The object file format specific derived classes are used in context
where the type is statically known. We don't use isa/dyn_cast and we
want to eliminate MCSymbol::Kind in the base class.
The object file format specific derived classes are used in context like
MCStreamer and MCObjectTargetWriter where the type is statically known.
We don't use isa/dyn_cast and we want to eliminate
MCSection::SectionVariant in the base class.
The object file format specific derived classes are used in context like
MCStreamer and MCObjectTargetWriter where the type is statically known.
We don't use isa/dyn_cast and we want to eliminate
MCSection::SectionVariant in the base class.
The object file format specific derived classes are used in context like
MCStreamer and MCObjectTargetWriter where the type is statically known.
We don't use isa/dyn_cast and we want to eliminate
MCSection::SectionVariant in the base class.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
Unlike other formats, the GOFF object file format uses a 2 dimensional structure
to define the location of data. For example, the equivalent of the ELF .text
section is made up of a Section Definition (SD) and a class (Element Definition;
ED). The name of the SD symbol depends on the application, while the class has
the predefined name C_CODE/C_CODE64 in AMODE31 and AMODE64 respectively.
Data can be placed into this structure in 2 ways. First, the data (in a text
record) can be associated with an ED symbol. To refer to data, a Label
Definition (LD) is used to give an offset into the data a name. When binding,
the whole data is pulled into the resulting executable, and the addresses
given by the LD symbols are resolved.
The alternative is to use a Part Definition (PR). In this case, the data (in
a text record) is associated with the part. When binding, only the data of
referenced PRs is pulled into the resulting binary.
Both approaches are used. SD, ED, and PR elements are modeled by nested
MCSectionGOFF instances, while LD elements are associated with MCSymbolGOFF
instances.
At the binary level, a record called "External Symbol Definition" (ESD) is used. The
ESD has a type (SD, ED, PR, LD), and depending on the type a different subset of
the fields is used.
This annotates the `Twine` passed to the constructors of the various
DiagnosticInfo subclasses with `[[clang::lifetimebound]]`, which causes
us to warn when we would try to print the twine after it had already
been destructed.
We also update `DiagnosticInfoUnsupported` to hold a `const Twine &`
like all of the other DiagnosticInfo classes, since this warning allows
us to clean up all of the places where it was being used incorrectly.
https://reviews.llvm.org/D17938 introduced lowerRelativeReference to
give ConstantExpr sub (A-B) special semantics in ELF: when `A` is an
`unnamed_addr` function, create a PLT-generating relocation. This was
intended for C++ relative vtables, but C++ relative vtable ended up
using DSOLocalEquivalent (lowerDSOLocalEquivalent).
This special treatment of `unnamed_addr` seems unusual.
Let's remove it. Only COFF needs an overload to generate a @IMGREL32
relocation specifier (llvm/test/MC/COFF/cross-section-relative.ll).
Pull Request: https://github.com/llvm/llvm-project/pull/134781
https://reviews.llvm.org/D17938 introduced lowerRelativeReference to
give ConstantExpr sub (A-B) special semantics in ELF: when `A` is an
`unnamed_addr` function, create a PLT-generating relocation. This was
intended for C++ relative vtables, but C++ relative vtable ended up
using DSOLocalEquivalent (lowerDSOLocalEquivalent).
This special treatment of `unnamed_addr` seems unusual.
Let's remove it. Only COFF needs an overload to generate a @IMGREL32
relocation specifier (llvm/test/MC/COFF/cross-section-relative.ll).
Pull Request: https://github.com/llvm/llvm-project/pull/132684
This is a follow-up patch of
https://github.com/llvm/llvm-project/pull/125756
In this PR, static-data-splitter pass produces the aggregated profile
counts of constants for constant pools in a global state
(`StateDataProfileInfo`), and asm printer consumes the profile counts to
produce `.hot` or `.unlikely` prefixes.
This implementation covers both x86 and aarch64 asm printer.
clang -fexperimental-relative-c++-abi-vtables might generate `@plt` and
`@gotpcrel` specifiers in data directives. The syntax is not used in
humand-written assembly code, and is not supported by GNU assembler.
Note: the `@plt` in `.word foo@plt` is different from
the legacy `call func@plt` (where `@plt` is simply ignored).
The `@plt` syntax was selected was simply due to a quirk of AsmParser:
the syntax was supported by all targets until I updated it
to be an opt-in feature in a0671758eb6e52a758bd1b096a9b421eec60204c
RISC-V favors the `%specifier(expr)` syntax following MIPS and Sparc,
and we should follow this convention.
This PR adds support for `.word %pltpcrel(foo+offset)` and
`.word %gotpcrel(foo)`, and drops `@plt` and `@gotpcrel`.
* MCValue::SymA can no longer have a SymbolVariant. Add an assert
similar to that of AArch64ELFObjectWriter.cpp before
https://reviews.llvm.org/D81446 (see my analysis at
https://maskray.me/blog/2025-03-16-relocation-generation-in-assemblers
if intrigued)
* `jump foo@plt, x31` now has a different diagnostic.
Pull Request: https://github.com/llvm/llvm-project/pull/132569
The function is only called by AsmPrinter, where there is a fallback
when lowerRelativeReference returns nullptr.
wasm and XCOFF could use the fallback code.
(lowerRelativeReference was introduced in 2016 (https://reviews.llvm.org/D17938)
for C++ relative vtables, but C++ relative vtables ended up using
dso_local_equivalent. llvm/test/MC/COFF/cross-section-relative.ll also
uses this.)
Migrate away from the deprecated MCSymbolRefExpr::VariantKind.
The name "Specifier" is utilized in a few *MCExpr.
> "Relocation specifier" is clear, aligns with Arm and IBM AIX's documentation, and fits the assembler's role seamlessly.
They have same semantics. NonUniqueID is more friendly for isUnique
implementation in MCSectionELF.
History: 97837b7 added support for unique IDs in sections and added
GenericSectionID. Later, 1dc16c7 added NonUniqueID.
https://github.com/llvm/llvm-project/pull/122183 adds a codegen pass to
infer machine jump table entry's hotness from the MBB hotness. This is a
follow-up PR to produce `.hot` and or `.unlikely` section prefix for
jump table's (read-only) data sections in the relocatable `.o` files.
When this patch is enabled, linker will see {`.rodata`, `.rodata.hot`,
`.rodata.unlikely`} in input sections. It can map `.rodata.hot` and
`.rodata` in the input sections to `.rodata.hot` in the executable, and
map `.rodata.unlikely` into `.rodata` with a pending extension to
`--keep-text-section-prefix` like
059e7cbb66,
or with a linker script.
1. To partition hot and jump tables, the AsmPrinter pass slices a function's jump table indices into two groups, one for hot and the other for cold jump tables. It then emits hot jump tables into a `.hot`-prefixed data section and cold ones into a `.unlikely`-prefixed data section, retaining the relative order of `LJT<N>` labels within each group.
2. [ELF only] To have data sections with _dynamic_ names (e.g., `.rodata.hot[.func]`), we implement
`TargetLoweringObjectFile::getSectionForJumpTable` method that accepts a `MachineJumpTableEntry` parameter, and update `selectELFSectionForGlobal` to generate `.hot` or `.unlikely` based on
MJTE's hotness.
- The dynamic JT section name doesn't depend on `-ffunction-section=true` or `-funique-section-names=true`, even though it leverages the similar underlying mechanism to have a MCSection with on-demand name as `-ffunction-section` does.
3. The new code path is off by default.
- Typically, `TargetOptions` conveys clang or LLVM tools' options to code generation passes. To follow the pattern, add option `EnableStaticDataPartitioning` bit in `TargetOptions` and make it
readable through `TargetMachine`.
- To enable the new code path in tools like `llc`, `partition-static-data-sections` option is introduced in
`CodeGen/CommandFlags.h/cpp`.
- A subsequent patch
([draft](8f36a13743)) will add a clang option to enable the new code path.
---------
Co-authored-by: Ellis Hoag <ellis.sparky.hoag@gmail.com>
Today, emitLinkerDirectives is private to TLOFCOFF-- it isolates parsing
and processing of the linker options. Similar processing is also done by
other TLOFs inline within emitModuleMetadata. This patch promotes
emitLinkerDirectives to a virtual (public) method so that this handling
is similarly isolated in the other TLOFs.
This also enables downstream targets to override just this handling
instead of the whole of emitModuleMetadata.
Re-apply #113148 after revert in #119331
If function pointer signing is enabled, sign personality function
pointer stored in `.DW.ref.__gxx_personality_v0` section with IA key,
0x7EAD = `ptrauth_string_discriminator("personality")` constant
discriminator and address diversity enabled.
If function pointer signing is enabled, sign personality function
pointer stored in `.DW.ref.__gxx_personality_v0` section with IA key,
0x7EAD = `ptrauth_string_discriminator("personality")` constant
discriminator and address diversity enabled.
Currently, WebAssembly/WASI target does not provide direct support for
code coverage.
This patch set fixes several issues to unlock the feature. The main
changes are:
1. Port `compiler-rt/lib/profile` to WebAssembly/WASI.
2. Adjust profile metadata sections for Wasm object file format.
- [CodeGen] Emit `__llvm_covmap` and `__llvm_covfun` as custom sections
instead of data segments.
- [lld] Align the interval space of custom sections at link time.
- [llvm-cov] Copy misaligned custom section data if the start address is
not aligned.
- [llvm-cov] Read `__llvm_prf_names` from data segments
3. [clang] Link with profile runtime libraries if requested
See each commit message for more details and rationale.
This is part of the effort to add code coverage support in Wasm target
of Swift toolchain.
MachineFunction's probably should not include a backreference to
the owning MachineModuleInfo. Most of these references were used
just to query the MCContext, which MachineFunction already directly
stores. Other contexts are using it to query the LLVMContext, which
can already be accessed through the IR function reference.
Follow-up to 05ba5c0648ae5e80d5afce270495bf3b1eef9af4. uint32_t is
preferred over const MCExpr * in the section stack uses because it
should only be evaluated once. Change the paramter type to match.
There are only three actual uses of the section kind in MCSection:
isText(), XCOFF, and WebAssembly. Store isText() in the MCSection, and
store other info in the actual section variants where required.
ELF and COFF flags also encode all relevant information, so for these
two section variants, remove the SectionKind parameter entirely.
This allows to remove the string switch (which is unnecessary and
inaccurate) from createELFSectionImpl. This was introduced in
[D133456](https://reviews.llvm.org/D133456), but apparently, it was
never hit for non-writable sections anyway and the resulting kind was
never used.
Gas uses encoding DW_EH_PE_absptr for PIC, and gnu ld converts it to
DW_EH_PE_sdata4|DW_EH_PE_pcrel.
LLD doesn't have this workarounding, thus complains
```
relocation R_MIPS_32 cannot be used against local symbol; recompile with -fPIC
relocation R_MIPS_64 cannot be used against local symbol; recompile with -fPIC
```
So, let's generates asm/obj files with `DW_EH_PE_sdata4|DW_EH_PE_pcrel`
encoding. In fact, GNU ld supports such OBJs well.
For N64, maybe we should use sdata8, while GNU ld doesn't support it
well, and in fact sdata4 is enough now. So we just ignore the `Large`
for `MCObjectFileInfo::initELFMCObjectFileInfo`. Maybe we should switch
back to sdata8 once GNU LD supports it well.
Fixes: #58377.
I'm planning to remove StringRef::equals in favor of
StringRef::operator==.
- StringRef::operator==/!= outnumber StringRef::equals by a factor of
53 under llvm/ in terms of their usage.
- The elimination of StringRef::equals brings StringRef closer to
std::string_view, which has operator== but not equals.
- S == "foo" is more readable than S.equals("foo"), especially for
!Long.Expression.equals("str") vs Long.Expression != "str".
When set, the compiler will use separate unique sections for global
symbols in named special sections (e.g. symbols that are annotated with
__attribute__((section(...)))). Doing so enables linker GC to collect
unused symbols without having to use a different section per-symbol.
D33412/D33413 introduced this to support a clang pragma to set section
names for a symbol depending on if it would be placed in
bss/data/rodata/text, which may not be known until the backend. However,
for text we know that only functions will go there, so just directly set
the section in clang instead of going through a completely separate
attribute.
Autoupgrade the "implicit-section-name" attribute to directly setting
the section on a Fuction.
Exploit the per global code model attribute on AIX. On AIX we need to
update both the code sequence used to access the global (either 1 or 2
instructions for small and large code model respectively) and the
storage mapping class that we emit the toc entry.
---------
Co-authored-by: Amy Kwan <akwan0907@gmail.com>
In WebAssembly, we have `WASM_SYMBOL_NO_STRIP` symbol flag to mark the
referenced content as retained. However, the flag is not enough to
express retained data that is not referenced by any symbol. This patch
adds a new segment flag`WASM_SEG_FLAG_RETAIN` to support "private"
linkage data that is retained by llvm.used.
This kind of data that is not referenced but must be retained is usually
used with encapsulation symbols (__start/__stop). Swift runtime uses
this technique and depends on the fact "all metadata sections in live
objects are retained", which was not guaranteed with `--gc-sections`
before this patch.
This is a revised version of https://reviews.llvm.org/D126950 (has been
reverted) based on @MaskRay's comments
This patch adds support for common and local symbols in the TOC for AIX.
Note that we need to update isVirtualSection so as a common symbol in
TOC will have the symbol type XTY_CM and will be initialized when placed
in the TOC so sections with this type are no longer virtual.
---------
Co-authored-by: Zaara Syeda <syzaara@ca.ibm.com>
