RT-Thread-使用 LLVM-for-Arm 工具链编译 RT-Thread 源码RT-Thread问答社区

使用 LLVM-for-Arm 工具链编译 RT-Thread 源码

发布于 2021-12-21 09:51:45 浏览：2400 订阅该版

[tocm]

# 使用 LLVM  编译 RT-Thread

## 硬件测试环境

pdd 不久前搞活动， 99 块买了两块阿里出的 L469 的开发板，最高主频为 80Mhz。所以本次测试硬件就使用该开发板进行测试。

![board.png](https://oss-club.rt-thread.org/uploads/20211221/0af7c3fce1796ec9b2b89e1862ef3654.png.webp)

## 工具准备

1. 使用 git 工具下载 llvm 工具链：

````shell
   git clone https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm.git
   ````

2. 下载 make 工具：

```shell
   git clone https://github.com/xpack-dev-tools/windows-build-tools-xpack.git
   ```

## 编译

1. 在 `rt-thread\bsp\stm32\stm32l496-ali-developer` 目录下打开 env 工具：

2. 使用命令 `scons --target=cmake` 生成 CMakelists.txt 文件：

3. 这里的命令生成的 CMake 文件使用的是 gcc 的工具链，需要修改一下使用 llvm 的工具链：

```cmake
   SET(CMAKE_C_COMPILER "D:/download/idm/LLVMEmbeddedToolchainForArm-13.0.0-windows/LLVMEmbeddedToolchainForArm-13.0.0/bin/clang.exe")
   SET(CMAKE_ASM_COMPILER "D:/download/idm/LLVMEmbeddedToolchainForArm-13.0.0-windows/LLVMEmbeddedToolchainForArm-13.0.0/bin/clang.exe")
   SET(CMAKE_C_FLAGS "--config armv7em_hard_fpv4_sp_d16_nosys -Os")
   SET(CMAKE_ASM_FLAGS " -c --config armv7em_hard_fpv4_sp_d16_nosys -Wa,-mimplicit-it=thumb")
   SET(CMAKE_C_COMPILER_WORKS TRUE)
   
   SET(CMAKE_CXX_COMPILER "D:/download/idm/LLVMEmbeddedToolchainForArm-13.0.0-windows/LLVMEmbeddedToolchainForArm-13.0.0/bin/clang++.exe")
   SET(CMAKE_CXX_FLAGS "--config armv7em_hard_fpv4_sp_d16_nosys -Os")
   SET(CMAKE_CXX_COMPILER_WORKS TRUE)
   
   SET(CMAKE_OBJCOPY "D:/download/idm/LLVMEmbeddedToolchainForArm-13.0.0-windows/LLVMEmbeddedToolchainForArm-13.0.0/bin/llvm-objcopy.exe")
   SET(CMAKE_SIZE "D:/download/idm/LLVMEmbeddedToolchainForArm-13.0.0-windows/LLVMEmbeddedToolchainForArm-13.0.0/bin/llvm-size.exe")
   
   SET(CMAKE_EXE_LINKER_FLAGS "--config armv7em_hard_fpv4_sp_d16_nosys ,--gc-sections,-Map=rtthread.map,-u,Reset_Handler -T ${CMAKE_SOURCE_DIR}/board/linker_scripts/link.lds")
   
   ```

4. 输入命令 `cd build & cmake -G "MinGW Makefiles" .. & D:\software\tools\xpack-windows-build-tools-2.12.2\bin\make.exe` 编译工程：

```shell
   LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\stm32\stm32l496-ali-developer
   $ cd build
   
   LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\stm32\stm32l496-ali-developer\build
   $ cmake -G "MinGW Makefiles" ..
   -- Configuring done
   -- Generating done
   -- Build files have been written to: D:/repo/github/rt-thread/bsp/stm32/stm32l496-ali-developer/build
   
   LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\stm32\stm32l496-ali-developer\build
   $ D:\software\tools\xpack-windows-build-tools-2.12.2\bin\make.exe
   [  1%] Building C object CMakeFiles/rtthread.elf.dir/applications/main.c.obj
   [  2%] Building C object CMakeFiles/rtthread.elf.dir/packages/CoreMark-latest/core_main.c.obj
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   [  5%] Building C object CMakeFiles/rtthread.elf.dir/packages/CoreMark-latest/core_portme.c.obj
   [  7%] Building C object CMakeFiles/rtthread.elf.dir/packages/CoreMark-latest/core_list_join.c.obj
   [  8%] Building C object CMakeFiles/rtthread.elf.dir/packages/CoreMark-latest/core_state.c.obj
   [ 10%] Building C object CMakeFiles/rtthread.elf.dir/packages/CoreMark-latest/core_matrix.c.obj
   [ 11%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/libcpu/arm/common/showmem.c.obj
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   clang: warning: argument unused during compilation: '-D HAVE_CCONFIG_H' [-Wunused-command-line-argument]
   clang: warning: argument unused during compilation: '-D RT_USING_NEWLIB' [-Wunused-command-line-argument]
   clang: warning: argument unused during compilation: '-D STM32L496xx' [-Wunused-command-line-argument]
   clang: warning: argument unused during compilation: '-D USE_HAL_DRIVER' [-Wunused-command-line-argument]
   clang: warning: argument unused during compilation: '-D __RTTHREAD__' [-Wunused-command-line-argument]
   [ 33%] Building C object CMakeFiles/rtthread.elf.dir/board/CubeMX_Config/Src/stm32l4xx_hal_msp.c.obj
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   [ 39%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/HAL_Drivers/drv_common.c.obj
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   [ 71%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_uart.c.obj
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   [ 82%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_dma_ex.c.obj
   [ 84%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_exti.c.obj
   [ 85%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_crc.c.obj
   [ 86%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal.c.obj
   [ 88%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_usart_ex.c.obj
   [ 89%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_uart_ex.c.obj
   [ 91%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_crc_ex.c.obj
   [ 92%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_comp.c.obj
   [ 94%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pwr_ex.c.obj
   [ 95%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_rng.c.obj
   [ 97%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/CMSIS/Device/ST/STM32L4xx/Source/Templates/system_stm32l4xx.c.obj
   [ 98%] Building C object CMakeFiles/rtthread.elf.dir/D_/repo/github/rt-thread/bsp/stm32/libraries/STM32L4xx_HAL/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_cryp_ex.c.obj
   [100%] Linking C executable rtthread.elf
   clang: warning: argument unused during compilation: '-Wa,-mimplicit-it=thumb' [-Wunused-command-line-argument]
      text    data     bss     dec     hex filename
    117152    2864    1844  121860   1dc04 rtthread.elf
   [100%] Built target rtthread.elf
   ```

5. 下载 bin 文件到开发板：

![down.png](https://oss-club.rt-thread.org/uploads/20211221/5172c10d0a8582ea50d645726093fdc7.png.webp)

6. llvm 的编译下载就完成啦。

## 跑分测试

使用 LLVM、GCC、IAR 三种工具链编译出来的可执行文件，测试一下跑分情况：

### GCC 5.4.1

优化等级：`-Os`

![gcc5.4.1.png](https://oss-club.rt-thread.org/uploads/20211221/6d5c77f12bf0d55be2e4711fe0f41620.png)

### GCC 10.3.1

优化等级：`-Os`

![gcc10.3.png](https://oss-club.rt-thread.org/uploads/20211221/9a5b0700d418394fab3081934aecef41.png)

### LLVM