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Re: [PATCH] Use HOST_WIDE_INTs in gcd and least_common_multiple.

From: Jay Foad <jay dot foad at gmail dot com>
To: "Joseph S. Myers" <joseph at codesourcery dot com>
Cc: Sebastian Pop <sebpop at gmail dot com>, gcc-patches at gcc dot gnu dot org
Date: Mon, 31 Jan 2011 14:22:20 +0000
Subject: Re: [PATCH] Use HOST_WIDE_INTs in gcd and least_common_multiple.
References: <Pine.LNX.4.64.1101252304070.1203@digraph.polyomino.org.uk> <1296235481-4039-1-git-send-email-sebpop@gmail.com> <AANLkTikkY1pKx=v+EeR2Ti=Tz_3P10L9YiWt6xE+_k1f@mail.gmail.com> <Pine.LNX.4.64.1101311410050.2150@digraph.polyomino.org.uk>

>> How about:
>>
>> HOST_WIDE_INT
>> mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y)
>> {
>> Â HOST_WIDE_INT r = x * y;
>
> At this point, undefined behavior may have occurred.

Well, then:

HOST_WIDE_INT r = (unsigned HOST_WIDE_INT) x * (unsigned HOST_WIDE_INT) y;

Jay.

References:
- Re: [PATCH 5/5] Remove the lambda framework and make -ftree-loop-linear an alias of -floop-interchange.
  - From: Joseph S. Myers
- [PATCH] Use HOST_WIDE_INTs in gcd and least_common_multiple.
  - From: Sebastian Pop
- Re: [PATCH] Use HOST_WIDE_INTs in gcd and least_common_multiple.
  - From: Jay Foad
- Re: [PATCH] Use HOST_WIDE_INTs in gcd and least_common_multiple.
  - From: Joseph S. Myers

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