[SYCL][NVPTX] Obey -nocudalib when linking against libdevice (#15378)

This commit also makes a clearer distinction in code between what NVPTX
and NativeCPU are required to link against.

It refactors some nearby code which was more complicated than it needed
to be.

clang/lib/Driver/Driver.cpp

@@ -5564,7 +5564,7 @@ class OffloadingActionBuilder final {
           SYCLDeviceLibLinked = addSYCLDeviceLibs(
               TC, SYCLDeviceLibs, UseAOTLink,
               C.getDefaultToolChain().getTriple().isWindowsMSVCEnvironment(),
-              IsSYCLNativeCPU, NativeCPULib);
+              IsSYCLNativeCPU, NativeCPULib, BoundArch);
         }
         JobAction *LinkSYCLLibs =
             C.MakeAction<LinkJobAction>(SYCLDeviceLibs, types::TY_LLVM_BC);
@@ -5842,7 +5842,7 @@ class OffloadingActionBuilder final {
 
     bool addSYCLDeviceLibs(const ToolChain *TC, ActionList &DeviceLinkObjects,
                            bool isSpirvAOT, bool isMSVCEnv, bool isNativeCPU,
-                           Action *&NativeCPULib) {
+                           Action *&NativeCPULib, const char *BoundArch) {
       int NumOfDeviceLibLinked = 0;
       SmallVector<SmallString<128>, 4> LibLocCandidates;
       SYCLInstallation.getSYCLDeviceLibPath(LibLocCandidates);
@@ -5852,14 +5852,10 @@ class OffloadingActionBuilder final {
           tools::SYCL::getDeviceLibraries(C, TC->getTriple(), isSpirvAOT);
 
       for (const auto &DeviceLib : DeviceLibraries) {
-        bool LibLocSelected = false;
         for (const auto &LLCandidate : LibLocCandidates) {
-          if (LibLocSelected)
-            break;
           SmallString<128> LibName(LLCandidate);
           llvm::sys::path::append(LibName, DeviceLib);
           if (llvm::sys::fs::exists(LibName)) {
-
             // NativeCPU currently only needs libsycl-nativecpu_utils and
             // libclc, so temporarily skip other device libs in invocation.
             // Todo: remove once NativeCPU tests the other libraries.
@@ -5897,8 +5893,6 @@ class OffloadingActionBuilder final {
                   C.MakeAction<InputAction>(*InputArg, types::TY_LLVM_BC);
               DeviceLinkObjects.push_back(SYCLDeviceLibsInputAction);
             }
-            if (!LibLocSelected)
-              LibLocSelected = !LibLocSelected;
 
             // The device link stage may remove symbols not referenced in the
             // source code. Since libsycl-nativecpu_utils contains such symbols
@@ -5909,22 +5903,26 @@ class OffloadingActionBuilder final {
               NativeCPULib = DeviceLinkObjects.back();
               DeviceLinkObjects.pop_back();
             }
+
+            break;
           }
         }
       }
 
-      // For NVPTX backend we need to also link libclc and CUDA libdevice
-      // at the same stage that we link all of the unbundled SYCL libdevice
-      // objects together.
-      if ((TC->getTriple().isNVPTX() || isNativeCPU) && NumOfDeviceLibLinked) {
+      if (!NumOfDeviceLibLinked)
+        return false;
+
+      // For NVPTX and NativeCPU we need to also link libclc at the same stage
+      // that we link all of the unbundled SYCL libdevice objects together.
+      if (TC->getTriple().isNVPTX() || isNativeCPU) {
         std::string LibSpirvFile;
         if (Args.hasArg(options::OPT_fsycl_libspirv_path_EQ)) {
           auto ProvidedPath =
               Args.getLastArgValue(options::OPT_fsycl_libspirv_path_EQ).str();
           if (llvm::sys::fs::exists(ProvidedPath))
             LibSpirvFile = ProvidedPath;
         } else {
-          SmallVector<StringRef, 8> LibraryPaths;
+          SmallVector<StringRef, 2> LibraryPaths;
 
           // Expected path w/out install.
           SmallString<256> WithoutInstallPath(C.getDriver().ResourceDir);
@@ -5936,22 +5934,17 @@ class OffloadingActionBuilder final {
           llvm::sys::path::append(WithInstallPath, Twine("../../../share/clc"));
           LibraryPaths.emplace_back(WithInstallPath.c_str());
 
-          // TODO: check if the isNVPTX() path can also use
-          // TC->getTripleString() so that the conditional could be removed
-          const std::string TrStr =
-              isNativeCPU ? TC->getTripleString() : "nvptx64-nvidia-cuda";
-
           // Select remangled libclc variant
           StringRef LibSpirvTargetNamePref =
               TC->getAuxTriple()->isOSWindows()
                   ? "remangled-l32-signed_char.libspirv-"
                   : "remangled-l64-signed_char.libspirv-";
-          llvm::Twine LibSpirvTargetNameTemp = LibSpirvTargetNamePref + TrStr;
-          llvm::Twine LibSpirvTargetName = LibSpirvTargetNameTemp + ".bc";
 
           for (StringRef LibraryPath : LibraryPaths) {
             SmallString<128> LibSpirvTargetFile(LibraryPath);
-            llvm::sys::path::append(LibSpirvTargetFile, LibSpirvTargetName);
+            llvm::sys::path::append(LibSpirvTargetFile,
+                                    LibSpirvTargetNamePref +
+                                        TC->getTripleString() + ".bc");
             if (llvm::sys::fs::exists(LibSpirvTargetFile) ||
                 Args.hasArg(options::OPT__HASH_HASH_HASH)) {
               LibSpirvFile = std::string(LibSpirvTargetFile.str());
@@ -5966,30 +5959,24 @@ class OffloadingActionBuilder final {
               C.MakeAction<InputAction>(*LibClcInputArg, types::TY_LLVM_BC);
           DeviceLinkObjects.push_back(SYCLLibClcInputAction);
         }
+      }
 
-        if (isNativeCPU) {
-          // return here to not generate cuda actions
-          return NumOfDeviceLibLinked != 0;
-        }
-
+      // For NVPTX we also need to link with the CUDA libdevice
+      if (TC->getTriple().isNVPTX() && !Args.hasArg(options::OPT_nogpulib)) {
         const toolchains::CudaToolChain *CudaTC =
             static_cast<const toolchains::CudaToolChain *>(TC);
-        for (const auto &LinkInputEnum : enumerate(DeviceLinkerInputs)) {
-          const char *BoundArch =
-              SYCLTargetInfoList[LinkInputEnum.index()].BoundArch;
-          std::string LibDeviceFile =
-              CudaTC->CudaInstallation.getLibDeviceFile(BoundArch);
-          if (!LibDeviceFile.empty()) {
-            Arg *CudaDeviceLibInputArg =
-                MakeInputArg(Args, C.getDriver().getOpts(),
-                             Args.MakeArgString(LibDeviceFile));
-            auto *SYCLDeviceLibInputAction = C.MakeAction<InputAction>(
-                *CudaDeviceLibInputArg, types::TY_LLVM_BC);
-            DeviceLinkObjects.push_back(SYCLDeviceLibInputAction);
-          }
+        std::string LibDeviceFile =
+            CudaTC->CudaInstallation.getLibDeviceFile(BoundArch);
+        if (!LibDeviceFile.empty()) {
+          Arg *CudaDeviceLibInputArg = MakeInputArg(
+              Args, C.getDriver().getOpts(), Args.MakeArgString(LibDeviceFile));
+          auto *SYCLDeviceLibInputAction = C.MakeAction<InputAction>(
+              *CudaDeviceLibInputArg, types::TY_LLVM_BC);
+          DeviceLinkObjects.push_back(SYCLDeviceLibInputAction);
         }
       }
-      return NumOfDeviceLibLinked != 0;
+
+      return true;
     }
 
     void appendLinkDependences(OffloadAction::DeviceDependences &DA) override {

clang/test/Driver/sycl-nvptx-link.cpp

@@ -28,6 +28,12 @@
 // RUN:    --sysroot=%S/Inputs/SYCL --cuda-path=%S/Inputs/CUDA_90/usr/local/cuda %s 2>&1 \
 // RUN:    | FileCheck %s --check-prefixes=CHECK,LIBDEVICE10
 
+// Check also that -nocudalib is obeyed
+// RUN: %clang -### -fsycl -fsycl-targets=nvptx64-nvidia-cuda -nocudalib \
+// RUN:    -Xsycl-target-backend --cuda-gpu-arch=sm_35 \
+// RUN:    --sysroot=%S/Inputs/SYCL --cuda-path=%S/Inputs/CUDA_90/usr/local/cuda %s 2>&1 \
+// RUN:    | FileCheck %s --check-prefixes=CHECK,NOLIBDEVICE
+
 // First link command: ignored
 // CHECK: llvm-link
 
@@ -39,3 +45,4 @@
 // LIBDEVICE30-SAME: libdevice.compute_30.10.bc
 // LIBDEVICE35-SAME: libdevice.compute_35.10.bc
 // LIBDEVICE50-SAME: libdevice.compute_50.10.bc
+// NOLIBDEVICE-NOT: libdevice.{{.*}}.10.bc