c++: asm clobber list

In g++, clobber lists for asm can be specified, for example:

asm ("somecode" : : "r1", "r2", "r3");

which means that the asm code changes register开发者_C百科s r1, r2, r3.

Now, my changed registers depend on a template parameter n (the asm block is inside of a template function), and registers r1, ..., rn will be changed. How can I express that?

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How many different register constellations are you confronted with? If not too many, you could provide a specific implementation for each. (Template Specialization)

Because, I apprehend that there's no possibility to create "templated statements".

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You can set all the register that you could use in the clobber list, so the compiler doesn't use them to store the value of a variable; I know this is a little bit slower, but if you don't need a very very high optimization, it will work.