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build: Use try_compile for robust RVV toolchain detection #3905

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build: Use try_compile for robust RVV toolchain detection #3905

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6374f24
build: Use try_compile for robust RVV toolchain detection
ihb2032 Sep 22, 2025
716268f
refactor(riscv): Simplify RVV build logic and fix duplicate flags
ihb2032 Sep 22, 2025
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84 changes: 76 additions & 8 deletions source/backend/cpu/riscv/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -4,14 +4,82 @@ ENDIF()

FILE(GLOB MNN_RVV_SRC ${CMAKE_CURRENT_LIST_DIR}/rvv/*.cpp)

if (MNN_USE_RVV AND (CMAKE_SYSTEM_PROCESSOR MATCHES "^riscv64" OR ARCHS STREQUAL "riscv64"))
message(STATUS "MNN_USE_RVV is ON. Checking for RVV support in user-provided compiler flags...")

set(RVV_CHECK_SOURCE_CONTENT
"
#ifndef __riscv_v
#error \"Compiler does not define __riscv_v. Check your global CMAKE_C(XX)_FLAGS.\"
#endif
int main() { return 0; }
"
)
set(TRY_COMPILE_DIR "${CMAKE_BINARY_DIR}/CMakeFiles/CMakeTmp")
set(RVV_CHECK_FILE_PATH "${TRY_COMPILE_DIR}/rvv_check.cpp")
file(WRITE "${RVV_CHECK_FILE_PATH}" "${RVV_CHECK_SOURCE_CONTENT}")

try_compile(
TOOLCHAIN_SUPPORTS_RVV
SOURCES "${RVV_CHECK_FILE_PATH}"
)

file(REMOVE_RECURSE "${TRY_COMPILE_DIR}")

if(TOOLCHAIN_SUPPORTS_RVV)
message(STATUS "Toolchain check passed. Enabling RVV source files.")
add_library(MNNRVV OBJECT ${MNN_RVV_SRC})
target_include_directories(MNNRVV PRIVATE ${CMAKE_CURRENT_LIST_DIR}/rvv/)
list(APPEND MNN_OBJECTS_TO_LINK $<TARGET_OBJECTS:MNNRVV>)
list(APPEND MNN_TARGETS MNNRVV)
add_definitions(-DMNN_USE_RVV)
else()
message(FATAL_ERROR "MNN_USE_RVV is ON, but the provided compiler flags do not support RVV. Please provide correct '-march=...v...' and '-mabi=...' flags in CMAKE_C_FLAGS and CMAKE_CXX_FLAGS.")
endif()
else()
message(STATUS "RVV optimizations are disabled (MNN_USE_RVV is OFF or target is not riscv64).")
endif()IF(NOT DEFINED ARCHS)
set(ARCHS ${CMAKE_SYSTEM_PROCESSOR})
ENDIF()

FILE(GLOB MNN_RVV_SRC ${CMAKE_CURRENT_LIST_DIR}/rvv/*.cpp)

if (CMAKE_SYSTEM_PROCESSOR MATCHES "^riscv64" OR ARCHS STREQUAL "riscv64")
message(STATUS "Enabling RVV Optimizations")
add_library(MNNRVV OBJECT ${MNN_RVV_SRC})
target_include_directories(MNNRVV PRIVATE ${CMAKE_CURRENT_LIST_DIR}/rvv/)
list(APPEND MNN_OBJECTS_TO_LINK $<TARGET_OBJECTS:MNNRVV>)
list(APPEND MNN_TARGETS MNNRVV)
add_definitions(-DMNN_USE_RVV)
target_compile_options(MNNRVV PRIVATE -march=rv64gcv -mabi=lp64d)
message(STATUS "Target is riscv64. Performing fine-grained toolchain check for RVV support...")
set(RVV_TEST_FLAGS "-march=rv64gcv -mabi=lp64d")

set(RVV_CHECK_SOURCE_CONTENT
"
#ifndef __riscv_v
#error \"Compiler does not define __riscv_v. RVV is not properly supported.\"
#endif
int main() { return 0; }
"
)
set(TRY_COMPILE_DIR "${CMAKE_BINARY_DIR}/CMakeFiles/CMakeTmp")
set(RVV_CHECK_FILE_PATH "${TRY_COMPILE_DIR}/rvv_check.cpp")
file(WRITE "${RVV_CHECK_FILE_PATH}" "${RVV_CHECK_SOURCE_CONTENT}")

try_compile(
TOOLCHAIN_SUPPORTS_RVV
SOURCES "${RVV_CHECK_FILE_PATH}"
CMAKE_FLAGS "-DCMAKE_CXX_FLAGS=${RVV_TEST_FLAGS}"
)

message(STATUS "Cleaning up temporary compile directory...")
file(REMOVE_RECURSE "${TRY_COMPILE_DIR}")

if(TOOLCHAIN_SUPPORTS_RVV)
message(STATUS "Toolchain check passed. Enabling RVV Optimizations.")
add_library(MNNRVV OBJECT ${MNN_RVV_SRC})
target_include_directories(MNNRVV PRIVATE ${CMAKE_CURRENT_LIST_DIR}/rvv/)
list(APPEND MNN_OBJECTS_TO_LINK $<TARGET_OBJECTS:MNNRVV>)
list(APPEND MNN_TARGETS MNNRVV)
add_definitions(-DMNN_USE_RVV)
target_compile_options(MNNRVV PRIVATE ${RVV_TEST_FLAGS})
else()
message(WARNING "Target is riscv64, but the toolchain check failed with flags (${RVV_TEST_FLAGS}). Please check if your compiler version supports the 'V' extension. RVV optimizations will be disabled.")
endif()
else()
message(WARNING "RVV optimizations are only supported on riscv64 architecture")
message(STATUS "RVV optimizations are skipped for non-riscv64 targets.")
endif()
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