[petsc-dev] COPTFLAGS

[Jed Brown]

Passing COPTFLAGS currently causes your flags to be passed _prior_ to
the flags that get added in compilerOptions.py.  This makes ./configure
COPTFLAGS='-Og -g' useless since -O0 gets passed afterward, for example.

https://bitbucket.org/petsc/petsc/commits/e3218094707942d5674f57c17eb63a9af846a945

> commit e3218094707942d5674f57c17eb63a9af846a945
> Author: Barry Smith <bsmith at mcs.anl.gov>
> Date:   Sat Mar 17 22:47:44 2012 -0500
> 
>     added -fno-inline for better debugging with gnu compilers; take it out if it breaks something
>     
>     Hg-commit: cee000f4e8f56981f3611284aa810e3c0419aa10
> 
> 	Modified   config/compilerOptions.py
> diff --git a/config/compilerOptions.py b/config/compilerOptions.py
> index e619c8e..612cb3f 100644
> --- a/config/compilerOptions.py
> +++ b/config/compilerOptions.py
> @@ -22,6 +22,8 @@ class CompilerOptions(config.base.Configure):
>          if self.framework.argDB['with-gcov']:
>            flags.extend(['-fprofile-arcs', '-ftest-coverage'])
>          flags.append('-g3')
> +        flags.append('-fno-inline')

       -fno-inline
           Do not expand any functions inline apart from those marked with the
           "always_inline" attribute.  This is the default when not optimizing.

I.e., this option should have no effect.

> +        flags.append('-O0')

This is the default and overrides COPTFLAGS since it comes later.

I would guess this was added to compensate for MPICH putting its CFLAGS
into the compiler wrappers (you need MPICHLIB_CFLAGS to avoid it), so
that "mpicc somefile.c" often defaults to high optimization.  That
behavior is bad and I agree that we need to work around it somehow, but
the fix in this patch was not applied to getCxxFlags or getFortranFlags.

The way I see, it, we can exit early when the user specifies COPTFLAGS

diff --git i/config/BuildSystem/config/compilerOptions.py w/config/BuildSystem/config/compilerOptions.py
index dadc5fb..2a3cfa0 100644
--- i/config/BuildSystem/config/compilerOptions.py
+++ w/config/BuildSystem/config/compilerOptions.py
@@ -14,6 +14,9 @@ class CompilerOptions(config.base.Configure):
       except:
         pass
 
+    if bopt and 'COPTFLAGS' in self.framework.argDB:
+      return []
+
     flags = []
     # GNU gcc
     if config.setCompilers.Configure.isGNU(compiler) or config.setCompilers.Configure.isClang(compiler):

and we can add -O0 to the other languages

@@ -96,6 +101,7 @@ class CompilerOptions(config.base.Configure):
           flags.extend(['-fprofile-arcs', '-ftest-coverage'])
         # -g3 causes an as SEGV on OSX
         flags.append('-g')
+        flags.append('-O0') # MPICH puts CXXFLAGS into wrappers, so ensure that we do not use optimization
       elif bopt in ['O']:
         if os.environ.has_key('USER'):
           flags.append('-O')

(similar for Fortran).  But this is also imperfect because some people
use non-Gnu compilers.

Is there a clean solution?


>        elif bopt == 'O':
>          flags.append('-O')
>      else:
> 	Modified   config/packages/MPI.py
> diff --git a/config/packages/MPI.py b/config/packages/MPI.py
> index 260acab..2328eb9 100644
> --- a/config/packages/MPI.py
> +++ b/config/packages/MPI.py
> @@ -11,7 +11,7 @@ from stat import *
>  class Configure(config.package.Package):
>    def __init__(self, framework):
>      config.package.Package.__init__(self, framework)
> -    self.download_openmpi   = ['http://www.open-mpi.org/software/ompi/v1.5/downloads/openmpi-1.5.4.tar.gz']
> +    self.download_openmpi   = ['http://www.open-mpi.org/software/ompi/v1.4/downloads/openmpi-1.4.4.tar.gz']
>      self.download_mpich     = ['http://www.mcs.anl.gov/research/projects/mpich2/downloads/tarballs/1.4.1p1/mpich2-1.4.1p1.tar.gz']
>      self.download           = ['redefine']
>      self.functions          = ['MPI_Init', 'MPI_Comm_create']
> 
> 
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