[libc-commits] [clang] [compiler-rt] [flang] [libc] [libcxx] [libcxxabi] [libunwind] [llvm] [openmp] [Flang] Move builtin .mod generation into runtimes (Reapply #137828) (PR #171515)

[Petr Hosek via libc-commits]

================
@@ -1179,6 +1179,37 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
   CmdArgs.push_back("-resource-dir");
   CmdArgs.push_back(D.ResourceDir.c_str());
 
+  // Default intrinsic module dirs must be added after any user-provided
+  // -fintrinsic-modules-path to have lower precedence
+  if (std::optional<std::string> IntrModPath =
+          TC.getDefaultIntrinsicModuleDir()) {
+    CmdArgs.push_back("-fintrinsic-modules-path");
+    CmdArgs.push_back(Args.MakeArgString(*IntrModPath));
+  }
+
+  // Ideally, every target triple has its own set of builtin modules since they
+  // are compiled with platform-dependent conditionals such as `#if __x86_64__`.
+  // However, getting the builtin modules for offload targets requires building
+  // the flang-rt and openmp for those targets as well:
+  // -DLLVM_RUNTIME_TARGETS=default;amdgcn-amd-amdhsa;nvptx64-nvidia-cuda.
+  // To reduce friction when build systems have not yet been updated, we also
+  // add the host's builtin module to the search path (with lower priority), in
+  // case a module file has not been found for the offload targets itself.
+  // FIXME: This workaround may mix module files targeting different triples and
+  //        should eventually be removed.
+  auto &&HostTCs =
+      C.getOffloadToolChains<clang::driver::OffloadAction ::OFK_Host>();
+  for (auto [OKind, HostTC] : llvm::make_range(HostTCs.first, HostTCs.second)) {
+    if (HostTC == &TC)
+      continue;
+
+    if (std::optional<std::string> IntrModPath =
+            HostTC->getDefaultIntrinsicModuleDir()) {
+      CmdArgs.push_back("-fintrinsic-modules-path");
+      CmdArgs.push_back(Args.MakeArgString(*IntrModPath));
+    }
+  }
----------------
petrhosek wrote:

Is there a test that covers this new logic?

https://github.com/llvm/llvm-project/pull/171515