[LLVMdev] Fwd: Debugging/Fixing 'Interval not live at use' errors

[Stephen McGruer]

Tim,

Thank you very much, that did indeed fix things. I believe the word I
should be saying is: 'oops'!

Stephen

On 24 October 2012 13:44, Tim Northover <t.p.northover at gmail.com> wrote:

> Hi Stephen,
>
> > I'm not entirely sure what is wrong here - I assume it has something to
> do
> > with my 'special' instruction LDri_ab. This instruction is a load with an
> > 'address writeback' - ld.ab r0, [r1, 5] is equivalent to ld r0, [r1]; add
> > r1, r1, 5. As it was very difficult to match such behaviour
> automatically, I
> > actually only generate them manually for prologue/epilogue emission, so
> the
> > tablegen def is like:
>
> That fits. This line
>
> LDri_ab %FP, %SP, 4
>
> should almost certainly be printed as:
>
> %FP = LDri_ab %SP, 4
>
> The most likely cause is a slightly malformed BuildMI that's adding
> %FP without a define flag. Usually you put the destination register
> inside the call to BuildMI, and inputs with "addReg(...)" and so on.
> All this actually does is fiddle the flags in an appropriate manner;
> you can emulate it with addReg, but why bother? So what you should be
> looking for is something like:
>
> BuildMI(LDri_ab).addReg(Dest).addReg(Src).addImm(Offset)
>
> and changing it to:
>
> BuildMI(LDri_ab, Dest).addReg(Src).addImm(Offset)
>
> Hope this helps.
>
> Tim.
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