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Date: Thu, 25 Feb 2021 14:19:13 +0000
From: Jonathan Wakely <jwakely@redhat.com>
To: cassio.neri@gmail.com
Cc: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 1/4] libstdc++: More efficient date from days.
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On 25/02/21 14:02 +0000, Jonathan Wakely wrote:
>On 25/02/21 13:46 +0000, Cassio Neri via Libstdc++ wrote:
>>Hi Jonathan,
>>
>>The issue is that I didn't cast __dp.count() to uint32_t:
>>
>>-      const auto __r0 = __dp.count() + __r2_e3;
>>+      const auto __r0 = static_cast<uint32_t>(__dp.count()) + __r2_e3;
>>
>>The above would be a better fix. Indeed, __r0 belongs to [0, 2^32[ which allows
>>all arithmetics that follow to be performed on uint32_t values. For performance
>>this is better than using signed integers.
>
>OK, I'll make that change shortly, thanks.

We still need to cast to int for the return value though, because
converting from uint32_t to int is still narrowing.