inline assembly operands

[Jim Wilson]

Luchezar Belev wrote:
> why out-of-function asm statements can't have operands?

Old-style asms just emit a string to the assembly file, and can appear 
anywhere.

Extended asms are converted into IL.  If they appear outside a function, 
then that is a serious problem, as we can't process IL outside of a 
function context.

We could perhaps handle a limited set of machine independent constraints 
outside a function, but quite a bit of new code would have to be 
written, and it isn't clear if it is worth the effort.  There would also 
be a documentation problem explaining what works outside functions and 
what doesn't.

> 	asm (".equ A, %0"::"i"(sizeof(something)));
> 	/* and compile with -masm=intel to make the
> 	 * compiler not to prefix the "immediate operand" */

There is usually a print code you can use to solve this.  %a0 works fine 
for x86, and probably also for many other targets.

> but now it seems unreliable since with the new
> unit-at-a-time feature the compiler may reorder
> the functions and top-level asm statements arbitrarily.

Yes.  It won't be reliable unless you use -fno-unit-at-a-time.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com