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* MCAssembler::evaluateFixup sets MCFixup::PCRel.
* ELFObjectWriter retrieves the bit from the MCFixup argument.
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Drop `OWriter.Renames.count(&Symbol)` from the fast path
(Used||Signature).
Place the two equated symbol (isVariable()) conditions together.
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This reverts commit 1108cf64196a056aa350baba98e3fab6d7529a59.
Caused a regression for a weird but interesting case (STT_SECTION symbol
as group signature). We no longer define `sec`
```
.section sec,"ax"
.section .foo,"axG",@progbits,sec
nop
```
Fix #146581
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... due to their close relationship. MCSection's inline functions (e.g.
iterator) access MCFragment, and we want MCFragment's inline functions
to access MCSection similarly (#146307).
Pull Request: https://github.com/llvm/llvm-project/pull/146315
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GNU Assembler supports symbol reassignment via .set, .equ, or =.
However, LLVM's integrated assembler only allows reassignment for
MCConstantExpr cases, as it struggles with scenarios like:
```
.data
.set x, 0
.long x // reference the first instance
x = .-.data
.long x // reference the second instance
.set x,.-.data
.long x // reference the third instance
```
Between two assignments binds, we cannot ensure that a reference binds
to the earlier assignment. We use MCSymbol::IsUsed and other conditions
to reject potentially unsafe reassignments, but certain MCConstantExpr
uses could be unsafe as well.
This patch enables reassignment by cloning the symbol upon reassignment
and updating the symbol table. Existing references to the original
symbol remain unchanged, and the original symbol is excluded from the
emitted symbol table.
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Use a variable symbol without any specifier instead of VK_WEAKREF.
Add code in ELFObjectWriter::executePostLayoutBinding to check
whether the target should be made an undefined weak symbol.
This change fixes several issues:
* Unreferenced `.weakref alias, target` no longer creates an undefined `target`.
* When `alias` is already defined, report an error instead of crashing.
.weakref is specific to ELF. llvm-ml has reused the VK_WEAKREF name for
a different concept. wasm incorrectly copied the ELF implementation.
Remove it.
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Replace MCSymbol argument with MCValue::AddSym. The minor difference in
.weakref handling is negligible, as our implementation may not fully
align with GAS, and .weakref is not used in practice.
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Additionally, swap MCFixup/MCValue order to match addReloc/recordRelocation.
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Prepare for removing MCContext from getRelocType functions.
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* Remove the MCAssembler * argument. Change subclasses to use MCAssembler *MCObjectWriter::Asm.
* Remove pure specifier and add an empty implementation
* Change MCFragment * to MCFragment &
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shouldForceRelocation
Introduce MCAsmBackend::addReloc to manage relocation appending.
The default implementation uses shouldForceRelocation to check
unresolved fixups and calls recordRelocation to append a relocation when
needed.
RISCV and LoongArch override addReloc to handle ADD/SUB relocations,
with potential support for RELAX relocations in the future.
AVR overrides addReloc to customize shouldForceRelocation behavior
(#121498).
applyFixup is moved into evaluateFixup.
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Add two helper functions to simplify checks for relocation types,
replacing direct comparisons with FirstRelocationKind and
FirstLiteralRelocationKind. Note: Some targets haven't utilized
isRelocation yet.
Also, update RelaxFixupKind to use 0 as the sentinel value.
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... to match GNU Assembler. This generalizes the
SHT_LLVM_CALL_GRAPH_PROFILE special case (which uses .reloc with
BFD_RELOC_NONE https://reviews.llvm.org/D104080).
Targets that want STT_SECTION adjustment cannot use
FirstLiteralRelocationKind derived fixup kinds.
Depends on the fix of #135521
Pull Request: https://github.com/llvm/llvm-project/pull/135519
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ELFObjectWriter::recordRelocation special case
The current implementation of R_LARCH_SUB{8,16,32,64} and TLS relocation types relies on fixup kinds FirstLiteralRelocationKind + offset (originally intended for .reloc directives). While this is clever and prevents switch cases like
```
case fixup_...sub8:
return ELF::R_LARCH_SUB8;
```
it needs revision.
GNU Assembler treats .reloc directives differently from standard relocations, notably by skipping
* Skipping STT_SECTION adjustments (when a referenced symbol is local and satisfies certain conditions, it can be redirected to a section symbol).
* Skipping STT_TLS symbol type setting for TLS relocations.
Encode relocatin type t with FirstRelocationKind+t instead of
FirstLiteralRelocationKind+t. The new value is less than
FirstLiteralRelocationKind and will not be treated as a .reloc
directive.
Close #135521
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Move `Fixup.getKind() >= FirstLiteralRelocationKind` from target hooks
to ELFObjectWriter::recordRelocation.
Currently, getRelocType cannot be skipped for LoongArch due to #135519
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This reverts commit 1c5961c0481b9c7421d38e3141d3c5a1e6084234.
Inadvertently pushed.
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to match GNU Assembler. This generalizes the SHT_LLVM_CALL_GRAPH_PROFILE
(which uses BFD_RELOC_NONE https://reviews.llvm.org/D104080) special case.
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We will replace the MCSymbolRefExpr member in MCValue with MCSymbol.
This change reduces dependence on MCSymbolRefExpr.
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ELFObjectWriter::recordRelocation
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MCValue::SymB is a MCSymbolRefExpr *, which might become MCSymbol * in
the future. Simplify some code that uses MCValue::SymB.
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And introduce MCValue::getAddSym & MCValue::getSubSym to simplify code.
We do not utilize the MCSymbol argument of needsRelocateWithSymbol
as it will go away in the future.
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It's the decision of backend needsRelocateWithSymbol whether the
STT_SECTION adjustment should be suppressed.
test/MC/AArch64/data-directive-specifier.s demonstrates how to test this
property.
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Finish the migration started by
eea7d32bd262bb5f61790c42ebaa147aa26c3979.
STT_TLS setting has been moved to backend getRelocType.
75f5a4f0dc7d96134cca86543ef3f86ef218ce77 migrated the last target, VE.
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Similar to previous migration done for other targets (PowerPC, X86, ARM,
etc). Switch from the confusing VariantKind to Specifier, which aligns
with Arm and IBM AIX's documentation.
In addition, rename *MCExpr::getKind, which confusingly shadows the base class getKind.
In the future, relocation specifiers should be encoded as part of
SystemZMCExpr instead of MCSymbolRefExpr.
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Move target-specific members outside of MCSymbolRefExpr::VariantKind
(a legacy interface I am eliminating). Most changes are mechanic,
except:
* ELFObjectWriter::shouldRelocateWithSymbol
* The legacy generic code uses `ELFObjectWriter::fixSymbolsInTLSFixups`
to set `STT_TLS` (and use an unnecessary expression walk). The better
way is to do this in `getRelocType`, which I have done for
AArch64, PowerPC, and RISC-V.
In the future, we should encode expressions with a relocation specifier
as X86MCExpr and use MCValue::RefKind to hold the specifier of the
relocatable expression.
https://maskray.me/blog/2025-03-16-relocation-generation-in-assemblers
While here, rename "Modifier' to "Specifier":
> "Relocation modifier", though concise, suggests adjustments happen during the linker's relocation step rather than the assembler's expression evaluation. I landed on "relocation specifier" as the winner. It's clear, aligns with Arm and IBM’s usage, and fits the assembler's role seamlessly.
Pull Request: https://github.com/llvm/llvm-project/pull/132149
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Most changes are mechanic, except:
* ELFObjectWriter::shouldRelocateWithSymbol: .TOC.@tocbase does not
register the undefined symbol. Move the handling into the
Sym->isUndefined() code path.
* ELFObjectWriter::fixSymbolsInTLSFixups's VK_PPC* cases are moved to
PPCELFObjectWriter::getRelocType. We should do similar refactoring
for other targets and eventually remove fixSymbolsInTLSFixups.
In the future, we should classify PPCMCExpr similar to AArch64MCExpr.
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so that we only need to do it once during recordRelocation. In the
future, we should change fixSymbolsInTLSFixups to apply to MCValue
instead of MCExpr, similar to GNU assembler.
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So we can distinguish between debug info sections written to .dwo files
and those written to the object file.
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Identified with misc-include-cleaner.
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Followup to #102363. This makes the `elf-object-writer.*Bytes` stats sum
up to `assembler.ObjectBytes`.
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More consistent casing + more accurate names.
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The o32 ABI specifies:
> Each relocation type of R_MIPS_HI16 must have an associated R_MIPS_LO16 entry immediately following it in the list of relocations. [...] the addend AHL is computed as (AHI << 16) + (short)ALO
In practice, the high-part and low-part relocations may not be adjacent
in assembly files, requiring the assembler to reorder relocations.
http://reviews.llvm.org/D19718 performed the reordering, but did not
optimize for the common case where a %lo immediately follows its
matching %hi. The quadratic time complexity could make sections with
many relocations very slow to process.
This patch implements the fast path, simplifies the code, and makes the
behavior more similar to GNU assembler (for the .rel.mips_hilo_8b test).
We also remove `OriginalSymbol`, removing overhead for other targets.
Fix #104562
Pull Request: https://github.com/llvm/llvm-project/pull/104723
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For MIPS's o32 ABI (REL), https://reviews.llvm.org/D19718 introduced
`OriginalAddend` to find the matching R_MIPS_LO16 relocation for
R_MIPS_GOT16 when STT_SECTION conversion is applicable.
lw $2, %lo(local1)
lui $2, %got(local1)
However, we could just store the original `Addend` in
`ELFRelocationEntry` and remove `OriginalAddend`.
Note: The relocation ordering algorithm in
https://reviews.llvm.org/D19718 is inefficient (#104562), which will be
addressed by another patch.
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Useful with other infrastructure that consume LLVM statistics to get an
idea of distribution of section sizes.
The breakdown of various section types is subject to change, this is
just an initial go at gather some sort of stats.
Example stats compiling X86ISelLowering.cpp (-g1):
```
"elf-object-writer.AllocROBytes": 308268,
"elf-object-writer.AllocRWBytes": 6240,
"elf-object-writer.AllocTextBytes": 1659203,
"elf-object-writer.DebugBytes": 3180386,
"elf-object-writer.OtherBytes": 5862,
"elf-object-writer.RelocationBytes": 2623440,
"elf-object-writer.StrtabBytes": 228599,
"elf-object-writer.SymtabBytes": 120336,
"elf-object-writer.UnwindBytes": 85216,
```
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