rtl generation & predicates

[Joern Rennecke]

> it's not that i confused between a predicate and a constraint. but the
> INSN_CODE field of an insn that appears at the filename.rtl dump has a
> value -1, which means, acc to the documentation (section: RTL
> Representation, subsection: Insns): 
> 
> INSN_CODE (i)
>        An integer that says which pattern in the machine description
> matches this insn, or -1 if the matching has not yet been attempted.
> 
> as i assumed the only use of predicates is during matching, predicates
> shud not have any role to play during RTL generation.

Predicates are used during rtl generation in general.  However, they
are not applied when you use the gen_* function for the insn.