[CUDA] Fix output name being replaced in device-only mode

[jhuber6]

Summary

When performing device only compilation, there was an issue where
cubin outputs were being renamed to cubin despite the user's name.
This is required in a normal compilation flow as the Nvidia tools only
understand specific filenames instead of checking magic bytes for some
unknown reason. We do not want to perform this transformation when the
user is performing device only compilation.

[tra]

clang/test/Driver/cuda-bindings.cu

148

Ideally we want to test that the output file actually survives the compilation. It's traky to do for in-tree tests as we don't have ptxas. However, we should be able to add a script which would just touch whatever is specified with -o argument and ignore the rest and then actually do run clang with --ptxas-path=/path/to/dummy-ptxas and then verify file existence.

[tra]

I can confirm that this patch fixes the issue.

[jhuber6]

clang/test/Driver/cuda-bindings.cu

148

Yeah, I wasn't sure if there was a good way. I don't have any CUDA machines to test so I just went with the simplest version.

[tra]

clang/test/Driver/cuda-bindings.cu

148

This is a more general problem, not specific to this test -- we have other tests where we assume that if something is printed by cc -###, then it must be real.
I guess it's more of a TODO note for a potential improvement.

This patch is good to go as is.

[jhuber6]

clang/test/Driver/cuda-bindings.cu

148

Okay, I'll land it soon.

clang/lib/Driver/ToolChains/Cuda.cpp

CudaToolChain::CudaToolChain(const Driver &D, const llvm::Triple &Triple,
   }
   // 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. 
-  if (Input.getType() != types::TY_Object)
+  // extensions. If the user requested device-only compilation don't change it.
+  if (Input.getType() != types::TY_Object || getDriver().offloadDeviceOnly())
     return ToolChain::getInputFilename(Input);
 
   // Replace extension for object files with cubin because nvlink relies on
   // these particular file names.
   SmallString<256> Filename(ToolChain::getInputFilename(Input));
   llvm::sys::path::replace_extension(Filename, "cubin");
   return std::string(Filename.str());
 }

clang/test/Driver/cuda-bindings.cu

 // Test two gpu architectures up to the assemble phase in device-only
 // compilation mode.
 //
 // RUN: %clang -target powerpc64le-ibm-linux-gnu -ccc-print-bindings \
 // RUN:        --cuda-gpu-arch=sm_30 --cuda-gpu-arch=sm_35 %s --cuda-device-only -S 2>&1 \
 // RUN: | FileCheck -check-prefix=DASM2 %s
 // DASM2: # "nvptx64-nvidia-cuda" - "clang",{{.*}} output: "cuda-bindings-cuda-nvptx64-nvidia-cuda-sm_30.s"
 // DASM2: # "nvptx64-nvidia-cuda" - "clang",{{.*}} output: "cuda-bindings-cuda-nvptx64-nvidia-cuda-sm_35.s"
+
+//
+// Ensure we output the user's specified name in device-only mode.
+//
+// RUN: %clang -target powerpc64le-ibm-linux-gnu -### \
+// RUN:        --cuda-gpu-arch=sm_52 --cuda-device-only -c -o foo.o %s 2>&1 \
+// RUN: | FileCheck -check-prefix=D_ONLY %s
+// RUN: %clang -target powerpc64le-ibm-linux-gnu -### --offload-new-driver \
+// RUN:        --cuda-gpu-arch=sm_52 --cuda-device-only -c -o foo.o %s 2>&1 \
+// RUN: | FileCheck -check-prefix=D_ONLY %s
+// D_ONLY: "foo.o"