CUDA: Compute CMAKE_CUDA_RUNTIME_LIBRARY default from toolchain

Since commit 0d0145138f (CUDA: Add abstraction for cuda runtime
selection, 2019-11-29, v3.17.0-rc1~83^2) we add CUDA runtime library
selection flags by default.

To maintain backwards compatibility the default CUDA runtime
library needs to be computed based on what libraries are found
on the initial compiler invocation. For example a toolchain
could establish initial flags that have all CUDA compilations
using the runtime version, and if we don't detect this we will
try to link to both the static and shared runtime.

Co-Author: Brad King <brad.king@kitware.com>
Fixes: #20708

10 files changed, 60 insertions, 6 deletions

diff --git a/Help/prop_tgt/CUDA_RUNTIME_LIBRARY.rst b/Help/prop_tgt/CUDA_RUNTIME_LIBRARY.rst
index 0782765..11b344c 100644
--- a/Help/prop_tgt/CUDA_RUNTIME_LIBRARY.rst
+++ b/Help/prop_tgt/CUDA_RUNTIME_LIBRARY.rst
@@ -10,8 +10,8 @@ The allowed case insensitive values are:
 Contents of ``CUDA_RUNTIME_LIBRARY`` may use
 :manual:`generator expressions <cmake-generator-expressions(7)>`.
 
-If this property is not set then CMake uses the default value
-``Static`` to select the CUDA runtime library.
+If that property is not set then CMake uses an appropriate default
+value based on the compiler to select the CUDA runtime library.
 
 .. note::
 
diff --git a/Help/variable/CMAKE_CUDA_RUNTIME_LIBRARY.rst b/Help/variable/CMAKE_CUDA_RUNTIME_LIBRARY.rst
index 698cae7..e3205d3 100644
--- a/Help/variable/CMAKE_CUDA_RUNTIME_LIBRARY.rst
+++ b/Help/variable/CMAKE_CUDA_RUNTIME_LIBRARY.rst
@@ -14,7 +14,8 @@ Contents of ``CMAKE_CUDA_RUNTIME_LIBRARY`` may use
 
 If this variable is not set then the :prop_tgt:`CUDA_RUNTIME_LIBRARY` target
 property will not be set automatically.  If that property is not set then
-CMake uses the default value ``Static`` to select the CUDA runtime library.
+CMake uses an appropriate default value based on the compiler to select the
+CUDA runtime library.
 
 .. note::
 
diff --git a/Modules/CMakeCUDACompiler.cmake.in b/Modules/CMakeCUDACompiler.cmake.in
index 4a615a3..04a4c42 100644
--- a/Modules/CMakeCUDACompiler.cmake.in
+++ b/Modules/CMakeCUDACompiler.cmake.in
@@ -53,5 +53,7 @@ set(CMAKE_CUDA_IMPLICIT_LINK_LIBRARIES "@CMAKE_CUDA_IMPLICIT_LINK_LIBRARIES@")
 set(CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES "@CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES@")
 set(CMAKE_CUDA_IMPLICIT_LINK_FRAMEWORK_DIRECTORIES "@CMAKE_CUDA_IMPLICIT_LINK_FRAMEWORK_DIRECTORIES@")
 
+@_SET_CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT@
+
 set(CMAKE_LINKER "@CMAKE_LINKER@")
 set(CMAKE_MT "@CMAKE_MT@")
diff --git a/Modules/CMakeDetermineCUDACompiler.cmake b/Modules/CMakeDetermineCUDACompiler.cmake
index 7d7fb9a..baf1501 100644
--- a/Modules/CMakeDetermineCUDACompiler.cmake
+++ b/Modules/CMakeDetermineCUDACompiler.cmake
@@ -86,6 +86,20 @@ if(${CMAKE_GENERATOR} MATCHES "Visual Studio")
   set(CMAKE_CUDA_HOST_IMPLICIT_LINK_LIBRARIES "")
   set(CMAKE_CUDA_HOST_IMPLICIT_LINK_DIRECTORIES "")
   set(CMAKE_CUDA_HOST_IMPLICIT_LINK_FRAMEWORK_DIRECTORIES "")
+
+  # We do not currently detect CMAKE_CUDA_HOST_IMPLICIT_LINK_LIBRARIES but we
+  # do need to detect CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT from the compiler by
+  # looking at which cudart library exists in the implicit link libraries passed
+  # to the host linker.
+  if(CMAKE_CUDA_COMPILER_PRODUCED_OUTPUT MATCHES "link\\.exe [^\n]*cudart_static\\.lib")
+    set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "STATIC")
+  elseif(CMAKE_CUDA_COMPILER_PRODUCED_OUTPUT MATCHES "link\\.exe [^\n]*cudart\\.lib")
+    set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "SHARED")
+  else()
+    set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "NONE")
+  endif()
+  set(_SET_CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT
+    "set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT \"${CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT}\")")
 elseif(CMAKE_CUDA_COMPILER_ID STREQUAL NVIDIA)
   set(_nvcc_log "")
   string(REPLACE "\r" "" _nvcc_output_orig "${CMAKE_CUDA_COMPILER_PRODUCED_OUTPUT}")
@@ -179,6 +193,20 @@ elseif(CMAKE_CUDA_COMPILER_ID STREQUAL NVIDIA)
                                    log
                                    "${CMAKE_CUDA_IMPLICIT_OBJECT_REGEX}")
 
+    # Detect CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT from the compiler by looking at which
+    # cudart library exists in the implicit link libraries passed to the host linker.
+    # This is required when a project sets the cuda runtime library as part of the
+    # initial flags.
+    if(";${CMAKE_CUDA_HOST_IMPLICIT_LINK_LIBRARIES};" MATCHES [[;cudart_static(\.lib)?;]])
+      set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "STATIC")
+    elseif(";${CMAKE_CUDA_HOST_IMPLICIT_LINK_LIBRARIES};" MATCHES [[;cudart(\.lib)?;]])
+      set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "SHARED")
+    else()
+      set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "NONE")
+    endif()
+    set(_SET_CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT
+      "set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT \"${CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT}\")")
+
     file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
       "Parsed CUDA nvcc implicit link information from above output:\n${_nvcc_log}\n${log}\n\n")
   else()
diff --git a/Modules/CMakeDetermineCompilerId.cmake b/Modules/CMakeDetermineCompilerId.cmake
index d3ed45b..9eeb7a1 100644
--- a/Modules/CMakeDetermineCompilerId.cmake
+++ b/Modules/CMakeDetermineCompilerId.cmake
@@ -381,7 +381,11 @@ Id flags: ${testflags} ${CMAKE_${lang}_COMPILER_ID_FLAGS_ALWAYS}
       if(CMAKE_VS_PLATFORM_NAME STREQUAL x64)
         set(id_ItemDefinitionGroup_entry "<CudaCompile><TargetMachinePlatform>64</TargetMachinePlatform><AdditionalOptions>%(AdditionalOptions)-v</AdditionalOptions></CudaCompile>")
       endif()
-      set(id_Link_AdditionalDependencies "<AdditionalDependencies>cudart.lib</AdditionalDependencies>")
+      if(CMAKE_CUDA_FLAGS MATCHES "(^| )-cudart +shared( |$)")
+        set(id_Link_AdditionalDependencies "<AdditionalDependencies>cudart.lib</AdditionalDependencies>")
+      else()
+        set(id_Link_AdditionalDependencies "<AdditionalDependencies>cudart_static.lib</AdditionalDependencies>")
+      endif()
     endif()
     configure_file(${CMAKE_ROOT}/Modules/CompilerId/VS-${v}.${ext}.in
       ${id_dir}/CompilerId${lang}.${ext} @ONLY)
diff --git a/Modules/Compiler/NVIDIA-CUDA.cmake b/Modules/Compiler/NVIDIA-CUDA.cmake
index 1f4d54d..671468d 100644
--- a/Modules/Compiler/NVIDIA-CUDA.cmake
+++ b/Modules/Compiler/NVIDIA-CUDA.cmake
@@ -43,7 +43,6 @@ endif()
 set(CMAKE_SHARED_LIBRARY_CREATE_CUDA_FLAGS -shared)
 set(CMAKE_INCLUDE_SYSTEM_FLAG_CUDA -isystem=)
 
-set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "STATIC")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_STATIC  "cudadevrt;cudart_static")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_SHARED  "cudadevrt;cudart")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_NONE    "")
diff --git a/Modules/Platform/Windows-NVIDIA-CUDA.cmake b/Modules/Platform/Windows-NVIDIA-CUDA.cmake
index f809094..98cd5ef 100644
--- a/Modules/Platform/Windows-NVIDIA-CUDA.cmake
+++ b/Modules/Platform/Windows-NVIDIA-CUDA.cmake
@@ -69,7 +69,6 @@ else()
 endif()
 unset(_cmp0092)
 
-set(CMAKE_CUDA_RUNTIME_LIBRARY_DEFAULT "STATIC")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_STATIC  "cudadevrt;cudart_static")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_SHARED  "cudadevrt;cudart")
 set(CMAKE_CUDA_RUNTIME_LIBRARY_LINK_OPTIONS_NONE    "")
diff --git a/Tests/CudaOnly/CMakeLists.txt b/Tests/CudaOnly/CMakeLists.txt
index cc1ee1a..3e3e44c 100644
--- a/Tests/CudaOnly/CMakeLists.txt
+++ b/Tests/CudaOnly/CMakeLists.txt
@@ -6,6 +6,7 @@ ADD_TEST_MACRO(CudaOnly.GPUDebugFlag CudaOnlyGPUDebugFlag)
 ADD_TEST_MACRO(CudaOnly.ResolveDeviceSymbols CudaOnlyResolveDeviceSymbols)
 ADD_TEST_MACRO(CudaOnly.SeparateCompilation CudaOnlySeparateCompilation)
 ADD_TEST_MACRO(CudaOnly.SharedRuntimePlusToolkit CudaOnlySharedRuntimePlusToolkit)
+ADD_TEST_MACRO(CudaOnly.SharedRuntimeViaCUDAFlags CudaOnlySharedRuntimeViaCUDAFlags)
 ADD_TEST_MACRO(CudaOnly.Standard98 CudaOnlyStandard98)
 ADD_TEST_MACRO(CudaOnly.Toolkit CudaOnlyToolkit)
 ADD_TEST_MACRO(CudaOnly.WithDefs CudaOnlyWithDefs)
diff --git a/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/CMakeLists.txt b/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/CMakeLists.txt
new file mode 100644
index 0000000..24ff478
--- /dev/null
+++ b/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/CMakeLists.txt
@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.17)
+project(SharedRuntimeViaCUDAFlags NONE)
+
+set(CMAKE_CUDA_FLAGS "")
+string(APPEND CMAKE_CUDA_FLAGS "-cudart shared")
+
+enable_language(CUDA)
+
+add_executable(CudaOnlySharedRuntimeViaCUDAFlags main.cu)
+
+if(UNIX)
+  # Help the shared cuda runtime find libcudart as it is not located
+  # in a default system searched location
+  set_property(TARGET CudaOnlySharedRuntimeViaCUDAFlags PROPERTY BUILD_RPATH ${CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES})
+endif()
diff --git a/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/main.cu b/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/main.cu
new file mode 100644
index 0000000..766b775
--- /dev/null
+++ b/Tests/CudaOnly/SharedRuntimeViaCUDAFlags/main.cu
@@ -0,0 +1,5 @@
+
+int main()
+{
+  return 0;
+}