There is a failure where we somehow get an invalid register
number being used to calculate the canonical frame address,
and this ends up with lldb crashing with a null deref because it
assumes that it is always able to find information about that
register.

This patch adds a check for a failure to get a register, and
declares the frame invalid in that case, with some additional
logging or an assert for debug builds.

Differential Revision: https://reviews.llvm.org/D143232
rdar://104428038

Improve LLDB reliability by fixing the following "uninitialized variables" static code inspection warnings from
scan.coverity.com:

1476275, 1274012, 1455035, 1364789, 1454282
1467483, 1406152, 1406255, 1454837, 1454416
1467446, 1462022, 1461909, 1420566, 1327228
1367767, 1431254, 1467299, 1312678, 1431780
1454731, 1490403

Differential Revision: https://reviews.llvm.org/D130528

This reverts commit b9aedd94e6796e4b4866ab4c091b736b3db58cb7.

Improve LLDB reliability by fixing the following "uninitialized variables" static code inspection warnings from
scan.coverity.com:

1476275, 1274012, 1455035, 1364789, 1454282
1467483, 1406152, 1406255, 1454837, 1454416
1467446, 1462022, 1461909, 1420566, 1327228
1367767, 1431254, 1467299, 1312678, 1431780
1454731, 1490403

Differential Revision: https://reviews.llvm.org/D130528

This reland 227dffd0b6d78154516ace45f6ed28259c7baa48 and
562c3467a6738aa89203f72fc1d1343e5baadf3c with failed api tests fixed by keeping
function base file addres in DWARFExpressionList.

This reverts commit 227dffd0b6d78154516ace45f6ed28259c7baa48 and its
follow up 562c3467a6738aa89203f72fc1d1343e5baadf3c because it breaks a
bunch of tests on GreenDragon:

https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/45155/

Differential Revision: https://reviews.llvm.org/D125509

When picking the UnwindPlan row to use to backtrace,
off of the zeroth frame, decrement the return pc so
we're in the address range of the call instruction.
If this is a noretrun function call, the instruction
at the "return address" is likely an entirely different
basic block with possibly very different unwind rules,
and this can cause the backtrace to be incorrect.

Differential Revision: https://reviews.llvm.org/D124957
rdar://84651805

Currently, all data buffers are assumed to be writable. This is a
problem on macOS where it's not allowed to load unsigned binaries in
memory as writable. To be more precise, MAP_RESILIENT_CODESIGN and
MAP_RESILIENT_MEDIA need to be set for mapped (unsigned) binaries on our
platform.

Binaries are mapped through FileSystem::CreateDataBuffer which returns a
DataBufferLLVM. The latter is backed by a llvm::WritableMemoryBuffer
because every DataBuffer in LLDB is considered to be writable. In order
to use a read-only llvm::MemoryBuffer I had to split our abstraction
around it.

This patch distinguishes between a DataBuffer (read-only) and
WritableDataBuffer (read-write) and updates LLDB to use the appropriate
one.

rdar://74890607

Differential revision: https://reviews.llvm.org/D122856

We already have a VASprintf function for this purpose, so I'm switching
the remaining few users to that.