Cray: fix Blue Waters support and user-built MPIs on Cray (#16593)

* Cray: fix Blue Waters support

* pkg-config env vars needed on Blue Waters

* cray platform: fix support for user-build MPI on cray machines

* reintroduce cray environment cleaning behind cnl version guard

* cray platform: fix support for user-build MPI on cray machines

Co-authored-by: Gregory <becker33@llnl.gov>

2 files changed, 19 insertions, 11 deletions

diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index f57ecd1e58..435de8594e 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -53,6 +53,7 @@ import spack.main
 import spack.paths
 import spack.schema.environment
 import spack.store
+import spack.architecture as arch
 from spack.util.string import plural
 from spack.util.environment import (
     env_flag, filter_system_paths, get_path, is_system_path,
@@ -141,17 +142,21 @@ def clean_environment():
     # can affect how some packages find libraries.  We want to make
     # sure that builds never pull in unintended external dependencies.
     env.unset('LD_LIBRARY_PATH')
-    env.unset('CRAY_LD_LIBRARY_PATH')
     env.unset('LIBRARY_PATH')
     env.unset('CPATH')
     env.unset('LD_RUN_PATH')
     env.unset('DYLD_LIBRARY_PATH')
     env.unset('DYLD_FALLBACK_LIBRARY_PATH')
 
-    # Remove all pkgconfig stuff from craype
-    for varname in os.environ.keys():
-        if 'PKGCONF' in varname:
-            env.unset(varname)
+    # On Cray systems newer than CNL5, unset CRAY_LD_LIBRARY_PATH to avoid
+    # interference with Spack dependencies. CNL5 (e.g. Blue Waters) requires
+    # these variables to be set.
+    hostarch = arch.Arch(arch.platform(), 'default_os', 'default_target')
+    if str(hostarch.platform) == 'cray' and str(hostarch.os) != 'cnl5':
+        env.unset('CRAY_LD_LIBRARY_PATH')
+        for varname in os.environ.keys():
+            if 'PKGCONF' in varname:
+                env.unset(varname)
 
     build_lang = spack.config.get('config:build_language')
     if build_lang:
@@ -355,10 +360,6 @@ def set_build_environment_variables(pkg, env, dirty):
         extra_rpaths = ':'.join(compiler.extra_rpaths)
         env.set('SPACK_COMPILER_EXTRA_RPATHS', extra_rpaths)
 
-    implicit_rpaths = compiler.implicit_rpaths()
-    if implicit_rpaths:
-        env.set('SPACK_COMPILER_IMPLICIT_RPATHS', ':'.join(implicit_rpaths))
-
     # Add bin directories from dependencies to the PATH for the build.
     for prefix in build_prefixes:
         for dirname in ['bin', 'bin64']:
@@ -733,6 +734,11 @@ def setup_package(pkg, dirty):
 
         load_external_modules(pkg)
 
+    implicit_rpaths = pkg.compiler.implicit_rpaths()
+    if implicit_rpaths:
+        build_env.set('SPACK_COMPILER_IMPLICIT_RPATHS',
+                      ':'.join(implicit_rpaths))
+
     # Make sure nothing's strange about the Spack environment.
     validate(build_env, tty.warn)
     build_env.apply_modifications()
diff --git a/lib/spack/spack/platforms/cray.py b/lib/spack/spack/platforms/cray.py
index 2fccf2fe55..9c8770c368 100644
--- a/lib/spack/spack/platforms/cray.py
+++ b/lib/spack/spack/platforms/cray.py
@@ -22,7 +22,9 @@ _craype_name_to_target_name = {
     'x86-naples': 'zen',
     'x86-rome': 'zen',  # Cheating because we have the wrong modules on rzcrayz
     'x86-skylake': 'skylake_avx512',
-    'mic-knl': 'mic_knl'
+    'mic-knl': 'mic_knl',
+    'interlagos': 'bulldozer',
+    'abudhabi': 'piledriver',
 }
 
 
@@ -176,7 +178,7 @@ class Cray(Platform):
             craype_default_path = '/opt/cray/pe/craype/default/modulefiles'
             if os.path.isdir(craype_default_path):
                 return os.listdir(craype_default_path)
-            return None
+            return []
 
         if getattr(self, '_craype_targets', None) is None:
             strategies = [