Labels are only supported in extended asm. GCC does not know about these jumps, and therefore cannot takeĪccount of them when deciding how to optimize. Relative to other code, including across jumps.Īsm statements may not perform jumps into other asm statements. Note that GCC’s optimizers can move asm statements If certain instructions need to remainĬonsecutive in the output, put them in a single multi-instruction asm
To access C data, it is better to use extendedĭo not expect a sequence of asm statements to remain perfectlyĬonsecutive after compilation. Safely accessing C data and calling functions from basic asm is moreĬomplex than it may appear. With the naked attribute also require basic asm Or write entire functions in assembly language. You can use this technique to emit assembler directives,ĭefine assembly language macros that can be invoked elsewhere in the file,
Outside of C functions, you must use basic asm. Extended asm statements have to be inside a Cįunction, so to write inline assembly language at file scope (‘top-level’),.
However, there are two situations where only basic asm Using extended asm typically produces smaller, safer, and moreĮfficient code, and in most cases it is a better solution than basicĪsm.
