c - IAR 的新 EWAVR32 (4.20)。编译器对内联汇编更加严格

Question

我使用的是 AVR32 AT32UC3C0512C 微 Controller 和 ASF 3.11 框架。将 IAR Workbench 从 4.10 更新到 4.20 新版本后，我遇到了一些 IAR 编译器问题。我在 IAR 的技术支持说明中发现，对内联汇编进行了一些更改。 (实际上不是 EWAVR32，而是 EWAVR):

使用内联汇编器时出现错误 [Og005] + [Og006]:标签必须在声明它们的同一汇编器语句中引用。在早期版本的编译器平台中，该行为不正确。新版本使用了新的内部编译器平台，该平台更加严格。”

我遇到了同样的问题，但无法编译的代码属于 FreeRTOS 端口。我假设编译器无法识别标签 LABEL_INT_SKIP_RESTORE_CONTEXT_ ，因为它没有在同一个 asm 语句中定义。这是代码:

#define portRESTORE_CONTEXT_OS_INT() { extern volatile unsigned portLONG ulCriticalNesting; 
    extern volatile void *volatile pxCurrentTCB; 
    /* Check if AVR32_INTC_INT0 or higher were being handled (case where the OS tick interrupted another */ 
    /* interrupt handler (which was of a higher priority level but decided to lower its priority */ 
    /* level and allow other lower interrupt level to occur). */ 
    /* In this case we don't want to do a task switch because we don't know what the stack */ 
    /* currently looks like (we don't know what the interrupted interrupt handler was doing). */ 
    /* Saving SP in pxCurrentTCB and then later restoring it (thinking restoring the task) */ 
    /* will just be restoring the interrupt handler, no way!!! */

    __asm__ __volatile__ ( 
        "ld.w r0, sp[9*4]\n\t" /* Read SR in stack */ 
        "bfextu r0, r0, 22, 3\n\t" /* Extract the mode bits to R0. */ 
        "cp.w r0, 1\n\t" /* Compare the mode bits with supervisor mode(b'001) */ 
        "brhi LABEL_INT_SKIP_RESTORE_CONTEXT_"ASTRINGZ(__LINE__) ); 

    /* Else */ 
    /* because it is here safe, always call vTaskSwitchContext() since an OS tick occurred. */ 
    /* A critical section has to be used here because vTaskSwitchContext handles FreeRTOS linked lists. */ 
    portENTER_CRITICAL(); 
    vTaskSwitchContext(); 
    portEXIT_CRITICAL(); 

    /* Restore all registers */ 
    __asm__ __volatile__ ( 
        /* Set SP to point to new stack */ 
        "mov r8, LWRD("ASTRINGZ(pxCurrentTCB)")\n\t" 
        "orh r8, HWRD("ASTRINGZ(pxCurrentTCB)")\n\t" 
        "ld.w r0, r8[0]\n\t" 
        "ld.w sp, r0[0]\n" 

        "LABEL_INT_SKIP_RESTORE_CONTEXT_"ASTRINGZ(__LINE__)":\n\t" 

        /* Restore ulCriticalNesting variable */ 
        "ld.w r0, sp++\n\t" 
        "mov r8, LWRD("ASTRINGZ(ulCriticalNesting)")\n\t" 
        "orh r8, HWRD("ASTRINGZ(ulCriticalNesting)")\n\t" 
        "st.w r8[0], r0\n\t" 

        /* Restore R0..R7 */ 
        "ldm sp++, r0-r7\n\t" 

        /* Now, the stack should be R8..R12, LR, PC and SR */ 
        "rete" 
    ); 

    /* Force import of global symbols from assembly */ 
    ulCriticalNesting; 
    pxCurrentTCB; } 

#endif

我一直在考虑尝试切换 asm 语句内的上下文(使用内联汇编调用 c 函数)，但我不确定这是否是最佳选择以及它是否真的有效。因此，很高兴在这里获得一些建议，如何以另一种方式恢复上下文并避免编译错误。谢谢!

如果您需要它，您可以在 ASF 中轻松找到此代码作为 FreeRTOS 示例 (...asf-3.11.0\common\services\usb\class\msc\device\example_freertos\at32uc3c0512c_uc3c_ek\iar\example_freertos.eww)

Answer 1

嗯，正如我在问题中已经说过的那样，我只是尝试切换 asm 语句内的上下文(使用内联汇编指令调用 c 函数)。因此，使用“RCALL”(相对调用子例程):

"RCALL vPortEnterCritical\n\t"
"RCALL vTaskSwitchContext\n\t"
"RCALL vPortExitCritical\n\t"

漏洞代码如下所示:

#define portRESTORE_CONTEXT_OS_INT() 
{ 
    extern volatile unsigned portLONG ulCriticalNesting; 
    extern volatile void *volatile pxCurrentTCB;

    /* Check if AVR32_INTC_INT0 or higher were being handled (case where the OS tick interrupted another */ 
    /* interrupt handler (which was of a higher priority level but decided to lower its priority */ 
    /* level and allow other lower interrupt level to occur). */ 
    /* In this case we don't want to do a task switch because we don't know what the stack */ 
    /* currently looks like (we don't know what the interrupted interrupt handler was doing). */ 
    /* Saving SP in pxCurrentTCB and then later restoring it (thinking restoring the task) */ 
    /* will just be restoring the interrupt handler, no way!!! */

    __asm__ __volatile__ ( 
        "ld.w r0, sp[9*4]\n\t" /* Read SR in stack */ 
        "bfextu r0, r0, 22, 3\n\t" /* Extract the mode bits to R0. */ 
        "cp.w r0, 1\n\t" /* Compare the mode bits with supervisor mode(b'001) */ 
        "brhi    LABEL_INT_SKIP_RESTORE_CONTEXT_"ASTRINGZ(__LINE__)"\n\t" 

        /* Else */ 
        /* because it is here safe, always call vTaskSwitchContext() since an OS tick occurred. */ 
        /* A critical section has to be used here because vTaskSwitchContext handles FreeRTOS linked lists. */ 
        "RCALL vPortEnterCritical\n\t"
        "RCALL vTaskSwitchContext\n\t"
        "RCALL vPortExitCritical\n\t" 

        /* Restore all registers */  
        /* Set SP to point to new stack */ 
        "mov r8, LWRD("ASTRINGZ(pxCurrentTCB)")\n\t" 
        "orh r8, HWRD("ASTRINGZ(pxCurrentTCB)")\n\t" 
        "ld.w r0, r8[0]\n\t" 
        "ld.w sp, r0[0]\n" 

        "LABEL_INT_SKIP_RESTORE_CONTEXT_"ASTRINGZ(__LINE__)":\n\t" 

        /* Restore ulCriticalNesting variable */ 
        "ld.w r0, sp++\n\t" 
        "mov r8, LWRD("ASTRINGZ(ulCriticalNesting)")\n\t" 
        "orh r8, HWRD("ASTRINGZ(ulCriticalNesting)")\n\t" 
        "st.w r8[0], r0\n\t" 

        /* Restore R0..R7 */ 
        "ldm sp++, r0-r7\n\t" 

        /* Now, the stack should be R8..R12, LR, PC and SR */ 
        "rete" 
    ); 

    /* Force import of global symbols from assembly */ 
    ulCriticalNesting; 
    pxCurrentTCB; 
} 

这对我有用，到目前为止我没有看到我们系统的行为有任何差异。我希望这可以帮助那些必须从 IAR Workbench 4.10 迁移到 4.20 的人。