Constraint for inline assembly with one register used for both an input variable and an output variable

[LIU Hao]

在 2025-6-6 17:11, Xi Ruoyao 写道:
> <source>:7:41: error: invalid input constraint '0' in asm
>      7 |     __asm__ volatile ("nop" : "+r"(t) : "0"(old));
>        |

This is equivalent to

    __asm__ volatile ("nop" : "=r"(t) : "0"(t), "0"(old));

  where the error is obvious.   ---------^-------^


-- 
Best regards,
LIU Hao
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