cmake: support ui asset generation without host tool

Author: romgenie

scripts/ui-assets.cmake

@@ -255,6 +255,68 @@ endfunction()
 function(emit_files)
     assets_present(present)
 
+    if("${LLAMA_UI_EMBED}" STREQUAL "")
+        set(h "#pragma once\n\n#include <stddef.h>\n\n")
+        if(present)
+            string(APPEND h "#define LLAMA_UI_HAS_ASSETS 1\n\n")
+        endif()
+        string(APPEND h
+            "struct llama_ui_asset {\n"
+            "    const char *          name;\n"
+            "    const unsigned char * data;\n"
+            "    size_t                size;\n"
+            "};\n\n"
+            "const llama_ui_asset * llama_ui_find_asset(const char * name);\n"
+        )
+
+        set(cpp "#include \"ui.h\"\n\n#include <string.h>\n\n")
+        if(present)
+            set(asset_index 0)
+            foreach(asset ${ASSETS})
+                file(READ "${DIST_DIR}/${asset}" asset_hex HEX)
+                string(REGEX REPLACE "([0-9A-Fa-f][0-9A-Fa-f])" "0x\\1," asset_bytes "${asset_hex}")
+                string(LENGTH "${asset_hex}" asset_hex_len)
+                math(EXPR asset_size "${asset_hex_len} / 2")
+                string(APPEND cpp
+                    "static const unsigned char asset_${asset_index}_data[] = {${asset_bytes}};\n"
+                    "static const size_t        asset_${asset_index}_size = ${asset_size};\n\n"
+                )
+                math(EXPR asset_index "${asset_index} + 1")
+            endforeach()
+
+            string(APPEND cpp "static const llama_ui_asset g_assets[] = {\n")
+            set(asset_index 0)
+            foreach(asset ${ASSETS})
+                string(APPEND cpp "    { \"${asset}\", asset_${asset_index}_data, asset_${asset_index}_size },\n")
+                math(EXPR asset_index "${asset_index} + 1")
+            endforeach()
+            string(APPEND cpp
+                "};\n\n"
+                "const llama_ui_asset * llama_ui_find_asset(const char * name) {\n"
+                "    for (const auto & a : g_assets) {\n"
+                "        if (strcmp(a.name, name) == 0) {\n"
+                "            return &a;\n"
+                "        }\n"
+                "    }\n"
+                "    return nullptr;\n"
+                "}\n"
+            )
+        else()
+            string(APPEND cpp
+                "const llama_ui_asset * llama_ui_find_asset(const char *) {\n"
+                "    return nullptr;\n"
+                "}\n"
+            )
+        endif()
+
+        file(WRITE "${UI_H}.tmp" "${h}")
+        file(WRITE "${UI_CPP}.tmp" "${cpp}")
+        execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different "${UI_H}.tmp" "${UI_H}")
+        execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different "${UI_CPP}.tmp" "${UI_CPP}")
+        file(REMOVE "${UI_H}.tmp" "${UI_CPP}.tmp")
+        return()
+    endif()
+
     set(args "${UI_CPP}" "${UI_H}")
     if(present)
         foreach(asset ${ASSETS})

tools/ui/CMakeLists.txt

@@ -36,6 +36,23 @@ set(UI_CPP "${CMAKE_CURRENT_BINARY_DIR}/ui.cpp")
 set(UI_H   "${CMAKE_CURRENT_BINARY_DIR}/ui.h")
 
 if(CMAKE_CROSSCOMPILING)
+    function(llama_check_host_cxx compiler out_var)
+        set(src "${CMAKE_CURRENT_BINARY_DIR}/host-cxx-check.cpp")
+        set(exe "${CMAKE_CURRENT_BINARY_DIR}/host-cxx-check${CMAKE_EXECUTABLE_SUFFIX}")
+        file(WRITE "${src}" "#include <stdio.h>\nint main() { puts(\"ok\"); return 0; }\n")
+        execute_process(
+            COMMAND "${compiler}" -std=c++17 "${src}" -o "${exe}"
+            RESULT_VARIABLE rc
+            OUTPUT_QUIET
+            ERROR_QUIET
+        )
+        if(rc EQUAL 0)
+            set(${out_var} TRUE PARENT_SCOPE)
+        else()
+            set(${out_var} FALSE PARENT_SCOPE)
+        endif()
+    endfunction()
+
     find_program(HOST_CXX_COMPILER
         NAMES c++ g++ clang++
         PATHS /usr/local/bin /usr/bin /bin
@@ -44,27 +61,39 @@ if(CMAKE_CROSSCOMPILING)
     if(NOT HOST_CXX_COMPILER)
         find_program(HOST_CXX_COMPILER NAMES c++ g++ clang++ NO_CMAKE_FIND_ROOT_PATH)
     endif()
-    if(NOT HOST_CXX_COMPILER)
-        message(FATAL_ERROR "UI: no host C++ compiler (g++/clang++) found to build llama-ui-embed; set -DHOST_CXX_COMPILER=<path>")
+    if(HOST_CXX_COMPILER)
+        llama_check_host_cxx("${HOST_CXX_COMPILER}" HOST_CXX_OK)
+        if(NOT HOST_CXX_OK)
+            message(STATUS "UI: ignoring unusable host compiler ${HOST_CXX_COMPILER}")
+            unset(HOST_CXX_COMPILER CACHE)
+            unset(HOST_CXX_COMPILER)
+        endif()
     endif()
-    message(STATUS "UI: building llama-ui-embed with host compiler ${HOST_CXX_COMPILER}")
 
-    if(CMAKE_HOST_WIN32)
-        set(LLAMA_UI_EMBED_EXE "${CMAKE_CURRENT_BINARY_DIR}/llama-ui-embed.exe")
+    if(HOST_CXX_COMPILER)
+        message(STATUS "UI: building llama-ui-embed with host compiler ${HOST_CXX_COMPILER}")
+
+        if(CMAKE_HOST_WIN32)
+            set(LLAMA_UI_EMBED_EXE "${CMAKE_CURRENT_BINARY_DIR}/llama-ui-embed.exe")
+        else()
+            set(LLAMA_UI_EMBED_EXE "${CMAKE_CURRENT_BINARY_DIR}/llama-ui-embed")
+        endif()
+
+        add_custom_command(
+            OUTPUT  "${LLAMA_UI_EMBED_EXE}"
+            COMMAND "${HOST_CXX_COMPILER}" -O2 -std=c++17
+                    -o "${LLAMA_UI_EMBED_EXE}" "${CMAKE_CURRENT_SOURCE_DIR}/embed.cpp"
+            DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/embed.cpp"
+            COMMENT "Building llama-ui-embed (host)"
+            VERBATIM
+        )
+        add_custom_target(llama-ui-embed-host DEPENDS "${LLAMA_UI_EMBED_EXE}")
+        set(LLAMA_UI_EMBED_TARGET llama-ui-embed-host)
     else()
-        set(LLAMA_UI_EMBED_EXE "${CMAKE_CURRENT_BINARY_DIR}/llama-ui-embed")
+        message(STATUS "UI: no usable host C++ compiler, using CMake asset emitter")
+        set(LLAMA_UI_EMBED_EXE "")
+        set(LLAMA_UI_EMBED_TARGET "")
     endif()
-
-    add_custom_command(
-        OUTPUT  "${LLAMA_UI_EMBED_EXE}"
-        COMMAND "${HOST_CXX_COMPILER}" -O2 -std=c++17
-                -o "${LLAMA_UI_EMBED_EXE}" "${CMAKE_CURRENT_SOURCE_DIR}/embed.cpp"
-        DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/embed.cpp"
-        COMMENT "Building llama-ui-embed (host)"
-        VERBATIM
-    )
-    add_custom_target(llama-ui-embed-host DEPENDS "${LLAMA_UI_EMBED_EXE}")
-    set(LLAMA_UI_EMBED_TARGET llama-ui-embed-host)
 else()
     add_executable(llama-ui-embed embed.cpp)
     target_compile_features(llama-ui-embed PRIVATE cxx_std_17)
@@ -94,7 +123,9 @@ add_custom_target(llama-ui-assets ALL
     VERBATIM
 )
 
-add_dependencies(llama-ui-assets ${LLAMA_UI_EMBED_TARGET})
+if(LLAMA_UI_EMBED_TARGET)
+    add_dependencies(llama-ui-assets ${LLAMA_UI_EMBED_TARGET})
+endif()
 
 set_source_files_properties(${UI_CPP} ${UI_H} PROPERTIES GENERATED TRUE)