>> +
>> +void helper_movreg2cf_i64(CPULoongArchState *env, uint32_t cd, uint64_t src)
>> +{
>> + env->active_fpu.cf[cd & 0x7] = src & 0x1;
>> +}
>> +
>> +/* fcmp.cond.s */
>> +uint32_t helper_fp_cmp_caf_s(CPULoongArchState *env, uint32_t fp,
>> + uint32_t fp1)
>> +{
>> + uint64_t ret;
>> + ret = (float32_unordered_quiet(fp1, fp, &env->active_fpu.fp_status), 0);
>> + update_fcsr0(env, GETPC());
>> + if (ret) {
>> + return -1;
>> + } else {
>> + return 0;
>> + }
>> +}
>
> I don't understand why you have split the compare from the store to cf?
>
> I don't understand why you're returning -1 instead of 1, when the result is supposed to be a boolean.
>
> Alternately, I don't understand why you want a helper function to perform a simple byte store operation. You could easily store a byte with tcg_gen_st8_{i32,i64}.
>
Hmm, this part is seem too bad.
>> +uint32_t helper_fp_cmp_cueq_s(CPULoongArchState *env, uint32_t fp,
>> + uint32_t fp1)
>> +{
>> + uint64_t ret;
>> + ret = float32_unordered_quiet(fp1, fp, &env->active_fpu.fp_status) ||
>> + float32_eq_quiet(fp, fp1, &env->active_fpu.fp_status);
>
> You're better off using
>
> FloatRelation cmp = float32_compare_quiet(fp0, fp1, status);
> update_fcsr0(env, GETPC();
> return cmp == float_relation_unordered ||
> cmp == float_relation_equal;
>
> Similarly with every other place you use two comparisons.
>
> Indeed, one could conceivably condense everything into exactly four helper functions: two using float{32,64}_compare_quiet and two using float{32,64}_compare (signalling). A 4th argument would be a bitmask of the different true conditions, exactly as listed in Table 9.
>
> Since FloatRelation is in {-1, 0, 1, 2}, one could write
>
> return (mask >> (cmp + 1)) & 1;
>
This is a good idea!
Thanks
Song Gao.
next prev parent reply other threads:[~2021-07-27 7:57 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
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 [this message]
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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