From: Peter Maydell <peter.maydell@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
"Emilio G . Cota" <cota@braap.org>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"QEMU Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH v4 6/6] qht: Fix threshold rate calculation
Date: Fri, 19 Jun 2020 18:31:03 +0100 [thread overview]
Message-ID: <CAFEAcA9rtVzZ8VQNQdEquZzHPrU-BugZdaEDYAy32sC97RJdGA@mail.gmail.com> (raw)
In-Reply-To: <c5a6e38c-0365-a695-8bbb-c61b381c668e@linaro.org>
On Wed, 17 Jun 2020 at 21:59, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 6/17/20 1:13 PM, Richard Henderson wrote:
> > - *threshold = rate * UINT64_MAX;
> > + *threshold = (rate * 0xffff000000000000ull)
> > + + (rate * 0x0000ffffffffffffull);
>
> Well, while this does silence the warning, it produces the exact same results
> as before, since the intermediate double result still only has 53 bits of
> precision.
>
> We're probably be better off with the nextafter(0x1p64, 0.0) form that we've
> used elsewhere.
Yeah, the code does look a bit odd. I'm going to apply this one to master
as well just to suppress all the patchew nagmails, but we should
figure out the correct thing to do here.
thanks
-- PMM
next prev parent reply other threads:[~2020-06-19 17:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 20:13 [PATCH v4 0/6] Vs clang-10 and gcc-9 warnings Richard Henderson
2020-06-17 20:13 ` [PATCH v4 1/6] fpu/softfloat: Silence 'bitwise negation of boolean expression' warning Richard Henderson
2020-06-17 20:13 ` [PATCH v4 2/6] migration: fix xbzrle encoding rate calculation Richard Henderson
2020-06-17 20:13 ` [PATCH v4 3/6] configure: Clean up warning flag lists Richard Henderson
2020-06-17 20:13 ` [PATCH v4 4/6] configure: Disable -Wtautological-type-limit-compare Richard Henderson
2020-06-17 20:13 ` [PATCH v4 5/6] configure: Add -Wno-psabi Richard Henderson
2020-06-17 20:13 ` [PATCH v4 6/6] qht: Fix threshold rate calculation Richard Henderson
2020-06-17 20:58 ` Richard Henderson
2020-06-19 17:31 ` Peter Maydell [this message]
2020-06-18 10:22 ` [PATCH v4 0/6] Vs clang-10 and gcc-9 warnings Peter Maydell
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