[CUDA] Warn about unsupported CUDA SDK version only if it's used.

[tra]

Summary

This fixes an issue with clang issuing a warning about unknown CUDA SDK if it's detected during non-CUDA compilation.

[tra]

Added a test.

[yaxunl]

LGTM. Thanks!

[tra]

clang-formatted the changes.

[tra]

@hans -- this should be cherry-picked into 10 if it's not too late yet.

[hans]

In D76030#1925445, @tra wrote:

@hans -- this should be cherry-picked into 10 if it's not too late yet.

It's probably too late for 10.0.0, but sounds like a good candidate for 10.0.1.

[hans]

In D76030#1928448, @hans wrote:

In D76030#1925445, @tra wrote:

@hans -- this should be cherry-picked into 10 if it's not too late yet.

It's probably too late for 10.0.0, but sounds like a good candidate for 10.0.1.

Sounds like I underestimated the importance of this. Merged as d32170dbd5b0d54436537b6b75beaf44324e0c28, as per https://bugs.llvm.org/show_bug.cgi?id=45270

clang/lib/Driver/ToolChains/Cuda.h

 namespace driver {
 
 /// A class to find a viable CUDA installation
 class CudaInstallationDetector {
 private:
   const Driver &D;
   bool IsValid = false;
   CudaVersion Version = CudaVersion::UNKNOWN;
+  std::string DetectedVersion;
+  bool DetectedVersionIsNotSupported = false;
   std::string InstallPath;
   std::string BinPath;
   std::string LibPath;
   std::string LibDevicePath;
   std::string IncludePath;
   llvm::StringMap<std::string> LibDeviceMap;
 
   // CUDA architectures for which we have raised an error in
public:
   /// Get the detected Cuda library path.
   StringRef getLibPath() const { return LibPath; }
   /// Get the detected Cuda device library path.
   StringRef getLibDevicePath() const { return LibDevicePath; }
   /// Get libdevice file for given architecture
   std::string getLibDeviceFile(StringRef Gpu) const {
     return LibDeviceMap.lookup(Gpu);
   }
+  void WarnIfUnsupportedVersion();
+
+private:
+  void ParseCudaVersionFile(llvm::StringRef V);
 };
 
 namespace tools {
 namespace NVPTX {
 
 // Run ptxas, the NVPTX assembler.
 class LLVM_LIBRARY_VISIBILITY Assembler : public Tool {
  public:

clang/lib/Driver/ToolChains/Cuda.cpp

 using namespace clang::driver;
 using namespace clang::driver::toolchains;
 using namespace clang::driver::tools;
 using namespace clang;
 using namespace llvm::opt;
 
 // Parses the contents of version.txt in an CUDA installation.  It should
 // contain one line of the from e.g. "CUDA Version 7.5.2".
-static CudaVersion ParseCudaVersionFile(const Driver &D, llvm::StringRef V) {
+void CudaInstallationDetector::ParseCudaVersionFile(llvm::StringRef V) {
+  Version = CudaVersion::UNKNOWN;
   if (!V.startswith("CUDA Version "))
-    return CudaVersion::UNKNOWN;
+    return;
   V = V.substr(strlen("CUDA Version "));
   SmallVector<StringRef,4> VersionParts;
   V.split(VersionParts, '.');
   if (VersionParts.size() < 2)
-    return CudaVersion::UNKNOWN;
-  std::string MajorMinor = join_items(".", VersionParts[0], VersionParts[1]);
-  CudaVersion Version = CudaStringToVersion(MajorMinor);
+    return;
+  DetectedVersion = join_items(".", VersionParts[0], VersionParts[1]);
+  Version = CudaStringToVersion(DetectedVersion);
   if (Version != CudaVersion::UNKNOWN)
-    return Version;
+    return;
 
-  // Issue a warning and assume that the version we've found is compatible with
-  // the latest version we support.
+  Version = CudaVersion::LATEST;
+  DetectedVersionIsNotSupported = true;
+}
+
+void CudaInstallationDetector::WarnIfUnsupportedVersion() {
+  if (DetectedVersionIsNotSupported)
     D.Diag(diag::warn_drv_unknown_cuda_version)
-      << MajorMinor << CudaVersionToString(CudaVersion::LATEST);
-  return CudaVersion::LATEST;
+        << DetectedVersion << CudaVersionToString(Version);
 }
 
 CudaInstallationDetector::CudaInstallationDetector(
     const Driver &D, const llvm::Triple &HostTriple,
     const llvm::opt::ArgList &Args)
     : D(D) {
   struct Candidate {
     std::string Path;
for (const auto &Candidate : Candidates) {
 
     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> VersionFile =
         FS.getBufferForFile(InstallPath + "/version.txt");
     if (!VersionFile) {
       // CUDA 7.0 doesn't have a version.txt, so guess that's our version if
       // version.txt isn't present.
       Version = CudaVersion::CUDA_70;
     } else {
-      Version = ParseCudaVersionFile(D, (*VersionFile)->getBuffer());
+      ParseCudaVersionFile((*VersionFile)->getBuffer());
     }
 
     if (Version >= CudaVersion::CUDA_90) {
       // CUDA-9+ uses single libdevice file for all GPU variants.
       std::string FilePath = LibDevicePath + "/libdevice.10.bc";
       if (FS.exists(FilePath)) {
         for (const char *GpuArchName :
              {"sm_30", "sm_32", "sm_35", "sm_37", "sm_50", "sm_52", "sm_53",

 /// which isn't properly a linker but nonetheless performs the step of stitching
 /// together object files from the assembler into a single blob.
 
 CudaToolChain::CudaToolChain(const Driver &D, const llvm::Triple &Triple,
                              const ToolChain &HostTC, const ArgList &Args,
                              const Action::OffloadKind OK)
     : ToolChain(D, Triple, Args), HostTC(HostTC),
       CudaInstallation(D, HostTC.getTriple(), Args), OK(OK) {
-  if (CudaInstallation.isValid())
+  if (CudaInstallation.isValid()) {
+    CudaInstallation.WarnIfUnsupportedVersion();
     getProgramPaths().push_back(std::string(CudaInstallation.getBinPath()));
+  }
   // Lookup binaries into the driver directory, this is used to
   // discover the clang-offload-bundler executable.
   getProgramPaths().push_back(getDriver().Dir);
 }
 
 std::string CudaToolChain::getInputFilename(const InputInfo &Input) const {
   // Only object files are changed, for example assembly files keep their .s
   // extensions. CUDA also continues to use .o as they don't use nvlink but

clang/test/Driver/cuda-version-check.cu

 // REQUIRES: clang-driver
 // REQUIRES: x86-registered-target
 // REQUIRES: nvptx-registered-target
 
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_20 --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_20 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA-unknown/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION
+// Make sure that we don't warn about CUDA version during C++ compilation.
+// RUN: %clang --target=x86_64-linux -v -### -x c++ --cuda-gpu-arch=sm_60 \
+// RUN:    --cuda-path=%S/Inputs/CUDA-unknown/usr/local/cuda 2>&1 %s | \
+// RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION_CXX
 
 // The installation at Inputs/CUDA is CUDA 7.0, which doesn't support sm_60.
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=ERR_SM60
 
 // This should only complain about sm_60, not sm_35.
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-gpu-arch=sm_35 \
 // RUN:    --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 %s | \

 // We should only get one error per architecture.
 // ERR_SM60: error: GPU arch sm_60 {{.*}}
 // ERR_SM60-NOT: error: GPU arch sm_60
 
 // ERR_SM61: error: GPU arch sm_61 {{.*}}
 // ERR_SM61-NOT: error: GPU arch sm_61
 
 // UNKNOWN_VERSION: Unknown CUDA version 999.999. Assuming the latest supported version
+// UNKNOWN_VERSION_CXX-NOT: Unknown CUDA version