[CUDA] Detect and link with CUDA's libdevice bitcode library.

- added detection of libdevice bitcode file and API to find one appropriate for the GPU we're compiling for.
- pass additional cc1 options for linking with detected libdevice bitcode
- added -nocudalib to prevent automatic linking with libdevice
- added test cases to verify new functionality

Differential Revision: http://reviews.llvm.org/D14556

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253387 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/Options.td

@@ -1597,6 +1597,7 @@ def no__dead__strip__inits__and__terms : Flag<["-"], "no_dead_strip_inits_and_te
 def nobuiltininc : Flag<["-"], "nobuiltininc">, Flags<[CC1Option]>,
   HelpText<"Disable builtin #include directories">;
 def nocudainc : Flag<["-"], "nocudainc">;
+def nocudalib : Flag<["-"], "nocudalib">;
 def nodefaultlibs : Flag<["-"], "nodefaultlibs">;
 def nofixprebinding : Flag<["-"], "nofixprebinding">;
 def nolibc : Flag<["-"], "nolibc">;

lib/Driver/ToolChains.cpp

@@ -1647,6 +1647,31 @@ void Generic_GCC::CudaInstallationDetector::init(
           D.getVFS().exists(CudaLibDevicePath)))
       continue;
 
+    std::error_code EC;
+    for (llvm::sys::fs::directory_iterator LI(CudaLibDevicePath, EC), LE;
+         !EC && LI != LE; LI = LI.increment(EC)) {
+      StringRef FilePath = LI->path();
+      StringRef FileName = llvm::sys::path::filename(FilePath);
+      // Process all bitcode filenames that look like libdevice.compute_XX.YY.bc
+      const StringRef LibDeviceName = "libdevice.";
+      if (!(FileName.startswith(LibDeviceName) && FileName.endswith(".bc")))
+        continue;
+      StringRef GpuArch = FileName.slice(
+          LibDeviceName.size(), FileName.find('.', LibDeviceName.size()));
+      CudaLibDeviceMap[GpuArch] = FilePath.str();
+      // Insert map entries for specifc devices with this compute capability.
+      if (GpuArch == "compute_20") {
+        CudaLibDeviceMap["sm_20"] = FilePath;
+        CudaLibDeviceMap["sm_21"] = FilePath;
+      } else if (GpuArch == "compute_30") {
+        CudaLibDeviceMap["sm_30"] = FilePath;
+        CudaLibDeviceMap["sm_32"] = FilePath;
+      } else if (GpuArch == "compute_35") {
+        CudaLibDeviceMap["sm_35"] = FilePath;
+        CudaLibDeviceMap["sm_37"] = FilePath;
+      }
+    }
+
     IsValid = true;
     break;
   }
@@ -4195,6 +4220,22 @@ CudaToolChain::addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args) const {
   Linux::addClangTargetOptions(DriverArgs, CC1Args);
   CC1Args.push_back("-fcuda-is-device");
+
+  if (DriverArgs.hasArg(options::OPT_nocudalib))
+    return;
+
+  std::string LibDeviceFile = CudaInstallation.getLibDeviceFile(
+      DriverArgs.getLastArgValue(options::OPT_march_EQ));
+  if (!LibDeviceFile.empty()) {
+    CC1Args.push_back("-mlink-cuda-bitcode");
+    CC1Args.push_back(DriverArgs.MakeArgString(LibDeviceFile));
+
+    // Libdevice in CUDA-7.0 requires PTX version that's more recent
+    // than LLVM defaults to. Use PTX4.2 which is the PTX version that
+    // came with CUDA-7.0.
+    CC1Args.push_back("-target-feature");
+    CC1Args.push_back("+ptx42");
+  }
 }
 
 llvm::opt::DerivedArgList *

lib/Driver/ToolChains.h

@@ -166,6 +166,7 @@ class LLVM_LIBRARY_VISIBILITY Generic_GCC : public ToolChain {
     std::string CudaLibPath;
     std::string CudaLibDevicePath;
     std::string CudaIncludePath;
+    llvm::StringMap<std::string> CudaLibDeviceMap;
 
   public:
     CudaInstallationDetector(const Driver &D) : IsValid(false), D(D) {}
@@ -185,6 +186,9 @@ class LLVM_LIBRARY_VISIBILITY Generic_GCC : public ToolChain {
     /// \brief Get the detected Cuda device library path.
     StringRef getLibDevicePath() const { return CudaLibDevicePath; }
     /// \brief Get libdevice file for given architecture
+    StringRef getLibDeviceFile(StringRef Gpu) const {
+      return CudaLibDeviceMap.lookup(Gpu);
+    }
   };
 
   CudaInstallationDetector CudaInstallation;

test/Driver/cuda-detect.cu

@@ -8,26 +8,51 @@
 // RUN: %clang -v --target=i386-unknown-linux \
 // RUN:   --sysroot=%S/Inputs/CUDA 2>&1 | FileCheck %s
 // RUN: %clang -v --target=i386-unknown-linux \
+// RUN:   --sysroot=%S/Inputs/CUDA 2>&1 | FileCheck %s
+// RUN: %clang -v --target=i386-unknown-linux \
 // RUN:   --cuda-path=%S/Inputs/CUDA/usr/local/cuda 2>&1 | FileCheck %s
 
-// Verify that CUDA include path gets added
+// Make sure we map libdevice bitcode files to proper GPUs.
+// RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_21 \
+// RUN:   --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s 2>&1 \
+// RUN:   | FileCheck %s -check-prefix COMMON \
+// RUN:     -check-prefix LIBDEVICE -check-prefix LIBDEVICE21
 // RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_35 \
 // RUN:   --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s 2>&1 \
-// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix CUDAINC
-// Verify that -nocudainc disables CUDA include paths.
+// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix CUDAINC \
+// RUN:     -check-prefix LIBDEVICE -check-prefix LIBDEVICE35
+// Verify that -nocudainc prevents adding include path to CUDA headers.
 // RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_35 \
 // RUN:   -nocudainc --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s 2>&1 \
-// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix NOCUDAINC
+// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix NOCUDAINC \
+// RUN:     -check-prefix LIBDEVICE -check-prefix LIBDEVICE35
 // We should not add any CUDA include paths if there's no valid CUDA installation
 // RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_35 \
 // RUN:   --cuda-path=%S/no-cuda-there %s 2>&1 \
 // RUN:   | FileCheck %s -check-prefix COMMON -check-prefix NOCUDAINC
 
+// Verify that no options related to bitcode linking are passes if
+// there's no bitcode file.
+// RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_30 \
+// RUN:   --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s 2>&1 \
+// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix NOLIBDEVICE
+// .. or if we explicitly passed -nocudalib
+// RUN: %clang -### -v --target=i386-unknown-linux --cuda-gpu-arch=sm_35 \
+// RUN:   -nocudalib --cuda-path=%S/Inputs/CUDA/usr/local/cuda %s 2>&1 \
+// RUN:   | FileCheck %s -check-prefix COMMON -check-prefix NOLIBDEVICE
+
 // CHECK: Found CUDA installation: {{.*}}/Inputs/CUDA/usr/local/cuda
 // NOCUDA-NOT: Found CUDA installation:
 
 // COMMON: "-triple" "nvptx-nvidia-cuda"
 // COMMON-SAME: "-fcuda-is-device"
+// LIBDEVICE-SAME: "-mlink-cuda-bitcode"
+// NOLIBDEVICE-NOT: "-mlink-cuda-bitcode"
+// LIBDEVICE21-SAME: libdevice.compute_20.10.bc
+// LIBDEVICE35-SAME: libdevice.compute_35.10.bc
+// NOLIBDEVICE-NOT: libdevice.compute_{{.*}}.bc
+// LIBDEVICE-SAME: "-target-feature" "+ptx42"
+// NOLIBDEVICE-NOT: "-target-feature" "+ptx42"
 // CUDAINC-SAME: "-internal-isystem" "{{.*}}/Inputs/CUDA/usr/local/cuda/include"
 // NOCUDAINC-NOT: "-internal-isystem" "{{.*}}/cuda/include"
 // COMMON-SAME: "-x" "cuda"