Multi-compiler support feature-complete. Fix SPACK-3, SPACK-4, SPACK-12.

- Fast compiler finding in path and for other directories
  - first time spack runs, it searches path.
  - user can add more compilers with 'spack compiler add'

- Finds intel, gcc, clang, and pgi compilers with custom version args.

- Builds can plug in alternate compilers with ease (e.g. %intel@12.1)

11 files changed, 519 insertions, 150 deletions

diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index 492e490320..b9d0c16353 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -94,13 +94,13 @@ def set_compiler_environment_variables(pkg):
 
     # Set SPACK compiler variables so that our wrapper knows what to call
     if compiler.cc:
-        os.environ['SPACK_CC']  = compiler.cc.command
+        os.environ['SPACK_CC']  = compiler.cc
     if compiler.cxx:
-        os.environ['SPACK_CXX'] = compiler.cxx.command
+        os.environ['SPACK_CXX'] = compiler.cxx
     if compiler.f77:
-        os.environ['SPACK_F77'] = compiler.f77.command
+        os.environ['SPACK_F77'] = compiler.f77
     if compiler.fc:
-        os.environ['SPACK_FC']  = compiler.fc.command
+        os.environ['SPACK_FC']  = compiler.fc
 
     os.environ['SPACK_COMPILER_SPEC']  = str(pkg.spec.compiler)
 
diff --git a/lib/spack/spack/cmd/compiler.py b/lib/spack/spack/cmd/compiler.py
new file mode 100644
index 0000000000..af69897ce9
--- /dev/null
+++ b/lib/spack/spack/cmd/compiler.py
@@ -0,0 +1,81 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import argparse
+
+from pprint import pprint
+
+import llnl.util.tty as tty
+from llnl.util.tty.colify import colify
+from llnl.util.lang import index_by
+
+import spack.compilers
+import spack.spec
+import spack.config
+from spack.compilation import get_path
+
+description = "Manage compilers"
+
+def setup_parser(subparser):
+    sp = subparser.add_subparsers(
+        metavar='SUBCOMMAND', dest='compiler_command')
+
+    update_parser = sp.add_parser(
+        'add', help='Add compilers to the Spack configuration.')
+    update_parser.add_argument('add_paths', nargs=argparse.REMAINDER)
+
+    remove_parser = sp.add_parser('remove', help='remove compiler')
+    remove_parser.add_argument('path')
+
+    list_parser   = sp.add_parser('list', help='list available compilers')
+
+
+def compiler_add(args):
+    paths = args.add_paths
+    if not paths:
+        paths = get_path('PATH')
+
+    compilers = spack.compilers.find_compilers(*args.add_paths)
+    spack.compilers.add_compilers_to_config('user', *compilers)
+
+
+def compiler_remove(args):
+    pass
+
+
+def compiler_list(args):
+    tty.msg("Available compilers")
+
+    index = index_by(spack.compilers.all_compilers(), 'name')
+    for name, compilers in index.items():
+        tty.hline(name, char='-', color=spack.spec.compiler_color)
+        colify(reversed(sorted(compilers)), indent=4)
+
+
+def compiler(parser, args):
+    action = { 'add'    : compiler_add,
+               'remove' : compiler_remove,
+               'list'   : compiler_list }
+    action[args.compiler_command](args)
+
diff --git a/lib/spack/spack/cmd/compilers.py b/lib/spack/spack/cmd/compilers.py
index c34118f033..8d046bfd7c 100644
--- a/lib/spack/spack/cmd/compilers.py
+++ b/lib/spack/spack/cmd/compilers.py
@@ -26,15 +26,9 @@ import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 from llnl.util.lang import index_by
 
-import spack.compilers
-import spack.spec
+from spack.cmd.compiler import compiler_list
 
-description = "List available compilers"
+description = "List available compilers. Same as 'spack compiler list'."
 
 def compilers(parser, args):
-    tty.msg("Available compilers")
-
-    index = index_by(spack.compilers.all_compilers(), 'name')
-    for name, compilers in index.items():
-        tty.hline(name, char='-', color=spack.spec.compiler_color)
-        colify(compilers, indent=4)
+    compiler_list(args)
diff --git a/lib/spack/spack/cmd/config.py b/lib/spack/spack/cmd/config.py
index 25d302f94b..85f9642019 100644
--- a/lib/spack/spack/cmd/config.py
+++ b/lib/spack/spack/cmd/config.py
@@ -32,9 +32,8 @@ import spack.config
 description = "Get and set configuration options."
 
 def setup_parser(subparser):
+    # User can only choose one
     scope_group = subparser.add_mutually_exclusive_group()
-
-    # File scope
     scope_group.add_argument(
         '--user', action='store_const', const='user', dest='scope',
         help="Use config file in user home directory (default).")
@@ -42,36 +41,44 @@ def setup_parser(subparser):
         '--site', action='store_const', const='site', dest='scope',
         help="Use config file in spack prefix.")
 
-    # Get (vs. default set)
-    subparser.add_argument(
-        '--get', action='store_true', dest='get',
-        help="Get the value associated with a key.")
+    sp = subparser.add_subparsers(metavar='SUBCOMMAND', dest='config_command')
 
-    # positional arguments (value is only used on set)
-    subparser.add_argument(
-        'key', help="Get the value associated with KEY")
-    subparser.add_argument(
-        'value', nargs='?', default=None,
-        help="Value to associate with key")
+    set_parser = sp.add_parser('set', help='Set configuration values.')
+    set_parser.add_argument('key', help="Key to set value for.")
+    set_parser.add_argument('value', nargs='?', default=None,
+                            help="Value to associate with key")
 
+    get_parser = sp.add_parser('get', help='Get configuration values.')
+    get_parser.add_argument('key', help="Key to get value for.")
+
+    edit_parser = sp.add_parser('edit', help='Edit configuration file.')
 
-def config(parser, args):
-    key, value = args.key, args.value
 
-    # If we're writing need to do a few checks.
-    if not args.get:
-        # Default scope for writing is user scope.
-        if not args.scope:
-            args.scope = 'user'
+def config_set(args):
+    # default scope for writing is 'user'
+    if not args.scope:
+        args.scope = 'user'
+
+    config = spack.config.get_config(args.scope)
+    config.set_value(args.key, args.value)
+    config.write()
 
-        if args.value is None:
-            tty.die("No value for '%s'.  " % args.key
-                    + "Spack config requires a key and a value.")
 
+def config_get(args):
     config = spack.config.get_config(args.scope)
+    print config.get_value(args.key)
+
+
+def config_edit(args):
+    if not args.scope:
+        args.scope = 'user'
+    config_file = spack.config.get_filename(args.scope)
+    spack.editor(config_file)
+
+
+def config(parser, args):
+    action = { 'set'  : config_set,
+               'get'  : config_get,
+               'edit' : config_edit }
+    action[args.config_command](args)
 
-    if args.get:
-        print config.get_value(key)
-    else:
-        config.set_value(key, value)
-        config.write()
diff --git a/lib/spack/spack/compiler.py b/lib/spack/spack/compiler.py
index f6e173c359..b04034bbdd 100644
--- a/lib/spack/spack/compiler.py
+++ b/lib/spack/spack/compiler.py
@@ -1,26 +1,67 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
 import os
 import re
 import itertools
+from datetime import datetime
 
+import llnl.util.tty as tty
 from llnl.util.lang import memoized
 from llnl.util.filesystem import join_path
 
 import spack.error
 import spack.spec
+from spack.util.multiproc import parmap
+from spack.util.executable import *
 from spack.version import Version
-from spack.util.executable import Executable, which
 from spack.compilation import get_path
 
-_default_order = ['']
+__all__ = ['Compiler', 'get_compiler_version']
 
 def _verify_executables(*paths):
     for path in paths:
         if not os.path.isfile(path) and os.access(path, os.X_OK):
             raise CompilerAccessError(path)
 
-@memoized
-def get_compiler_version(compiler, version_arg):
-    return compiler(version_arg, return_output=True)
+
+_version_cache = {}
+
+def get_compiler_version(compiler_path, version_arg, regex='(.*)'):
+    if not compiler_path in _version_cache:
+        compiler = Executable(compiler_path)
+        output = compiler(version_arg, return_output=True, error=None)
+
+        match = re.search(regex, output)
+        _version_cache[compiler_path] = match.group(1) if match else None
+
+    return _version_cache[compiler_path]
+
+
+def dumpversion(compiler_path):
+    """Simple default dumpversion method -- this is what gcc does."""
+    return get_compiler_version(compiler_path, '-dumpversion')
 
 
 class Compiler(object):
@@ -48,37 +89,67 @@ class Compiler(object):
     # Optional suffix regexes for searching for this type of compiler.
     # Suffixes are used by some frameworks, e.g. macports uses an '-mp-X.Y'
     # version suffix for gcc.
-    suffixes = []
+    suffixes = [r'-.*']
 
     # Names of generic arguments used by this compiler
-    arg_version = '-dumpversion'
     arg_rpath   = '-Wl,-rpath,%s'
 
 
-    def __init__(self, cc, cxx, f77, fc):
-        def make_exe(exe):
+    def __init__(self, cc, cxx, f77, fc, version=None):
+        def check(exe):
             if exe is None:
                 return None
             _verify_executables(exe)
-            return Executable(exe)
-
-        self.cc  = make_exe(cc)
-        self.cxx = make_exe(cxx)
-        self.f77 = make_exe(f77)
-        self.fc  = make_exe(fc)
+            return exe
 
+        self.cc  = check(cc)
+        self.cxx = check(cxx)
+        self.f77 = check(f77)
+        self.fc  = check(fc)
 
-    def _tuple(self):
-        return (self.cc, self.cxx, self.f77, self.fc)
+        # Allow versions to be memoized so we don't have to run
+        # compilers many times.  Record them in the version cache if
+        # we get them in a constructor
+        #
+        # TODO: what to do if compilers have different versions?
+        #
+        self._version = version
+        self._cache_version()
 
 
     @property
     def version(self):
-        for comp in self._tuple():
-            if comp is not None:
-                v = get_compiler_version(comp, self.arg_version)
+        if not self._version:
+            v = self.cc_version(self.cc)
+            if v is not None:
+                self._version = v
+                return Version(v)
+
+            v = self.cxx_version(self.cxx)
+            if v is not None:
+                self._version = v
                 return Version(v)
-        raise InvalidCompilerError()
+
+            v = self.f77_version(self.f77)
+            if v is not None:
+                self._version = v
+                return Version(v)
+
+            v = self.fc_version(self.fc)
+            if v is not None:
+                self._version = v
+                return Version(v)
+
+            raise InvalidCompilerError()
+
+        return Version(self._version)
+
+
+    def _cache_version(self):
+        _version_cache[self.cc] = self._version
+        _version_cache[self.cxx] = self._version
+        _version_cache[self.f77] = self._version
+        _version_cache[self.fc] = self._version
 
 
     @property
@@ -87,66 +158,115 @@ class Compiler(object):
 
 
     @classmethod
-    def _find_matches_in_path(cls, compiler_names, *path):
-        """Try to find compilers with the supplied names in any of the suppled
-           paths.  Searches for all combinations of each name with the
-           compiler's specified prefixes and suffixes.  Compilers are
-           returned in a dict from (prefix, suffix) tuples to paths to
-           the compilers with those prefixes and suffixes.
+    def default_version(cls, cc):
+        """Override just this to override all compiler version functions."""
+        return dumpversion(cc)
+
+    @classmethod
+    def cc_version(cls, cc):
+        return cls.default_version(cc)
+
+    @classmethod
+    def cxx_version(cls, cxx):
+        return cls.default_version(cxx)
+
+    @classmethod
+    def f77_version(cls, f77):
+        return cls.default_version(f77)
+
+    @classmethod
+    def fc_version(cls, fc):
+        return cls.default_version(fc)
+
+
+    @classmethod
+    def _find_matches_in_path(cls, compiler_names, detect_version, *path):
+        """Finds compilers in the paths supplied.
+
+           Looks for all combinations of ``compiler_names`` with the
+           ``prefixes`` and ``suffixes`` defined for this compiler
+           class.  If any compilers match the compiler_names,
+           prefixes, or suffixes, uses ``detect_version`` to figure
+           out what version the compiler is.
+
+           This returns a dict with compilers grouped by (prefix,
+           suffix, version) tuples.  This can be further organized by
+           find().
         """
         if not path:
             path = get_path('PATH')
 
-        matches = {}
-        ps_pairs = [p for p in itertools.product(
-            [''] + cls.prefixes, [''] + cls.suffixes)]
+        prefixes = [''] + cls.prefixes
+        suffixes = [''] + cls.suffixes
 
+        checks = []
         for directory in path:
             files = os.listdir(directory)
+            for exe in files:
+                full_path = join_path(directory, exe)
+
+                prod = itertools.product(prefixes, compiler_names, suffixes)
+                for pre, name, suf in prod:
+                    regex = r'^(%s)%s(%s)$' % (pre, re.escape(name), suf)
+
+                    match = re.match(regex, exe)
+                    if match:
+                        key = (full_path,) + match.groups()
+                        checks.append(key)
+
+        def check(key):
+            try:
+                full_path, prefix, suffix = key
+                version = detect_version(full_path)
+                return (version, prefix, suffix, full_path)
+            except ProcessError, e:
+                tty.debug("Couldn't get version for compiler %s" % full_path, e)
+                return None
 
-            for pre_re, suf_re in ps_pairs:
-                for compiler_name in compiler_names:
-                    regex = r'^(%s)%s(%s)$' % (
-                        pre_re, re.escape(compiler_name), suf_re)
-
-                    for exe in files:
-                        match = re.match(regex, exe)
-                        if match:
-                            pair = match.groups()
-                            if pair not in matches:
-                                matches[pair] = join_path(directory, exe)
-
-        return matches
+        successful = [key for key in parmap(check, checks) if key is not None]
+        return { (v, p, s) : path for v, p, s, path in successful }
 
     @classmethod
     def find(cls, *path):
-        """Try to find this type of compiler in the user's environment. For
-           each set of compilers found, this returns a 4-tuple with
-           the cc, cxx, f77, and fc paths.
+        """Try to find this type of compiler in the user's
+           environment. For each set of compilers found, this returns
+           compiler objects with the cc, cxx, f77, fc paths and the
+           version filled in.
 
            This will search for compilers with the names in cc_names,
-           cxx_names, etc. and it will group 4-tuples if they have
-           common prefixes and suffixes.  e.g., gcc-mp-4.7 would be
-           grouped with g++-mp-4.7 and gfortran-mp-4.7.
+           cxx_names, etc. and it will group them if they have common
+           prefixes, suffixes, and versions.  e.g., gcc-mp-4.7 would
+           be grouped with g++-mp-4.7 and gfortran-mp-4.7.
 
            Example return values::
 
-               [ ('/usr/bin/gcc',      '/usr/bin/g++',
-                  '/usr/bin/gfortran', '/usr/bin/gfortran'),
-
-                 ('/usr/bin/gcc-mp-4.5',      '/usr/bin/g++-mp-4.5',
-                  '/usr/bin/gfortran-mp-4.5', '/usr/bin/gfortran-mp-4.5') ]
+               [ gcc('/usr/bin/gcc',      '/usr/bin/g++',
+                     '/usr/bin/gfortran', '/usr/bin/gfortran',
+                     Version('4.4.5')),
+                 gcc('/usr/bin/gcc-mp-4.5',      '/usr/bin/g++-mp-4.5',
+                     '/usr/bin/gfortran-mp-4.5', '/usr/bin/gfortran-mp-4.5',
+                     Version('4.7.2')) ]
 
         """
-        pair_names = [cls._find_matches_in_path(names, *path) for names in (
-            cls.cc_names, cls.cxx_names, cls.f77_names, cls.fc_names)]
+        dicts = parmap(
+            lambda t: cls._find_matches_in_path(*t),
+            [(cls.cc_names,  cls.cc_version)  + tuple(path),
+             (cls.cxx_names, cls.cxx_version) + tuple(path),
+             (cls.f77_names, cls.f77_version) + tuple(path),
+             (cls.fc_names,  cls.fc_version)  + tuple(path)])
+
+        all_keys = set()
+        for d in dicts:
+            all_keys.update(d)
 
-        keys = set()
-        for p in pair_names:
-            keys.update(p)
+        compilers = []
+        for k in all_keys:
+            ver, pre, suf = k
+            paths = tuple(pn[k] if k in pn else None for pn in dicts)
+            args = paths + (ver,)
+            compilers.append(cls(*args))
 
-        return [ tuple(pn[k] if k in pn else None for pn in pair_names)
-                 for k in keys ]
+        return compilers
 
 
     def __repr__(self):
@@ -156,11 +276,8 @@ class Compiler(object):
 
     def __str__(self):
         """Return a string represntation of the compiler toolchain."""
-        def p(path):
-            return ' '.join(path.exe) if path else None
-        return "%s(%s, %s, %s, %s)" % (
-            self.name,
-            p(self.cc), p(self.cxx), p(self.f77), p(self.fc))
+        return "%s(%s)" % (
+            self.name, '\n     '.join((str(s) for s in (self.cc, self.cxx, self.f77, self.fc))))
 
 
 class CompilerAccessError(spack.error.SpackError):
diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index 4b21dd6f7e..36d995b6bd 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -22,7 +22,11 @@
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
+"""This module contains functions related to finding compilers on the
+system and configuring Spack to use multiple compilers.
+"""
 import imp
+import os
 
 from llnl.util.lang import memoized, list_modules
 from llnl.util.filesystem import join_path
@@ -32,13 +36,16 @@ import spack.error
 import spack.spec
 import spack.config
 
+from spack.util.multiproc import parmap
 from spack.compiler import Compiler
 from spack.util.executable import which
 from spack.util.naming import mod_to_class
+from spack.compilation import get_path
 
 _imported_compilers_module = 'spack.compilers'
 _required_instance_vars = ['cc', 'cxx', 'f77', 'fc']
 
+_default_order = ['gcc', 'intel', 'pgi', 'clang']
 
 def _auto_compiler_spec(function):
     def converter(cspec_like):
@@ -59,23 +66,72 @@ def _get_config():
     if existing:
         return config
 
-    user_config = spack.config.get_config('user')
-
-    compilers = find_default_compilers()
-    for name, clist in compilers.items():
-        for compiler in clist:
-            if compiler.spec not in existing:
-                add_compiler(user_config, compiler)
-    user_config.write()
+    compilers = find_compilers(*get_path('PATH'))
+    new_compilers = [
+        c for c in compilers if c.spec not in existing]
+    add_compilers_to_config('user', *new_compilers)
 
     # After writing compilers to the user config, return a full config
     # from all files.
-    return spack.config.get_config()
+    return spack.config.get_config(refresh=True)
+
+
+@memoized
+def default_compiler():
+    versions = []
+    for name in _default_order:  # TODO: customize order.
+        versions = find(name)
+        if versions: break
+
+    if not versions:
+        raise NoCompilersError()
+
+    return sorted(versions)[-1]
+
+
+def find_compilers(*path):
+    """Return a list of compilers found in the suppied paths.
+       This invokes the find() method for each Compiler class,
+       and appends the compilers detected to a list.
+    """
+    # Make sure path elements exist, and include /bin directories
+    # under prefixes.
+    filtered_path = []
+    for p in path:
+        # Eliminate symlinks and just take the real directories.
+        p = os.path.realpath(p)
+        if not os.path.isdir(p):
+            continue
+        filtered_path.append(p)
+
+        # Check for a bin directory, add it if it exists
+        bin = join_path(p, 'bin')
+        if os.path.isdir(bin):
+            filtered_path.append(os.path.realpath(bin))
+
+    # Once the paths are cleaned up, do a search for each type of
+    # compiler.  We can spawn a bunch of parallel searches to reduce
+    # the overhead of spelunking all these directories.
+    types = all_compiler_types()
+    compiler_lists = parmap(lambda cls: cls.find(*filtered_path), types)
+
+    # ensure all the version calls we made are cached in the parent
+    # process, as well.  This speeds up Spack a lot.
+    clist = reduce(lambda x,y: x+y, compiler_lists)
+    for c in clist: c._cache_version()
+    return clist
+
+
+def add_compilers_to_config(scope, *compilers):
+    config = spack.config.get_config(scope)
+    for compiler in compilers:
+        add_compiler(config, compiler)
+    config.write()
 
 
 def add_compiler(config, compiler):
     def setup_field(cspec, name, exe):
-        path = ' '.join(exe.exe) if exe else "None"
+        path = exe if exe else "None"
         config.set_value('compiler', cspec, name, path)
 
     for c in _required_instance_vars:
@@ -134,7 +190,9 @@ def compilers_for_spec(compiler_spec):
                 compiler_paths.append(compiler_path)
             else:
                 compiler_paths.append(None)
-        return cls(*compiler_paths)
+
+        args = tuple(compiler_paths) + (compiler_spec.version,)
+        return cls(*args)
 
     matches = find(compiler_spec)
     return [get_compiler(cspec) for cspec in matches]
@@ -168,34 +226,14 @@ def all_compiler_types():
     return [class_for_compiler_name(c) for c in supported_compilers()]
 
 
-def find_default_compilers():
-    """Search the user's environment to get default compilers.  Each
-       compiler class can have its own find() class method that can be
-       customized to locate that type of compiler.
-    """
-    # Compiler name is inserted on load by class_for_compiler_name
-    return {
-        Compiler.name : [Compiler(*c) for c in Compiler.find()]
-        for Compiler in all_compiler_types() }
-
-
-@memoized
-def default_compiler():
-    """Get the spec for the default compiler on the system.
-       Currently just returns the system's default gcc.
-
-       TODO: provide a more sensible default.  e.g. on Intel systems
-             we probably want icc.  On Mac OS, clang.  Probably need
-             to inspect the system and figure this out.
-    """
-    gcc = which('gcc', required=True)
-    version = gcc('-dumpversion', return_output=True)
-    return spack.spec.CompilerSpec('gcc', version)
-
-
 class InvalidCompilerConfigurationError(spack.error.SpackError):
     def __init__(self, compiler_spec):
         super(InvalidCompilerConfigurationError, self).__init__(
             "Invalid configuration for [compiler \"%s\"]: " % compiler_spec,
             "Compiler configuration must contain entries for all compilers: %s"
             % _required_instance_vars)
+
+
+class NoCompilersError(spack.error.SpackError):
+    def __init__(self):
+        super(NoCompilersError, self).__init__("Spack could not find any compilers!")
diff --git a/lib/spack/spack/compilers/clang.py b/lib/spack/spack/compilers/clang.py
index 1616fcaf08..73c462b49f 100644
--- a/lib/spack/spack/compilers/clang.py
+++ b/lib/spack/spack/compilers/clang.py
@@ -37,5 +37,16 @@ class Clang(Compiler):
     # Subclasses use possible names of Fortran 90 compiler
     fc_names = []
 
-    def __init__(self, cc, cxx, f77, fc):
-        super(Clang, self).__init__(cc, cxx, f77, fc)
+
+    @classmethod
+    def default_version(self, comp):
+        """The '--version' option works for clang compilers.
+           Output looks like this::
+
+               clang version 3.1 (trunk 149096)
+               Target: x86_64-unknown-linux-gnu
+               Thread model: posix
+        """
+        return get_compiler_version(
+            comp, '--version', r'clang version ([^ ]+)')
+
diff --git a/lib/spack/spack/compilers/gcc.py b/lib/spack/spack/compilers/gcc.py
index 05dae96e65..cc3c52ca61 100644
--- a/lib/spack/spack/compilers/gcc.py
+++ b/lib/spack/spack/compilers/gcc.py
@@ -22,7 +22,7 @@
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
-from spack.compiler import Compiler
+from spack.compiler import *
 
 class Gcc(Compiler):
     # Subclasses use possible names of C compiler
@@ -40,5 +40,14 @@ class Gcc(Compiler):
     # MacPorts builds gcc versions with prefixes and -mp-X.Y suffixes.
     suffixes = [r'-mp-\d\.\d']
 
-    def __init__(self, cc, cxx, f77, fc):
-        super(Gcc, self).__init__(cc, cxx, f77, fc)
+    @classmethod
+    def fc_version(cls, fc):
+        return get_compiler_version(
+            fc, '-dumpversion',
+            # older gfortran versions don't have simple dumpversion output.
+            r'(?:GNU Fortran \(GCC\))?(\d+\.\d+\.\d+)')
+
+
+    @classmethod
+    def f77_version(cls, f77):
+        return cls.fc_version(f77)
diff --git a/lib/spack/spack/compilers/intel.py b/lib/spack/spack/compilers/intel.py
index fe2aabd864..02e3b96b19 100644
--- a/lib/spack/spack/compilers/intel.py
+++ b/lib/spack/spack/compilers/intel.py
@@ -22,7 +22,7 @@
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
-from spack.compiler import Compiler
+from spack.compiler import *
 
 class Intel(Compiler):
     # Subclasses use possible names of C compiler
@@ -37,5 +37,21 @@ class Intel(Compiler):
     # Subclasses use possible names of Fortran 90 compiler
     fc_names = ['ifort']
 
-    def __init__(self, cc, cxx, f77, fc):
-        super(Intel, self).__init__(cc, cxx, f77, fc)
+
+    @classmethod
+    def default_version(cls, comp):
+        """The '--version' option seems to be the most consistent one
+           for intel compilers.  Output looks like this::
+
+               icpc (ICC) 12.1.5 20120612
+               Copyright (C) 1985-2012 Intel Corporation.  All rights reserved.
+
+           or::
+
+               ifort (IFORT) 12.1.5 20120612
+               Copyright (C) 1985-2012 Intel Corporation.  All rights reserved.
+        """
+        return get_compiler_version(
+            comp, '--version', r'\((?:IFORT|ICC)\) ([^ ]+)')
+
+
diff --git a/lib/spack/spack/compilers/pgi.py b/lib/spack/spack/compilers/pgi.py
new file mode 100644
index 0000000000..d97f24c12e
--- /dev/null
+++ b/lib/spack/spack/compilers/pgi.py
@@ -0,0 +1,51 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+from spack.compiler import *
+
+class Pgi(Compiler):
+    # Subclasses use possible names of C compiler
+    cc_names = ['pgcc']
+
+    # Subclasses use possible names of C++ compiler
+    cxx_names = ['pgCC']
+
+    # Subclasses use possible names of Fortran 77 compiler
+    f77_names = ['pgf77']
+
+    # Subclasses use possible names of Fortran 90 compiler
+    fc_names = ['pgf95', 'pgf90']
+
+    @classmethod
+    def default_version(cls, comp):
+        """The '-V' option works for all the PGI compilers.
+           Output looks like this::
+
+               pgf95 10.2-0 64-bit target on x86-64 Linux -tp nehalem-64
+               Copyright 1989-2000, The Portland Group, Inc.  All Rights Reserved.
+               Copyright 2000-2010, STMicroelectronics, Inc.  All Rights Reserved.
+        """
+        return get_compiler_version(
+            comp, '-V', r'pg[^ ]* ([^ ]+) \d\d\d?-bit target')
+
diff --git a/lib/spack/spack/util/multiproc.py b/lib/spack/spack/util/multiproc.py
new file mode 100644
index 0000000000..9e045a090f
--- /dev/null
+++ b/lib/spack/spack/util/multiproc.py
@@ -0,0 +1,45 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+"""
+This implements a parallel map operation but it can accept more values
+than multiprocessing.Pool.apply() can.  For example, apply() will fail
+to pickle functions if they're passed indirectly as parameters.
+"""
+from multiprocessing import Process, Pipe
+from itertools import izip
+
+def spawn(f):
+    def fun(pipe,x):
+        pipe.send(f(x))
+        pipe.close()
+    return fun
+
+def parmap(f,X):
+    pipe=[Pipe() for x in X]
+    proc=[Process(target=spawn(f),args=(c,x)) for x,(p,c) in izip(X,pipe)]
+    [p.start() for p in proc]
+    [p.join() for p in proc]
+    return [p.recv() for (p,c) in pipe]
+