Split OpenMP from Clang in LLVM

As the OpenMP-V implementation requires to be built with nOS-V, we can
split the OpenMP package in a different derivation to prevent rebuilds
of clang. Additionally, as OpenMP-V now can be build alongside the
vanilla OpenMP runtime, we simply build a single openmp derivation with
both runtimes. Only a single build of the clang compiler is now
required.

Reviewed-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>
Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>

overlay.nix

@@ -12,11 +12,10 @@ let
   bscPkgs = {
     bench6 = callPackage ./pkgs/bench6/default.nix { };
     clangOmpss2 = callPackage ./pkgs/llvm-ompss2/default.nix { };
+    openmp = callPackage ./pkgs/llvm-ompss2/openmp.nix { monorepoSrc = final.clangOmpss2Unwrapped.src; version = final.clangOmpss2Unwrapped.version; };
     clangOmpss2Nanos6 = callPackage ./pkgs/llvm-ompss2/default.nix { ompss2rt = final.nanos6; };
     clangOmpss2Nodes = callPackage ./pkgs/llvm-ompss2/default.nix { ompss2rt = final.nodes; };
-    clangOmpss2OpenmpNodes = callPackage ./pkgs/llvm-ompss2/default.nix { ompss2rt = final.nodes; clangOmpss2Unwrapped = final.clangOmpss2OpenmpUnwrapped; };
     clangOmpss2Unwrapped = callPackage ./pkgs/llvm-ompss2/clang.nix { };
-    clangOmpss2OpenmpUnwrapped = final.clangOmpss2Unwrapped.override { enableNosv = true; };
     #extrae = callPackage ./pkgs/extrae/default.nix { }; # Broken and outdated
     gpi-2 = callPackage ./pkgs/gpi-2/default.nix { };
     intelPackages_2023 = callPackage ./pkgs/intel-oneapi/2023.nix { };
@@ -41,7 +40,6 @@ let
     stdenvClangOmpss2 = final.stdenv.override { cc = final.clangOmpss2; allowedRequisites = null; };
     stdenvClangOmpss2Nanos6 = final.stdenv.override { cc = final.clangOmpss2Nanos6; allowedRequisites = null; };
     stdenvClangOmpss2Nodes = final.stdenv.override { cc = final.clangOmpss2Nodes; allowedRequisites = null; };
-    stdenvClangOmpss2OpenmpNodes = final.stdenv.override { cc = final.clangOmpss2OpenmpNodes; allowedRequisites = null; };
     tagaspi = callPackage ./pkgs/tagaspi/default.nix { };
     tampi = callPackage ./pkgs/tampi/default.nix { };
     wxparaver = callPackage ./pkgs/paraver/default.nix { };
@@ -76,10 +74,10 @@ in bscPkgs // {
         stdenv = final.stdenvClangOmpss2Nodes;
       };
       clangNosvOpenmp-task = callPackage ./test/compilers/clang-openmp.nix {
-        stdenv = final.stdenvClangOmpss2OpenmpNodes;
+        stdenv = final.stdenvClangOmpss2Nodes;
       };
       clangNosvOpenmp-nosv = callPackage ./test/compilers/clang-openmp-nosv.nix {
-        stdenv = final.stdenvClangOmpss2OpenmpNodes;
+        stdenv = final.stdenvClangOmpss2Nodes;
       };
     };
 

pkgs/llvm-ompss2/clang.nix

@@ -10,11 +10,9 @@
 , elfutils
 , libffi
 , zlib
-, nosv
 , pkg-config
 , gcc # needed to set the rpath of libstdc++ for clang-tblgen
 , enableDebug ? false
-, enableNosv ? false
 , useGit ? false
 , gitUrl ? "ssh://git@bscpm03.bsc.es/llvm-ompss/llvm-mono.git"
 , gitBranch ? "master"
@@ -73,8 +71,6 @@ in stdenv.mkDerivation rec {
     pkg-config
     zlib
     gcc.cc.lib # Required for libstdc++.so.6
-  ] ++ lib.optionals enableNosv [
-    nosv
   ];
 
   # Error with -D_FORTIFY_SOURCE=2, see https://bugs.gentoo.org/636604:
@@ -107,15 +103,12 @@ in stdenv.mkDerivation rec {
       "-DCMAKE_CXX_FLAGS_DEBUG=-g -ggnu-pubnames"
       "-DCMAKE_EXE_LINKER_FLAGS_DEBUG=-Wl,--gdb-index"
       "-DLLVM_LIT_ARGS=-sv --xunit-xml-output=xunit.xml"
-      "-DLLVM_ENABLE_PROJECTS=clang;openmp;compiler-rt;lld"
+      "-DLLVM_ENABLE_PROJECTS=clang;compiler-rt;lld"
       "-DLLVM_ENABLE_ASSERTIONS=ON"
       "-DLLVM_INSTALL_TOOLCHAIN_ONLY=ON"
       "-DCMAKE_INSTALL_BINDIR=bin"
       "-DLLVM_ENABLE_ZLIB=FORCE_ON"
       "-DLLVM_ENABLE_LIBXML2=OFF"
-  '' + (lib.optionalString enableNosv ''
-      "-DCLANG_DEFAULT_NOSV_HOME=${nosv}"
-  '') + ''
       # Set the rpath to include external libraries (zlib) both on build and
       # install
       "-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON"
@@ -124,12 +117,6 @@ in stdenv.mkDerivation rec {
 
   '';
 
-  # Remove support for GNU and Intel Openmp
-  postInstall = ''
-    rm -f $out/lib/libgomp*
-    rm -f $out/lib/libiomp*
-  '';
-
 # About "-DCLANG_DEFAULT_NANOS6_HOME=${nanos6}", we could specify a default
 # nanos6 installation, but this is would require a recompilation of clang each
 # time nanos6 is changed. Better to use the environment variable NANOS6_HOME,

pkgs/llvm-ompss2/openmp.nix

@@ -0,0 +1,57 @@
+{ lib
+, llvmPackages_latest
+, monorepoSrc
+, runCommand
+, cmake
+, ninja
+, llvm
+, perl
+, pkg-config
+, version
+, nosv
+, enableDebug ? false
+}:
+
+let
+  stdenv = llvmPackages_latest.stdenv;
+in
+stdenv.mkDerivation rec {
+  pname = "openmp";
+  inherit version;
+
+  src = runCommand "${pname}-src" {} ''
+    mkdir -p "$out"
+    cp -r ${monorepoSrc}/cmake "$out"
+    cp -r ${monorepoSrc}/${pname} "$out"
+  '';
+
+  sourceRoot = "${src.name}/${pname}";
+
+  nativeBuildInputs = [
+    cmake
+    ninja
+    perl
+    pkg-config
+    nosv
+  ];
+
+  doCheck = false;
+
+  hardeningDisable = [ "all" ];
+
+  cmakeBuildType = if enableDebug then "Debug" else "Release";
+
+  dontStrip = enableDebug;
+
+  cmakeFlags = [
+    "-DLIBOMP_OMPD_SUPPORT=OFF"
+    "-DOPENMP_ENABLE_LIBOMPTARGET=OFF"
+  ];
+
+  # Remove support for GNU and Intel Openmp
+  postInstall = ''
+    rm -f $out/lib/libgomp*
+    rm -f $out/lib/libiomp*
+  '';
+}
+

test/compilers/clang-openmp-nosv.nix

@@ -2,6 +2,7 @@
   stdenv
 , nosv
 , writeText
+, openmp
 }:
 
 let
@@ -40,7 +41,7 @@ in stdenv.mkDerivation {
   # fail to run otherwise, so we disable the sandbox for this test.
   __noChroot = true;
 
-  buildInputs = [ nosv ];
+  buildInputs = [ nosv openmp ];
 
   buildPhase = ''
     set -x

test/compilers/clang-openmp.nix

@@ -1,6 +1,7 @@
 { 
   stdenv
 , writeText
+, openmp
 }:
 
 let
@@ -28,6 +29,8 @@ in stdenv.mkDerivation {
   # fail to run otherwise, so we disable the sandbox for this test.
   __noChroot = true;
 
+  buildInputs = [ openmp ];
+
   buildPhase = ''
     set -x