Subzero: Remove IceString.
The purpose is to get control over excess string creation and deletion, especially when the strings are long enough to involve malloc/free.
Strings that interface with the outside world, or used for dump/debug, are now explicitly std::string.
Variable names and node names are represented as string IDs and pooled locally in the CFG. (In a non-DUMP build, this pool should always be empty.)
Other strings that are used across functions are represented as string IDs and pooled globally in the GlobalContext.
The --dump-strings flag allows these strings to be dumped for sanity checking, even in a MINIMAL build. In a MINIMAL build, the set of strings includes external symbol names, intrinsic names, helper function names, and label names of pooled constants to facilitate deterministic ELF string table output. For now, it also includes jump table entry names until that gets sorted out.
Constants are fixed so that the name and pooled fields are properly immutable after the constant is fully initialized.
BUG= https://bugs.chromium.org/p/nativeclient/issues/detail?id=4360
R=jpp@chromium.org
Review URL: https://codereview.chromium.org/1838753002 .
diff --git a/src/IceELFObjectWriter.cpp b/src/IceELFObjectWriter.cpp
index 98b774b..c3ba9b0 100644
--- a/src/IceELFObjectWriter.cpp
+++ b/src/IceELFObjectWriter.cpp
@@ -76,16 +76,16 @@
ELFObjectWriter::ELFObjectWriter(GlobalContext &Ctx, ELFStreamer &Out)
: Ctx(Ctx), Str(Out), ELF64(isELF64(Ctx.getFlags())) {
// Create the special bookkeeping sections now.
- const IceString NullSectionName("");
+ constexpr char NullSectionName[] = "";
NullSection = new (Ctx.allocate<ELFSection>())
ELFSection(NullSectionName, SHT_NULL, 0, 0, 0);
- const IceString ShStrTabName(".shstrtab");
+ constexpr char ShStrTabName[] = ".shstrtab";
ShStrTab = new (Ctx.allocate<ELFStringTableSection>())
ELFStringTableSection(ShStrTabName, SHT_STRTAB, 0, 1, 0);
ShStrTab->add(ShStrTabName);
- const IceString SymTabName(".symtab");
+ constexpr char SymTabName[] = ".symtab";
const Elf64_Xword SymTabAlign = ELF64 ? 8 : 4;
const Elf64_Xword SymTabEntSize =
ELF64 ? sizeof(Elf64_Sym) : sizeof(Elf32_Sym);
@@ -93,15 +93,15 @@
"Elf_Sym sizes cannot be derived from sizeof");
SymTab = createSection<ELFSymbolTableSection>(SymTabName, SHT_SYMTAB, 0,
SymTabAlign, SymTabEntSize);
- SymTab->createNullSymbol(NullSection);
+ SymTab->createNullSymbol(NullSection, &Ctx);
- const IceString StrTabName(".strtab");
+ constexpr char StrTabName[] = ".strtab";
StrTab =
createSection<ELFStringTableSection>(StrTabName, SHT_STRTAB, 0, 1, 0);
}
template <typename T>
-T *ELFObjectWriter::createSection(const IceString &Name, Elf64_Word ShType,
+T *ELFObjectWriter::createSection(const std::string &Name, Elf64_Word ShType,
Elf64_Xword ShFlags, Elf64_Xword ShAddralign,
Elf64_Xword ShEntsize) {
assert(!SectionNumbersAssigned);
@@ -117,8 +117,8 @@
// practice we've only had .rela for elf64 (x86-64). In the future, the two
// properties may need to be decoupled and the ShEntSize can vary more.
const Elf64_Word ShType = ELF64 ? SHT_RELA : SHT_REL;
- const IceString RelPrefix = ELF64 ? ".rela" : ".rel";
- const IceString RelSectionName = RelPrefix + RelatedSection->getName();
+ const std::string RelPrefix = ELF64 ? ".rela" : ".rel";
+ const std::string RelSectionName = RelPrefix + RelatedSection->getName();
const Elf64_Xword ShAlign = ELF64 ? 8 : 4;
const Elf64_Xword ShEntSize = ELF64 ? sizeof(Elf64_Rela) : sizeof(Elf32_Rel);
static_assert(sizeof(Elf64_Rela) == 24 && sizeof(Elf32_Rel) == 8,
@@ -216,16 +216,16 @@
return OffsetInFile;
}
-void ELFObjectWriter::writeFunctionCode(const IceString &FuncName,
- bool IsInternal, Assembler *Asm) {
+void ELFObjectWriter::writeFunctionCode(GlobalString FuncName, bool IsInternal,
+ Assembler *Asm) {
assert(!SectionNumbersAssigned);
- TimerMarker T_func(&Ctx, FuncName);
+ TimerMarker T_func(&Ctx, FuncName.toStringOrEmpty());
TimerMarker Timer(TimerStack::TT_writeELF, &Ctx);
ELFTextSection *Section = nullptr;
ELFRelocationSection *RelSection = nullptr;
const bool FunctionSections = Ctx.getFlags().getFunctionSections();
if (TextSections.empty() || FunctionSections) {
- IceString SectionName = ".text";
+ std::string SectionName = ".text";
if (FunctionSections)
SectionName += "." + FuncName;
constexpr Elf64_Xword ShFlags = SHF_ALLOC | SHF_EXECINSTR;
@@ -289,7 +289,7 @@
// is non-empty, then only the TranslateOnly variable is kept for emission.
void partitionGlobalsBySection(const VariableDeclarationList &Vars,
VariableDeclarationPartition VarsBySection[],
- const IceString &TranslateOnly) {
+ const std::string &TranslateOnly) {
for (VariableDeclaration *Var : Vars) {
if (GlobalContext::matchSymbolName(Var->getName(), TranslateOnly)) {
size_t Section = classifyGlobalSection(Var);
@@ -303,7 +303,7 @@
void ELFObjectWriter::writeDataSection(const VariableDeclarationList &Vars,
FixupKind RelocationKind,
- const IceString &SectionSuffix,
+ const std::string &SectionSuffix,
bool IsPIC) {
TimerMarker Timer(TimerStack::TT_writeELF, &Ctx);
assert(!SectionNumbersAssigned);
@@ -320,7 +320,7 @@
}
namespace {
-IceString MangleSectionName(const char Base[], const IceString &Suffix) {
+std::string MangleSectionName(const char Base[], const std::string &Suffix) {
if (Suffix.empty())
return Base;
return Base + ("." + Suffix);
@@ -331,7 +331,7 @@
void ELFObjectWriter::writeDataOfType(SectionType ST,
const VariableDeclarationPartition &Vars,
FixupKind RelocationKind,
- const IceString &SectionSuffix,
+ const std::string &SectionSuffix,
bool IsPIC) {
if (Vars.empty())
return;
@@ -346,7 +346,7 @@
// Lift this out, so it can be re-used if we do fdata-sections?
switch (ST) {
case ROData: {
- const IceString SectionName =
+ const std::string SectionName =
MangleSectionName(IsPIC ? ".data.rel.ro" : ".rodata", SectionSuffix);
const Elf64_Xword ShFlags = IsPIC ? (SHF_ALLOC | SHF_WRITE) : SHF_ALLOC;
Section = createSection<ELFDataSection>(SectionName, SHT_PROGBITS, ShFlags,
@@ -358,7 +358,7 @@
break;
}
case Data: {
- const IceString SectionName = MangleSectionName(".data", SectionSuffix);
+ const std::string SectionName = MangleSectionName(".data", SectionSuffix);
constexpr Elf64_Xword ShFlags = SHF_ALLOC | SHF_WRITE;
Section = createSection<ELFDataSection>(SectionName, SHT_PROGBITS, ShFlags,
ShAddralign, ShEntsize);
@@ -369,7 +369,7 @@
break;
}
case BSS: {
- const IceString SectionName = MangleSectionName(".bss", SectionSuffix);
+ const std::string SectionName = MangleSectionName(".bss", SectionSuffix);
constexpr Elf64_Xword ShFlags = SHF_ALLOC | SHF_WRITE;
Section = createSection<ELFDataSection>(SectionName, SHT_NOBITS, ShFlags,
ShAddralign, ShEntsize);
@@ -394,7 +394,7 @@
SizeT SymbolSize = Var->getNumBytes();
bool IsExternal = Var->isExternal() || Ctx.getFlags().getDisableInternal();
const uint8_t SymbolBinding = IsExternal ? STB_GLOBAL : STB_LOCAL;
- const IceString &Name = Var->getName();
+ GlobalString Name = Var->getName();
SymTab->createDefinedSym(Name, SymbolType, SymbolBinding, Section,
Section->getCurrentSize(), SymbolSize);
StrTab->add(Name);
@@ -545,10 +545,7 @@
if (!C->getShouldBePooled())
continue;
auto *Const = llvm::cast<ConstType>(C);
- std::string SymBuffer;
- llvm::raw_string_ostream SymStrBuf(SymBuffer);
- Const->emitPoolLabel(SymStrBuf);
- std::string &SymName = SymStrBuf.str();
+ GlobalString SymName = Const->getLabelName();
SymTab->createDefinedSym(SymName, STT_NOTYPE, STB_LOCAL, Section,
OffsetInSection, SymbolSize);
StrTab->add(SymName);
@@ -585,8 +582,12 @@
const Elf64_Xword PointerSize = typeWidthInBytes(getPointerType());
const Elf64_Xword ShAddralign = PointerSize;
const Elf64_Xword ShEntsize = PointerSize;
- const IceString SectionName = MangleSectionName(
- IsPIC ? ".data.rel.ro" : ".rodata", JT.getFunctionName() + "$jumptable");
+ const GlobalString JTName = JT.getFunctionName();
+ const std::string SectionName = MangleSectionName(
+ IsPIC ? ".data.rel.ro" : ".rodata",
+ (JTName.hasStdString() ? JTName.toString()
+ : std::to_string(JTName.getID())) +
+ "$jumptable");
Section = createSection<ELFDataSection>(SectionName, SHT_PROGBITS, SHF_ALLOC,
ShAddralign, ShEntsize);
Section->setFileOffset(alignFileOffset(ShAddralign));
@@ -598,8 +599,8 @@
Section->padToAlignment(Str, PointerSize);
const bool IsExternal = Ctx.getFlags().getDisableInternal();
const uint8_t SymbolBinding = IsExternal ? STB_GLOBAL : STB_LOCAL;
- const IceString JumpTableName =
- InstJumpTable::makeName(JT.getFunctionName(), JT.getId());
+ GlobalString JumpTableName = Ctx.getGlobalString(
+ InstJumpTable::makeName(JT.getFunctionName(), JT.getId()));
SymTab->createDefinedSym(JumpTableName, SymbolType, SymbolBinding, Section,
Section->getCurrentSize(), PointerSize);
StrTab->add(JumpTableName);
@@ -618,7 +619,8 @@
TimerMarker Timer(TimerStack::TT_writeELF, &Ctx);
for (const Constant *S : UndefSyms) {
const auto *Sym = llvm::cast<ConstantRelocatable>(S);
- const IceString &Name = Sym->getName();
+ GlobalString Name = Sym->getName();
+ assert(Name.hasStdString());
bool BadIntrinsic;
const Intrinsics::FullIntrinsicInfo *Info =
Ctx.getIntrinsicsInfo().find(Name, BadIntrinsic);
