R devel - Nov 2005 - [PATCH] Add fpicflags for Intel(R) Fortran Compiler (PR#8344)

Full_Name: Danny van Dyk
Version: R-2.2.0
OS: Gentoo/AMD64
Submission from: (NULL) (83.129.50.65)


I have successfully compiled R-2.2.0 using ifc-9.0.026 on my x86_64 box.
The only (minor) change that hade to be made was adding
fpicflags="-fPIC" to
configure.ac in case F77 matches either "ifc" (old name) or
"ifort" (new name).

Please apply following patch:

dvandyk at phi trunk $ svn diff
        Index: configure.ac
==================================================================---
configure.ac        (revision 36420)
+++ configure.ac        (working copy)
@@ -942,7 +942,7 @@
   rm -f Imakefile Makefile
 fi

-## Step 2.  GNU compilers.
+## Step 2.  GNU and Intel compilers.
 if test "${GCC}" = yes; then
   cpicflags="-fPIC"
   shlib_ldflags="-shared"
@@ -954,6 +954,11 @@
   cxxpicflags="-fPIC"
   shlib_cxxldflags="-shared"
 fi
+case "${F77}" in
+  ifc|ifort)
+    fpicflags="-fPIC"
+    ;;
+esac

 ## Step 3.  Individual platform overrides.
 case "${host_os}" in
==================================================================
Danny

1) The documented way to specify this is to set FPICFLAGS in config.site: 
see the example in R-admin for the PG compilers.  When you tried that, 
what went wrong?

2) It seems strange to specify this for the Fortran compiler and not the C 
or C++ compiler.

3) You have suggested the change to a section for all OSes.  Do you know 
for sure that all compilers called 'ifort' on all OSes need the -fPIC 
flag?  Or is it really just for Linux (and AFAICS, just x86_64 Linux, as 
i386 Linux seems to work with icc/ifort without it).

On Tue, 22 Nov 2005 kugelfang at gentoo.org wrote:
> Full_Name: Danny van Dyk
> Version: R-2.2.0
> OS: Gentoo/AMD64
> Submission from: (NULL) (83.129.50.65)
>
>
> I have successfully compiled R-2.2.0 using ifc-9.0.026 on my x86_64 box.
> The only (minor) change that hade to be made was adding
fpicflags="-fPIC" to
> configure.ac in case F77 matches either "ifc" (old name) or
"ifort" (new name).
>
> Please apply following patch:
>
> dvandyk at phi trunk $ svn diff
>        Index: configure.ac
> ==================================================================> ---
configure.ac        (revision 36420)
> +++ configure.ac        (working copy)
> @@ -942,7 +942,7 @@
>   rm -f Imakefile Makefile
> fi
>
> -## Step 2.  GNU compilers.
> +## Step 2.  GNU and Intel compilers.
> if test "${GCC}" = yes; then
>   cpicflags="-fPIC"
>   shlib_ldflags="-shared"
> @@ -954,6 +954,11 @@
>   cxxpicflags="-fPIC"
>   shlib_cxxldflags="-shared"
> fi
> +case "${F77}" in
> +  ifc|ifort)
> +    fpicflags="-fPIC"
> +    ;;
> +esac
>
> ## Step 3.  Individual platform overrides.
> case "${host_os}" in
> ==================================================================>
> Danny
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Dear Prof. Ripley,

Prof Brian Ripley schrieb:
| 1) The documented way to specify this is to set FPICFLAGS in
| config.site: see the example in R-admin for the PG compilers.  When you
| tried that, what went wrong?
Nothing went wrong. However, I was of the opinion that support of
ifc/ifort 'out-of-the-box' is worthwhile. This is why I asked to include
it into the source-tree. As a matter of fact, I stumbled upon this when
testing Gentoo's R-2.2.0 buildscripts and added a similar patch to our
repository.

| 2) It seems strange to specify this for the Fortran compiler and not the
| C or C++ compiler.
I used the combination of 'gcc/g++/ifort' to build and test R. Testing
the combination of 'icc/ifort' on Gentoo is scheduled already.

| 3) You have suggested the change to a section for all OSes.  Do you know
| for sure that all compilers called 'ifort' on all OSes need the -fPIC
| flag?  Or is it really just for Linux (and AFAICS, just x86_64 Linux, as
| i386 Linux seems to work with icc/ifort without it).
a) For building shared ELF-libraries on x86_64 and ia64, you need to
instruct the compiler to build PIC. As a matter of fact, this isn't
necessary for x86, but it is strongly recommended as it should improve
performance due to the lack of text relocations the dynamic linker would
have to perform otherwise. This affects all OSes that can handle ELF
binaries (Linux, FreeBSD, Solaris, tbc.).

b) I surely can't guarantee that there never will be a different fortran
compiler with same name on any OS. However, I think that it is a safe
assumption to say that there currently is no such compiler on OSes
supported by autotools.


The number of target OSes and and supported ISAs makes it - in my eyes -
worthwhile to add the check to the 'general' section of the configure.ac
script. If - in a rare case - a conflict with other compiler emerged, it
would still be possible to work around a problem in the following
section of the script: '## Step 3.  Individual platform overrides.'.
(Emphasis here on 'individual' and 'override')

Danny
- --
Danny van Dyk <kugelfang at gentoo.org>
Gentoo/AMD64 Project, Gentoo Scientific Project
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I've some playing with the Intel compilers, currently only on ia32.  As 
far as I can see Intel provides compilers for only two OSes and on 50% of 
those -fPIC is wrong so I do think this is really Linux-specific.
I have put in a Linux-specific change to set FPICFLAGS, but that is the 
least of the problems I have found.

The reason there is not a problem with the C compiler is that configure 
reports

 	checking whether we are using the GNU C compiler... yes

and so configure takes the builtin defaults for gcc.  This seems to come 
from the test of

int
main ()
{
#ifndef __GNUC__
        choke me
#endif

   ;
   return 0;
}

and so it seems that the masquerading by icc is intentional.  This has 
some consequences: for example package foreign assumes that GCC accepts 
-Wno-long-long, but icc does not act on it.  More seriously, it means that 
the default CFLAGS get set to "-g -O2", which is not what is
documented.
And with those flags, the build fails, incorrectly reporting that a regexp 
is invalid.

There are also problems with optimizing src/modules/dlamc.f under ifort.


On Tue, 22 Nov 2005, Danny van Dyk wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Dear Prof. Ripley,
>
> Prof Brian Ripley schrieb:
> | 1) The documented way to specify this is to set FPICFLAGS in
> | config.site: see the example in R-admin for the PG compilers.  When you
> | tried that, what went wrong?
> Nothing went wrong. However, I was of the opinion that support of
> ifc/ifort 'out-of-the-box' is worthwhile. This is why I asked to
include
> it into the source-tree. As a matter of fact, I stumbled upon this when
> testing Gentoo's R-2.2.0 buildscripts and added a similar patch to our
> repository.
>
> | 2) It seems strange to specify this for the Fortran compiler and not the
> | C or C++ compiler.
> I used the combination of 'gcc/g++/ifort' to build and test R.
Testing
> the combination of 'icc/ifort' on Gentoo is scheduled already.
>
> | 3) You have suggested the change to a section for all OSes.  Do you know
> | for sure that all compilers called 'ifort' on all OSes need the
-fPIC
> | flag?  Or is it really just for Linux (and AFAICS, just x86_64 Linux, as
> | i386 Linux seems to work with icc/ifort without it).
> a) For building shared ELF-libraries on x86_64 and ia64, you need to
> instruct the compiler to build PIC. As a matter of fact, this isn't
> necessary for x86, but it is strongly recommended as it should improve
> performance due to the lack of text relocations the dynamic linker would
> have to perform otherwise. This affects all OSes that can handle ELF
> binaries (Linux, FreeBSD, Solaris, tbc.).
>
> b) I surely can't guarantee that there never will be a different
fortran
> compiler with same name on any OS. However, I think that it is a safe
> assumption to say that there currently is no such compiler on OSes
> supported by autotools.
>
>
> The number of target OSes and and supported ISAs makes it - in my eyes -
> worthwhile to add the check to the 'general' section of the
configure.ac
> script. If - in a rare case - a conflict with other compiler emerged, it
> would still be possible to work around a problem in the following
> section of the script: '## Step 3.  Individual platform
overrides.'.
> (Emphasis here on 'individual' and 'override')
>
> Danny
> - --
> Danny van Dyk <kugelfang at gentoo.org>
> Gentoo/AMD64 Project, Gentoo Scientific Project
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.1 (GNU/Linux)
>
> iD8DBQFDg120aVNL8NrtU6IRAqVFAJ9Nv3FnfUjzGU2q4FEf+3TRek2HTQCfQG4R
> DD5dVT076/1HBJw5B4N+mck> =eBBz
> -----END PGP SIGNATURE-----
>
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595