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Re: RFC: machine specific alternative cost modifier
On Sat, 25 Oct 2008, Joern Rennecke wrote:
> Moreover, the .md file also doesn't get more readable if I replace
> a three character constraint string with a multiword iterator invocation...
> for something like eight out of 14 alternatives for some instructions.
Um yeah, there is that...
> FWIW, I realized that overloaded constraints are not a panacea, either:
> I can prevent the use for reloading of the alternative for
> this particular operand, which is admittedly sometimes exactly what
> is wanted, but I can't use it to disable the use of the alternative
> altogether for reloading. I.e. if the non-matching part is a matching
> constraint, and I want to stop reload to 'fix' this operand to match,
> I need to manipulate the alternative cost.
Sounds like a perfect use for the new feature attribute-enabled;
skipping alternatives depending on TARGET_... See md.texi
"@subsection Disable insn alternatives using the @code{enabled}
attribute".
brgds, H-P