From: Richard Henderson <richard.henderson@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>,
Gavin Shan <gshan@redhat.com>,
qemu-devel@nongnu.org
Cc: thuth@redhat.com, qemu-arm@nongnu.org, philmd@redhat.com,
laurent@vivier.eu, shan.gavin@gmail.com
Subject: Re: [PATCH] configure: Improve alias attribute check
Date: Sat, 20 Mar 2021 16:33:55 -0600 [thread overview]
Message-ID: <107a73a0-aafe-bfce-7c28-8ed5fe6c022f@linaro.org> (raw)
In-Reply-To: <5a6e5d96-7b23-7a56-3096-fb80155cac26@redhat.com>
On 3/20/21 11:52 AM, Paolo Bonzini wrote:
>> +int main(void)
>> +{
>> + return read_y();
>> +}
>
> I think this should be "read_y() == 1 ? 0 : 1".
As a testcase returning 0 on success, yes.
> I can reproduce it with -flto -O2 but not without -flto, do you agree?
Agreed. Replicated with a random recent gcc 11 snapshot.
This is really annoying of lto. It's clear something needs to change though.
> Perhaps we can obtain the same optimization by wrapping reads of the page size
> in an inline __attribute__((const)) function. Richard, what do you think?
I'll give it a shot and see what happens.
r~
next prev parent reply other threads:[~2021-03-20 22:34 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-20 4:27 [PATCH] configure: Improve alias attribute check Gavin Shan
2021-03-20 4:48 ` Thomas Huth
2021-03-20 23:32 ` Gavin Shan
2021-03-20 17:52 ` Paolo Bonzini
2021-03-20 22:33 ` Richard Henderson [this message]
2021-03-20 23:36 ` Gavin Shan
2021-03-21 15:49 ` Richard Henderson
2021-03-21 16:50 ` Paolo Bonzini
2021-03-21 17:34 ` Richard Henderson
2021-03-21 17:43 ` Paolo Bonzini
2021-03-21 17:46 ` Paolo Bonzini
2021-03-21 18:23 ` Richard Henderson
2021-03-22 10:54 ` Gavin Shan
2021-03-22 20:59 ` Richard Henderson
2021-03-23 3:13 ` Gavin Shan
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