[gmx-users] no altivec support found when compiling on macosx G5 gcc 3.3

[Erik Lindahl]

Hi,

Play around with compiler options; the macro __VEC__ should be defined 
when the compiler supports altivec. Earlier versions of gcc did this 
with -faltivec, but read the docs and see if it has changed :-)

Cheers,

Erik

On Mar 23, 2004, at 12:22 PM, Pim Schravendijk wrote:

>
> Hi list,
>
> I'm compiling gromacs 3.2.1 on macosx on a G5 and get a warning:
>
> WARNING: no altivec support found - On G4 and later Motorola PowerPC 
> CPUs
> you can get a HUGE performance gain by using an altivec-enabled 
> compiler.
> Download the latest devtools from Apple, or gcc-3.1 from ftp.gnu.org
>
> Since I'm using gcc 3.3, "upgrading" to 3.1 seems not logical. I have
> -fast as CFLAGS option and used ./configure without any options except
> the --prefix= option.
>
> Now I'd of course like to have this "HUGE performance gain" so I am
> wondering how I could get this option to work. Any ideas?
>
> Greetings, Pim
>
> version numbers:
> Darwin Kernel Version 7.3.0: Fri Mar  5 14:22:55 PST 2004;
> gcc version 3.3 20030304 (Apple Computer, Inc. build 1495)
>
> complete warning message:
> configure:5013: checking whether gcc accepts -faltivec
> configure:5031: result: yes
> configure:5087: checking whether gcc accepts -funroll-all-loops
> configure:5105: result: yes
> configure:5118: checking whether gcc accepts -mcpu=7450
> configure:5136: result: yes
> configure:5148: checking whether gcc accepts -mtune=970
> configure:5166: result: yes
> configure:5481: checking whether the compiler supports altivec 
> extensions
> configure:5510: gcc -c -fast
> -I/people/thnfs/homes/schraven/bin/fftwmacsingle/include/ conftest.c >&
> 5
> configure: In function `main':
> configure:5509: error: `choke_me' undeclared (first use in this 
> function)
> configure:5509: error: (Each undeclared identifier is reported only 
> once
> configure:5509: error: for each function it appears in.)
> configure:5513: $? = 1
> configure: failed program was:
> | #line 5483 "configure"
> | /* confdefs.h.  */
> |
> | #define PACKAGE_NAME "GROMACS"
> | #define PACKAGE_TARNAME "gromacs"
> | #define PACKAGE_VERSION "3.2.1"
> | #define PACKAGE_STRING "GROMACS 3.2.1"
> | #define PACKAGE_BUGREPORT "gmx-users at gromacs.org"
> | #define PACKAGE "gromacs"
> | #define VERSION "3.2.1"
> | #define SOFTWARE_INVSQRT
> | /* end confdefs.h.  */
> |
> | #ifdef F77_DUMMY_MAIN
> | #  ifdef __cplusplus
> |      extern "C"
> | #  endif
> |    int F77_DUMMY_MAIN() { return 1; }
> | #endif
> | int
> | main ()
> | {
> |
> | #ifndef __VEC__
> | choke_me
> | #endif
> |
> |   ;
> |   return 0;
> | }
> configure:5535: result: no
> configure:5539: WARNING: no altivec support found - On G4 and later
> Motorola PowerPC
> CPUs you can get a HUGE performance gain by using an altivec-enabled
> compiler.
> Download the latest devtools from Apple, or gcc-3.1 from ftp.gnu.org
>
>
> --
> Pim Schravendijk - PhD Student
> Max Planck Institute for Polymer Research
> http://www.mpip-mainz.mpg.de/~schraven/
>
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