All users of MCCodeEmitter::encodeInstruction use a raw_svector_ostream
to encode the instruction into a SmallVector. The raw_ostream however
incurs some overhead for the actual encoding.
This change allows an MCCodeEmitter to directly emit an instruction into
a SmallVector without using a raw_ostream and therefore allow for
performance improvments in encoding. A default path that uses existing
raw_ostream implementations is provided.
Reviewed By: MaskRay, Amir
Differential Revision: https://reviews.llvm.org/D145791
This patch fixes few problems with supporting dynamic relocations in CI.
1. After dynamic relocations and functions were read search for dynamic
relocations located in functions. Currently we expected them only to be
relative and only to be in constant island. Mark islands of such
functions to have dynamic relocations and create CI access symbol on the
relocation offset, so the BD would be created for such place.
2. During function disassemble and handling address reference for
constant island check if the referred external CI has dynamic
relocation. And if it has one we would continue to refer original CI
rather then creating a local copy.
3. After function disassembly stage mark function that has dynamic reloc
in CI as non-simple. We don't want such functions to be optimized, since
such passes as split function would create 2 copies of CI which we
unable to support currently.
4. During updating output values for BF search for BD located in CI and
update their output locations.
5. On dynamic relocation patching stage search for binary data located
on relocation offset. If it was moved use new relocation offset value
rather then an old one.
Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei
Differential Revision: https://reviews.llvm.org/D143748
ICF optimization runs multiple passes and the order in which functions
are folded could be dependent on the order they are being processed.
This order is indeterministic as functions are intermediately stored in
std::unordered_map<>. Note that this order is mostly stable, but is not
guaranteed to be and can change e.g. after switching to a different C++
library implementation.
Because the processing (and folding) order is indeterministic, the
previous way of calculating merged function call count could produce
different results.
Change the way we calculate the ICF call count to make it independent of
the function folding/processing order.
Mostly NFC as the output binary should remain the same, the change
affects only the console output.
Reviewed By: yota9
Differential Revision: https://reviews.llvm.org/D144807
`isChildOf` is a more concise name for the check. Also, there's no need to
test if the function is a fragment before doing `isChildOf` check.
Reviewed By: #bolt, rafauler, maksfb
Differential Revision: https://reviews.llvm.org/D142667
In lite mode, include split function fragments to the list of functions to
process even if a fragment has no samples. This is required to properly
detect and update split jump tables (jump tables that contain pointers to code
in the main and cold fragments).
Reviewed By: #bolt, maksfb
Differential Revision: https://reviews.llvm.org/D140457
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
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
This has the following advantages:
- std::shared_timed_mutex is macOS 10.12+ only. llvm::sys::RWMutex
automatically switches to a different implementation internally
when targeting older macOS versions.
- bolt only needs std::shared_mutex, not std::shared_timed_mutex.
llvm::sys::RWMutex automatically uses std::shared_mutex internally
where available.
std::shared_mutex and RWMutex have the same API, so no code changes
other than types and includes are needed.
Differential Revision: https://reviews.llvm.org/D138423
This patch replaces NoneType() and NoneType::None with None in
preparation for migration from llvm::Optional to std::optional.
In the std::optional world, we are not guranteed to be able to
default-construct std::nullopt_t or peek what's inside it, so neither
NoneType() nor NoneType::None has a corresponding expression in the
std::optional world.
Once we consistently use None, we should even be able to replace the
contents of llvm/include/llvm/ADT/None.h with something like:
using NoneType = std::nullopt_t;
inline constexpr std::nullopt_t None = std::nullopt;
to ease the migration from llvm::Optional to std::optional.
Differential Revision: https://reviews.llvm.org/D138376
matchLinkerVeneer() returns 3 if `Instruction` and the last
two instructions in `[Instructions.begin, Instructions.end())`
match the pattern
ADRP x16, imm
ADD x16, x16, imm
BR x16
BinaryContext.cpp used to use
--Count;
for (auto It = std::prev(Instructions.end()); Count != 0;
It = std::prev(It), --Count) {
...use It...
}
to walk these instructions. The first `--Count` skips the
instruction that's in `Instruction` instead of in `Instructions`.
The loop then walks over `Instructions`.
However, on the last iteration, this calls `std::prev()` on an
iterator that points at the container's begin(), which can blow
up.
Instead, use rbegin(), which sidesteps this issue.
Fixes test/AArch64/veneer-gold.s on a macOS host.
With this, check-bolt passes on macOS.
Differential Revision: https://reviews.llvm.org/D138313
If NewName twine has reference to the old name, then after
Section.Name = NewName.str(); this reference is invalidated,
so we cannot use NewName.str() anymore.
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D137616
Always use non-symbolizing disassembler for instruction encoding
validation as symbols will be treated as undefined/zeros be the encoder
and causing byte sequence mismatches.
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D136118
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
Put code that creates references to symbol+addend behind MCPlusBuilder.
Will use this later in validate memory references pass.
Reviewed By: #bolt, maksfb, yota9
Differential Revision: https://reviews.llvm.org/D134097
In non-pie binaries BOLT unconditionally converted type encoding
from indirect to absptr, which broke std exceptions since pointers
to their typeinfo were only assigned at runtime in .data section.
In this patch we preserve original encoding so that indirect
remains indirect and can be resolved at runtime, and absolute remains absolute.
Reviewed By: rafauler, maksfb
Differential Revision: https://reviews.llvm.org/D132484
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
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
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
Move logging into LLVM_DEBUG scope.
Remove redundant printing of jump table parents:
Old logging:
```
failed to analyze jump table in function _ZN12_GLOBAL__N_116InitHeaderSearch23Ad
dDefaultCIncludePathsERKN4llvm6TripleERKN5clang19HeaderSearchOptionsE/1(*2)
PIC Jump table JUMP_TABLE/_ZN12_GLOBAL__N_116InitHeaderSearch23AddDefaultCInclud
ePathsERKN4llvm6TripleERKN5clang19HeaderSearchOptionsE/1.1 for function _ZN12_GL
OBAL__N_116InitHeaderSearch23AddDefaultCIncludePathsERKN4llvm6TripleERKN5clang19
HeaderSearchOptionsE/1(*2) at 0x65996e0 with a total count of 0:
0x9dc
next jump table at 0x659a810 belongs to function _ZN5clang5Lexer40LexDependencyD
irectiveTokenWhileSkippingERNS_5TokenE
PIC Jump table JUMP_TABLE/_ZN5clang5Lexer40LexDependencyDirectiveTokenWhileSkipp
ingERNS_5TokenE.0 for function _ZN5clang5Lexer40LexDependencyDirectiveTokenWhile
SkippingERNS_5TokenE at 0x659a810 with a total count of 0:
jump table heuristic failure
```
New logging:
```
failed to analyze PIC Jump table JUMP_TABLE/_ZN12_GLOBAL__N_116InitHeaderSearch2
3AddDefaultCIncludePathsERKN4llvm6TripleERKN5clang19HeaderSearchOptionsE/1.1 for
function _ZN12_GLOBAL__N_116InitHeaderSearch23AddDefaultCIncludePathsERKN4llvm6T
ripleERKN5clang19HeaderSearchOptionsE/1(*2) at 0x65996e0 with a total count of 0:
absolute offset: 0x52ac58c
next PIC Jump table JUMP_TABLE/_ZN5clang5Lexer40LexDependencyDirectiveTokenWhile
SkippingERNS_5TokenE.0 for function _ZN5clang5Lexer40LexDependencyDirectiveToken
WhileSkippingERNS_5TokenE at 0x659a810 with a total count of 0:
jump table heuristic failure
```
Reviewed By: rafauler
Differential Revision: https://reviews.llvm.org/D131243
This diff uncovers an ASAN leak in getOrCreateJumpTable:
```
Indirect leak of 264 byte(s) in 1 object(s) allocated from:
#1 0x4f6e48c in llvm::bolt::BinaryContext::getOrCreateJumpTable ...
```
The removal of an assertion needs to be accompanied by proper deallocation of
a `JumpTable` object for which `analyzeJumpTable` was unsuccessful.
This reverts commit 52cd00cabf479aa7eb6dbb063b7ba41ea57bce9e.
Disassembly and branch target analysis are not decoupled, so any
analysis that depends on disassembly may not operate properly.
In specific, analyzeJumpTable uses instruction bounds check property.
A jump table was analyzed twice: (a) during disassembly, and (b) after
disassembly, so there are potentially some mismatched results.
In this update, functions that access JTs which fail the second check
will be marked as ignored.
Test Plan:
```
ninja check-bolt
```
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D130431
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
The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.
Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei
Differential Revision: https://reviews.llvm.org/D129260
Since we now have +all feature for AArch64 disassembler, we can use it
in BOLT and allow it to disassemble all ARM instructions supported by LLVM.
Reviewed by: rafauler
Differential Revision: https://reviews.llvm.org/D129139
Added support for mixing monolithic DWARF5 with legacy DWARF, and monolithic legacy and DWARF5 split dwarf.
Reviewed By: maksfb
Differential Revision: https://reviews.llvm.org/D128232
This reverts commit 425dda76e9fac93117289fd68a2abdfb1e4a0ba5.
This commit is currently causing BOLT to crash in one of our
binaries and needs a bit more checking to make sure it is safe
to land.
The gold linker veneers are written between functions without symbols,
so we to handle it specially in BOLT.
Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei
Differential Revision: https://reviews.llvm.org/D128082
Resolve a crash related to split functions
Due to split function optimization, a function can be divided to two
fragments, and both fragments can access same jump table. This
violates the assumption that a jump table can only have one parent
function, which causes a crash during instrumentation.
We want to support the case: different functions cannot access same
jump tables, but different fragments of same function can!
As all fragments are from same function, we point JT::Parent to one
specific fragment. Right now it is the first disassembled fragment, but
we can point it to the function's main fragment later.
Functions are disassembled sequentially. Previously, at the end of
processing a function, JT::OffsetEntries is cleared, so other fragment
can no longer reuse JT::OffsetEntries. To extend the support for split
function, we only clear JT::OffsetEntries after all functions are
disassembled.
Let say A.hot and A.cold access JT of three targets {X, Y, Z}, where
X and Y are in A.hot, and Z is in A.cold. Suppose that A.hot is
disassembled first, JT::OffsetEntries = {X',Y',INVALID_OFFSET}. When
A.cold is disassembled, it cannot reuse JT::OffsetEntries above due to
different fragment start. A simple solution:
A.hot = {X',Y',INVALID_OFFSET}
A.cold = {INVALID_OFFSET, INVALID_OFFSET, INVALID_OFFSET}
We update the assertion to allow different fragments of same function
to get the same JumpTable object.
Potential improvements:
A.hot = {X',Y',INVALID_OFFSET}
A.cold = {INVALID_OFFSET, INVALID_OFFSET, Z'}
The main issue is A.hot and A.cold have separate CFGs, thus jump table
targets are still constrained within fragment bounds.
Future improvements:
A.hot = {X, Y, Z}
A.cold = {X, Y, Z}
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D127924
Mark fragments related to split jump table as non-simple.
A function could be splitted into hot and cold fragments. A split jump table is
challenging for correctly reconstructing control flow graphs, so it was marked
as ignored. This update marks those fragments as non-simple, allowing them
to be printed and partial control flow graph construction.
Test Plan:
```
llvm-lit -a tools/bolt/test/X86/split-func-icf.s
```
This test has two functions (main, main2), each has a jump table target to the
same cold portion main2.cold.1(*2). We try to print out only this cold portion.
If it is ignored, it cannot be printed. If it is non-simple, it can be printed. We
verify that it can be printed.
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D127464
Summary:
While disassembling instructions, we need to replace certain immediate
operands with symbols. This symbolizing process relies on reading
relocations against instructions. However, some X86 instructions can
have multiple immediate operands and up to two relocations against
them. Thus, correctly matching a relocation to an operand is not
always possible without knowing the operand offset within the
instruction.
Luckily, LLVM provides an interface for passing the required info from
the disassembler via a virtual MCSymbolizer class. Creating a
target-specific version allows a precise matching of relocations to
operands.
This diff adds X86MCSymbolizer class that performs X86-specific
symbolizing (currently limited to non-branch instructions).
Reviewers: yota9, Amir, ayermolo, rafauler, zr33
Differential Revision: https://reviews.llvm.org/D120928
Fix BOLT's constant island mapping when a constant island marked by $d
spans multiple functions. Currently, because BOLT only marks the
constant island in the first function where $d is located, if the next
function contains data at its start, BOLT will miss the data and try
to disassemble it. This patch adds code to explicitly go through all
symbols between $d and $x markers and mark their respective offsets as
data, which stops BOLT from trying to disassemble data. It also adds
MarkerType enum and refactors related functions.
Reviewed By: yota9, rafauler
Differential Revision: https://reviews.llvm.org/D126177
