Looking for advice here -- while I haven't seen this bug trigger in
the mainline, it triggers with the range splitting code I've been
working on.
Reload has the ability to replace a pseudo with its equivalent memory
location. This is fine and good.
Imagine:
1. We have a pseudo (call is pseudo A) with a read-only memory
equivalent. Pseudo A does not get a hard reg
2. Pseudo A crosses a call (because the memory is readonly, we will
not invalidate the equivalency)
3. The equivalent memory address references another pseudo (call it
pseudo B)
4. Pseudo B does not cross calls and is assigned a call-clobbered
hard reg.
5. reload replaces pseudo A with its equivalent memory form and in
doing so lengthens the lifetime of pseudo B and causes pseudo B to be
live across a call.
Obviously this is bad. The question is where/how do we want to catch it.
The easy solution is to go ahead and invalidate the equivalency once we
notice that pseudo A crosses a call, even though the memory equivalent
is readonly. Seems a little harsh, but it's a one line change.
Other approaches?
Jeff
