Start writing out some relocation sections (text).
Pass the full assembler pointer to the elf writer, so
that it has access to both the text buffer and the fixups.
Remove some child classes of AssemblerFixups. They didn't
really do much, and were pretty much identical to the
original AssemblerFixup class. Dart had a virtual method
for fixups to do necessary patching, but we currently
don't do the patching and just emit the relocations.
TODO see if patching is more efficient than writing out
relocations and letting the linker do the work.
This CL also makes AssemblerFixups POD.
Change the fixup kind to be a plain unsigned int, which
the target can fill w/ target/container-specific values.
Move the fwd declaration of Assembler to IceDefs and remove
the others. Do similar for fwd declaration refactoring for
ELFWriter.
Make the createAssembler method return a std::unique_ptr.
BUG=none
R=stichnot@chromium.org
Review URL: https://codereview.chromium.org/828873002
diff --git a/src/IceELFObjectWriter.cpp b/src/IceELFObjectWriter.cpp
index 7eebfa9..f1b698b 100644
--- a/src/IceELFObjectWriter.cpp
+++ b/src/IceELFObjectWriter.cpp
@@ -11,6 +11,7 @@
//
//===----------------------------------------------------------------------===//
+#include "assembler.h"
#include "IceDefs.h"
#include "IceELFObjectWriter.h"
#include "IceELFSection.h"
@@ -114,7 +115,7 @@
UserSection->setNameStrIndex(ShStrTab->getIndex(UserSection->getName()));
AllSections.push_back(UserSection);
if (RelIt != RelE) {
- ELFRelocationSectionBase *RelSection = *RelIt;
+ ELFRelocationSection *RelSection = *RelIt;
if (RelSection->getRelatedSection() == UserSection) {
RelSection->setInfoNum(UserSection->getNumber());
RelSection->setNumber(CurSectionNumber++);
@@ -131,7 +132,7 @@
void ELFObjectWriter::assignRelLinkNum(SizeT SymTabNumber,
RelSectionList &RelSections) {
- for (ELFRelocationSectionBase *S : RelSections) {
+ for (ELFRelocationSection *S : RelSections) {
S->setLinkNum(SymTabNumber);
}
}
@@ -187,12 +188,11 @@
}
void ELFObjectWriter::writeFunctionCode(const IceString &FuncName,
- bool IsInternal,
- const llvm::StringRef Data) {
+ bool IsInternal, const Assembler *Asm) {
assert(!SectionNumbersAssigned);
+ ELFTextSection *Section = nullptr;
// TODO(jvoung): handle ffunction-sections.
IceString SectionName = ".text";
- ELFTextSection *Section = nullptr;
if (TextSections.size() == 0) {
const Elf64_Xword ShFlags = SHF_ALLOC | SHF_EXECINSTR;
// TODO(jvoung): Should be bundle size. Grab it from that target?
@@ -209,7 +209,7 @@
// Function symbols are set to 0 size in the symbol table,
// in contrast to data symbols which have a proper size.
SizeT SymbolSize = 0;
- Section->appendData(Str, Data);
+ Section->appendData(Str, Asm->getBufferView());
uint8_t SymbolType;
uint8_t SymbolBinding;
if (IsInternal) {
@@ -222,6 +222,38 @@
SymTab->createDefinedSym(FuncName, SymbolType, SymbolBinding, Section,
OffsetInSection, SymbolSize);
StrTab->add(FuncName);
+
+ // Create a relocation section for the text section if needed, and copy the
+ // fixup information from per-function Assembler memory to the object
+ // writer's memory, for writing later.
+ if (!Asm->fixups().empty()) {
+ bool IsELF64 = isELF64(Ctx.getTargetArch());
+ IceString RelSectionName = IsELF64 ? ".rela" : ".rel";
+ RelSectionName += SectionName;
+ ELFRelocationSection *RelSection = nullptr;
+ // TODO(jvoung): Make this more efficient if -ffunction-sections
+ // efficiency becomes a problem.
+ auto RSI =
+ std::find_if(RelTextSections.begin(), RelTextSections.end(),
+ [&RelSectionName](const ELFRelocationSection *S)
+ -> bool { return S->getName() == RelSectionName; });
+ if (RSI != RelTextSections.end()) {
+ RelSection = *RSI;
+ } else {
+ const Elf64_Word ShType = IsELF64 ? SHT_RELA : SHT_REL;
+ const Elf64_Xword ShAlign = IsELF64 ? 8 : 4;
+ const Elf64_Xword ShEntSize =
+ IsELF64 ? sizeof(Elf64_Rela) : sizeof(Elf32_Rel);
+ static_assert(sizeof(Elf64_Rela) == 24 && sizeof(Elf32_Rel) == 8,
+ "Elf_Rel/Rela sizes cannot be derived from sizeof");
+ const Elf64_Xword ShFlags = 0;
+ RelSection = createSection<ELFRelocationSection>(
+ RelSectionName, ShType, ShFlags, ShAlign, ShEntSize);
+ RelSection->setRelatedSection(Section);
+ RelTextSections.push_back(RelSection);
+ }
+ RelSection->addRelocations(OffsetInSection, Asm->fixups());
+ }
}
void ELFObjectWriter::writeDataInitializer(const IceString &VarName,
@@ -347,6 +379,26 @@
template void ELFObjectWriter::writeConstantPool<ConstantDouble>(Type Ty);
+void ELFObjectWriter::writeAllRelocationSections(bool IsELF64) {
+ writeRelocationSections(IsELF64, RelTextSections);
+ writeRelocationSections(IsELF64, RelDataSections);
+ writeRelocationSections(IsELF64, RelRoDataSections);
+}
+
+void ELFObjectWriter::writeRelocationSections(bool IsELF64,
+ RelSectionList &RelSections) {
+ for (ELFRelocationSection *RelSec : RelSections) {
+ Elf64_Off Offset = alignFileOffset(RelSec->getSectionAlign());
+ RelSec->setFileOffset(Offset);
+ RelSec->setSize(RelSec->getSectionDataSize(Ctx, SymTab));
+ if (IsELF64) {
+ RelSec->writeData<true>(Ctx, Str, SymTab);
+ } else {
+ RelSec->writeData<false>(Ctx, Str, SymTab);
+ }
+ }
+}
+
void ELFObjectWriter::writeNonUserSections() {
bool IsELF64 = isELF64(Ctx.getTargetArch());
@@ -375,9 +427,7 @@
StrTab->setFileOffset(StrTabOffset);
Str.writeBytes(StrTab->getSectionData());
- // TODO: Write out the relocation sections.
- // May also be able to seek around the file and resolve function calls
- // that are for functions within the same section.
+ writeAllRelocationSections(IsELF64);
// Write out the section headers.
const size_t ShdrAlign = IsELF64 ? 8 : 4;
