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 188b0747c1. 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
and document the shortcomings of LLDB's partially defined DW_OP_piece
handling.
This would manifest as "DW_OP_piece for offset foo but top of stack is
of size bar".
rdar://problem/46262998
Differential Revision: https://reviews.llvm.org/D72880
By switching to Scalars that are backed by explicitly-sized APInts we
can avoid a bug that increases the buffer reserved for a small piece
to the next-largest host integer type.
This manifests as "DW_OP_piece for offset foo but top of stack is of size bar".
Differential Revision: https://reviews.llvm.org/D72879
Summary:
Many of our tests need to initialize certain subsystems/plugins of LLDB such as
`FileSystem` or `HostInfo` by calling their static `Initialize` functions before the
test starts and then calling `::Terminate` after the test is done (in reverse order).
This adds a lot of error-prone boilerplate code to our testing code.
This patch adds a RAII called SubsystemRAII that ensures that we always call
::Initialize and then call ::Terminate after the test is done (and that the Terminate
calls are always in the reverse order of the ::Initialize calls). It also gets rid of
all of the boilerplate that we had for these calls.
Per-fixture initialization is still not very nice with this approach as it would
require some kind of static unique_ptr that gets manually assigned/reseted
from the gtest SetUpTestCase/TearDownTestCase functions. Because of that
I changed all per-fixture setup to now do per-test setup which can be done
by just having the SubsystemRAII as a member of the test fixture. This change doesn't
influence our normal test runtime as LIT anyway runs each test case separately
(and the Initialize/Terminate calls are anyway not very expensive). It will however
make running all tests in a single executable slightly slower.
Reviewers: labath, JDevlieghere, martong, espindola, shafik
Reviewed By: labath
Subscribers: mgorny, rnkovacs, emaste, MaskRay, abidh, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D71630
This patch adds basic support for DW_OP_convert[1] for integer
types. Recent versions of LLVM's optimizer may insert this opcode into
DWARF expressions. DW_OP_convert is effectively a type cast operation
that takes a reference to a base type DIE (or zero) and then casts the
value at the top of the DWARF stack to that type. Internally this
works by changing the bit size of the APInt that is used as backing
storage for LLDB's DWARF stack.
I managed to write a unit test for this by implementing a mock YAML
object file / module that takes debug info sections in yaml2obj
format.
[1] Typed DWARF stack. http://www.dwarfstd.org/ShowIssue.php?issue=140425.1
<rdar://problem/48167864>
Differential Revision: https://reviews.llvm.org/D67369
llvm-svn: 371532
Summary:
The DWARFExpression methods have a lot of arguments. This removes two of
them by removing the ability to slice the expression via two offset+size
parameters. This is a functionality that it is not always needed, and
when it is, we already have a different handy way of slicing a data
extractor which we can use instead.
Reviewers: JDevlieghere, clayborg
Subscribers: aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D66745
llvm-svn: 370027
Summary:
The DWARF spec states that the DWARF stack arguments are numbered from
the top. Our implementation of DW_OP_pick was counting them from the
bottom.
This bug probably wasn't noticed because nobody (except my upcoming
postfix-to-DWARF converter) uses DW_OP_pick, but I've cross-checked with
gdb to confirm that counting from the top is the expected behavior.
This patch fixes the implementation to match the spec and gdb behavior
and adds a test.
Reviewers: jasonmolenda, clayborg
Subscribers: mgorny, aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D61182
llvm-svn: 359436
Adrian Prantl