* Segher Boessenkool: > Hi! > > On Wed, Sep 29, 2021 at 02:28:37PM +0200, Florian Weimer wrote: >> If you need a specific instruction emitted, you need a compiler >> intrinsic or inline assembly. > > Not an intrinsic. Builtins (like almost all other code) do not say > "generate this particular machine code", they say "generate code that > does <this>". That is one reason why builtins are more powerful than > inline assembler (another related reason is that they tell the compiler > exactly what behaviour is expected). I meant that if the object code has to contain a specific instruction sequence involving a conditional, it needs some form of compiler support. Adding some volatile here and some form of a compiler barrier there is very brittle. >> I don't think it's possible to piggy-back this on something else. > > Unless we get a description of what this does in term of language > semantics (instead of generated machine code), there is no hope, even. True. For example, if the argument contains a sequence point, what does that even mean? Thanks, Florian
