LLVM Symbolizer attempt to symbolize addresses of optimized binaries
reports missing line numbers for some cases. It maybe due to compiler
which sometimes cannot map an instruction to line number due to
optimizations. Symbolizer should handle those cases gracefully.

Adding an option '--skip-line-zero' to symbolizer so as to report the
nearest non-zero line number.

---------

Co-authored-by: Amit Pandey <amit.pandey@amd.com>

We recently ran into some bad DWARF where the `DW_AT_stmt_list` of many
compile units was randomly set to invalid values and was causing LLDB to
crash due to an assertion about address sizes not matching. Instead of
asserting, we should return an appropriate recoverable `llvm::Error`.

The DWARF proposal that the DW_LNCT_LLVM_source extension is based on
(https://dwarfstd.org/issues/180201.1.html) allows to mix source and
non-source files in the same CU by storing an empty string as a
sentinel value.

This patch implements this feature.

Review in https://github.com/llvm/llvm-project/pull/73877

This extends DWARFDebugLine to properly parse line number programs with
maximum_operations_per_instruction > 1 for VLIW targets.

No functions that use that parsed output to retrieve line information
have been extended to support multiple op-indexes. This means that when
retrieving information for an address with multiple op-indexes, e.g.
when using llvm-addr2line, the penultimate row for that address will be
used, which in most cases is the row for the second largest op-index.
This will be addressed in further changes, but this patch at least
allows us to correctly parse such line number programs, with a warning
saying that the line number information may be incorrect (incomplete).

Reviewed By: StephenTozer

Differential Revision: https://reviews.llvm.org/D152536

This is a preparatory patch for extending DWARFDebugLine to properly
parse line number programs with maximum_operations_per_instruction > 1
for VLIW targets.

Add some scaffolding for handling op-index in line number programs, and
add printouts for that in the table. As this affects a lot of tests,
this is done in a separate commit to get a cleaner review for the actual
op-index implementation.

Verbose printouts are not present in many tests, and adding op-index to
those will require a bit more code changes, so that is done in the
actual implementation patch.

Reviewed By: StephenTozer

Differential Revision: https://reviews.llvm.org/D152535

This allows the DWARFDebugLine::SectionParser to try parsing line tables
at 4 or 8-byte boundaries if the unaligned offset appears invalid. If
aligning the offset does not reduce errors the offset is used unchanged.

This is needed for llvm-dwarfdump to be able to extract the line tables
(with --debug-lines) from binaries produced by certain compilers that
like to align each line table in the .debug_line section. Note that this
alignment does not seem to be invalid since the units do point to the
correct line table offsets via the DW_AT_stmt_list attribute.

Differential Revision: https://reviews.llvm.org/D143513

value() has undesired exception checking semantics and calls
__throw_bad_optional_access in libc++. Moreover, the API is unavailable without
_LIBCPP_NO_EXCEPTIONS on older Mach-O platforms (see
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS).

This commit fixes LLVMAnalysis and its dependencies.

These source files no longer use Optional<T>, so they do not need to
include Optional.h.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716