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

[Bernd Schmidt]

Joseph S. Myers wrote:
> Yes.  For SPE, the subregs used in these *frob_* patterns represent 
> concepts including the high-part of a register (only used by certain 
> instructions that treat registers as 64 bits) and a DImode value stored in 
> one 64-bit register (normal layout is in two) or a DFmode value on E500v2 
> stored in the low parts of two registers (normal layout is in one 
> register).  That is, the subregs of hard registers cannot be represented 
> as single regs because they represent data laid out in registers in a 
> different way from how a single reg in that mode is interpreted.  This 
> works fine given the subreg_info infrastructure I added.

Let me ask a stupid question.  Do you need to use the rtx code SUBREG 
for this at all, or would an UNSPEC work just as well?  In other words, 
do these SUBREGs appear in other insns, or are they restricted to just 
these patterns?


Bernd
-- 
This footer brought to you by insane German lawmakers.
Analog Devices GmbH      Wilhelm-Wagenfeld-Str. 6      80807 Muenchen
Sitz der Gesellschaft Muenchen, Registergericht Muenchen HRB 40368
Geschaeftsfuehrer Thomas Wessel, William A. Martin, Margaret Seif