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From: Richard Henderson <richard.henderson@linaro.org>
To: "Alex Bennée" <alex.bennee@linaro.org>
Cc: qemu-devel@nongnu.org, david@redhat.com
Subject: Re: [PATCH v2 04/28] softfloat: Move minmax_flags to softfloat-parts.c.inc
Date: Wed, 2 Jun 2021 15:23:27 -0700	[thread overview]
Message-ID: <ed6ad6ba-838f-9b67-fd8b-81a6dad0351d@linaro.org> (raw)
In-Reply-To: <87wnrc9f3c.fsf@linaro.org>

On 6/2/21 1:36 PM, Alex Bennée wrote:
> 
> Richard Henderson <richard.henderson@linaro.org> writes:
> 
>> Rename to parts$N_minmax.  Combine 3 bool arguments to a bitmask,
>> return a tri-state value to indicate nan vs unchanged operand.
>> Introduce ftype_minmax functions as a common optimization point.
>> Fold bfloat16 expansions into the same macro as the other types.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
> <snip>
>> -        switch (a.cls) {
>> -        case float_class_normal:
>> -            a_exp = a.exp;
>> -            break;
>> -        case float_class_inf:
>> -            a_exp = INT_MAX;
>> -            break;
>> -        case float_class_zero:
>> -            a_exp = INT_MIN;
>> -            break;
>> -        default:
>> -            g_assert_not_reached();
>> -            break;
>> -        }
>> -        switch (b.cls) {
>> -        case float_class_normal:
>> -            b_exp = b.exp;
>> -            break;
>> -        case float_class_inf:
>> -            b_exp = INT_MAX;
>> -            break;
>> -        case float_class_zero:
>> -            b_exp = INT_MIN;
>> -            break;
>> -        default:
>> -            g_assert_not_reached();
>> -            break;
>> -        }
>> -
> <snip>
>> +    if (unlikely(ab_mask != float_cmask_normal)) {
>> +        switch (a->cls) {
>> +        case float_class_normal:
>> +            break;
>> +        case float_class_inf:
>> +            a_exp = INT16_MAX;
> 
> We've gone from min/max of our internal representation to INT16_MIN/MAX
> - I guess that doesn't break until we get to Float256 but why the change?

Ah, because I've changed from "bool a_less" to "int cmp".  I subtract the two 
exponents and I don't want that subtraction to overflow.


r~


  reply	other threads:[~2021-06-02 22:24 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 15:06 [PATCH v2 00/28] Convert floatx80 and float128 to FloatParts Richard Henderson
2021-05-25 15:06 ` [PATCH v2 01/28] softfloat: Move round_to_uint_and_pack to softfloat-parts.c.inc Richard Henderson
2021-06-02 11:12   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 02/28] softfloat: Move int_to_float " Richard Henderson
2021-05-26 13:34   ` David Hildenbrand
2021-06-02 11:14   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 03/28] softfloat: Move uint_to_float " Richard Henderson
2021-05-26 13:36   ` David Hildenbrand
2021-06-02 11:31   ` Alex Bennée
2021-06-02 16:28     ` Richard Henderson
2021-05-25 15:06 ` [PATCH v2 04/28] softfloat: Move minmax_flags " Richard Henderson
2021-05-26 13:45   ` David Hildenbrand
2021-06-02 20:36   ` Alex Bennée
2021-06-02 22:23     ` Richard Henderson [this message]
2021-06-02 22:29   ` Richard Henderson
2021-05-25 15:06 ` [PATCH v2 05/28] softfloat: Move compare_floats " Richard Henderson
2021-06-03  9:00   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 06/28] softfloat: Move scalbn_decomposed " Richard Henderson
2021-06-03  9:01   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 07/28] softfloat: Move sqrt_float " Richard Henderson
2021-06-03  9:17   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 08/28] softfloat: Split out parts_uncanon_normal Richard Henderson
2021-06-03  9:22   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 09/28] softfloat: Reduce FloatFmt Richard Henderson
2021-06-03  9:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 10/28] softfloat: Introduce Floatx80RoundPrec Richard Henderson
2021-06-03  9:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 11/28] softfloat: Adjust parts_uncanon_normal for floatx80 Richard Henderson
2021-06-03 11:58   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 12/28] tests/fp/fp-test: Reverse order of floatx80 precision tests Richard Henderson
2021-05-25 15:06 ` [PATCH v2 13/28] softfloat: Convert floatx80_add/sub to FloatParts Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 14/28] softfloat: Convert floatx80_mul " Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 15/28] softfloat: Convert floatx80_div " Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 16/28] softfloat: Convert floatx80_sqrt " Richard Henderson
2021-06-03 14:24   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 17/28] softfloat: Convert floatx80_round " Richard Henderson
2021-06-03 14:25   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 18/28] softfloat: Convert floatx80_round_to_int " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 19/28] softfloat: Convert integer to floatx80 " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 20/28] softfloat: Convert floatx80 float conversions " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 21/28] softfloat: Convert floatx80 to integer " Richard Henderson
2021-06-03 14:27   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 22/28] softfloat: Convert floatx80_scalbn " Richard Henderson
2021-06-03 14:34   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 23/28] softfloat: Convert floatx80 compare " Richard Henderson
2021-06-03 14:34   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 24/28] softfloat: Convert float32_exp2 " Richard Henderson
2021-06-03 14:44   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 25/28] softfloat: Move floatN_log2 to softfloat-parts.c.inc Richard Henderson
2021-06-02 15:28   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 26/28] softfloat: Convert modrem operations to FloatParts Richard Henderson
2021-06-03 14:48   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 27/28] tests/fp: Enable more tests Richard Henderson
2021-05-25 15:07 ` [PATCH v2 28/28] softfloat: Use hard-float for {u}int64_to_float{32, 64} Richard Henderson
2021-06-03 14:57   ` [PATCH v2 28/28] softfloat: Use hard-float for {u}int64_to_float{32,64} Alex Bennée
2021-05-25 16:51 ` [PATCH v2 00/28] Convert floatx80 and float128 to FloatParts no-reply

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