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Re: GAS .fpu directive

Hi Renato,

It seems GAS accepts .fpu anywhere in the file, and the meaning is
that it can change the FPU type mid-way through an assembly file, or
even in a block.

Is that intentional?


Is there any real usage for this kind of thing?


I naively assumed that .cpu / .fpu were like .eabi_attribute flags
that would tell what the *file* is, because normally one assembly
won't run on different machines at the same time.


The only use case I can think of is if there is a conditional jump
based on the existence of instructions, so a block that has neon is
only executed if there's no exception, but that still doesn't need a
.fpu vfp somewhere else.

Right. Basically such an sceanario is theoretically possible, but it is unlikely that it will ever turn up in real code. The real reason why the directive is accepted anywhere is that it was just too much bother to write additional code to make sure that it is only used once, and then only in an appropriate place. Much easier to just let it be accepted anywhere and to rely upon the assembler programmer or the compiler to only generate one instance of the directive.


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