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Re: Special Memory Constraint [was Re: Indirect memory addresses vs. lra]
On Mon, Aug 19, 2019 at 10:07:11AM -0500, Segher Boessenkool wrote:
> ? As I remember there were a few other ideas from Richard Biener and
> Segher Boessenkool.? I also proposed to add a new address register which
> will be always a fixed stack memory slot at the end. Unfortunately I am
> not familiar with the target and the port to say in details how to do
> it.? But I think it is worth to try.
The m68hc11 port used the fake Z register approach, and I believe it had
some special machine pass to get rid of it right before assembler output.
(r171302 is when it was removed -- last version was
for the machine reorg stuff).
No idea how well it works... But it's only needed if you are forced to
have a frame pointer IIUC?
Most of these suggestions involve adding some sort of virtual registers
So I hacked the machine description to add two new registers Z1 and Z2
with the same mode as X and Y.
Obviously the assembler balks at this. However the compiler still
ICEs at the same place as before.
So this suggests that our original diagnosis, viz: there are not enough
address registers was not accurate, and in fact there is some other
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