Use ExternalProject for build tools x-compile

Author: alexreinking

Makefile

@@ -958,7 +958,7 @@ $(INCLUDE_DIR)/HalidePyTorchCudaHelpers.h: $(SRC_DIR)/runtime/HalidePyTorchCudaH
 	@mkdir -p $(@D)
 	cp $< $(INCLUDE_DIR)/
 
-$(BIN_DIR)/build_halide_h: $(ROOT_DIR)/tools/build_halide_h.cpp
+$(BIN_DIR)/build_halide_h: $(ROOT_DIR)/src/tools/build_halide_h.cpp
 	@-mkdir -p $(@D)
 	$(CXX) -std=c++11 $< -o $@
 
@@ -1020,7 +1020,7 @@ $(BUILD_DIR)/initmod.inlined_c.cpp: $(BIN_DIR)/binary2cpp $(SRC_DIR)/runtime/hal
 $(BUILD_DIR)/initmod_ptx.%_ll.cpp: $(BIN_DIR)/binary2cpp $(SRC_DIR)/runtime/nvidia_libdevice_bitcode/libdevice.%.bc
 	./$(BIN_DIR)/binary2cpp halide_internal_initmod_ptx_$(basename $*)_ll < $(SRC_DIR)/runtime/nvidia_libdevice_bitcode/libdevice.$*.bc > $@
 
-$(BIN_DIR)/binary2cpp: $(ROOT_DIR)/tools/binary2cpp.cpp
+$(BIN_DIR)/binary2cpp: $(ROOT_DIR)/src/tools/binary2cpp.cpp
 	@mkdir -p $(@D)
 	$(CXX) $< -o $@
 
@@ -1339,7 +1339,7 @@ $(FILTERS_DIR)/cxx_mangling_externs.o: $(ROOT_DIR)/test/generator/cxx_mangling_e
 $(FILTERS_DIR)/cxx_mangling.a: $(BIN_DIR)/cxx_mangling.generator $(FILTERS_DIR)/cxx_mangling_externs.o
 	@mkdir -p $(@D)
 	$(CURDIR)/$< -g cxx_mangling $(GEN_AOT_OUTPUTS) -o $(CURDIR)/$(FILTERS_DIR) target=$(TARGET)-no_runtime-c_plus_plus_name_mangling -f "HalideTest::AnotherNamespace::cxx_mangling"
-	$(ROOT_DIR)/tools/makelib.sh $@ $@ $(FILTERS_DIR)/cxx_mangling_externs.o
+	$(ROOT_DIR)/src/tools/makelib.sh $@ $@ $(FILTERS_DIR)/cxx_mangling_externs.o
 
 ifneq ($(TEST_CUDA), )
 # Also build with a gpu target to ensure that the GPU-Host generation
@@ -1348,7 +1348,7 @@ ifneq ($(TEST_CUDA), )
 $(FILTERS_DIR)/cxx_mangling_gpu.a: $(BIN_DIR)/cxx_mangling.generator $(FILTERS_DIR)/cxx_mangling_externs.o
 	@mkdir -p $(@D)
 	$(CURDIR)/$< -g cxx_mangling $(GEN_AOT_OUTPUTS) -o $(CURDIR)/$(FILTERS_DIR) target=$(TARGET)-no_runtime-c_plus_plus_name_mangling-cuda-cuda_capability_30 -f "HalideTest::cxx_mangling_gpu"
-	$(ROOT_DIR)/tools/makelib.sh $@ $@ $(FILTERS_DIR)/cxx_mangling_externs.o
+	$(ROOT_DIR)/src/tools/makelib.sh $@ $@ $(FILTERS_DIR)/cxx_mangling_externs.o
 endif
 
 $(FILTERS_DIR)/cxx_mangling_define_extern_externs.o: $(ROOT_DIR)/test/generator/cxx_mangling_define_extern_externs.cpp $(FILTERS_DIR)/cxx_mangling.h
@@ -1358,7 +1358,7 @@ $(FILTERS_DIR)/cxx_mangling_define_extern_externs.o: $(ROOT_DIR)/test/generator/
 $(FILTERS_DIR)/cxx_mangling_define_extern.a: $(BIN_DIR)/cxx_mangling_define_extern.generator $(FILTERS_DIR)/cxx_mangling_define_extern_externs.o
 	@mkdir -p $(@D)
 	$(CURDIR)/$< -g cxx_mangling_define_extern $(GEN_AOT_OUTPUTS) -o $(CURDIR)/$(FILTERS_DIR) target=$(TARGET)-no_runtime-c_plus_plus_name_mangling-user_context -f "HalideTest::cxx_mangling_define_extern"
-	$(ROOT_DIR)/tools/makelib.sh $@ $@  $(FILTERS_DIR)/cxx_mangling_define_extern_externs.o
+	$(ROOT_DIR)/src/tools/makelib.sh $@ $@  $(FILTERS_DIR)/cxx_mangling_define_extern_externs.o
 
 # pyramid needs a custom arg.
 $(FILTERS_DIR)/pyramid.a: $(BIN_DIR)/pyramid.generator

src/CMakeLists.txt

@@ -341,6 +341,48 @@ set(SOURCE_FILES
     WrapCalls.cpp
     )
 
+##
+# Build time tools
+##
+
+if (CMAKE_CROSSCOMPILING)
+    # Note: using CMAKE_EXECUTABLE_SUFFIX breaks cross-OS builds involving Windows.
+    include(ExternalProject)
+    ExternalProject_Add(host-tools
+                        BUILD_BYPRODUCTS
+                        "<INSTALL_DIR>/bin/build_halide_h${CMAKE_EXECUTABLE_SUFFIX}"
+                        "<INSTALL_DIR>/bin/binary2cpp${CMAKE_EXECUTABLE_SUFFIX}"
+                        SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/tools
+                        INSTALL_DIR ${CMAKE_CURRENT_BINARY_DIR}/host-tools
+                        CMAKE_ARGS
+                        -D CMAKE_TOOLCHAIN_FILE=${Halide_HOST_TOOLCHAIN_FILE}
+                        -D CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                        -D CMAKE_INSTALL_PREFIX=<INSTALL_DIR>
+                        BUILD_ALWAYS YES)
+
+    # We avoid a full super-build by manually creating imported targets here.
+    # If we start adding lots of build-time tools, we should migrate to the
+    # export() mechanism, which would also avoid the cross-OS bug.
+    ExternalProject_Get_Property(host-tools INSTALL_DIR)
+
+    add_executable(build_halide_h IMPORTED GLOBAL)
+    set_target_properties(build_halide_h
+                          PROPERTIES
+                          IMPORTED_LOCATION "${INSTALL_DIR}/bin/build_halide_h${CMAKE_EXECUTABLE_SUFFIX}"
+                          CROSSCOMPILING_EMULATOR "")
+    add_dependencies(build_halide_h host-tools)
+
+    add_executable(binary2cpp IMPORTED GLOBAL)
+    set_target_properties(binary2cpp
+                          PROPERTIES
+                          IMPORTED_LOCATION "${INSTALL_DIR}/bin/binary2cpp${CMAKE_EXECUTABLE_SUFFIX}"
+                          CROSSCOMPILING_EMULATOR "")
+    add_dependencies(binary2cpp host-tools)
+else ()
+    # Do the safe, reliable thing when not cross-compiling.
+    add_subdirectory(tools)
+endif ()
+
 ##
 # Build and import the runtime.
 ##
@@ -351,11 +393,12 @@ add_subdirectory(runtime)
 # Build the Halide mono-header.
 ##
 
+file(MAKE_DIRECTORY ${Halide_BINARY_DIR}/include)
+
 set(HALIDE_H "${Halide_BINARY_DIR}/include/Halide.h")
 set(LICENSE_PATH "${Halide_SOURCE_DIR}/LICENSE.txt")
 add_custom_command(OUTPUT "${Halide_BINARY_DIR}/include/Halide.h"
                    VERBATIM
-                   COMMAND ${CMAKE_COMMAND} -E make_directory "$<SHELL_PATH:${Halide_BINARY_DIR}/include>"
                    COMMAND build_halide_h "$<SHELL_PATH:${LICENSE_PATH}>" ${HEADER_FILES} > "$<SHELL_PATH:${HALIDE_H}>"
                    WORKING_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}"
                    DEPENDS build_halide_h "${LICENSE_PATH}" ${HEADER_FILES})

src/tools/CMakeLists.txt

@@ -0,0 +1,19 @@
+cmake_minimum_required(VERSION 3.16)
+project(host-tools)
+
+# Require standard C++14
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+add_executable(binary2cpp binary2cpp.cpp)
+add_executable(build_halide_h build_halide_h.cpp)
+add_executable(find_inverse find_inverse.cpp)
+
+# Don't install when included via add_subdirectory.
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+    include(GNUInstallDirs)
+    install(TARGETS build_halide_h binary2cpp find_inverse
+            EXPORT host-tools
+            RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+endif ()

tools/binary2cpp.cpp renamed to src/tools/binary2cpp.cpp

@@ -1,13 +1,3 @@
-##
-# Build time tools
-##
-
-add_executable(build_halide_h build_halide_h.cpp)
-target_compile_options(build_halide_h PRIVATE $<$<CXX_COMPILER_ID:MSVC>:/wd4996>)
-
-add_executable(binary2cpp binary2cpp.cpp)
-target_compile_options(binary2cpp PRIVATE $<$<CXX_COMPILER_ID:MSVC>:/wd4996>)
-
 ##
 # Interface target for enabling PNG/JPEG support in Halide
 ##
@@ -54,4 +44,4 @@ add_library(Halide::Tools ALIAS Halide_Tools)
 target_include_directories(Halide_Tools
                            INTERFACE
                            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
-set_target_properties(Halide_Tools PROPERTIES EXPORT_NAME Tools)
+set_target_properties(Halide_Tools PROPERTIES EXPORT_NAME Tools)