On Sun, 2013-06-16 at 16:30 +1000, Erik de Castro Lopo wrote:
> Been busy, but I'm back looking at this.
>
> David Laight wrote:
>
> > With a scratch register there are some two instruction sequences.
> > Reusing the destination register something like:
> >
> > addis %r30,%r31,hi(.label - 1
Been busy, but I'm back looking at this.
David Laight wrote:
> With a scratch register there are some two instruction sequences.
> Reusing the destination register something like:
>
> addis %r30,%r31,hi(.label - 1b)
> lwzx%r30,lo(.label - 1b)(%r30)
>
I've managed to convert th
On Mon, 2013-06-10 at 21:14 +1000, Erik de Castro Lopo wrote:
> Benjamin Herrenschmidt wrote:
>
> > No, this loads a 32-bit value (16-bit would be lhz).
>
> My understanding so far (which may be wrong) is that it loads a
> 32 bit value but it loads it from a memory location that needs
> to be wit
> > Note: It's more readable if you use the register names, ie:
> >
> > lwz %r30, .label - (1b)(%r31)
> >
> > The form of lwz is
> >
> > lwz dest_reg, offset(address_reg)
> >
> > So it will load a 32-bit value from memory at the address contained in
> > r31 offset by ".label - 1b" w
Benjamin Herrenschmidt wrote:
> No, this loads a 32-bit value (16-bit would be lhz).
My understanding so far (which may be wrong) is that it loads a
32 bit value but it loads it from a memory location that needs
to be within +/- 32k of the instriction doing the load.
The reason I think this is b
On Mon, 2013-06-10 at 09:01 +1000, Erik de Castro Lopo wrote:
> Hi all,
>
> I'm trying to fix a problem in the PowerPC backend of the Glasgow
> Haskell Compiler (GHC) and have a problem with the following
> instruction form:
>
> lwz 30, .label - (1b)(31)
>
> Reading the documentation I c
