The LLVM Coding Standards [1] specify that:
> [T]o match error message styles commonly produced by other tools,
> start the first sentence with a lowercase letter, and finish the last
> sentence without a period, if it would end in one otherwise.
Historically, that hasn't been something we've enforced in LLDB, but in
the past year or so I've started to pay more attention to this in code
reviews. This PR brings more error messages in compliance, further
increasing consistency.
I also adopted `createStringErrorV` where it improved the code as a
drive-by for lines I was already touching.
[1] https://llvm.org/docs/CodingStandards.html#error-and-warning-messages
Assisted-by: Claude Code
Value::ResolveValue() only does something if the value has an associated
compiler type, which is never set on values used in DWARF expressions.
Simplify code by inlining the method.
The only difference between them is that OptionalBool's third state
is "unknown" and LazyBool's is "calculate". We don't need to tell
the difference in a single context, so I've made a new eLazyBoolDontKnow
which is an alias of eLazyBoolCalculate.
- it is always passed as zero
- a lot of plugins aren't using it correctly
- the data extractor class already has the capability to look at a
subset of bytes
This is to highlight places where we (probably unintentionally)
construct an `Address` object from an already resolved address, making
it unresolved again.
See the changes in `DynamicLoaderDarwin.cpp` for a quick example.
Also, use this constructor instead of `Address(lldb::addr_t file_addr,
const SectionList *section_list)` when `section_list` is `nullptr`.
Some plugins were returning the number of specifications they have
added, while others were returning the total final number. Particularly
devious plugins (Minidump) were clearing the specification list
altogether. This resulted in nondeterministic failures (depending on
plugin ininitialization order) in TestSBModule.
This PR defines the problem away by having each plugin only return the
specifications it is responsible for. If the caller wants to merge them,
it is free to do so. This *might* be slighly less efficient, but this is
hardly hot code.
I'm not touching the ObjectFile::GetModuleSpecifications function (the
caller of all these functions) as the PR is big enough, although the
same approach might be warranted there as well.
Fixes https://github.com/llvm/llvm-project/issues/178625.
lldb had three preprocessor defines for logging,
LLDB_LOG - formatv style argument
LLDB_LOGF - printf style argument
LLDB_LOGV - formatv style argument, only when verbose enabled
If you weren't looking at Log.h and the definition of these three, and
wanted to log something with formatv, it was easy to use LLDB_LOGV by
accident. We just had a situation where an important log statement
wasn't logging and it turned out to be this. This is fragile if you
aren't looking at the header directly, so I'd like to make this more
explicit. My proposal:
LLDB_LOG - formatv style argument
LLDB_LOG_VERBOSE - formatv style argument, only when verbose enabled
LLDB_LOGF - printf style argument
LLDB_LOGF_VERBOSE - printf style argument, only when verbose enabled
The new fouth one is to remove several places where we do `if (log &&
log->GetVerbose()) LLDB_LOGF (...)` in the sources today, and make both
styles consistent.
This PR implements that change, mechanically changing all LLDB_LOGV's to
LLDB_LOG_VERBOSE.
It also updates many of the `if (log && log->GetVerbose()) LLDB_LOGF`'s.
Some uses of this conditional expression do extra calculations in
addition to logging, and so those were left as-is so we're not doing
throwaway work when running without verbose logging.
There were many instances throughout lldb where callers are still doing
`if (log) LLDB_LOG*(...)`, a remnant of when all calls were to the `Log`
object's `Printf()` method, and you had to check if your local Log*
pointer was non-nullptr before calling the method. I removed those,
again keeping ones where work for logging is done in the block of code.
The code changes are all mechanical and uninteresting, but the question
of whether this naming change is widely agreed on is maybe worth
discussing.
BranchInst currently represents both unconditional and conditional
branches. However, these are quite different operations that are often
handled separately. Therefore, split them into separate opcodes and
classes to allow distinguishing these operations in the type system.
Additionally, this also slightly improves compile-time performance.
This PR replaces the Get*CallbackAtIndex pattern in the PluginManager
with returning a snapshot of callbacks that the caller can iterate over
using a range-based for loop. This is a continuation of #184452 which
added thread safety by using snapshots. However, that introduced a bunch
of unnecessary copies which are largely eliminated again by getting the
snapshot once when gather all the callbacks, rather than doing that on
each iteration when querying a plugin for a given index. It also
eliminates the possibility of the snapshot changing underneath you when
iterating over the plugins.
This change was largely mechanical and I used Claude to do the menial
work of updating the signatures and call sites.
Depends on:
* https://github.com/llvm/llvm-project/pull/177921
* https://github.com/llvm/llvm-project/pull/177926
(only last commit is relevant for this review)
This patch emits a workaround suggestion (in the form of a `note:`
diagnostic) when an expression fails due to trying to mutate state/call
functions with CV-qualifiers that are disallowed by C++ language rules
based on the context the expression is evaluated in. The note looks as
follows:
```
(lldb) expr next.method()
˄
╰─ error: 'this' argument to member function 'method' has type 'const Bar', but function is not marked const
note: Ran expression as 'C++14'.
note: note: 'method' declared here
note: Possibly trying to mutate object in a const context. Try running the expression with: expression --c++-ignore-context-qualifiers -- <your expression>
```
This reapplies #175292 with the fixed test. The original test used
integer types with different bit widths on different platforms.
----- Original message:
This allows expressions that use these conversions to be executed when
JIT is not available.
In a PR last month I changed the ObjectFile CreateInstance etc methods
to accept an optional DataExtractorSP instead of a DataBufferSP, and
retain the extractor in a shared pointer internally in all of the
ObjectFile subclasses. This is laying the groundwork for using a
VirtualDataExtractor for some Mach-O binaries on macOS, where the
segments of the binary are out-of-order in actual memory, and we add a
lookup table to make it appear that the TEXT segment is at offset 0 in
the Extractor, etc. Working on the actual implementation, I realized we
were still using DataBufferSP's in ModuleSpec and Module, as well as in
ObjectFile::GetModuleSpecifications.
I originally was making a much larger NFC change where I had all
ObjectFile subclasses operating on DataExtractors throughout their
implementation, as well as in the DWARF parser. It was a very large
patchset. Many subclasses start with their DataExtractor, then create
smaller DataExtractors for parts of the binary image - the string table,
the symbol table, etc., for processing.
After consideration and discussion with Jonas, we agreed that a
segment/section of a binary will never require a lookup table to access
the bytes within it, so I changed
VirtualDataExtractor::GetSubsetExtractorSP to (1) require that the
Subset be contained within a single lookup table entry, and (2) return a
simple DataExtractor bounded on that byte range. By doing this, I was
able to remove all of my very-invasive changes to the ObjectFile
subclass internals; it's only when they are operating on the entire
binary image that care is needed.
One pattern that subclasses like ObjectFileBreakpad use is to take an
ArrayRef of the DataBuffer for a binary, then create a StringRef of
that, then look for strings in it. With a VirtualDataExtractor and
out-of-order binary segments, with gaps between them, this allows us to
search the entire buffer looking for a string, and segfault when it gets
to an unmapped region of the buffer. I added a
VirtualDataExtractor::GetSubsetExtractorSP(0) which gets the largest
contiguous memory region starting at offset 0 for this use case, and I
added a comment about what was being done there because I know it is not
obvious, and people not working on macOS wouldn't be familiar with the
requirement. (when we have a ModuleSpec with a DataExtractor, any of the
ObjectFile subclasses get a shot at Creating, so they all have to be
able to iterate on these)
rdar://148939795
Instead of creating a new `UserExpressionSP` for the fix-it expression,
just re-use the existing `user_expression_sp`. We used to always reset
it when an expression failed, even if no fix-it was available. An
upcoming patch will need the `user_expression_sp` to be alive at the
point where we set up the diagnostic errors. So this patch removes the
unconditional `reset()` on `!parse_success` in favour of resetting it to
the new fixed expression, if one is available.
Replace patterns that manually compute allocation sizes by multiplying
getTypeAllocSize(getAllocatedType()) by the array size with calls to the
getAllocationSize(DL) API, which handles this correctly and concisely,
returning nullopt for VLAs.
This fixes several places that were not accounting for array allocations
when computing sizes, simplifies code that was doing this manually, and
adds some explicit isFixed checks where implied convert was being used.
This PR is because now that we have opaque pointers, I hate that some
AllocaInst still has type information being consumed by some passes
instead of just using the size, since passes rarely handle that type
information well or correctly. I hope this will grow into a sequence of
commits to slowly eliminate uses of getAllocatedType from AllocaInst.
And similarly later to remove type information from GlobalValue too (it
can be replaced with just dereferenceable bytes, similar to arguments).
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Introducing `llvm::createStringErrorV` caused a `0.5%` compile-time
regression because it's an inline function in a core header. This moves
the API to a new header to prevent including this function in files that
don't need it.
Also includes the header in the source files that have been using
`createStringErrorV` (which currently is just LLDB).
Trimming the content of the progress event is the responsibility of the
consumer, not the producer. For example, when using the statusline,
there's plenty of space to show longer expressions.
rdar://166879951
When you run an expression and the result has a dynamic type that is
different from the expression's static result type, we print the result
variable using the dynamic type, but at present when you use the result
variable in an expression later on, we only give you access to the
static type. For instance:
```
(lldb) expr MakeADerivedReportABase()
(Derived *) $0 = 0x00000001007e93e0
(lldb) expr $0->method_from_derived()
^
error: no member named 'method_from_derived' in 'Base'
(lldb)
```
The static return type of that function is `Base *`, but we printed that
the result was a `Derived *` and then only used the `Base *` part of it
in subsequent expressions. That's not very helpful, and forces you to
guess and then cast the result types to their dynamic type in order to
be able to access the full type you were returned, which is
inconvenient.
This patch makes lldb retain the dynamic type of the result variable
(and ditto for persistent result variables).
It also adds more testing of expression result variables with various
types of dynamic values, to ensure we can access both the ivars and
methods of the type we print the result as.
The ObjectFile plugin interface accepts an optional DataBufferSP
argument. If the caller has the contents of the binary, it can provide
this in that DataBufferSP. The ObjectFile subclasses in their
CreateInstance methods will fill in the DataBufferSP with the actual
binary contents if it is not set.
ObjectFile base class creates an ivar DataExtractor from the
DataBufferSP passed in.
My next patch will be a caller that creates a VirtualDataExtractor with
the binary data, and needs to pass that in to the ObjectFile plugin,
instead of the bag-of-bytes DataBufferSP. It builds on the previous
patch changing ObjectFile's ivar from DataExtractor to DataExtractorSP
so I could pass in a subclass in the shared ptr. And it will be using
the VirtualDataExtractor that Jonas added in
https://github.com/llvm/llvm-project/pull/168802
No behavior is changed by the patch; we're simply moving the creation of
the DataExtractor to the caller, instead of a DataBuffer that is
immediately used to set up the ObjectFile DataExtractor. The patch is a
bit complicated because all of the ObjectFile subclasses have to
initialize their DataExtractor to pass in to the base class.
I ran the testsuite on macOS and on AArch64 Ubutnu. (btw David, I ran it
under qemu on my M4 mac with SME-no-SVE again, Ubuntu 25.10, checked
lshw(1) cpu capabilities, and qemu doesn't seem to be virtualizing the
SME, that explains why the testsuite passes)
rdar://148939795
---------
Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>
This commit modifies the dwarf expression evaluator in how we handle the
deref operation for register and implicit locations on the stack. For a
typical memory location a deref operation will read the value from
memory. For register and implicit locations the deref operation will
read the value from the register or its implicit location. In lldb we
eagerly read register and implicit values and push them on the stack so
the deref operation for these becomes a "no-op" that leaves the value on
the stack and updates the tracked location kind.
The motivation for this change is to handle `DW_OP_deref*` operations on
location descriptions as described by the heterogenious debugging
[extensions](https://rocm.docs.amd.com/projects/llvm-project/en/latest/LLVM/llvm/html/AMDGPUDwarfExtensionsForHeterogeneousDebugging.html#a-2-5-4-4-4-register-location-description-operations).
Specifically, for register locations it states
> These operations obtain a register location. To fetch the contents of
> a register, it is necessary to use DW_OP_regval_type, use one of the
> DW_OP_breg* register-based addressing operations, or use DW_OP_deref*
on
> a register location description.
My understanding is that this is the intended behavior from dwarf5 as
well and is not a change in behavior.
ObjectFile has an m_data DataExtractor ivar which may be default
constructed initially, or initialized with a DataBuffer passed in to its
ctor. If the DataExtractor does not get a DataBuffer source passed in,
the subclass will initialize it with access to the object file's data.
When a DataBuffer is passed in to the base class ctor, the DataExtractor
only has its buffer initialized; ObjectFile doesn't yet know the address
size and endianness to fully initialize the DataExtractor.
This patch changes ObjectFile to instead have a DataExtractorSP ivar
which is always initialized with at least a default-constructed
DataExtractor object in the base class ctor. The next patch I will be
writing is to change the ObjectFile ctor to take an optional
DataExtractorSP, so the caller can pass a DataExtractor subclass -- the
VirtualizeDataExtractor being added via
https://github.com/llvm/llvm-project/pull/168802
instead of a DataBuffer which is trivially saved into the DataExtractor.
The change is otherwise mechanical; all `m_data.` changed to
`m_data_sp->` and all the places where `m_data` was passed in for a
by-ref call were changed to `*m_data_sp.get()`. The shared pointer is
always initialized to contain an object.
I built & ran the testsuite on macOS and on aarch64-Ubuntu (thanks for
getting the Linux testsuite to run on SME-only systems David). All of
the ObjectFile subclasses I modifed compile cleanly, but I haven't
tested them beyond any unit tests they may have (prob breakpad).
rdar://148939795
This commit unifies the code in the dwarf expression evaluator that
handles these two deref operations. Previously we had similar, but not
identical code for handling them.
The implementation was taken from the DW_OP_deref_size code path since
that handles the general case. We put that code into an
Evaluate_DW_OP_deref_size function and call it with the address size
when evaluating DW_OP_deref.
There were initially two test failures when I made the change. The
`DW_op_deref_no_ptr_fixing` unittest failed because we were not
correctly setting the address size when we created the DataExtractor.
The `DW_OP_deref test` failed because previously the expression
`DW_OP_lit4, DW_OP_deref` would evaluate to a LoadAddress, but the code
for deref_size was evaluating it to a scalar.
The difference was in how it handled a deref of a scalar value type. In
the deref code path we convert a scalar to a load address, but this was
not done in the deref_size code path.
```
case Value::ValueType::Scalar:
stack.back().SetValueType(Value::ValueType::LoadAddress);
```
I decided to modify the deref_size code to also convert the value to a
load address to keep the test passing.
There is no functional change intended here. The motivation is to reduce
the number of code paths that implement the deref operation.
This patch fixes and eliminates the possibility of SupportFileSP ever
being nullptr. The support file was originally treated like a value
type, but became a polymorphic type and therefore has to be stored and
passed around as a pointer.
To avoid having all the callers check the validity of the pointer, I
introduced the invariant that SupportFileSP is never null and always
default constructed. However, without enforcement at the type level,
that's fragile and indeed, we already identified two crashes where
someone accidentally broke that invariant.
This PR introduces a NonNullSharedPtr to prevent that. NonNullSharedPtr
is a smart pointer wrapper around std::shared_ptr that guarantees the
pointer is never null. If default-constructed, it creates a
default-constructed instance of the contained type. Note that I'm using
private inheritance because you shouldn't inherit from standard library
classes due to the lack of virtual destructor. So while the new
abstraction looks like a `std::shared_ptr`, it is in fact **not** a
shared pointer. Given that our destructor is trivial, we could use
public inheritance, but currently there's no need for it.
rdar://164989579
This is a fixed version of #167886.
The build previously failed with `BUILD_SHARED_LIBS=ON`. After trying
that locally, I uncovered a few other instances of lldb non-plugin
libraries depending on clang transitively through lldbValueObject, so I
added the correct clang libraries to their dependencies.
This avoids unintentional comparisons between `SourceLanguage` and
`LanguageType`.
Also marks `operator bool` explicit so we don't implicitly convert to
bool.
Starting with https://github.com/llvm/llvm-project/pull/148877 we
started encoding the module ID of the function DIE we are currently
parsing into its `AsmLabel` in the AST. When the JIT asks LLDB to
resolve our special mangled name, we would locate the module and resolve
the function/symbol we found in it.
If we are debugging with a `SymbolFileDWARFDebugMap`, the module ID we
encode is that of the `.o` file that is tracked by the debug-map. To
resolve the address of the DIE in that `.o` file, we have to ask
`SymbolFileDWARFDebugMap::LinkOSOAddress` to turn the address of the
`.o` DIE into a real address in the linked executable. This will only
work if the `.o` address was actually tracked by the debug-map. However,
if the function definition appears in multiple `.o` files (which is the
case for functions defined in headers), the linker will most likely
de-deuplicate that definition. So most `.o`'s definition DIEs for that
function won't have a contribution in the debug-map, and thus we fail to
resolve the address.
When debugging Clang on Darwin, e.g., you'd see:
```
(lldb) expr CXXDecl->getName()
error: Couldn't look up symbols:
$__lldb_func::0x1:0x4000d000002359da:_ZNK5clang9NamedDecl7getNameEv
Hint: The expression tried to call a function that is not present in the target, perhaps because it was optimized out by the compiler.
```
unless you were stopped in the `.o` file whose definition of `getName`
made it into the final executable.
The fix here is to error out if we fail to resolve the address, causing
us to fall back on the old flow which did a lookup by mangled name,
which the `SymbolFileDWARFDebugMap` will handle correctly.
An alternative fix to this would be to encode the
`SymbolFileDWARFDebugMap`'s module-id. And implement
`SymbolFileDWARFDebugMap::ResolveFunctionCallLabel` by doing a mangled
name lookup. The proposed approach doesn't stop us from implementing
that, so we could choose to do it in a follow-up.
rdar://161393045
…lts (#159460)""
The original had an issue on "AArch-less" bots.
Fixed it with some ifdefs around the presence of the AArch ABI plugin.
This reverts commit 1a4685df13282ae5c1d7dce055a71a7130bfab3c.
When evaluating any DWARF expression that ended in OP_deref and whose
previous value on the dwarf stack -- the pointer address for the deref
-- was a load address, we were treating the result itself as a pointer,
calling Process:FixCodeAddress(result). This is wrong: there's no
guarantee that the result is a pointer itself.
[lldb] Track CFA pointer metadata in StackID
In this commit:
9c8e71644227 [lldb] Make StackID call Fix{Code,Data} pointers (#152796)
We made StackID keep track of the CFA without any pointer metadata in
it. This is necessary when comparing two StackIDs to determine which one
is "younger".
However, the CFA inside StackIDs is also used in other contexts through
the method StackID::GetCallFrameAddress. One notable case is
DWARFExpression: the computation of `DW_OP_call_frame_address` is done
using StackID. This feeds into many other places, e.g. expression
evaluation may require the address of a variable that is computed from
the CFA; to access the variable without faulting, we may need to
preserve the pointer metadata. As such, StackID must be able to provide
both versions of the CFA.
In the spirit of allowing consumers of pointers to decide what to do
with pointer metadata, this patch changes StackID to store both versions
of the cfa pointer. Two getter methods are provided, and all call sites
except DWARFExpression preserve their existing behavior (stripped
pointer). Other alternatives were considered:
* Just store the raw pointer. This would require changing the
comparisong operator `<` to also receive a Process, as the comparison
requires stripped pointers. It wasn't clear if all call-sites had a
non-null process, whereas we know we have a process when creating a
StackID.
* Store a weak pointer to the process inside the class, and then strip
metadata as needed. This would require a `weak_ptr::lock` in many
operations of LLDB, and it felt wasteful. It also prevents stripping
of the pointer if the process has gone away.
This patch also changes RegisterContextUnwind::ReadFrameAddress, which
is the method computing the CFA fed into StackID, to also preserve the
signature pointers.
One of those arguments should be called `pointer` to correlate it to the
name of the function and to distinguish it from the address where it
will be written.
Depends on
* https://github.com/llvm/llvm-project/pull/148877
* https://github.com/llvm/llvm-project/pull/155483
* https://github.com/llvm/llvm-project/pull/155485
* https://github.com/llvm/llvm-project/pull/154137
* https://github.com/llvm/llvm-project/pull/154142
This patch is an implementation of [this
discussion](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816/7)
about handling ABI-tagged structors during expression evaluation.
**Motivation**
LLDB encodes the mangled name of a `DW_TAG_subprogram` into `AsmLabel`s
on function and method Clang AST nodes. This means that when calls to
these functions get lowered into IR (when running JITted expressions),
the address resolver can locate the appropriate symbol by mangled name
(and it is guaranteed to find the symbol because we got the mangled name
from debug-info, instead of letting Clang mangle it based on AST
structure). However, we don't do this for
`CXXConstructorDecl`s/`CXXDestructorDecl`s because these structor
declarations in DWARF don't have a linkage name. This is because there
can be multiple variants of a structor, each with a distinct mangling in
the Itanium ABI. Each structor variant has its own definition
`DW_TAG_subprogram`. So LLDB doesn't know which mangled name to put into
the `AsmLabel`.
Currently this means using ABI-tagged structors in LLDB expressions
won't work (see [this
RFC](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816)
for concrete examples).
**Proposed Solution**
The `FunctionCallLabel` encoding that we put into `AsmLabel`s already
supports stuffing more info about a DIE into it. So this patch extends
the `FunctionCallLabel` to contain an optional discriminator (a sequence
of bytes) which the `SymbolFileDWARF` plugin interprets as the
constructor/destructor variant of that DIE. So when searching for the
definition DIE, LLDB will include the structor variant in its heuristic
for determining a match.
There's a few subtleties here:
1. At the point at which LLDB first constructs the label, it has no way
of knowing (just by looking at the debug-info declaration), which
structor variant the expression evaluator is supposed to call. That's
something that gets decided when compiling the expression. So we let the
Clang mangler inject the correct structor variant into the `AsmLabel`
during JITing. I adjusted the `AsmLabelAttr` mangling for this in
https://github.com/llvm/llvm-project/pull/155485. An option would've
been to create a new Clang attribute which behaved like an `AsmLabel`
but with these special semantics for LLDB. My main concern there is that
we'd have to adjust all the `AsmLabelAttr` checks around Clang to also
now account for this new attribute.
2. The compiler is free to omit the `C1` variant of a constructor if the
`C2` variant is sufficient. In that case it may alias `C1` to `C2`,
leaving us with only the `C2` `DW_TAG_subprogram` in the object file.
Linux is one of the platforms where this occurs. For those cases I added
a heuristic in `SymbolFileDWARF` where we pick `C2` if we asked for `C1`
but it doesn't exist. This may not always be correct (e.g., if the
compiler decided to drop `C1` for other reasons).
3. In https://github.com/llvm/llvm-project/pull/154142 Clang will emit
`C4`/`D4` variants of ctors/dtors on declarations. When resolving the
`FunctionCallLabel` we will now substitute the actual variant that Clang
told us we need to call into the mangled name. We do this using LLDB's
`ManglingSubstitutor`. That way we find the definition DIE exactly the
same way we do for regular function calls.
4. In cases where declarations and definitions live in separate modules,
the DIE ID encoded in the function call label may not be enough to find
the definition DIE in the encoded module ID. For those cases we fall
back to how LLDB used to work: look up in all images of the target. To
make sure we don't use the unified mangled name for the fallback lookup,
we change the lookup name to whatever mangled name the FunctionCallLabel
resolved to.
rdar://104968288
The LLVM Style Guide says the following about error and warning messages
[1]:
> [T]o match error message styles commonly produced by other tools,
> start the first sentence with a lowercase letter, and finish the last
> sentence without a period, if it would end in one otherwise.
I often provide this feedback during code review, but we still have a
bunch of places where we have inconsistent error message, which bothers
me as a user. This PR identifies a handful of those places and updates
the messages to be consistent.
[1] https://llvm.org/docs/CodingStandards.html#error-and-warning-messages
In architectures where pointers may contain metadata, such as arm64e,
the metadata may need to be cleaned prior to sending this pointer to be
used in expression evaluation generated code.
This patch is a step towards allowing consumers of pointers to decide
whether they want to keep or remove metadata, as opposed to discarding
metadata at the moment pointers are created. See #150537.
This was tested running the LLDB test suite on arm64e.
(The first attempt at this patch caused a failure in
TestScriptedProcessEmptyMemoryRegion.py. This test exercises a case
where IRMemoryMap uses host memory in its allocations; pointers to such
allocations should not be fixed, which is what the original patch failed
to account for).
**Context**
Follow-up to
[#147460](https://github.com/llvm/llvm-project/pull/147460), which added
the ability to surface register-resident variable locations.
This PR moves the annotation logic out of `Instruction::Dump()` and into
`Disassembler::PrintInstructions()`, and adds lightweight state tracking
so we only print changes at range starts and when variables go out of
scope.
---
## What this does
While iterating the instructions for a function, we maintain a “live
variable map” keyed by `lldb::user_id_t` (the `Variable`’s ID) to
remember each variable’s last emitted location string. For each
instruction:
- **New (or newly visible) variable** → print `name = <location>` once
at the start of its DWARF location range, cache it.
- **Location changed** (e.g., DWARF range switched to a different
register/const) → print the updated mapping.
- **Out of scope** (was tracked previously but not found for the current
PC) → print `name = <undef>` and drop it.
This produces **concise, stateful annotations** that highlight variable
lifetime transitions without spamming every line.
---
## Why in `PrintInstructions()`?
- Keeps `Instruction` stateless and avoids changing the
`Instruction::Dump()` virtual API.
- Makes it straightforward to diff state across instructions (`prev →
current`) inside the single driver loop.
---
## How it works (high-level)
1. For the current PC, get in-scope variables via
`StackFrame::GetInScopeVariableList(/*get_parent=*/true)`.
2. For each `Variable`, query
`DWARFExpressionList::GetExpressionEntryAtAddress(func_load_addr,
current_pc)` (added in #144238).
3. If the entry exists, call `DumpLocation(..., eDescriptionLevelBrief,
abi)` to get a short, ABI-aware location string (e.g., `DW_OP_reg3 RBX →
RBX`).
4. Compare against the last emitted location in the live map:
- If not present → emit `name = <location>` and record it.
- If different → emit updated mapping and record it.
5. After processing current in-scope variables, compute the set
difference vs. the previous map and emit `name = <undef>` for any that
disappeared.
Internally:
- We respect file↔load address translation already provided by
`DWARFExpressionList`.
- We reuse the ABI to map LLVM register numbers to arch register names.
---
## Example output (x86_64, simplified)
```
-> 0x55c6f5f6a140 <+0>: cmpl $0x2, %edi ; argc = RDI, argv = RSI
0x55c6f5f6a143 <+3>: jl 0x55c6f5f6a176 ; <+54> at d_original_example.c:6:3
0x55c6f5f6a145 <+5>: pushq %r15
0x55c6f5f6a147 <+7>: pushq %r14
0x55c6f5f6a149 <+9>: pushq %rbx
0x55c6f5f6a14a <+10>: movq %rsi, %rbx
0x55c6f5f6a14d <+13>: movl %edi, %r14d
0x55c6f5f6a150 <+16>: movl $0x1, %r15d ; argc = R14
0x55c6f5f6a156 <+22>: nopw %cs:(%rax,%rax) ; i = R15, argv = RBX
0x55c6f5f6a160 <+32>: movq (%rbx,%r15,8), %rdi
0x55c6f5f6a164 <+36>: callq 0x55c6f5f6a030 ; symbol stub for: puts
0x55c6f5f6a169 <+41>: incq %r15
0x55c6f5f6a16c <+44>: cmpq %r15, %r14
0x55c6f5f6a16f <+47>: jne 0x55c6f5f6a160 ; <+32> at d_original_example.c:5:10
0x55c6f5f6a171 <+49>: popq %rbx ; i = <undef>
0x55c6f5f6a172 <+50>: popq %r14 ; argv = RSI
0x55c6f5f6a174 <+52>: popq %r15 ; argc = RDI
0x55c6f5f6a176 <+54>: xorl %eax, %eax
0x55c6f5f6a178 <+56>: retq
```
Only transitions are shown: the start of a location, changes, and
end-of-lifetime.
---
## Scope & limitations (by design)
- Handles **simple locations** first (registers, const-in-register cases
surfaced by `DumpLocation`).
- **Memory/composite locations** are out of scope for this PR.
- Annotations appear **only at range boundaries** (start/change/end) to
minimize noise.
- Output is **target-independent**; register names come from the target
ABI.
## Implementation notes
- All annotation printing now happens in
`Disassembler::PrintInstructions()`.
- Uses `std::unordered_map<lldb::user_id_t, std::string>` as the live
map.
- No persistent state across calls; the map is rebuilt while walking
instruction by instruction.
- **No changes** to the `Instruction` interface.
---
## Requested feedback
- Placement and wording of the `<undef>` marker.
- Whether we should optionally gate this behind a setting (currently
always on when disassembling with an `ExecutionContext`).
- Preference for immediate inclusion of tests vs. follow-up patch.
---
Thanks for reviewing! Happy to adjust behavior/format based on feedback.
---------
Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>
Co-authored-by: Adrian Prantl <adrian.prantl@gmail.com>
This fixes a few bugs, effectively through a fallback to `p` when `po` fails.
The motivating bug this fixes is when an error within the compiler causes `po` to fail.
Previously when that happened, only its value (typically an object's address) was
printed – and problematically, no compiler diagnostics were shown. With this change,
compiler diagnostics are shown, _and_ the object is fully printed (ie `p`).
Another bug this fixes is when `po` is used on a type that doesn't provide an object
description (such as a struct). Again, the normal `ValueObject` printing is used.
Additionally, this also improves how lldb handles an object description method that
fails in some way. Now an error will be shown (it wasn't before), and the value will be
printed normally.
Relates to https://github.com/llvm/llvm-project/issues/135707
Where it was reported that reading the PC using "register read" had
different results to an expression "$pc".
This was happening because registers are treated in lldb as pure
"values" that don't really have an endian. We have to store them
somewhere on the host of course, so the endian becomes host endian.
When you want to use a register as a value in an expression you're
pretending that it's a variable in memory. In target memory. Therefore
we must convert the register value to that endian before use.
The test I have added is based on the one used for XML register flags.
Where I fake an AArch64 little endian and an s390x big endian target. I
set up the data in such a way the pc value should print the same for
both, either with register read or an expression.
I considered just adding a live process test that checks the two are the
same but with on one doing cross endian testing, I doubt it would have
ever caught this bug.
Simulating this means most of the time, little endian hosts will test
little to little and little to big. In the minority of cases with a big
endian host, they'll check the reverse. Covering all the combinations.
In architectures where pointers may contain metadata, such as arm64e,
the metadata may need to be cleaned prior to sending this pointer to be
used in expression evaluation generated code.
This patch is a step towards allowing consumers of pointers to decide
whether they want to keep or remove metadata, as opposed to discarding
metadata at the moment pointers are created. See
https://github.com/llvm/llvm-project/pull/150537.
This was tested running the LLDB test suite on arm64e.
Factors out code to locate a definition DIE from a `FunctionCallLabel`
into a helper. This will be useful for an upcoming refactor that extends
`FindFunctionDefinition`.
Drive-by:
* adjusts some error messages in the `FunctionCallLabel` support code.
I discovered this building the lldb test suite with `-mthumb` set, so
that all test programs are purely Arm Thumb code.
When C++ expressions did a function lookup, they took a different path
from C programs. That path happened to land on the line that I've
changed. Where we try to look something up as a function, but don't then
resolve the address as if it's a callable.
With Thumb, if you do the non-callable lookup, the bottom bit won't be
set. This means when lldb's expression wrapper function branches into
the found function, it'll be in Arm mode trying to execute Thumb code.
Thumb is the only instance where you'd notice this. Aside from maybe
MicroMIPS or MIPS16 perhaps but I expect that there are 0 users of that
and lldb.
I have added a new test case that will simulate this situation in
"normal" Arm builds so that it will get run on Linaro's buildbot.
This change also fixes the following existing tests when `-mthumb` is
used:
```
lldb-api :: commands/expression/anonymous-struct/TestCallUserAnonTypedef.py
lldb-api :: commands/expression/argument_passing_restrictions/TestArgumentPassingRestrictions.py
lldb-api :: commands/expression/call-function/TestCallStopAndContinue.py
lldb-api :: commands/expression/call-function/TestCallUserDefinedFunction.py
lldb-api :: commands/expression/char/TestExprsChar.py
lldb-api :: commands/expression/class_template_specialization_empty_pack/TestClassTemplateSpecializationParametersHandling.py
lldb-api :: commands/expression/context-object/TestContextObject.py
lldb-api :: commands/expression/formatters/TestFormatters.py
lldb-api :: commands/expression/import_base_class_when_class_has_derived_member/TestImportBaseClassWhenClassHasDerivedMember.py
lldb-api :: commands/expression/inline-namespace/TestInlineNamespace.py
lldb-api :: commands/expression/namespace-alias/TestInlineNamespaceAlias.py
lldb-api :: commands/expression/no-deadlock/TestExprDoesntBlock.py
lldb-api :: commands/expression/pr35310/TestExprsBug35310.py
lldb-api :: commands/expression/static-initializers/TestStaticInitializers.py
lldb-api :: commands/expression/test/TestExprs.py
lldb-api :: commands/expression/timeout/TestCallWithTimeout.py
lldb-api :: commands/expression/top-level/TestTopLevelExprs.py
lldb-api :: commands/expression/unwind_expression/TestUnwindExpression.py
lldb-api :: commands/expression/xvalue/TestXValuePrinting.py
lldb-api :: functionalities/thread/main_thread_exit/TestMainThreadExit.py
lldb-api :: lang/cpp/call-function/TestCallCPPFunction.py
lldb-api :: lang/cpp/chained-calls/TestCppChainedCalls.py
lldb-api :: lang/cpp/class-template-parameter-pack/TestClassTemplateParameterPack.py
lldb-api :: lang/cpp/constructors/TestCppConstructors.py
lldb-api :: lang/cpp/function-qualifiers/TestCppFunctionQualifiers.py
lldb-api :: lang/cpp/function-ref-qualifiers/TestCppFunctionRefQualifiers.py
lldb-api :: lang/cpp/global_operators/TestCppGlobalOperators.py
lldb-api :: lang/cpp/llvm-style/TestLLVMStyle.py
lldb-api :: lang/cpp/multiple-inheritance/TestCppMultipleInheritance.py
lldb-api :: lang/cpp/namespace/TestNamespace.py
lldb-api :: lang/cpp/namespace/TestNamespaceLookup.py
lldb-api :: lang/cpp/namespace_conflicts/TestNamespaceConflicts.py
lldb-api :: lang/cpp/operators/TestCppOperators.py
lldb-api :: lang/cpp/overloaded-functions/TestOverloadedFunctions.py
lldb-api :: lang/cpp/rvalue-references/TestRvalueReferences.py
lldb-api :: lang/cpp/static_methods/TestCPPStaticMethods.py
lldb-api :: lang/cpp/template/TestTemplateArgs.py
lldb-api :: python_api/thread/TestThreadAPI.py
```
There are other failures that are due to different problems, and this
change does not make those worse.
(I have no plans to run the test suite with `-mthumb` regularly, I just
did it to test some other refactoring)
### 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
LLDB currently attaches `AsmLabel`s to `FunctionDecl`s such that that
the `IRExecutionUnit` can determine which mangled name to call (we can't
rely on Clang deriving the correct mangled name to call because the
debug-info AST doesn't contain all the info that would be encoded in the
DWARF linkage names). However, we don't attach `AsmLabel`s for structors
because they have multiple variants and thus it's not clear which
mangled name to use. In the [RFC on fixing expression evaluation of
abi-tagged
structors](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816)
we discussed encoding the structor variant into the `AsmLabel`s.
Specifically in [this
thread](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816/7)
we discussed that the contents of the `AsmLabel` are completely under
LLDB's control and we could make use of it to uniquely identify a
function by encoding the exact module and DIE that the function is
associated with (mangled names need not be enough since two identical
mangled symbols may live in different modules). So if we already have a
custom `AsmLabel` format, we can encode the structor variant in a
follow-up (the current idea is to append the structor variant as a
suffix to our custom `AsmLabel` when Clang emits the mangled name into
the JITted IR). Then we would just have to teach the `IRExecutionUnit`
to pick the correct structor variant DIE during symbol resolution. The
draft of this is available
[here](https://github.com/llvm/llvm-project/pull/149827)
This patch sets up the infrastructure for the custom `AsmLabel` format
by encoding the module id, DIE id and mangled name in it.
**Implementation**
The flow is as follows:
1. Create the label in `DWARFASTParserClang`. The format is:
`$__lldb_func:module_id:die_id:mangled_name`
2. When resolving external symbols in `IRExecutionUnit`, we parse this
label and then do a lookup by DIE ID (or mangled name into the module if
the encoded DIE is a declaration).
Depends on https://github.com/llvm/llvm-project/pull/151355
This patch fixes updating persistent variables when memory cannot be
allocated in an inferior process:
```
> lldb -c test.core
(lldb) expr int $i = 5
(lldb) expr $i = 55
(int) $0 = 55
(lldb) expr $i
(int) $i = 5
```
With this patch, the last command prints:
```
(int) $i = 55
```
The issue was introduced in #145599.
