Similar to commit 28fcafb50274be2520117eacb0a886adafefe59d (2011) for
MachObjectWriter and commit 9539a7796094ff5fb59d9c685140ea2e214b945c for
WinCOFFObjectWriter.
MCELFStreamer can now access ELFObjectWriter directly without adding
ELF-specific markGnuAbi (https://reviews.llvm.org/D97976) and
setOverrideABIVersion to MCObjectWriter.
A few member variables have to be made public since we cannot use a
friend declaration for ELFWriter.
Avoid needless copying of instructions and fixups and directly emit into
the fragment small vectors.
This (optionally, second commit) also removes the single use of the
MCCompactEncodedInstFragment to simplify code.
Follow-up to e48c4011ca80385573f1b92793c75dc98abb228f ("[MC] Cache current fragment in MCStreamer").
Prerequisite: a few commits that removed nullable getCurrentSectionOnly calls.
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.
When both aligned bundling and RelaxAll are enabled, bundle padding is
directly written into fragments (https://reviews.llvm.org/D8072).
(The original motivation was memory usage, which has been achieved from
different angles with recent assembler improvement).
The code presents challenges with the work to replace fragment
representation (e.g. #94950#95077). This patch removes the special
handling. RelaxAll still works but the behavior seems slightly different
as revealed by 2 changed tests. However, most `-mc-relax-all` tests are
unchanged.
RelaxAll used to be the default for clang -O0. This mode has significant
code size drawbacks and newer Clang doesn't use it (#90013).
---
flushPendingLabels: The FOffset parameter can be removed: pending labels
will be assigned to the incoming fragment at offset 0.
Pull Request: https://github.com/llvm/llvm-project/pull/95188
`allocFragment` might be changed to a placement new when the allocation
strategy changes.
`allocInitialFragment` is to deduplicate the following pattern
```
auto *F = new MCDataFragment();
Result->addFragment(*F);
F->setParent(Result);
```
Pull Request: https://github.com/llvm/llvm-project/pull/95197
Related to clean-up opportunities discussed at #90013.
After these cleanups, the `RelaxAll` parameter from
`createMCObjectStreamer` can be removed as well. As
`createMCObjectStreamer` is a more user-facing API and used by two files
in mlir/, we postpone the cleanup to the future.
When `sym` in `.reloc ., BFD_RELOC_NONE, sym` is not referenced
elsewhere, `sym` is not in the symbol table and the relocation
references the null symbol. Visit the expression to fix the issue.
`MCExpr::evaluateAsAbsolute` has a longstanding bug. When the MCAssembler is
non-null and the MCAsmLayout is null, it may incorrectly fold A-B even if A and
B are separated by a linker-relaxable instruction. This behavior can suppress
some ADD/SUB relocations and lead to wrong results if the linker performs
relaxation.
To fix the bug, ensure that linker-relaxable instructions only appear at the end
of an MCDataFragment, thereby making them terminate the fragment. When computing
A-B, suppress folding if A and B are separated by a linker-relaxable
instruction.
* `.subsection` now correctly give errors for non-foldable expressions.
* gen-dwarf.s will pass even if we add back the .debug_line or .eh_frame/.debug_frame code from D150004
* This will fix suppressed relocation when we add R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128.
In the future, we should investigate the desired behavior for
`MCExpr::evaluateAsAbsolute` when both MCAssembler and MCAsmLayout are non-null.
(Note: MCRelaxableFragment is only for assembler-relaxation. If we ever need
linker-relaxable MCRelaxableFragment, we would need to adjust RISCVMCExpr.cpp
(D58943/D73211).)
Depends on D153096
Differential Revision: https://reviews.llvm.org/D153097
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This handling is
currently restricted to weak_anti_dep symbols, because we depend on the
current behavior of resolving weak symbols in some cases.
Differential Revision: https://reviews.llvm.org/D145208
This reverts commit 10c17c97ebaf81ac26f6830e51a7a57ddcf63cd2. It causes undefined symbol error on chromium windows build. A small repro was uploaded to the code review.
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This required a few
changes to the way we handle weak symbols on Windows.
Differential Revision: https://reviews.llvm.org/D145208
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This required a few
changes to the way we handle weak symbols on Windows.
Differential Revision: https://reviews.llvm.org/D145208
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
Next patch after D139548 and D139439. Same expectations, the change seems safe with as far as llvm goes, we cannot check downstream implementations.
Differential Revision: https://reviews.llvm.org/D139614
In the same vein as D139439, the patch is not NFC as there is no way to check all downstream implementations but the patch seems pretty safe.
Differential Revision: https://reviews.llvm.org/D139548
Before performing this change, I checked that `ByteAlignment` was never `0` inside `MCAsmStreamer:emitZeroFill` and `MCAsmStreamer::emitLocalCommonSymbol`.
I believe it is NFC as `0` values are illegal in `emitZeroFill` anyways, `Log2(ByteAlignment)` would be undefined.
And currently, all calls to `emitLocalCommonSymbol` are provably `>0`.
Differential Revision: https://reviews.llvm.org/D139439
This breaks Windows bots with
`warning C4334: '<<': result of 32-bit shift implicitly converted to 64 bits (was 64-bit shift intended?)`
Some shift operators are lacking a proper literal unit ('1ULL' instead of
'1'). Will reland once fixed.
This reverts commit c621c1a8e81856e6bf2be79714767d80466e9ede.
Before performing this change, I checked that `ByteAlignment` was never `0` inside `MCAsmStreamer:emitZeroFill` and `MCAsmStreamer::emitLocalCommonSymbol`.
I believe it is NFC as `0` values are illegal in `emitZeroFill` anyways, `Log2(ByteAlignment)` would be undefined.
And currently, all calls to `emitLocalCommonSymbol` are provably `>0`.
Differential Revision: https://reviews.llvm.org/D139439
Extends the Asm reader/writer to support reading and writing the
'.memtag' directive (including allowing it on internal global
variables). Also add some extra tooling support, including objdump and
yaml2obj/obj2yaml.
Test that the sanitize_memtag IR attribute produces the expected asm
directive.
Uses the new Aarch64 MemtagABI specification
(https://github.com/ARM-software/abi-aa/blob/main/memtagabielf64/memtagabielf64.rst)
to identify symbols as tagged in object files. This is done using a
R_AARCH64_NONE relocation that identifies each tagged symbol, and these
relocations are tagged in a special SHT_AARCH64_MEMTAG_GLOBALS_STATIC
section. This signals to the linker that the global variable should be
tagged.
Reviewed By: fmayer, MaskRay, peter.smith
Differential Revision: https://reviews.llvm.org/D128958
This patch makes code less readable but it will clean itself after all functions are converted.
Differential Revision: https://reviews.llvm.org/D138665
Similar to D107861. Some tools required the GNU ABI mark to output
the symbol is a IFUNC type correctly (for instance binutils readelf).
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D131162
For the AIX linker, under default options, global or weak symbols which
have no visibility bits set to zero (i.e. no visibility, similar to ELF
default) are only exported if specified on an export list provided to
the linker. So AIX has an additional visibility style called
"exported" which indicates to the linker that the symbol should
be explicitly globally exported.
This change maps "dllexport" in the LLVM IR to correspond to XCOFF
exported as we feel this best models the intended semantic (discussion
on the discourse RFC thread: https://discourse.llvm.org/t/rfc-adding-exported-visibility-style-to-the-ir-to-model-xcoff-exported-visibility/61853)
and allows us to enable writing this visibility for the AIX target
in the assembly path.
Reviewed By: DiggerLin
Differential Revision: https://reviews.llvm.org/D123951
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
As described on D111049, we're trying to remove the <string> dependency from error handling and replace uses of report_fatal_error(const std::string&) with the Twine() variant which can be forward declared.
In preparation for passing the MCSubtargetInfo (STI) through to writeNops
so that it can use the STI in operation at the time, we need to record the
STI in operation when a MCAlignFragment may write nops as padding. The
STI is currently unused, a further patch will pass it through to
writeNops.
There are many places that can create an MCAlignFragment, in most cases
we can find out the STI in operation at the time. In a few places this
isn't possible as we are in initialisation or finalisation, or are
emitting constant pools. When possible I've tried to find the most
appropriate existing fragment to obtain the STI from, when none is
available use the per module STI.
For constant pools we don't actually need to use EmitCodeAlign as the
constant pools are data anyway so falling through into it via an
executable NOP is no better than falling through into data padding.
This is a prerequisite for D45962 which uses the STI to emit the
appropriate NOP for the STI. Which can differ per fragment.
Note that involves an interface change to InitSections. It is now
called initSections and requires a SubtargetInfo as a parameter.
Differential Revision: https://reviews.llvm.org/D45961
This makes sure, that the text section will have a 2-byte alignment, if
the +c extension is enabled.
Reviewed By: MaskRay, luismarques
Differential Revision: https://reviews.llvm.org/D102052
Similar to D97976.
On Linux, most GCC installations are configured with
`--enable-gnu-unique-object` and such GCC emits `@gnu_unique_object` assembly.
The feature is highly controversial and disliked by many folks.
(On glibc DF_1_NODELETE is implicitly enabled and makes dlclose a no-op).
In llvm-project STB_GNU_UNIQUE is assembly only. Clang does not use STB_GNU_UNIQUE.
Use ELFOSABI_GNU to match GNU as behavior and avoid collision with other
OSABI binding values.
Reviewed By: jrtc27
Differential Revision: https://reviews.llvm.org/D107861
Enable the emission of a GNU attributes section by reusing the code for
emitting the ARM build attributes section.
The GNU attributes follow the exact same section format as the ARM
BuildAttributes section, so this can be factored out and reused for GNU
attributes generally.
The immediate motivation for this is to emit a GNU attributes section for the
vector ABI on SystemZ (https://reviews.llvm.org/D105067).
Review: Logan Chien, Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D102894
... even on targets preferring RELA. The section is only consumed by ld.lld
which can handle REL.
Follow-up to D104080 as I explained in the review. There are two advantages:
* The D104080 code only handles RELA, so arm/i386/mips32 etc may warn for -fprofile-use=/-fprofile-sample-use= usage.
* Decrease object file size for RELA targets
While here, change the relocation to relocate weights, instead of 0,1,2,3,..
I failed to catch the issue during review.
Currently when .llvm.call-graph-profile is created by llvm it explicitly encodes the symbol indices. This section is basically a black box for post processing tools. For example, if we run strip -s on the object files the symbol table changes, but indices in that section do not. In non-visible behavior indices point to wrong symbols. The visible behavior indices point outside of Symbol table: "invalid symbol index".
This patch changes the format by using R_*_NONE relocations to indicate the from/to symbols. The Frequency (Weight) will still be in the .llvm.call-graph-profile, but symbol information will be in relocation section. In LLD information from both sections is used to reconstruct call graph profile. Relocations themselves will never be applied.
With this approach post processing tools that handle relocations correctly work for this section also. Tools can add/remove symbols and as long as they handle relocation sections with this approach information stays correct.
Doing a quick experiment with clang-13.
The size went up from 107KB to 322KB, aggregate of all the input sections. Size of clang-13 binary is ~118MB. For users of -fprofile-use/-fprofile-sample-use the size of object files will go up slightly, it will not impact final binary size.
Reviewed By: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D104080
