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[BOLT] Fix order of R_*_IRELATIVE in .rela.plt #106515

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[BOLT] Fix order of R_*_IRELATIVE in .rela.plt #106515

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3 changes: 3 additions & 0 deletions bolt/include/bolt/Core/Relocation.h
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,9 @@ struct Relocation {
/// Return code for a RELATIVE relocation
static uint64_t getRelative();

/// Return code for a IRELATIVE relocation
static uint64_t getIRelative();

/// Return true if this relocation is PC-relative. Return false otherwise.
bool isPCRelative() const { return isPCRelative(Type); }

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15 changes: 14 additions & 1 deletion bolt/lib/Core/Relocation.cpp
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Expand Up @@ -899,7 +899,7 @@ bool Relocation::isIRelative(uint64_t Type) {
case Triple::aarch64:
return Type == ELF::R_AARCH64_IRELATIVE;
case Triple::riscv64:
llvm_unreachable("not implemented");
return Type == ELF::R_RISCV_IRELATIVE;
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Can we replace the whole function body with return Type == getIRelative();?

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Can we replace the whole function body with return Type == getIRelative();?

Some extensions may introduce new variants（R_AARCH64_AUTH_[I]RELATIVE）, but currently, BOLT has no plans to support them, so I think we can make this chang. Do you have any suggestions?

case Triple::x86_64:
return Type == ELF::R_X86_64_IRELATIVE;
}
Expand Down Expand Up @@ -1009,6 +1009,19 @@ uint64_t Relocation::getRelative() {
}
}

uint64_t Relocation::getIRelative() {
switch (Arch) {
default:
llvm_unreachable("Unsupported architecture");
case Triple::aarch64:
return ELF::R_AARCH64_IRELATIVE;
case Triple::riscv64:
return ELF::R_RISCV_IRELATIVE;
case Triple::x86_64:
return ELF::R_X86_64_IRELATIVE;
}
}

size_t Relocation::emit(MCStreamer *Streamer) const {
const size_t Size = getSizeForType(Type);
const auto *Value = createExpr(Streamer);
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19 changes: 16 additions & 3 deletions bolt/lib/Rewrite/RewriteInstance.cpp
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Expand Up @@ -5185,12 +5185,15 @@ RewriteInstance::patchELFAllocatableRelaSections(ELFObjectFile<ELFT> *File) {

DynamicRelativeRelocationsCount = 0;

const bool HasIRelativeInPLT =
IsJmpRelocation.contains(Relocation::getIRelative());

auto writeRela = [&OS](const Elf_Rela *RelA, uint64_t &Offset) {
OS.pwrite(reinterpret_cast<const char *>(RelA), sizeof(*RelA), Offset);
Offset += sizeof(*RelA);
};

auto writeRelocations = [&](bool PatchRelative) {
auto writeRelocations = [&](bool PatchRelative, bool PatchIRelativeInPLT) {
for (BinarySection &Section : BC->allocatableSections()) {
const uint64_t SectionInputAddress = Section.getAddress();
uint64_t SectionAddress = Section.getOutputAddress();
Expand All @@ -5199,9 +5202,14 @@ RewriteInstance::patchELFAllocatableRelaSections(ELFObjectFile<ELFT> *File) {

for (const Relocation &Rel : Section.dynamicRelocations()) {
const bool IsRelative = Rel.isRelative();
const bool IsIRelativeInPLT = HasIRelativeInPLT && Rel.isIRelative();

if (PatchRelative != IsRelative)
continue;

if (PatchIRelativeInPLT != IsIRelativeInPLT)
continue;

if (IsRelative)
++DynamicRelativeRelocationsCount;

Expand Down Expand Up @@ -5249,8 +5257,13 @@ RewriteInstance::patchELFAllocatableRelaSections(ELFObjectFile<ELFT> *File) {
// The dynamic linker expects all R_*_RELATIVE relocations in RELA
// to be emitted first.
if (!DynamicRelrAddress)
writeRelocations(/* PatchRelative */ true);
writeRelocations(/* PatchRelative */ false);
writeRelocations(/* PatchRelative */ true, /* PatchIRelativeInPLT */ false);
writeRelocations(/* PatchRelative */ false, /* PatchIRelativeInPLT */ false);

// Place R_*_IRELATIVE after all R_*_JUMP_SLOT relocations emitted if
// R_*_IRELATIVE is presented at .rela.plt
if (HasIRelativeInPLT)
writeRelocations(/* PatchRelative */ false, /* PatchIRelativeInPLT */ true);

auto fillNone = [&](uint64_t &Offset, uint64_t EndOffset) {
if (!Offset)
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