From bbaf24341026cdacd1e313dd3f8e3501e9c4070e Mon Sep 17 00:00:00 2001
From: Robert Maynard <robert.maynard@kitware.com>
Date: Sun, 4 Sep 2016 16:29:44 -0400
Subject: CUDA: add support for specifying an explicit host compiler.

---
 Modules/CMakeCUDAInformation.cmake       | 14 ++++++++++----
 Modules/CMakeDetermineCUDACompiler.cmake | 13 ++++++++++++-
 Source/cmCoreTryCompile.cxx              |  3 +++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/Modules/CMakeCUDAInformation.cmake b/Modules/CMakeCUDAInformation.cmake
index 41ed34f..858fee7 100644
--- a/Modules/CMakeCUDAInformation.cmake
+++ b/Modules/CMakeCUDAInformation.cmake
@@ -59,10 +59,16 @@ include(CMakeCommonLanguageInclude)
 # CMAKE_CUDA_COMPILE_OBJECT
 # CMAKE_CUDA_LINK_EXECUTABLE
 
+if(CMAKE_CUDA_HOST_COMPILER)
+  set(CMAKE_CUDA_HOST_FLAGS "-ccbin \"${CMAKE_CUDA_HOST_COMPILER}\" ")
+else()
+  set(CMAKE_CUDA_HOST_FLAGS "")
+endif()
+
 # create a shared library
 if(NOT CMAKE_CUDA_CREATE_SHARED_LIBRARY)
   set(CMAKE_CUDA_CREATE_SHARED_LIBRARY
-      "<CMAKE_CUDA_COMPILER> <CMAKE_SHARED_LIBRARY_CUDA_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_CUDA_FLAGS> <SONAME_FLAG><TARGET_SONAME> -o <TARGET> <OBJECTS> <LINK_LIBRARIES>")
+      "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <CMAKE_SHARED_LIBRARY_CUDA_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_CUDA_FLAGS> <SONAME_FLAG><TARGET_SONAME> -o <TARGET> <OBJECTS> <LINK_LIBRARIES>")
 endif()
 
 # create a shared module copy the shared library rule by default
@@ -85,7 +91,7 @@ endif()
 # compile a cu file into an object file
 if(NOT CMAKE_CUDA_COMPILE_OBJECT)
   set(CMAKE_CUDA_COMPILE_OBJECT
-    "<CMAKE_CUDA_COMPILER>  <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT>")
+    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT>")
 
   #The Ninja generator uses the make file dependency files to determine what
   #files need to be recompiled. Unfortunately, nvcc doesn't support building
@@ -96,7 +102,7 @@ if(NOT CMAKE_CUDA_COMPILE_OBJECT)
   #it is exempt from this logic.
   if(CMAKE_GENERATOR STREQUAL "Ninja")
     list(APPEND CMAKE_CUDA_COMPILE_OBJECT
-      "<CMAKE_CUDA_COMPILER>  <DEFINES> <INCLUDES> <FLAGS> -x cu -M <SOURCE> -MT <OBJECT> -o $DEP_FILE")
+      "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -M <SOURCE> -MT <OBJECT> -o $DEP_FILE")
   endif()
 
 endif()
@@ -104,7 +110,7 @@ endif()
 # compile a cu file into an executable
 if(NOT CMAKE_CUDA_LINK_EXECUTABLE)
   set(CMAKE_CUDA_LINK_EXECUTABLE
-    "<CMAKE_CUDA_COMPILER>  <FLAGS> <CMAKE_CUDA_LINK_FLAGS> <LINK_FLAGS> <OBJECTS>  -o <TARGET> <LINK_LIBRARIES>")
+    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <FLAGS> <CMAKE_CUDA_LINK_FLAGS> <LINK_FLAGS> <OBJECTS>  -o <TARGET> <LINK_LIBRARIES>")
 endif()
 
 
diff --git a/Modules/CMakeDetermineCUDACompiler.cmake b/Modules/CMakeDetermineCUDACompiler.cmake
index a6863ef..d5dc9f4 100644
--- a/Modules/CMakeDetermineCUDACompiler.cmake
+++ b/Modules/CMakeDetermineCUDACompiler.cmake
@@ -23,6 +23,10 @@ endif()
 
 mark_as_advanced(CMAKE_CUDA_COMPILER)
 
+#Allow the user to specify a host compiler
+#todo: need to specify this to compiler test passes
+set(CMAKE_CUDA_HOST_COMPILER "" CACHE FILEPATH "Host compiler to be used by nvcc")
+
 # Build a small source file to identify the compiler.
 if(NOT CMAKE_CUDA_COMPILER_ID_RUN)
   set(CMAKE_CUDA_COMPILER_ID_RUN 1)
@@ -39,9 +43,16 @@ if(NOT CMAKE_CUDA_COMPILER_ID_RUN)
   set(CMAKE_CXX_COMPILER_ID_TOOL_MATCH_REGEX "\nLd[^\n]*(\n[ \t]+[^\n]*)*\n[ \t]+([^ \t\r\n]+)[^\r\n]*-o[^\r\n]*CompilerIdCUDA/(\\./)?(CompilerIdCUDA.xctest/)?CompilerIdCUDA[ \t\n\\\"]")
   set(CMAKE_CXX_COMPILER_ID_TOOL_MATCH_INDEX 2)
 
+  if(CMAKE_CUDA_HOST_COMPILER)
+      # Each entry in this list is a set of extra flags to try
+      # adding to the compile line to see if it helps produce
+      # a valid identification file. In our case this would just
+      # be the explicit host compiler
+      set(CMAKE_CUDA_COMPILER_ID_TEST_FLAGS_FIRST "-ccbin=${CMAKE_CUDA_HOST_COMPILER}")
+  endif()
+
   include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
   CMAKE_DETERMINE_COMPILER_ID(CUDA CUDAFLAGS CMakeCUDACompilerId.cu)
-
 endif()
 
 include(CMakeFindBinUtils)
diff --git a/Source/cmCoreTryCompile.cxx b/Source/cmCoreTryCompile.cxx
index 3b46fc0..b1d3775 100644
--- a/Source/cmCoreTryCompile.cxx
+++ b/Source/cmCoreTryCompile.cxx
@@ -44,6 +44,8 @@ static std::string const kCMAKE_TRY_COMPILE_OSX_ARCHITECTURES =
   "CMAKE_TRY_COMPILE_OSX_ARCHITECTURES";
 static std::string const kCMAKE_TRY_COMPILE_PLATFORM_VARIABLES =
   "CMAKE_TRY_COMPILE_PLATFORM_VARIABLES";
+static std::string const kCMAKE_CUDA_HOST_COMPILER =
+  "CMAKE_CUDA_HOST_COMPILER";
 
 int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
                                      bool isTryRun)
@@ -453,6 +455,7 @@ int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv,
       vars.insert(kCMAKE_OSX_SYSROOT);
       vars.insert(kCMAKE_POSITION_INDEPENDENT_CODE);
       vars.insert(kCMAKE_SYSROOT);
+      vars.insert(kCMAKE_CUDA_HOST_COMPILER);
 
       if (const char* varListStr = this->Makefile->GetDefinition(
             kCMAKE_TRY_COMPILE_PLATFORM_VARIABLES)) {
-- 
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