We noticed some binaries with duplicated global symbol
entries (same name, address and size). Ignore them as it is possibly a
bug in the linker, and continue processing, unless the symbol has a
different size or address.
Reviewed By: #bolt, maksfb
Differential Revision: https://reviews.llvm.org/D136122
Calling registerName() for the same symbol twice, even with a different
size, has no effect other than the lookup overhead. Avoid the
redundancy.
Fixesfacebookincubator/BOLT#299
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D136115
Simplify the logic of handling sections in BOLT. This change brings more
direct and predictable mapping of BinarySection instances to sections in
the input and output files.
* Only sections from the input binary will have a non-null SectionRef.
When a new section is created as a copy of the input section,
its SectionRef is reset to null.
* RewriteInstance::getOutputSectionName() is removed as the section name
in the output file is now defined by BinarySection::getOutputName().
* Querying BinaryContext for sections by name uses their original name.
E.g., getUniqueSectionByName(".rodata") will return the original
section even if the new .rodata section was created.
* Input file sections (with relocations applied) are emitted via MC with
".bolt.org" prefix. However, their name in the output binary is
unchanged unless a new section with the same name is created.
* New sections are emitted internally with ".bolt.new" prefix if there's
a name conflict with an input file section. Their original name is
preserved in the output file.
* Section header string table is properly populated with section names
that are actually used. Previously we used to include discarded
section names as well.
* Fix the problem when dynamic relocations were propagated to a new
section with a name that matched a section in the input binary.
E.g., the new .rodata with jump tables had dynamic relocations from
the original .rodata.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D135494
This adds a round of checks to memory references, looking for
incorrect references to jump table objects. Fix them by replacing the
jump table reference with another object reference + offset.
This solves bugs related to regular data references in code
accidentally being bound to a jump table, and this reference being
updated to a new (incorrect) location because we moved this jump
table.
Fixes#55004
Reviewed By: #bolt, maksfb
Differential Revision: https://reviews.llvm.org/D134098
When BOLT updates .eh_frame section, it concatenates newly-generated
contents (from CFI directives) with the original .eh_frame that has
relocations applied to it. However, if no new content is generated,
the original .eh_frame has to be left intact. In that case, BOLT was
still writing out the relocatable copy of the original .eh_frame section
to the new segment, even though this copy was never used and was not
even marked in the section header table.
Detect the scenario above and skip allocating extra space for .eh_frame.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D135223
To properly set the "_end" symbol, we need to track the last allocatable
address. Simply emitting "_end" at the end of some section is not
sufficient since the order of section allocation is unknown during the
emission step.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D135121
We can emit a binary without a new text section. Hence, the text section
assertion is not needed.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D135120
In lite mode, BOLT only transforms a subset of functions, leave the
remaining functions intact.
For NoPIC, it is fine. BOLT can scan relocations and fix-up all refs
that point to any function body in the subset.
For no-split function PIC, it is fine. Since jump tables are intra-
procedural transfer, BOLT can find both the jump table base and the
target within same function. Thus, BOLT can update and/or move jump
tables.
However, it is wrong to process a subset of functions in split function
PIC. This is because BOLT does not know if functions in the subset are
isolated, i.e., cannot be accessed by functions out of the subset,
especially via split jump table.
For example, BOLT only process three functions A, B and C. Suppose that
A is reached via jump table from A.cold, which is not processed. When
A is moved (due to optimization), the jump table in A.cold is invalid.
We cannot fix-up this jump table since it is only recognized in A.cold,
which BOLT does not process.
Solution: Disable lite mode if split function is present.
Future improvement: In lite mode, if split function is found, BOLT
processes both functions in the subset and all of their sibling
fragments.
Test Plan:
```
ninja check-bolt
```
Reviewed By: Amir, maksfb
Differential Revision: https://reviews.llvm.org/D131283
This does *not* link with libLLVM, but with static archives instead. Not
super-great, but at least the build works, which is probably better than
failing.
Related to #57551
Differential Revision: https://reviews.llvm.org/D134434
In perf2bolt and `-aggregate-only` BOLT mode, the output profile file is written
in fdata format by default. Provide a knob `-profile-format=[fdata,yaml]` to
control the format.
Note that `-w` option still dumps in YAML format.
Reviewed By: #bolt, maksfb
Differential Revision: https://reviews.llvm.org/D133995
This patch fixes warnings during a release build:
mlir/lib/Dialect/Transform/IR/TransformInterfaces.cpp:198:52: error:
lambda capture 'this' is not used [-Werror,-Wunused-lambda-capture]
bolt/lib/Rewrite/RewriteInstance.cpp:5318:18: error: unused variable
'HasNoAddress' [-Werror,-Wunused-variable]
When we derive EFMM from SectionMemoryManager, it brings into EFMM extra
functionality, such as the registry of exception handling sections,
page permission management, etc. Such functionality is of no use to
llvm-bolt and can even be detrimental (see
https://github.com/llvm/llvm-project/issues/56726).
Change the base class of ExecutableFileMemoryManager to MemoryManager,
avoid registering EH sections, and skip memory finalization.
Fixes#56726
Reviewed By: yota9
Differential Revision: https://reviews.llvm.org/D133994
We were trying to process .debug_addr for CU that doesn't have it. This resulted
in assert. Example came from GCC that also doesn't use DW_OP_addrx in
DW_FORM_exprloc.
Reviewed By: maksfb
Differential Revision: https://reviews.llvm.org/D132422
To generate all symbols correctly, it is necessary to record the address
of each fragment. This patch moves the address info for the main and
cold fragments from BinaryFunction to FunctionFragment, where this data
is recorded for all fragments.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132051
This changes `FunctionFragment` from being used as a temporary proxy
object to access basic block ranges to a heap-allocated object that can
store fragment-specific information.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132050
A const-qualified reference to function layout allows accessing
non-const qualified basic blocks on a const-qualified function. This
patch adds or removes const-qualifiers where necessary to indicate where
basic blocks are used in a non-const manner.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132049
To generate all symbols correctly, it is necessary to record the address
of each fragment. This patch moves the address info for the main and
cold fragments from BinaryFunction to FunctionFragment, where this data
is recorded for all fragments.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132051
This changes `FunctionFragment` from being used as a temporary proxy
object to access basic block ranges to a heap-allocated object that can
store fragment-specific information.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132050
A const-qualified reference to function layout allows accessing
non-const qualified basic blocks on a const-qualified function. This
patch adds or removes const-qualifiers where necessary to indicate where
basic blocks are used in a non-const manner.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132049
Wasn't handling correctly creating DW_AT_rnglists_base in UnitDie when
converting access pattern for DW_AT_ranges from offset to index for DWARF5.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132087
This patch adds support to generate any number of sections that are
assigned to fragments of functions that are split more than two-way.
With this, a function's *nth* split fragment goes into section
`.text.cold.n`.
This also changes `FunctionLayout::erase` to make sure, that there are
no empty fragments at the end of the function. This sometimes happens
when blocks are erased from the function. To avoid creating symbols
pointing to these fragments, they need to be removed.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D130521
This changes code emission such that it can emit specific function
fragments instead of scanning all basic blocks of a function and just
emitting those that are hot or cold.
To implement this, `FunctionLayout` explicitly distinguishes the "main"
fragment (i.e. the one that contains the entry block and is associated
with the original symbol) from "split" fragments. Additionally,
`BinaryFunction` receives support for multiple cold symbols - one for
each split fragment.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D130052
With reduced indentation, some strings can be reformatted to take less lines.
Also strategically apply `formatv` to shorten them.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132088
Split out the body of a for-loop in `RewriteInstance::readRelocations` into a
separate function (`handleRelocation`). It's still over 300 lines of code,
so it's worth splitting down further.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132078
We were resetting DW_AT_low_pc to zero when DW_AT_high_pc was zero, or
DW_AT_low_pc == DW_AT_high_pc. This resulted in LLDB to print error "adding
range [0x0-0x0) which has a base that is less than the function's low PC".
Changed it so that when this case arises we set DW_AT_low_pc to the start
address.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132059
DW_TAG_call_site/DW_AT_call_return_pc can contain address that is not in any
function. In this case getBinaryFunctionContainingAddress returns nullptr. For
this case preserving original address.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D132057
We were not handling correclty multiple DW_OP_addrx in the location expression.
This was exposed by clang-15 build in release mode with debug information.
Reviewed By: maksfb
Differential Revision: https://reviews.llvm.org/D130812
This patch refactors BAT to be testable as a library, so we
can have open-source tests on it. This further fixes an issue with
basic blocks that lack a valid input offset, making BAT omit those
when writing translation tables.
Test Plan: new testcases added, new testing tool added (llvm-bat-dump)
Differential Revision: https://reviews.llvm.org/D129382
AllowStripped has not been used in BOLT.
This option is replaced by actively detecting stripped binary.
Test Plan:
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D130036
Determine stripped status of a binary based on .symtab
Test Plan:
```
ninja check-bolt
```
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D130034
`LastSymbol` handling in `discoverFileObjects` assumes a non-zero number of
symbols in an object file. It's not the case for broken_dynsym.test added in
D130073, and potentially other stripped binaries.
Reviewed By: maksfb
Differential Revision: https://reviews.llvm.org/D130544
Strip tools cause a few symbols in .dynsym to have bad section index.
This update safely keeps such broken symbols intact.
Test Plan:
```
ninja check-bolt
```
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D130073
This patch adds a dedicated class to keep track of each function's
layout. It also lays the groundwork for splitting functions into
multiple fragments (as opposed to a strict hot/cold split).
Reviewed By: maksfb
Differential Revision: https://reviews.llvm.org/D129518
We previously support split jump table, where some jump table entries
target different fragments of same function. In this fix, we provide
support for another type of intra-indirect transfer: landing pad.
When C++ exception handling is used, compiler emits .gcc_except_table
that describes the location of catch block (landing pad) for specific
range that potentially invokes a throw(). Normally landing pads reside
in the function, but with -fsplit-machine-functions, landing pads can
be moved to another fragment. The intuition is, landing pads are rarely
executed, so compiler can move them to .cold section.
This update will mark all fragments that have landing pad to another
fragment as non-simple, and later propagate non-simple to all related
fragments.
This update also includes one manual test case: split-landing-pad.s
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D128561
There are two assumptions regarding jump table:
(a) It is accessed by only one fragment, say, Parent
(b) All entries target instructions in Parent
For (a), BOLT stores jump table entries as relative offset to Parent.
For (b), BOLT treats jump table entries target somewhere out of Parent
as INVALID_OFFSET, including fragment of same split function.
In this update, we extend (a) and (b) to include fragment of same split
functinon. For (a), we store jump table entries in absolute offset
instead. In addition, jump table will store all fragments that access
it. A fragment uses this information to only create label for jump table
entries that target to that fragment.
For (b), using absolute offset allows jump table entries to target
fragments of same split function, i.e., extend support for split jump
table. This can be done using relocation (fragment start/size) and
fragment detection heuristics (e.g., using symbol name pattern for
non-stripped binaries).
For jump table targets that can only be reached by one fragment, we
mark them as local label; otherwise, they would be the secondary
function entry to the target fragment.
Test Plan
```
ninja check-bolt
```
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D128474
Rafael Auler