On Tue, Jul 12, 2016 at 05:17:04PM +0200, Bernd Schmidt wrote:
> The Blackfin thing happens frequently with -fomit-frame-pointer when we have
>
> (insn 66 64 70 8 (set (reg:SI 96 [ ivtmp.32 ])
> (reg/f:SI 15 FP)) 19 {*movsi_insn}
>
> Which LRA transforms to an invalid insn:
>
> (insn 66 64 70 8 (set (reg:SI 15 FP [orig:96 ivtmp.32 ] [96])
> (plus:SI (reg/f:SI 14 SP)
> (const_int 4 [0x4]))) 50 {addsi3}
> (expr_list:REG_EQUAL (reg/f:SI 15 FP)
> (nil)))
>
> Haven't fully debugged it but it looks like an instance of the same
> problem: not using the correct register numbers in elimination. An FP+FP
> addition would be fine (which is how I'm guessing we arrived at this
> pattern), but once you substitute the real register number you get an
> invalid insn. So LRA is somewhat defective in this area.
Do you have a testcase? This sounds like fun :-)
Segher
