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Re: wide-int, ada

From: Kenneth Zadeck <zadeck at naturalbridge dot com>
To: Richard Biener <richard dot guenther at gmail dot com>, "H.J. Lu" <hjl dot tools at gmail dot com>
Cc: Andrew Pinski <pinskia at gmail dot com>, Richard Earnshaw <rearnsha at arm dot com>, Eric Botcazou <ebotcazou at adacore dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Mike Stump <mikestump at comcast dot net>
Date: Tue, 26 Nov 2013 10:38:12 -0500
Subject: Re: wide-int, ada
Authentication-results: sourceware.org; auth=none
References: <0075C6DB-B432-4E6F-8A48-3AE0C4D842FE at comcast dot net> <1464599 dot QpNUskFgRu at polaris> <5293FE59 dot 6090801 at naturalbridge dot com> <14902105 dot e0dHrA5yuq at polaris> <5294A5AF dot 4080803 at arm dot com> <CAFiYyc0hWZh+9xZd7po=KdhLm2a=jtqfHDnrdPJoqE9+cBmGkQ at mail dot gmail dot com> <CAMe9rOqhkzwRaLTtH2+oxKUEoNJ+1B2pRrwgUJ39LM=vQ1hP+g at mail dot gmail dot com> <AD249CE6-A0C0-484D-B796-14129FC9C5B2 at gmail dot com> <CAMe9rOr_vOcRWuh4c0kfv0egNzv1GBdGqfV+ytwBA0Uw78CYMQ at mail dot gmail dot com> <CAFiYyc3qEvPGiZMDEaXfY0YMo=N_cxo8OGb4Hqz5xWdOepHdhA at mail dot gmail dot com>


On 11/26/2013 09:16 AM, Richard Biener wrote:

On Tue, Nov 26, 2013 at 3:15 PM, H.J. Lu <hjl.tools@gmail.com> wrote:

On Tue, Nov 26, 2013 at 6:03 AM,  <pinskia@gmail.com> wrote:

On Nov 26, 2013, at 6:00 AM, "H.J. Lu" <hjl.tools@gmail.com> wrote:

On Tue, Nov 26, 2013 at 5:55 AM, Richard Biener
<richard.guenther@gmail.com> wrote:

On Tue, Nov 26, 2013 at 2:44 PM, Richard Earnshaw <rearnsha@arm.com> wrote:

On 26/11/13 09:18, Eric Botcazou wrote:

you are correct - this was an incorrect change.   I believe that the
patch below would be correct, but it is impossible to test it because (i
believe) that gcc no longer works if the host_bits_per_wide_int is 32.
I could be wrong about this but if i am correct, what do you want me to do?

While you're right that most mainstream architectures now require a 64-bit
HWI, not all of them do according to config.gcc, so I don't think that this
path is entirely dead yet.  I'll carry out the testing once we agree on the
final change.

I'm hoping, once this patch series is in that we might be able to
migrate the ARM port back to supporting a 32-bit HWI.  The driving
factor behind the original switch was supporting 128-bit constants for
Neon and these patches should resolve that.

i?86 would be another candidate (if you don't build a compiler with -m64
support).

Not true for x86 since we have

Variable
HOST_WIDE_INT ix86_isa_flags = TARGET_64BIT_DEFAULT |
TARGET_SUBTARGET_ISA_DEFAULT

in i386.opt.   We need more than 32 bits for ix86_isa_flags.

Then that should be HOST_WIDEST_INT instead.

Also one function in i386.c generates less optimal
results when HOST_WIDE_INT is 32-bit such that
we were generating different outputs from the same
input on x86 and on x86-64 with -m32.

Well - we knew the code would bitrot once we decided to always
default to 64bit HWI ...

Richard.

--
H.J.

Just for the record, the straw the broke the camel's back for me wassome bit map data structure in one of the gen functions that has a HWIworth of bits and i needed 35 of them for the port i was trying. Itwas all fixable, but i had already signed up for one task that seemedlike it was going to take the rest of my like and i did not need another.


kenny

References:
- wide-int, ada
  - From: Mike Stump
- Re: wide-int, ada
  - From: Eric Botcazou
- Re: wide-int, ada
  - From: Kenneth Zadeck
- Re: wide-int, ada
  - From: Eric Botcazou
- Re: wide-int, ada
  - From: Richard Earnshaw
- Re: wide-int, ada
  - From: Richard Biener
- Re: wide-int, ada
  - From: H.J. Lu
- Re: wide-int, ada
  - From: pinskia
- Re: wide-int, ada
  - From: H.J. Lu
- Re: wide-int, ada
  - From: Richard Biener

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