[trunk] Addition to subreg section of rtl.text.

[Bernd Schmidt]

Joern Rennecke wrote:
>>> And @code{(subreg:SI (reg:DF 10) 0)} would be a natural way to express that
>>> you are using the floating point register as a 32 bit integer register,
>>> with writes clobbering the entire 64 bit of the register.
>> Yes, this is one possible definition.  But there's no reason in this
>> situation why you couldn't just use a single REG.  Why use subregs at all?
> 
> Because before reload, you use pseudos.  And in order for
> (subreg:SI (reg:DF ...) ...) to be viable, it still has to be viable between
> hard register allocation and alter_reg.

Is that even valid?  Are there any known ports using this?  AFAIR the 
middle-end doesn't create this (although it will use (subreg:SF (reg:DI)).


Bernd
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