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From: Richard Sandiford <richard.sandiford@linaro.org>
To: Prakhar Bahuguna <prakhar.bahuguna@arm.com>
Cc: <gcc-patches@gcc.gnu.org>,  <nd@arm.com>
Subject: Re: [PATCH, GCC/ARM/gcc-7-branch] Backport PR71607
Date: Wed, 31 May 2017 13:20:00 -0000	[thread overview]
Message-ID: <87fuflmar4.fsf@linaro.org> (raw)
In-Reply-To: <20170531124844.y263emgdovlu7z2f@e107464-lin.cambridge.arm.com>	(Prakhar Bahuguna's message of "Wed, 31 May 2017 13:48:44 +0100")

Prakhar Bahuguna <prakhar.bahuguna@arm.com> writes:
> On 31/05/2017 09:19:40, Richard Sandiford wrote:
>> const_ints are supposed to be stored in sign-extended form, so a 32-bit
>> integer with the MSB set should be 0xffffffff80000000|x instead of
>> 0x80000000|x.  It's a bug if you have one where that isn't true.
>> 
>> In the patch it looks like this could come from:
>> ...these two splits, where the GEN_INTs should probably be:
>> 
>>   gen_int_mode (..., SImode);
>> 
>> instead.
>
> Hi Richard, thanks for the tip. Is there a test case that could produce an
> incorrect result? I've attempted to create one using negative doubles and
> floats but haven't succeeded.

Just to check, are you testing with --enable-checking=yes,rtl?

When the values you tried were split, did you get the sign-extended form
or the zero-extended form?

Thanks,
Richard

  reply	other threads:[~2017-05-31 13:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-25 14:02 Prakhar Bahuguna
2017-05-31  8:25 ` Richard Sandiford
2017-05-31 13:11   ` Prakhar Bahuguna
2017-05-31 13:20     ` Richard Sandiford [this message]
2017-05-31 15:40       ` Prakhar Bahuguna
2017-06-01  6:16         ` Richard Sandiford
2017-06-01 10:21           ` Prakhar Bahuguna

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