Split openmp versions in separate derivations

The openmp derivation provides both libomp and libompv. To avoid
accidentally linking with the wrong library and to avoid the nosv
dependency on libomp, this patch separates each version in a different
derivation.

Also, it adapts the clang wrappers and stdenvs to provide an stdenv per
openmp library where each openmp will be used by default when the
compiler flag "-fopenmp" is used. This eases linking ompv with nixpkgs
libraries, such as blis, that expect openmp to be provided with stdenv.

Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Tested-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>

pkgs/llvm-ompss2/default.nix

@@ -3,15 +3,24 @@
 , lib
 , gcc
 , clangOmpss2Unwrapped
+, openmp ? null
 , wrapCCWith
 , llvmPackages_latest
 , ompss2rt ? null
 }:
 
+let
+  usingNodesAndOmpv = (openmp.pname == "openmp-v" && ompss2rt.pname == "nodes");
+  sameNosv = openmp.nosv == ompss2rt.nosv;
+in
+
+assert lib.assertMsg (usingNodesAndOmpv -> sameNosv) "OpenMP-V and NODES must share the same nOS-V";
 
 let
   homevar = if ompss2rt.pname == "nanos6" then "NANOS6_HOME" else "NODES_HOME";
   rtname  = if ompss2rt.pname == "nanos6" then "libnanos6" else "libnodes";
+  ompname = if openmp.pname == "openmp-v" then  "libompv" else "libomp";
+
 
   # We need to replace the lld linker from bintools with our linker just built,
   # otherwise we run into incompatibility issues when mixing compiler and linker
@@ -27,6 +36,8 @@ let
   cc = clangOmpss2Unwrapped;
 in wrapCCWith {
   inherit cc bintools;
+  # extraPackages adds packages to depsTargetTargetPropagated
+  extraPackages = lib.optional (openmp != null) openmp;
   extraBuildCommands = ''
     echo "-target ${targetConfig}" >> $out/nix-support/cc-cflags
     echo "-B${gcc.cc}/lib/gcc/${targetConfig}/${gcc.version}" >> $out/nix-support/cc-cflags
@@ -43,6 +54,9 @@ in wrapCCWith {
     echo "--gcc-toolchain=${gcc}" >> $out/nix-support/cc-cflags
 
     wrap clang++  $wrapper $ccPath/clang++
+
+  '' + lib.optionalString (openmp != null) ''
+    echo "export OPENMP_RUNTIME=${ompname}" >> $out/nix-support/cc-wrapper-hook
   '' + lib.optionalString (ompss2rt != null) ''
     echo "export OMPSS2_RUNTIME=${rtname}" >> $out/nix-support/cc-wrapper-hook
     echo "export ${homevar}=${ompss2rt}"   >> $out/nix-support/cc-wrapper-hook

pkgs/llvm-ompss2/openmp.nix

@@ -9,6 +9,7 @@
 , pkg-config
 , version
 , nosv
+, enableNosv ? false
 , enableDebug ? false
 }:
 
@@ -16,22 +17,23 @@ let
   stdenv = llvmPackages_latest.stdenv;
 in
 stdenv.mkDerivation rec {
-  pname = "openmp";
+  pname = "openmp" + (lib.optionalString enableNosv "-v");
   inherit version;
 
   src = runCommand "${pname}-src" {} ''
     mkdir -p "$out"
     cp -r ${monorepoSrc}/cmake "$out"
-    cp -r ${monorepoSrc}/${pname} "$out"
+    cp -r ${monorepoSrc}/openmp "$out"
   '';
 
-  sourceRoot = "${src.name}/${pname}";
+  sourceRoot = "${src.name}/openmp";
 
   nativeBuildInputs = [
     cmake
     ninja
     perl
     pkg-config
+  ] ++ lib.optionals enableNosv [
     nosv
   ];
 
@@ -48,10 +50,18 @@ stdenv.mkDerivation rec {
     "-DOPENMP_ENABLE_LIBOMPTARGET=OFF"
   ];
 
-  # Remove support for GNU and Intel Openmp
+  # Remove support for GNU and Intel Openmp.
+  # Also, remove libomp if building with nosv, as there is no support to build
+  # only one runtime at a time.
   postInstall = ''
     rm -f $out/lib/libgomp*
     rm -f $out/lib/libiomp*
+  '' + lib.optionalString enableNosv ''
+    rm -f $out/lib/libomp.*
   '';
+
+  passthru = {
+    inherit nosv;
+  };
 }