### Summary
We have internally seen cases like this
`DW_OP_lit0, DW_OP_stack_value, DW_OP_piece 0x28`
where we have longer op pieces than what Scalar supports (32, 64 or 128
bits). In these cases LLDB is currently hitting the assertion
`assert(ap_int.getBitWidth() >= bit_size);`
We are extending the generated APInt to the piece size by filling zeros.
### Test plan
Added a unit to cover this case.
### Reviewers
@clayborg , @jeffreytan81 , @Jlalond
Add support for DW_OP_WASM_location in DWARFExpression. This PR rebases
#78977 and cleans up the unit test. The DWARF extensions are documented
at https://yurydelendik.github.io/webassembly-dwarf/ and supported by
LLVM-based toolchains such as Clang, Swift, Emscripten, and Rust.
Eliminate the `lldb_private::dwarf` namespace, in favor of using
`llvm::dwarf` directly. The latter is shorter, and this avoids ambiguity
in the ABI plugins that define a `dwarf` namespace inside an anonymous
namespace.
Target::ReadMemory may or may not read live memory, but whether it did
read from live memory or from the filecache is opaque to callers. Add an
extra out parameter to indicate whether live memory was read or not.
Change the signature of `DWARFExpression::Evaluate` and
`DWARFExpressionList::Evaluate` to return an `llvm::Expected` instead of a
boolean. This eliminates the `Status` output parameter and generally improves
error handling.
We received a bug report where someone was trying to print a global
variable without a process. This would succeed in a debug build but fail
in a on optimized build. We traced the issue back to the location being
described by a DW_OP_addr + DW_OP_piece.
The issue is that the DWARF expression evaluator only support reading
pieces from a load address. There's no reason it cannot do the same for
a file address, and indeed, that solves the problem.
I unsuccessfully tried to craft a test case to illustrate the original
example, using a global struct and trying to trick the compiler into
breaking it apart with SROA. Instead I wrote a unit test that uses a
mock target to read memory from.
rdar://127435923
This rewrites DW_OP_addrx inside DWARFExpression as an DW_OP_addr so
that we can update addresses that are originally located in the
debug_addr section.
The full discussion behind this can be found in
https://discourse.llvm.org/t/dwarfexpression-and-dw-op-addrx/71627/12, but a
summary follows.
When SymbolFileDWARF::ParseVariableDIE creates DWARFExpressions for
variables whose location is an OP_addr, it knows how to remap
addresses appropriately in the DebugMap case. It then calls
DWARFExpression::Update_DW_OP_addr, which updates the value associated
with OP_addr.
However, when we have an OP_addrx, the update function does
nothing. This makes sense, as the DWARFExpression does not have a
mutable view of the debug_addr section. In non-DebugMap flows this is
not an issue, as the debug_addr contains the correct addresses of
variables. In DebugMap flows, this is problematic because the work
done by RelinkOSOAddress is lost. By updating the OP to OP_addr, we
can also update the address as required,
We also explored the alternative of relinking the debug_addr section
when we are initializing OSOs (InitOSO). However, this creates an
inconsistent story for users of
DWARFExpression::GetLocation_DW_OP_addr. This function returns an
address without telling callers whether that address came from an
OP_addr or an OP_addrx. If we preemptively relink OP_addrx results
without doing the same for OP_addr results, then callers can’t know
whether the address they got was an executable address or an object
file address. In other words, they can’t know whether they need to
call LinkOSOFileAddress on those results or not.
This patch addresses the majority of test failures when enabling DWARF
5 for MachO (over 200 test failures).
Differential Revision: https://reviews.llvm.org/D155198
On a subsequent commit, I intend to update the expression and call the evaluate
function more times. This refactors enables reusing some of the existing code
for that.
Differential Revision: https://reviews.llvm.org/D155197
This came out of from https://discourse.llvm.org/t/dwarf-dwp-4gb-limit/63902
With big binaries we can have .dwp files where .debug_info.dwo section can grow
beyond 4GB. We would like to support this in LLVM and in LLDB.
The plan is to enable manual parsing of cu/tu index in DWARF library
(https://reviews.llvm.org/D137882), and then
switch internal index data structure to 64 bit.
For the second part is to enable 64bit offset support in LLDB with
this patch.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D138618
This came out of from https://discourse.llvm.org/t/dwarf-dwp-4gb-limit/63902
With big binaries we can have .dwp files where .debug_info.dwo section can grow
beyond 4GB. We would like to support this in LLVM and in LLDB.
The plan is to enable manual parsing of cu/tu index in DWARF library
(https://reviews.llvm.org/D137882), and then
switch internal index data structure to 64 bit.
For the second part is to enable 64bit offset support in LLDB with
this patch.
Depends on D139955
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D138618
This came out of from https://discourse.llvm.org/t/dwarf-dwp-4gb-limit/63902
With big binaries we can have .dwp files where .debug_info.dwo section can grow
beyond 4GB. We would like to support this in LLVM and in LLDB.
The plan is to enable manual parsing of cu/tu index in DWARF library
(https://reviews.llvm.org/D137882), and then
switch internal index data structure to 64 bit.
For the second part is to enable 64bit offset support in LLDB with
this patch.
Depends on D139955
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D138618
This patch is preparatory work for Scripted Platform support and does
multiple things:
First, it introduces new options for the `platform select` command and
`SBPlatform::Create` API, to hold a reference to the debugger object,
the name of the python script managing the Scripted Platform and a
structured data dictionary that the user can use to pass arbitrary data.
Then, it updates the various `Create` and `GetOrCreate` methods for
the `Platform` and `PlatformList` classes to pass down the new parameter
to the `Platform::CreateInstance` callbacks.
Finally, it updates every callback to reflect these changes.
Differential Revision: https://reviews.llvm.org/D139249
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
Parsing DWARF expressions currently does not support DW_OPs that are vendor
extensions. With this change expression parsing calls into SymbolFileDWARF for
unknown opcodes, which is the semantically "closest" plugin that we have right
now. Plugins can then extend SymbolFileDWARF to add support for vendor
extensions.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D137247
When resolving absolute addresses for DW_OP_addr or DW_OP_addrx, these are always load addresses rather than file addresses in wasm.
Reviewed By: DavidSpickett
Differential Revision: https://reviews.llvm.org/D135664
Debugging some DWARF5 binaries was causing errors to appear when DWARFExpression::Evaluate was called:
error: GetDIE for DIE 0x31 is outside of its CU 0x123450
The issue is in the DWARF expression evaluator. Fixed with this.
Differential Revision: https://reviews.llvm.org/D133623
Make constructors of the Process and its subclasses class protected,
to prevent accidentally constructing Process on stack when it could be
afterwards accessed via a shared_ptr (since it uses
std::enable_shared_from_this<>).
The only place where a stack allocation was used were unittests,
and fixing them via declaring an explicit public constructor
in the respective mock classes is trivial.
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D131275
DW_OP_skip/DW_OP_bra can move offset to the end of the data, which means that this was the last instruction to execute and the interpreter should terminate.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D130285
We have using namespace llvm::dwarf in dwarf.h header globally. Replacing that
with a using namespace within lldb_private::dwarf and moving to a
using namespace lldb_private::dwarf in .cpp files and fully qualified names
in the few header files.
Differential Revision: https://reviews.llvm.org/D120836
There is no reason why this function should be returning a ConstString.
While modifying these files, I also fixed several instances where
GetPluginName and GetPluginNameStatic were returning different strings.
I am not changing the return type of GetPluginNameStatic in this patch, as that
would necessitate additional changes, and this patch is big enough as it is.
Differential Revision: https://reviews.llvm.org/D111877
In all these years, we haven't found a use for this function (it has
zero callers). Lets just remove the boilerplate.
Differential Revision: https://reviews.llvm.org/D109600
DWARFExpression implements the DWARF2 expression model that left
ambiguity on whether the result of an expression was a value or an
address. This patch implements the DWARF location description model
introduces in DWARF 4 and sets the result Value's kind accordingly, if
the expression comes from a DWARF v4+ compile unit. The nomenclature
is taken from DWARF 5, chapter 2.6 "Location Descriptions".
Differential Revision: https://reviews.llvm.org/D98996
This is a follow-up to 188b0747c1664d962e94f00b5e3caac529fa1e26. This
is a very narrow fix to a more general problem. LLDB should be better
at distinguishing between implict and memory location descriptions.
rdar://74902042
Swift async functions receive function arguments inside a
heap-allocated data structure, similar to how ObjC block captures or
C++ coroutine arguments are implement. In DWARF they are described
relative to an entry value that produces a pointer into that heap
object. At typical location looks like
DW_OP_entry_value [ DW_OP_reg14 ] DW_OP_deref DW_OP_plus_uconst 32 DW_OP_deref
This allows the unwinder (which has special ABI knowledge to restore
the contents of r14) to push the base address onto the stack thus
allowing the deref/offset operations to continue. The result of the
entry value is a scalar, because DW_OP_reg14 is a register location —
as it should be since we want to restore the pointer value contained
in r14 at the beginning of the function and not the historical memory
contents it was pointing to. The entry value should restore the
address, which is still valid, not the contents at function entry.
To make this work, we need to allow LLDB to dereference Scalar stack
results like load addresses, which is what this patch
does. Unfortunately it is difficult to test this in isolation, since
the DWARFExpression unit test doesn't have a process.
Differential Revision: https://reviews.llvm.org/D96549
The comment for ValueType claims that all values <1 are errors, but
not all switch statements take this into account. This patch
introduces an explicit Error case and deletes all default: cases, so
we get warned about incomplete switch coverage.
https://reviews.llvm.org/D96537
Dwarf says (Section 2.5.1.1. of DWARF v5) that these operations should
push "generic" (pointer-sized) values. This was not the case for
DW_OP_const operations (which were pushing values based on the size of
arguments), nor DW_OP_litN (which were always pushing 64-bit values).
The practical effect of this that were were unable to display the values
of variables if the size of the DW_OP_const opcode was smaller than the
value of the variable it was describing. This would happen because we
would store this (small) result into a buffer and then would not be able
to read sufficient data out of it (in Value::GetValueAsData). Gcc emits
debug info like this.
Other (more subtle) effects are also possible.
The same fix should be applied to DW_OP_const[us] (leb128 versions), but
I'm not doing that right now, because that would cause us to display
wrong (truncated) values of variables on 32-bit targets (pr48087).
Differential Revision: https://reviews.llvm.org/D90840
The class only supports a single DWARF unit (needed for my new test), and it
reimplements chunks of object and symbol file classes. We can just make it use
the real thing, save some LOC and get the full feature set.
Differential Revision: https://reviews.llvm.org/D90393
This patch completes https://reviews.llvm.org/D83560. Now that the
compiler can emit `DW_OP_implicit_value` into DWARF expressions, lldb
needed to learn reading these opcodes for variable inspection and
expression evaluation.
This implicit location descriptor specifies an immediate value with two
operands: the length (ULEB128) followed by a block representing the value
in the target memory representation.
rdar://67406091
Differential revision: https://reviews.llvm.org/D89842
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
The Length, AbbrOffset and Values fields of the debug_info section are
optional. This patch helps remove them and simplify test cases.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D86857
This patch adds support for emitting multiple abbrev tables. Currently,
compilation units will always reference the first abbrev table.
Reviewed By: jhenderson, labath
Differential Revision: https://reviews.llvm.org/D86194
'InitialLength' is replaced with 'Format' (DWARF32 by default) and 'Length' in this patch.
Besides, test cases for DWARFv4 and DWARFv5, DWARF32 and DWARF64 is
added.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D82622
The "type" argument to the function is mostly useless -- the only
interesting aspect of it is signedness. Pass signedness directly and
compute the value of bits and signedness fields -- that's exactly
what the single caller of this function does.
Previously, we were simply ignoring them and continuing the evaluation.
This behavior does not seem useful, because the resulting value will
most likely be completely bogus.
This patch fixes a crash that happens on the DWARF expression evaluator
when trying to access the top of the stack while it's empty.
rdar://60512489
Differential Revision: https://reviews.llvm.org/D77108
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
This patch fixes a crash that happens on the DWARF expression evaluator
when trying to access the top of the stack while it's empty.
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).
This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).
Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D73258
