SSA-based dead-code elimination

Richard Henderson rth@cygnus.com
Thu Aug 3 16:31:00 GMT 2000


On Wed, Aug 02, 2000 at 05:36:49PM -0400, Michael Meissner wrote:
> One such way would be to us an empty asm (which given it doesn't specify
> target and input arguments, should be treated as volatile):
> 
> 	int i;
> 
> 	for (i = 0; i < n; i++)
> 	  __asm__ ("");

Which we may happily unroll, so that you get all N nothings side by side.
No.  There is no way to generate a machine-independant empty loop.

Of course, the concept of a machine-independant delay loop is ludicrous.
You should just do the whole loop in assembly where you know what the
timing of the instructions are going to be.


r~


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