我正在学习RISC V汇编语言，我一直在研究一些代码（我喜欢看别人如何编码的实际例子）。我在CH32003V的启动代码中发现了一个奇怪的汇编指令（一个新的RISC V MPU）。到目前为止，我已经搜索了一些材料，但没有找到任何关于". weak"指令的信息。下面是我找到它的代码片段。任何帮助都很感激。-）

.section  .init, "ax", @progbits
    .globl  _start
    .align  2
_start:
    .option   norvc;
    j       handle_reset
    .word   0
    .word   NMI_Handler                  /* NMI Handler */
    .word   HardFault_Handler            /* Hard Fault Handler */
    .word   0
    .word   0
    .word   0
    .word   0
    .word   0
    .word   0
    .word   0
    .word   0
    .word   SysTick_Handler             /* SysTick Handler */
    .word   0
    .word   SW_Handler                  /* SW Handler */
    .word   0
    /* External Interrupts */
    .word   WWDG_IRQHandler             /* Window Watchdog */
    .word   PVD_IRQHandler              /* PVD through EXTI Line detect */
    .word   FLASH_IRQHandler            /* Flash */
    .word   RCC_IRQHandler              /* RCC */
    .word   EXTI7_0_IRQHandler          /* EXTI Line 7..0 */
    .word   AWU_IRQHandler              /* AWU */
    .word   DMA1_Channel1_IRQHandler    /* DMA1 Channel 1 */
    .word   DMA1_Channel2_IRQHandler    /* DMA1 Channel 2 */
    .word   DMA1_Channel3_IRQHandler    /* DMA1 Channel 3 */
    .word   DMA1_Channel4_IRQHandler    /* DMA1 Channel 4 */
    .word   DMA1_Channel5_IRQHandler    /* DMA1 Channel 5 */
    .word   DMA1_Channel6_IRQHandler    /* DMA1 Channel 6 */
    .word   DMA1_Channel7_IRQHandler    /* DMA1 Channel 7 */
    .word   ADC1_IRQHandler             /* ADC1 */
    .word   I2C1_EV_IRQHandler          /* I2C1 Event */
    .word   I2C1_ER_IRQHandler          /* I2C1 Error */
    .word   USART1_IRQHandler           /* USART1 */
    .word   SPI1_IRQHandler             /* SPI1 */
    .word   TIM1_BRK_IRQHandler         /* TIM1 Break */
    .word   TIM1_UP_IRQHandler          /* TIM1 Update */
    .word   TIM1_TRG_COM_IRQHandler     /* TIM1 Trigger and Commutation */
    .word   TIM1_CC_IRQHandler          /* TIM1 Capture Compare */
    .word   TIM2_IRQHandler             /* TIM2 */

    .option rvc;
    .section  .text.vector_handler, "ax", @progbits
    .weak   NMI_Handler
    .weak   HardFault_Handler
    .weak   SysTick_Handler
    .weak   SW_Handler
    .weak   WWDG_IRQHandler
    .weak   PVD_IRQHandler
    .weak   FLASH_IRQHandler 

    .weak   RCC_IRQHandler