Add helper for cross-compiling Halide generators.

apps/hannk/halide/CMakeLists.txt

@@ -1,45 +1,3 @@
-add_custom_target(hannk-halide_generators)
-
-# This function adds the target ${TARGET} to the hannk-halide_generators
-# CMake package that exists in the build-tree of a host build. It also adds
-# it to the target of the same name that can be used as a convenience for
-# just building the host targets.
-function(_export_host_target TARGET)
-    add_dependencies(hannk-halide_generators ${TARGET})
-    export(TARGETS ${TARGET}
-           NAMESPACE hannk::halide_generators::
-           APPEND FILE "${hannk_BINARY_DIR}/hannk-halide_generators-config.cmake")
-endfunction()
-
-# Emscripten tries to disable finding packages outside its sysroot,
-# but we need our native generators. Setting CMAKE_FIND_ROOT_PATH_BOTH
-# here overrides Emscripten's search preference.
-find_package(hannk-halide_generators QUIET CMAKE_FIND_ROOT_PATH_BOTH)
-
-if (hannk-halide_generators_FOUND)
-    message(STATUS "Using hannk-halide_generators from ${hannk-halide_generators_DIR}")
-else ()
-    if (CMAKE_CROSSCOMPILING)
-        message(WARNING
-                "hannk-halide_generators were not found and it looks like you are cross-compiling. "
-                "This is likely to fail. Please set -Dhannk-halide_generators_ROOT=... at the CMake "
-                "command line to the build directory of a host-built hannk.")
-    endif ()
-    find_package(Halide REQUIRED)
-endif ()
-
-if (NOT TARGET hannk::halide_generators::common_halide)
-    add_library(common_halide STATIC common_halide.cpp)
-    add_library(hannk::halide_generators::common_halide ALIAS common_halide)
-
-    target_link_libraries(common_halide PRIVATE Halide::Halide)
-    target_include_directories(common_halide PUBLIC $<BUILD_INTERFACE:${hannk_SOURCE_DIR}>)
-
-    _export_host_target(common_halide)
-endif ()
-
-# ----------------------------
-
 function(_begin_halide_library_set LIBRARY_SET)
     add_library(${LIBRARY_SET} INTERFACE)
     target_include_directories(${LIBRARY_SET} INTERFACE "$<BUILD_INTERFACE:${hannk_BINARY_DIR}>")
@@ -50,22 +8,16 @@ endfunction()
 function(_add_halide_library_set LIBRARY_SET)
     set(options)
     set(oneValueArgs TARGET GENERATOR_NAME)
-    set(multiValueArgs SRCS GENERATOR_ARGS GENERATOR_DEPS FEATURES)
+    set(multiValueArgs SRCS GENERATOR_ARGS FEATURES)
     cmake_parse_arguments(args "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
-    set(gen hannk::halide_generators::${args_TARGET}.generator)
-
-    if (NOT TARGET ${gen})
-        add_executable(${args_TARGET}.generator ${args_SRCS})
-        add_executable(${gen} ALIAS ${args_TARGET}.generator)
-
-        target_link_libraries(${args_TARGET}.generator PRIVATE ${args_GENERATOR_DEPS} common_halide Halide::Generator)
-        target_include_directories(${args_TARGET}.generator PUBLIC $<BUILD_INTERFACE:${hannk_SOURCE_DIR}>)
-
-        _export_host_target(${args_TARGET}.generator)
+    add_halide_generator(${args_TARGET}.generator ${args_SRCS})
+    if (TARGET ${args_TARGET}.generator)
+        target_link_libraries(${args_TARGET}.generator PRIVATE common_halide)
+        target_include_directories(${args_TARGET}.generator PRIVATE $<BUILD_INTERFACE:${hannk_SOURCE_DIR}>)
     endif ()
 
-    add_halide_library(${args_TARGET} FROM ${gen}
+    add_halide_library(${args_TARGET} FROM hannk::halide_generators::${args_TARGET}.generator
                        NAMESPACE hannk
                        GENERATOR ${args_GENERATOR_NAME}
                        FEATURES c_plus_plus_name_mangling ${args_FEATURES}
@@ -76,7 +28,18 @@ function(_add_halide_library_set LIBRARY_SET)
 endfunction()
 
 function(_finish_halide_library_set LIBRARY_SET)
-    # Nothing to do for now.
+    # Create common sources target if it wasn't imported by add_halide_generator above.
+    if (NOT TARGET hannk::halide_generators::common_halide)
+        add_library(common_halide STATIC common_halide.cpp)
+        add_library(hannk::halide_generators::common_halide ALIAS common_halide)
+
+        target_link_libraries(common_halide PRIVATE Halide::Halide)
+        target_include_directories(common_halide PUBLIC $<BUILD_INTERFACE:${hannk_SOURCE_DIR}>)
+
+        export(TARGETS common_halide
+               NAMESPACE hannk::halide_generators::
+               APPEND FILE "${hannk_BINARY_DIR}/cmake/hannk-halide_generators-config.cmake")
+    endif ()
 endfunction()
 
 # ---------------------------
@@ -88,134 +51,116 @@ _add_halide_library_set(halide_op_implementations
         SRCS elementwise_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Add
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET average_pool_uint8
         SRCS pool_generator.cpp
         GENERATOR_NAME AveragePool
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET conv_u8_u8_u8
         SRCS conv_generator.cpp
         GENERATOR_NAME Conv
-        GENERATOR_ARGS output.type=uint8
-        GENERATOR_DEPS)
+        GENERATOR_ARGS output.type=uint8)
 
 _add_halide_library_set(halide_op_implementations
         TARGET conv_u8_u8_i16
         SRCS conv_generator.cpp
         GENERATOR_NAME Conv
-        GENERATOR_ARGS output.type=int16
-        GENERATOR_DEPS)
+        GENERATOR_ARGS output.type=int16)
 
 _add_halide_library_set(halide_op_implementations
         TARGET copy_uint8_uint8
         SRCS copy_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Copy
-        GENERATOR_ARGS input.type=uint8 output.type=uint8
-        GENERATOR_DEPS)
+        GENERATOR_ARGS input.type=uint8 output.type=uint8)
 
 _add_halide_library_set(halide_op_implementations
         TARGET depthwise_conv_uint8
         SRCS depthwise_conv_generator.cpp
         GENERATOR_NAME DepthwiseConv
-        GENERATOR_ARGS inv_depth_multiplier=1
-        GENERATOR_DEPS)
+        GENERATOR_ARGS inv_depth_multiplier=1)
 
 _add_halide_library_set(halide_op_implementations
         TARGET depthwise_conv_broadcast_uint8
         SRCS depthwise_conv_generator.cpp
         GENERATOR_NAME DepthwiseConv
-        GENERATOR_ARGS inv_depth_multiplier=0
-        GENERATOR_DEPS)
+        GENERATOR_ARGS inv_depth_multiplier=0)
 
 _add_halide_library_set(halide_op_implementations
         TARGET depthwise_conv_shallow_uint8
         SRCS depthwise_conv_generator.cpp
         GENERATOR_NAME DepthwiseConv
-        GENERATOR_ARGS inv_depth_multiplier=1 shallow=true
-        GENERATOR_DEPS)
+        GENERATOR_ARGS inv_depth_multiplier=1 shallow=true)
 
 _add_halide_library_set(halide_op_implementations
         TARGET fill_uint8
         SRCS fill_generator.cpp
         FEATURES no_bounds_query no_asserts
         GENERATOR_NAME Fill
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET elementwise_5xuint8_1xuint8
         SRCS elementwise_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Elementwise
-        GENERATOR_ARGS inputs.size=5 inputs.type=uint8 output1_type=uint8
-        GENERATOR_DEPS)
+        GENERATOR_ARGS inputs.size=5 inputs.type=uint8 output1_type=uint8)
 
 _add_halide_library_set(halide_op_implementations
         TARGET elementwise_5xint16_1xuint8int16
         SRCS elementwise_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Elementwise
-        GENERATOR_ARGS inputs.size=5 inputs.type=int16 output1_type=uint8 output2_type=int16
-        GENERATOR_DEPS)
+        GENERATOR_ARGS inputs.size=5 inputs.type=int16 output1_type=uint8 output2_type=int16)
 
 _add_halide_library_set(halide_op_implementations
         TARGET l2_normalization_uint8
         SRCS normalizations_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME L2Normalization
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET max_pool_uint8
         SRCS pool_generator.cpp
         GENERATOR_NAME MaxPool
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET mean_uint8
         SRCS reductions_generator.cpp
         GENERATOR_NAME Mean
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET mul_uint8_uint8_uint8
         SRCS elementwise_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Mul
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET softmax_uint8
         SRCS normalizations_generator.cpp
         FEATURES no_bounds_query
         GENERATOR_NAME Softmax
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET tile_conv_filter_uint8
         SRCS conv_generator.cpp
         GENERATOR_NAME TileConvFilter
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _add_halide_library_set(halide_op_implementations
         TARGET upsample_channels_uint8
         SRCS depthwise_conv_generator.cpp
         GENERATOR_NAME UpsampleChannels
-        GENERATOR_ARGS
-        GENERATOR_DEPS)
+        GENERATOR_ARGS)
 
 _finish_halide_library_set(halide_op_implementations)
 

cmake/HalideGeneratorHelpers.cmake

@@ -10,6 +10,90 @@ define_property(TARGET PROPERTY Halide_GENERATOR_HAS_POST_BUILD
                 BRIEF_DOCS "On a Halide generator target, true if Halide.dll copy command has already been added."
                 FULL_DOCS "On a Halide generator target, true if Halide.dll copy command has already been added.")
 
+##
+# Function to simplify writing the CMake rules for creating a generator executable
+# that follows our recommended cross-compiling workflow.
+##
+
+function(add_halide_generator TARGET)
+    set(options "")
+    set(oneValueArgs PACKAGE_NAME PACKAGE_NAMESPACE EXPORT_FILE)
+    set(multiValueArgs SOURCES)
+    cmake_parse_arguments(ARG "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+    if (NOT ARG_PACKAGE_NAME)
+        set(ARG_PACKAGE_NAME "${PROJECT_NAME}-halide_generators")
+    endif ()
+
+    if (NOT ARG_PACKAGE_NAMESPACE)
+        set(ARG_PACKAGE_NAMESPACE "${PROJECT_NAME}::halide_generators::")
+    endif ()
+
+    if (NOT ARG_EXPORT_FILE)
+        file(MAKE_DIRECTORY "${PROJECT_BINARY_DIR}/cmake")
+        set(ARG_EXPORT_FILE "${PROJECT_BINARY_DIR}/cmake/${ARG_PACKAGE_NAME}-config.cmake")
+    endif ()
+
+    if (NOT ARG_SOURCES)
+        set(ARG_SOURCES "${ARG_UNPARSED_ARGUMENTS}")
+    endif ()
+
+    _Halide_try_load_generators()
+
+    # Communicate found information to the caller
+    set(${ARG_PACKAGE_NAME}_FOUND "${${ARG_PACKAGE_NAME}_FOUND}" PARENT_SCOPE)
+
+    set(gen "${ARG_PACKAGE_NAMESPACE}${TARGET}")
+    if (NOT TARGET "${gen}")
+        if (NOT TARGET "${ARG_PACKAGE_NAME}")
+            add_custom_target("${ARG_PACKAGE_NAME}")
+        endif ()
+
+        if (NOT Halide_FOUND)
+            find_package(Halide REQUIRED)
+        endif ()
+
+        add_executable(${TARGET} ${ARG_SOURCES})
+        add_executable(${gen} ALIAS ${TARGET})
+        target_link_libraries(${TARGET} PRIVATE Halide::Generator)
+
+        add_dependencies("${ARG_PACKAGE_NAME}" ${TARGET})
+        export(TARGETS ${TARGET}
+               NAMESPACE ${ARG_PACKAGE_NAMESPACE}
+               APPEND FILE "${ARG_EXPORT_FILE}")
+    endif ()
+endfunction()
+
+# NOTE: this function must only be called by add_halide_generator
+# since it reads from its scope.
+function(_Halide_try_load_generators)
+    # Don't repeatedly run the search for the tools package.
+    if (NOT DEFINED ${ARG_PACKAGE_NAME}_FOUND)
+        # Some toolchains, like Emscripten, try to disable finding packages
+        # outside their sysroots, but we always want to find the native
+        # generators. Setting CMAKE_FIND_ROOT_PATH_BOTH here overrides
+        # the toolchain search preference. This is okay since a user can
+        # always override this call by setting ${ARG_PACKAGE_NAME}_ROOT.
+        find_package(${ARG_PACKAGE_NAME} QUIET
+                     CMAKE_FIND_ROOT_PATH_BOTH)
+
+        # Communicate found information to the caller
+        set(${ARG_PACKAGE_NAME}_FOUND "${${ARG_PACKAGE_NAME}_FOUND}" PARENT_SCOPE)
+
+        if (NOT ${ARG_PACKAGE_NAME}_FOUND AND CMAKE_CROSSCOMPILING)
+            message(WARNING
+                    "${ARG_PACKAGE_NAME} were not found and it looks like you are cross-compiling. "
+                    "This is likely to fail. Please set -D${ARG_PACKAGE_NAME}_ROOT=... at the CMake "
+                    "command line to the build directory of a host-built ${PROJECT_NAME}.")
+        endif ()
+    endif ()
+endfunction()
+
+##
+# Function to simplify writing the CMake rules for invoking a generator executable
+# and getting a usable CMake library out of it.
+##
+
 function(add_halide_library TARGET)
     ##
     # Set up argument parsing for extra outputs.

test/integration/CMakeLists.txt

@@ -129,7 +129,7 @@ if (CMAKE_HOST_SYSTEM_NAME MATCHES "Linux")
              --build-options
              -DCMAKE_TOOLCHAIN_FILE=${CMAKE_CURRENT_LIST_DIR}/../../cmake/toolchain.linux-aarch64.cmake
              -DCMAKE_BUILD_TYPE=Release
-             "-Dxc-generators_ROOT=${CMAKE_CURRENT_BINARY_DIR}/xc-host"
+             "-Dxc-halide_generators_ROOT=${CMAKE_CURRENT_BINARY_DIR}/xc-host"
              --test-command ${CMAKE_CTEST_COMMAND} --output-on-failure)
 
     set_tests_properties(cross_compile_host PROPERTIES FIXTURES_SETUP xc-host)

test/integration/xc/CMakeLists.txt

@@ -3,10 +3,15 @@ project(xc)
 
 enable_testing()
 
-if (CMAKE_CROSSCOMPILING)
-    find_package(xc-generators REQUIRED)
-else ()
-    add_subdirectory(generators)
-endif ()
+# Only need the platform-independent / source-only helpers.
+find_package(HalideHelpers REQUIRED)
 
-add_subdirectory(add)
+add_halide_generator(add_gen add.cpp)
+add_halide_library(add FROM xc::halide_generators::add_gen
+                   REGISTRATION add_reg_cpp)
+
+add_executable(run_add ${add_reg_cpp})
+target_link_libraries(run_add PRIVATE add Halide::RunGenMain)
+
+add_test(NAME run_add
+         COMMAND run_add --output_extents=[10,10] --benchmarks=all)