CUDA: Allow both CUDA_SEPARABLE_COMPILATION and CUDA_PTX_COMPILATION

The target properties `CUDA_SEPARABLE_COMPILATION` and `CUDA_PTX_COMPILATION`
now aren't mutually exclusive and can now be used together on the same
target.

Help/release/dev/cuda-ptx-separable-compilation.rst

@@ -0,0 +1,5 @@
+cuda-ptx-separable-compilation
+------------------------------
+
+* ``CUDA`` targets can now enable both :prop_tgt:`CUDA_SEPARABLE_COMPILATION` and
+  :prop_tgt:`CUDA_PTX_COMPILATION`.

Modules/CMakeCUDAInformation.cmake

@@ -160,22 +160,9 @@ if(NOT DEFINED CMAKE_CUDA_ARCHIVE_FINISH)
   set(CMAKE_CUDA_ARCHIVE_FINISH "<CMAKE_RANLIB> <TARGET>")
 endif()
 
-#Specify how to compile when ptx has been requested
-if(NOT CMAKE_CUDA_COMPILE_PTX_COMPILATION)
-  set(CMAKE_CUDA_COMPILE_PTX_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} ${_CMAKE_CUDA_PTX_FLAG} <SOURCE> -o <OBJECT>")
-endif()
-
-#Specify how to compile when separable compilation has been requested
-if(NOT CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION)
-  set(CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} ${_CMAKE_CUDA_DEVICE_CODE} <SOURCE> -o <OBJECT>")
-endif()
-
-#Specify how to compile when whole compilation has been requested
-if(NOT CMAKE_CUDA_COMPILE_WHOLE_COMPILATION)
-  set(CMAKE_CUDA_COMPILE_WHOLE_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} -c <SOURCE> -o <OBJECT>")
+if(NOT CMAKE_CUDA_COMPILE_OBJECT)
+  set(CMAKE_CUDA_COMPILE_OBJECT
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} <CUDA_COMPILE_MODE> <SOURCE> -o <OBJECT>")
 endif()
 
 # compile a cu file into an executable

Modules/Compiler/Clang-CUDA.cmake

@@ -18,8 +18,9 @@ __compiler_clang_cxx_standards(CUDA)
 
 set(CMAKE_CUDA_COMPILER_HAS_DEVICE_LINK_PHASE TRUE)
 set(_CMAKE_COMPILE_AS_CUDA_FLAG "-x cuda")
+set(_CMAKE_CUDA_WHOLE_FLAG "-c")
+set(_CMAKE_CUDA_RDC_FLAG "-fgpu-rdc")
 set(_CMAKE_CUDA_PTX_FLAG "--cuda-device-only -S")
-set(_CMAKE_CUDA_DEVICE_CODE "-fgpu-rdc -c")
 
 # RulePlaceholderExpander expands crosscompile variables like sysroot and target only for CMAKE_<LANG>_COMPILER. Override the default.
 set(CMAKE_CUDA_LINK_EXECUTABLE "<CMAKE_CUDA_COMPILER> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICIT_LINKS}")

Modules/Compiler/NVIDIA-CUDA.cmake

@@ -5,8 +5,9 @@ set(CMAKE_CUDA_VERBOSE_FLAG "-v")
 set(CMAKE_CUDA_VERBOSE_COMPILE_FLAG "-Xcompiler=-v")
 
 set(_CMAKE_COMPILE_AS_CUDA_FLAG "-x cu")
+set(_CMAKE_CUDA_WHOLE_FLAG "-c")
+set(_CMAKE_CUDA_RDC_FLAG "-rdc=true")
 set(_CMAKE_CUDA_PTX_FLAG "-ptx")
-set(_CMAKE_CUDA_DEVICE_CODE "-dc")
 
 if (CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL 10.2.89)
   # The -forward-unknown-to-host-compiler flag was only

Modules/Platform/Windows-NVIDIA-CUDA.cmake

@@ -1,11 +1,7 @@
 include(Platform/Windows-MSVC)
 
-set(CMAKE_CUDA_COMPILE_PTX_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} -ptx <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
-set(CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} -dc <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
-set(CMAKE_CUDA_COMPILE_WHOLE_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} -c <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
+set(CMAKE_CUDA_COMPILE_OBJECT
+  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> ${_CMAKE_COMPILE_AS_CUDA_FLAG} <CUDA_COMPILE_MODE> <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
 
 set(__IMPLICIT_LINKS)
 foreach(dir ${CMAKE_CUDA_HOST_IMPLICIT_LINK_DIRECTORIES})

Source/cmMakefileTargetGenerator.cxx

@@ -897,28 +897,31 @@ void cmMakefileTargetGenerator::WriteObjectRuleFiles(
 
   // Construct the compile rules.
   {
-    std::vector<std::string> compileCommands;
+    std::string cudaCompileMode;
     if (lang == "CUDA") {
-      std::string cmdVar;
       if (this->GeneratorTarget->GetPropertyAsBool(
             "CUDA_SEPARABLE_COMPILATION")) {
-        cmdVar = "CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION";
-      } else if (this->GeneratorTarget->GetPropertyAsBool(
-                   "CUDA_PTX_COMPILATION")) {
-        cmdVar = "CMAKE_CUDA_COMPILE_PTX_COMPILATION";
+        const std::string& rdcFlag =
+          this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_RDC_FLAG");
+        cudaCompileMode = cmStrCat(cudaCompileMode, rdcFlag, " ");
+      }
+      if (this->GeneratorTarget->GetPropertyAsBool("CUDA_PTX_COMPILATION")) {
+        const std::string& ptxFlag =
+          this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_PTX_FLAG");
+        cudaCompileMode = cmStrCat(cudaCompileMode, ptxFlag);
       } else {
-        cmdVar = "CMAKE_CUDA_COMPILE_WHOLE_COMPILATION";
+        const std::string& wholeFlag =
+          this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_WHOLE_FLAG");
+        cudaCompileMode = cmStrCat(cudaCompileMode, wholeFlag);
       }
-      const std::string& compileRule =
-        this->Makefile->GetRequiredDefinition(cmdVar);
-      cmExpandList(compileRule, compileCommands);
-    } else {
-      const std::string cmdVar = "CMAKE_" + lang + "_COMPILE_OBJECT";
-      const std::string& compileRule =
-        this->Makefile->GetRequiredDefinition(cmdVar);
-      cmExpandList(compileRule, compileCommands);
+      vars.CudaCompileMode = cudaCompileMode.c_str();
     }
 
+    std::vector<std::string> compileCommands;
+    const std::string& compileRule = this->Makefile->GetRequiredDefinition(
+      "CMAKE_" + lang + "_COMPILE_OBJECT");
+    cmExpandList(compileRule, compileCommands);
+
     if (this->GeneratorTarget->GetPropertyAsBool("EXPORT_COMPILE_COMMANDS") &&
         lang_can_export_cmds && compileCommands.size() == 1) {
       std::string compileCommand = compileCommands[0];

Source/cmNinjaTargetGenerator.cxx

@@ -605,6 +605,7 @@ void cmNinjaTargetGenerator::WriteCompileRule(const std::string& lang,
   vars.TargetCompilePDB = "$TARGET_COMPILE_PDB";
   vars.ObjectDir = "$OBJECT_DIR";
   vars.ObjectFileDir = "$OBJECT_FILE_DIR";
+  vars.CudaCompileMode = "$CUDA_COMPILE_MODE";
   vars.ISPCHeader = "$ISPC_HEADER_FILE";
 
   cmMakefile* mf = this->GetMakefile();
@@ -815,27 +816,32 @@ void cmNinjaTargetGenerator::WriteCompileRule(const std::string& lang,
   vars.Flags = flags.c_str();
   vars.DependencyFile = rule.DepFile.c_str();
 
-  // Rule for compiling object file.
-  std::vector<std::string> compileCmds;
+  std::string cudaCompileMode;
   if (lang == "CUDA") {
-    std::string cmdVar;
     if (this->GeneratorTarget->GetPropertyAsBool(
           "CUDA_SEPARABLE_COMPILATION")) {
-      cmdVar = "CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION";
-    } else if (this->GeneratorTarget->GetPropertyAsBool(
-                 "CUDA_PTX_COMPILATION")) {
-      cmdVar = "CMAKE_CUDA_COMPILE_PTX_COMPILATION";
+      const std::string& rdcFlag =
+        this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_RDC_FLAG");
+      cudaCompileMode = cmStrCat(cudaCompileMode, rdcFlag, " ");
+    }
+    if (this->GeneratorTarget->GetPropertyAsBool("CUDA_PTX_COMPILATION")) {
+      const std::string& ptxFlag =
+        this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_PTX_FLAG");
+      cudaCompileMode = cmStrCat(cudaCompileMode, ptxFlag);
     } else {
-      cmdVar = "CMAKE_CUDA_COMPILE_WHOLE_COMPILATION";
+      const std::string& wholeFlag =
+        this->Makefile->GetRequiredDefinition("_CMAKE_CUDA_WHOLE_FLAG");
+      cudaCompileMode = cmStrCat(cudaCompileMode, wholeFlag);
     }
-    const std::string& compileCmd = mf->GetRequiredDefinition(cmdVar);
-    cmExpandList(compileCmd, compileCmds);
-  } else {
-    const std::string cmdVar = cmStrCat("CMAKE_", lang, "_COMPILE_OBJECT");
-    const std::string& compileCmd = mf->GetRequiredDefinition(cmdVar);
-    cmExpandList(compileCmd, compileCmds);
+    vars.CudaCompileMode = cudaCompileMode.c_str();
   }
 
+  // Rule for compiling object file.
+  std::vector<std::string> compileCmds;
+  const std::string cmdVar = cmStrCat("CMAKE_", lang, "_COMPILE_OBJECT");
+  const std::string& compileCmd = mf->GetRequiredDefinition(cmdVar);
+  cmExpandList(compileCmd, compileCmds);
+
   // See if we need to use a compiler launcher like ccache or distcc
   std::string compilerLauncher;
   if (!compileCmds.empty() &&

Source/cmRulePlaceholderExpander.cxx

@@ -85,6 +85,11 @@ std::string cmRulePlaceholderExpander::ExpandRuleVariable(
       return replaceValues.ObjectsQuoted;
     }
   }
+  if (replaceValues.CudaCompileMode) {
+    if (variable == "CUDA_COMPILE_MODE") {
+      return replaceValues.CudaCompileMode;
+    }
+  }
   if (replaceValues.AIXExports) {
     if (variable == "AIX_EXPORTS") {
       return replaceValues.AIXExports;

Source/cmRulePlaceholderExpander.h

@@ -65,6 +65,7 @@ public:
     const char* SwiftOutputFileMap = nullptr;
     const char* SwiftSources = nullptr;
     const char* ISPCHeader = nullptr;
+    const char* CudaCompileMode = nullptr;
     const char* Fatbinary = nullptr;
     const char* RegisterFile = nullptr;
     const char* Launcher = nullptr;

Source/cmVisualStudio10TargetGenerator.cxx

@@ -3211,18 +3211,17 @@ bool cmVisualStudio10TargetGenerator::ComputeCudaOptions(
   // the default to not have any extension
   cudaOptions.AddFlag("CompileOut", "$(IntDir)%(Filename).obj");
 
-  bool notPtx = true;
   if (this->GeneratorTarget->GetPropertyAsBool("CUDA_SEPARABLE_COMPILATION")) {
     cudaOptions.AddFlag("GenerateRelocatableDeviceCode", "true");
-  } else if (this->GeneratorTarget->GetPropertyAsBool(
-               "CUDA_PTX_COMPILATION")) {
+  }
+  bool notPtx = true;
+  if (this->GeneratorTarget->GetPropertyAsBool("CUDA_PTX_COMPILATION")) {
     cudaOptions.AddFlag("NvccCompilation", "ptx");
     // We drop the %(Extension) component as CMake expects all PTX files
     // to not have the source file extension at all
     cudaOptions.AddFlag("CompileOut", "$(IntDir)%(Filename).ptx");
     notPtx = false;
   }
-
   if (notPtx &&
       cmSystemTools::VersionCompareGreaterEq(
         "8.0", this->GlobalGenerator->GetPlatformToolsetCudaString())) {

Tests/CudaOnly/CMakeLists.txt

@@ -16,6 +16,7 @@ add_cuda_test_macro(CudaOnly.WithDefs CudaOnlyWithDefs)
 add_cuda_test_macro(CudaOnly.CircularLinkLine CudaOnlyCircularLinkLine)
 add_cuda_test_macro(CudaOnly.ResolveDeviceSymbols CudaOnlyResolveDeviceSymbols)
 add_cuda_test_macro(CudaOnly.SeparateCompilation main/CudaOnlySeparateCompilation)
+add_cuda_test_macro(CudaOnly.SeparateCompilationPTX CudaOnlySeparateCompilationPTX)
 
 if(CMake_TEST_CUDA AND NOT CMake_TEST_CUDA STREQUAL "Clang")
   # Clang doesn't have flags for selecting the runtime.

Tests/CudaOnly/ExportPTX/CMakeLists.txt

@@ -56,7 +56,7 @@ add_custom_command(
     "-DBIN_TO_C_COMMAND=${bin_to_c}"
     "-DOBJECTS=$<TARGET_OBJECTS:CudaPTX>"
     "-DOUTPUT=${output_file}"
-    -P ${CMAKE_CURRENT_SOURCE_DIR}/bin2c_wrapper.cmake
+    -P ${CMAKE_CURRENT_SOURCE_DIR}/../utils/bin2c_wrapper.cmake
   VERBATIM
   DEPENDS $<TARGET_OBJECTS:CudaPTX>
   COMMENT "Converting Object files to a C header"

Tests/CudaOnly/SeparateCompilationPTX/CMakeLists.txt

@@ -0,0 +1,51 @@
+cmake_minimum_required(VERSION 3.19)
+project (SeparateCompPTX CUDA)
+
+#Goal for this example:
+# How to generate PTX files with RDC enabled
+
+# PTX can be compiled only for a single virtual architecture at a time
+list(POP_FRONT CMAKE_CUDA_ARCHITECTURES temp)
+set(CMAKE_CUDA_ARCHITECTURES ${temp})
+string(APPEND CMAKE_CUDA_ARCHITECTURES "-virtual")
+
+add_library(CudaPTX OBJECT kernels.cu)
+set_property(TARGET CudaPTX PROPERTY CUDA_PTX_COMPILATION ON)
+set_property(TARGET CudaPTX PROPERTY CUDA_SEPARABLE_COMPILATION ON)
+
+
+set(output_file ${CMAKE_CURRENT_BINARY_DIR}/embedded_objs.h)
+
+find_package(CUDAToolkit REQUIRED)
+find_program(bin_to_c
+  NAMES bin2c
+  PATHS ${CUDAToolkit_BIN_DIR}
+  )
+if(NOT bin_to_c)
+  message(FATAL_ERROR
+    "bin2c not found:\n"
+    "  CUDAToolkit_BIN_DIR='${CUDAToolkit_BIN_DIR}'\n"
+    )
+endif()
+
+add_custom_command(
+  OUTPUT "${output_file}"
+  COMMAND ${CMAKE_COMMAND}
+    "-DBIN_TO_C_COMMAND=${bin_to_c}"
+    "-DOBJECTS=$<TARGET_OBJECTS:CudaPTX>"
+    "-DOUTPUT=${output_file}"
+    -P ${CMAKE_CURRENT_SOURCE_DIR}/../utils/bin2c_wrapper.cmake
+  VERBATIM
+  DEPENDS $<TARGET_OBJECTS:CudaPTX>
+  COMMENT "Converting Object files to a C header"
+  )
+
+add_executable(CudaOnlySeparateCompilationPTX main.cu ${output_file})
+target_compile_features(CudaOnlySeparateCompilationPTX PRIVATE cuda_std_11)
+target_include_directories(CudaOnlySeparateCompilationPTX PRIVATE
+                           ${CMAKE_CURRENT_BINARY_DIR} )
+target_link_libraries(CudaOnlySeparateCompilationPTX PRIVATE CUDA::cuda_driver)
+if(APPLE)
+  # Help the static cuda runtime find the driver (libcuda.dyllib) at runtime.
+  set_property(TARGET CudaOnlySeparateCompilationPTX PROPERTY BUILD_RPATH ${CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES})
+endif()

Tests/CudaOnly/SeparateCompilationPTX/kernels.cu

@@ -0,0 +1,14 @@
+
+__global__ void kernelA(float* r, float* x, float* y, float* z, int size)
+{
+  for (int i = threadIdx.x; i < size; i += blockDim.x) {
+    r[i] = x[i] * y[i] + z[i];
+  }
+}
+
+__global__ void kernelB(float* r, float* x, float* y, float* z, int size)
+{
+  for (int i = threadIdx.x; i < size; i += blockDim.x) {
+    r[i] = x[i] * y[i] + z[i];
+  }
+}

Tests/CudaOnly/SeparateCompilationPTX/main.cu

@@ -0,0 +1,30 @@
+#include <iostream>
+
+#include <cuda.h>
+
+#include "embedded_objs.h"
+
+int main()
+{
+  cuInit(0);
+  int count = 0;
+  cuDeviceGetCount(&count);
+  if (count == 0) {
+    std::cerr << "No CUDA devices found\n";
+    return 1;
+  }
+
+  CUdevice device;
+  cuDeviceGet(&device, 0);
+
+  CUcontext context;
+  cuCtxCreate(&context, 0, device);
+
+  CUmodule module;
+  cuModuleLoadData(&module, kernels);
+  if (module == nullptr) {
+    std::cerr << "Failed to load the embedded ptx" << std::endl;
+    return 1;
+  }
+  std::cout << module << std::endl;
+}