labath marked an inline comment as done.
labath added inline comments.
================
Comment at: include/lldb/Symbol/FuncUnwinders.h:117
+ class LazyPlan {
+ lldb::UnwindPlanSP m_plan_sp;
+
----------------
clayborg wrote:
> clayborg wrote:
> > labath wrote:
> > > clayborg wrote:
> > > > maybe use:
> > > >
> > > > ```
> > > > llvm::Optional<lldb::UnwindPlanSP> m_plan_sp;
> > > > ```
> > > >
> > > > Then just check if it has no value, and if so compute and set it either
> > > > to a valid shared pointer or an empty one?
> > > That would work, but it would increase the size of the FuncUnwinders
> > > struct by about 80 bytes (8 bytes for each LazyPlan object). I can do
> > > that, but given that "uncomputed value" trick is internal to the class
> > > and does not leak out or affect the implementation, it seemed like a
> > > worthwhile optimization to me.
> > Actually isn't there a pointer union class that can steal bool bits from
> > the aligned values and not increase the size?
> I believe the clang type system steals 3 bits from a Type * to encode "const"
> and a few other type qualifiers
Yes, there is a `llvm::PointerIntPair`, but AFAICT that only works with a raw
pointer, not a shared_ptr. I believe implementing a similar trick for
shared_ptr would be possible, but it would definitely be tricky. Way more
trickier than this..
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D61779/new/
https://reviews.llvm.org/D61779
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