The generic ABI says:
> Padding is present, if necessary, to ensure 8 or 4-byte alignment for the next note entry (depending on whether the file is a 64-bit or 32-bit object). Such padding is not included in descsz.
Our parsing code currently aligns n_namesz. Fix the bug by aligning the start
offset of the descriptor instead. This issue has been benign because the primary
uses of sh_addralign=8 notes are `.note.gnu.property`, where
`sizeof(Elf_Nhdr) + sizeof("GNU") = 16` (already aligned by 8).
In practice, many 64-bit systems incorrectly use sh_addralign=4 notes.
We can use sh_addralign (= p_align) to decide the descriptor padding.
Treat an alignment of 0 and 1 as 4. This approach matches modern GNU readelf
(since 2018).
We have a few tests incorrectly using sh_addralign=0. We may make our behavior
stricter after fixing these tests.
Linux kernel dumped core files use `p_align=0` notes, so we need to support the
case for compatibility.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D150022
This patch details the GOFF file format and implements the GOFFObjectfile class
with support for only the HDR, ESD and END GOFF records.
Reviewed By: jhenderson, kpn
Differential Revision: https://reviews.llvm.org/D98437
This patch details the GOFF file format and implements the GOFFObjectfile class
with support for only the HDR, ESD and END GOFF records.
Reviewed By: jhenderson, kpn
Differential Revision: https://reviews.llvm.org/D98437
This refactoring will allow for this utility function to be used in
other places in the codebase outside of the llvm-readobj tool.
Reviewed By: jhenderson, rahmanl
Differential Revision: https://reviews.llvm.org/D144783
The forwarding header is left in place because of its use in
`polly/lib/External/isl/interface/extract_interface.cc`, but I have
added a GCC warning about the fact it is deprecated, because it is used
in `isl` from where it is included by Polly.
This patch continues implementing DirectX pipeline state validation
information by adding support for resource binding metadata.
Reviewed By: python3kgae
Differential Revision: https://reviews.llvm.org/D143130
Basically NFC: A TEST/TEST_F/etc that bails out early (usually because
setup failed or some other runtime condition wasn't met) generally
should use GTEST_SKIP() to report its status correctly, unless it
takes steps to report another status (e.g., FAIL()).
I did see a handful of tests show up as SKIPPED after this change,
which is not unexpected. The status seemed appropriate in all the new
cases.
Let Propeller use specialized IDs for basic blocks, instead of MBB number.
This allows optimizations not just prior to asm-printer, but throughout the entire codegen.
This patch only implements the functionality under the new `LLVM_BB_ADDR_MAP` version, but the old version is still being used. A later patch will change the used version.
####Background
Today Propeller uses machine basic block (MBB) numbers, which already exist, to map native assembly to machine IR. This is done as follows.
- Basic block addresses are captured and dumped into the `LLVM_BB_ADDR_MAP` section just before the AsmPrinter pass which writes out object files. This ensures that we have a mapping that is close to assembly.
- Profiling mapping works by taking a virtual address of an instruction and looking up the `LLVM_BB_ADDR_MAP` section to find the MBB number it corresponds to.
- While this works well today, we need to do better when we scale Propeller to target other Machine IR optimizations like spill code optimization. Register allocation happens earlier in the Machine IR pipeline and we need an annotation mechanism that is valid at that point.
- The current scheme will not work in this scenario because the MBB number of a particular basic block is not fixed and changes over the course of codegen (via renumbering, adding, and removing the basic blocks).
- In other words, the volatile MBB numbers do not provide a one-to-one correspondence throughout the lifetime of Machine IR. Profile annotation using MBB numbers is restricted to a fixed point; only valid at the exact point where it was dumped.
- Further, the object file can only be dumped before AsmPrinter and cannot be dumped at an arbitrary point in the Machine IR pass pipeline. Hence, MBB numbers are not suitable and we need something else.
####Solution
We propose using fixed unique incremental MBB IDs for basic blocks instead of volatile MBB numbers. These IDs are assigned upon the creation of machine basic blocks. We modify `MachineFunction::CreateMachineBasicBlock` to assign the fixed ID to every newly created basic block. It assigns `MachineFunction::NextMBBID` to the MBB ID and then increments it, which ensures having unique IDs.
To ensure correct profile attribution, multiple equivalent compilations must generate the same Propeller IDs. This is guaranteed as long as the MachineFunction passes run in the same order. Since the `NextBBID` variable is scoped to `MachineFunction`, interleaving of codegen for different functions won't cause any inconsistencies.
The new encoding is generated under the new version number 2 and we keep backward-compatibility with older versions.
####Impact on Size of the `LLVM_BB_ADDR_MAP` Section
Emitting the Propeller ID results in a 23% increase in the size of the `LLVM_BB_ADDR_MAP` section for the clang binary.
Reviewed By: tmsriram
Differential Revision: https://reviews.llvm.org/D100808
Use deduction guides instead of helper functions.
The only non-automatic changes have been:
1. ArrayRef(some_uint8_pointer, 0) needs to be changed into ArrayRef(some_uint8_pointer, (size_t)0) to avoid an ambiguous call with ArrayRef((uint8_t*), (uint8_t*))
2. CVSymbol sym(makeArrayRef(symStorage)); needed to be rewritten as CVSymbol sym{ArrayRef(symStorage)}; otherwise the compiler is confused and thinks we have a (bad) function prototype. There was a few similar situation across the codebase.
3. ADL doesn't seem to work the same for deduction-guides and functions, so at some point the llvm namespace must be explicitly stated.
4. The "reference mode" of makeArrayRef(ArrayRef<T> &) that acts as no-op is not supported (a constructor cannot achieve that).
Per reviewers' comment, some useless makeArrayRef have been removed in the process.
This is a follow-up to https://reviews.llvm.org/D140896 that introduced
the deduction guides.
Differential Revision: https://reviews.llvm.org/D140955
This change refactors the parte parsing logic to operate on StringRefs
of the part data rather than starting from an offset and splicing down.
It also improves some of the error reporting around part layout.
Specifically, this code now reports a distinct error if there isn't
enough data in the buffer to store the part size and it reports an
error if the parts overlap.
Reviewed By: bob80905
Differential Revision: https://reviews.llvm.org/D139681
Add file with Xtensa ELF relocations. Add Xtensa support to ELF.h,
ELFObject.h and ELFYAML.cpp. Add simple test of Xtensa ELF representation in YAML.
Differential Revision: https://reviews.llvm.org/D64827
This is a fairly large changeset, but it can be broken into a few
pieces:
- `llvm/Support/*TargetParser*` are all moved from the LLVM Support
component into a new LLVM Component called "TargetParser". This
potentially enables using tablegen to maintain this information, as
is shown in https://reviews.llvm.org/D137517. This cannot currently
be done, as llvm-tblgen relies on LLVM's Support component.
- This also moves two files from Support which use and depend on
information in the TargetParser:
- `llvm/Support/Host.{h,cpp}` which contains functions for inspecting
the current Host machine for info about it, primarily to support
getting the host triple, but also for `-mcpu=native` support in e.g.
Clang. This is fairly tightly intertwined with the information in
`X86TargetParser.h`, so keeping them in the same component makes
sense.
- `llvm/ADT/Triple.h` and `llvm/Support/Triple.cpp`, which contains
the target triple parser and representation. This is very intertwined
with the Arm target parser, because the arm architecture version
appears in canonical triples on arm platforms.
- I moved the relevant unittests to their own directory.
And so, we end up with a single component that has all the information
about the following, which to me seems like a unified component:
- Triples that LLVM Knows about
- Architecture names and CPUs that LLVM knows about
- CPU detection logic for LLVM
Given this, I have also moved `RISCVISAInfo.h` into this component, as
it seems to me to be part of that same set of functionality.
If you get link errors in your components after this patch, you likely
need to add TargetParser into LLVM_LINK_COMPONENTS in CMake.
Differential Revision: https://reviews.llvm.org/D137838
value() has undesired exception checking semantics and calls
__throw_bad_optional_access in libc++. Moreover, the API is unavailable without
_LIBCPP_NO_EXCEPTIONS on older Mach-O platforms (see
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS).
This fixes check-llvm.
The tests that are focused on testing the file structure should use
fake part names so that the errors get triggered consistently. As we
add parsing support for known data types and structures under the parts
the parsing errors change to be more semantically accurate.
This change ensures the general errors continue to work with less churn
on the test cases in the future.
Let Propeller use specialized IDs for basic blocks, instead of MBB number.
This allows optimizations not just prior to asm-printer, but throughout the entire codegen.
This patch only implements the functionality under the new `LLVM_BB_ADDR_MAP` version, but the old version is still being used. A later patch will change the used version.
####Background
Today Propeller uses machine basic block (MBB) numbers, which already exist, to map native assembly to machine IR. This is done as follows.
- Basic block addresses are captured and dumped into the `LLVM_BB_ADDR_MAP` section just before the AsmPrinter pass which writes out object files. This ensures that we have a mapping that is close to assembly.
- Profiling mapping works by taking a virtual address of an instruction and looking up the `LLVM_BB_ADDR_MAP` section to find the MBB number it corresponds to.
- While this works well today, we need to do better when we scale Propeller to target other Machine IR optimizations like spill code optimization. Register allocation happens earlier in the Machine IR pipeline and we need an annotation mechanism that is valid at that point.
- The current scheme will not work in this scenario because the MBB number of a particular basic block is not fixed and changes over the course of codegen (via renumbering, adding, and removing the basic blocks).
- In other words, the volatile MBB numbers do not provide a one-to-one correspondence throughout the lifetime of Machine IR. Profile annotation using MBB numbers is restricted to a fixed point; only valid at the exact point where it was dumped.
- Further, the object file can only be dumped before AsmPrinter and cannot be dumped at an arbitrary point in the Machine IR pass pipeline. Hence, MBB numbers are not suitable and we need something else.
####Solution
We propose using fixed unique incremental MBB IDs for basic blocks instead of volatile MBB numbers. These IDs are assigned upon the creation of machine basic blocks. We modify `MachineFunction::CreateMachineBasicBlock` to assign the fixed ID to every newly created basic block. It assigns `MachineFunction::NextMBBID` to the MBB ID and then increments it, which ensures having unique IDs.
To ensure correct profile attribution, multiple equivalent compilations must generate the same Propeller IDs. This is guaranteed as long as the MachineFunction passes run in the same order. Since the `NextBBID` variable is scoped to `MachineFunction`, interleaving of codegen for different functions won't cause any inconsistencies.
The new encoding is generated under the new version number 2 and we keep backward-compatibility with older versions.
####Impact on Size of the `LLVM_BB_ADDR_MAP` Section
Emitting the Propeller ID results in a 23% increase in the size of the `LLVM_BB_ADDR_MAP` section for the clang binary.
Reviewed By: tmsriram
Differential Revision: https://reviews.llvm.org/D100808
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
Add ELFObjectFileBase::getLoongArchFeatures, and return the proper ELF
relative reloc type for LoongArch.
Reviewed By: MaskRay, SixWeining
Differential Revision: https://reviews.llvm.org/D138016
This is a resurrection of D106421 with the change that it keeps backward-compatibility. This means decoding the previous version of `LLVM_BB_ADDR_MAP` will work. This is required as the profile mapping tool is not released with LLVM (AutoFDO). As suggested by @jhenderson we rename the original section type value to `SHT_LLVM_BB_ADDR_MAP_V0` and assign a new value to the `SHT_LLVM_BB_ADDR_MAP` section type. The new encoding adds a version byte to each function entry to specify the encoding version for that function. This patch also adds a feature byte to be used with more flexibility in the future. An use-case example for the feature field is encoding multi-section functions more concisely using a different format.
Conceptually, the new encoding emits basic block offsets and sizes as label differences between each two consecutive basic block begin and end label. When decoding, offsets must be aggregated along with basic block sizes to calculate the final offsets of basic blocks relative to the function address.
This encoding uses smaller values compared to the existing one (offsets relative to function symbol).
Smaller values tend to occupy fewer bytes in ULEB128 encoding. As a result, we get about 17% total reduction in the size of the bb-address-map section (from about 11MB to 9MB for the clang PGO binary).
The extra two bytes (version and feature fields) incur a small 3% size overhead to the `LLVM_BB_ADDR_MAP` section size.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D121346
Summary:
The OffloadingBinary uses a convenience struct to help manage the memory
that will be serialized using the binary format. This currently uses a
reference to an existing buffer, but this should own the memory instead
so it is easier to work with seeing as its only current use requires
saving the buffer anyway.
We use the `OffloadBinary` to create binary images of offloading files
and their corresonding metadata. This patch changes this to inherit from
the base `Binary` class. This allows us to create and insepect these
more generically. This patch includes all the necessary glue to
implement this as a new binary format, along with added the magic bytes
we use to distinguish the offloading binary to the `file_magic`
implementation.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D126812
This is failing on an arm32 builder, and it is going to take me a while
to debug. To not block further progress I'm disabling this test on
arm32 configuraitons.
This is failing on an arm32 builder, and it is going to take me a while
to debug. To not block further progress I'm disabling this test on
arm32 configuraitons.
DXContainer files are structured as parts. This patch adds support for
parsing out the file part offsets and file part headers.
Reviewed By: kuhar
Differential Revision: https://reviews.llvm.org/D124804
`--symbolize-operands` already symbolizes branch targets based on the disassembly. When the object file is created with `-fbasic-block-sections=labels` (ELF-only) it will include a SHT_LLVM_BB_ADDR_MAP section which maps basic blocks to their addresses. In such case `llvm-objdump` can annotate the disassembly based on labels inferred on this section.
In contrast to the current labels, SHT_LLVM_BB_ADDR_MAP-based labels are created for every machine basic block including empty blocks and those which are not branched into (fallthrough blocks).
The old logic is still executed even when the SHT_LLVM_BB_ADDR_MAP section is present to handle functions which have not been received an entry in this section.
Reviewed By: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D124560
This patch begins adding DXContainer parsing support to libObject.
Following the pattern used by ELFFile my goal here is to write a
standalone DXContainer parser and later write an adapter interface to
support a subset of the ObjectFile interfaces so that we can add
limited objdump support. I will also be adding ObjectYAML support to
help drive testing of the object tools and MC-level object writers as
those come together.
DXContainer is a slightly odd format. It is arranged in "parts" that
are semantically similar to sections, but it doesn't support symbol
listing.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124643
We need to embed certain metadata along with a binary image when we wish
to perform a device-linking job on it. Currently this metadata was
embedded in the section name of the data itself. This worked, but made
adding new metadata very difficult and didn't work if the user did any
sort of section linking.
This patch introduces a custom binary format for bundling offloading
metadata with a device object file. This binary format is fundamentally
a simple string map table with some additional data and an embedded
image. I decided to use a custom format rather than using an existing
format (ELF, JSON, etc) because of the specialty use-case of this. We
need a simple binary format that can be concatenated without requiring
other external dependencies.
This extension will make it easier to extend the linker wrapper's
capabilties with whatever data is necessary. Eventually this will allow
us to remove all the external arguments passed to the linker wrapper and
embed it directly in the host's linker so device linking behaves exactly
like host linking.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D122069
This patch adds necessary definitions for LoongArch ELF files, including
relocation types. Also adds initial support to ELFYaml, llvm-objdump,
and llvm-readobj in order to work with LoongArch ELFs.
Differential revision: https://reviews.llvm.org/D115859
Change getELFRelativeRelocationType() to return R_VE_RELATIVE
as a preparation of lld for VE.
Reviewed By: simoll
Differential Revision: https://reviews.llvm.org/D115592
Summary: This patch improves the error message context of the
XCOFF interfaces by providing more details.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D110320
getRelocatedSection interface should not check that the object file is
relocatable, as executable files may have relocations preserved with
`--emit-relocs` linker flag. The relocations are useful in context of post-link
binary analysis for function reference identification. For example, BOLT relies
on relocations to perform function reordering.
Reviewed By: MaskRay, jhenderson
Differential Revision: https://reviews.llvm.org/D102296
Add in the ability of parsing symbol table for 64 bit object.
Reviewed By: jhenderson, DiggerLin
Differential Revision: https://reviews.llvm.org/D85774
