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//===-- RecordStreamer.cpp - Record asm defined and used symbols ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "RecordStreamer.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
using namespace llvm;
void RecordStreamer::markDefined(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Global:
S = DefinedGlobal;
break;
case NeverSeen:
case Defined:
case Used:
S = Defined;
break;
case DefinedWeak:
break;
case UndefinedWeak:
S = DefinedWeak;
}
}
void RecordStreamer::markGlobal(const MCSymbol &Symbol,
MCSymbolAttr Attribute) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
S = (Attribute == MCSA_Weak) ? DefinedWeak : DefinedGlobal;
break;
case NeverSeen:
case Global:
case Used:
S = (Attribute == MCSA_Weak) ? UndefinedWeak : Global;
break;
case UndefinedWeak:
case DefinedWeak:
break;
}
}
void RecordStreamer::markUsed(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
case Global:
case DefinedWeak:
case UndefinedWeak:
break;
case NeverSeen:
case Used:
S = Used;
break;
}
}
void RecordStreamer::visitUsedSymbol(const MCSymbol &Sym) { markUsed(Sym); }
RecordStreamer::RecordStreamer(MCContext &Context, const Module &M)
: MCStreamer(Context), M(M) {}
RecordStreamer::const_iterator RecordStreamer::begin() {
return Symbols.begin();
}
RecordStreamer::const_iterator RecordStreamer::end() { return Symbols.end(); }
void RecordStreamer::emitInstruction(const MCInst &Inst,
const MCSubtargetInfo &STI) {
MCStreamer::emitInstruction(Inst, STI);
}
void RecordStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
MCStreamer::emitLabel(Symbol);
markDefined(*Symbol);
}
void RecordStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
markDefined(*Symbol);
MCStreamer::emitAssignment(Symbol, Value);
}
bool RecordStreamer::emitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) {
if (Attribute == MCSA_Global || Attribute == MCSA_Weak)
markGlobal(*Symbol, Attribute);
if (Attribute == MCSA_LazyReference)
markUsed(*Symbol);
return true;
}
void RecordStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment,
SMLoc Loc) {
markDefined(*Symbol);
}
void RecordStreamer::emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
markDefined(*Symbol);
}
RecordStreamer::State RecordStreamer::getSymbolState(const MCSymbol *Sym) {
auto SI = Symbols.find(Sym->getName());
if (SI == Symbols.end())
return NeverSeen;
return SI->second;
}
void RecordStreamer::emitELFSymverDirective(StringRef AliasName,
const MCSymbol *Aliasee) {
SymverAliasMap[Aliasee].push_back(AliasName);
}
iterator_range<RecordStreamer::const_symver_iterator>
RecordStreamer::symverAliases() {
return {SymverAliasMap.begin(), SymverAliasMap.end()};
}
void RecordStreamer::flushSymverDirectives() {
// Mapping from mangled name to GV.
StringMap<const GlobalValue *> MangledNameMap;
// The name in the assembler will be mangled, but the name in the IR
// might not, so we first compute a mapping from mangled name to GV.
Mangler Mang;
SmallString<64> MangledName;
for (const GlobalValue &GV : M.global_values()) {
if (!GV.hasName())
continue;
MangledName.clear();
MangledName.reserve(GV.getName().size() + 1);
Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
MangledNameMap[MangledName] = &GV;
}
// Walk all the recorded .symver aliases, and set up the binding
// for each alias.
for (auto &Symver : SymverAliasMap) {
const MCSymbol *Aliasee = Symver.first;
MCSymbolAttr Attr = MCSA_Invalid;
bool IsDefined = false;
// First check if the aliasee binding was recorded in the asm.
RecordStreamer::State state = getSymbolState(Aliasee);
switch (state) {
case RecordStreamer::Global:
case RecordStreamer::DefinedGlobal:
Attr = MCSA_Global;
break;
case RecordStreamer::UndefinedWeak:
case RecordStreamer::DefinedWeak:
Attr = MCSA_Weak;
break;
default:
break;
}
switch (state) {
case RecordStreamer::Defined:
case RecordStreamer::DefinedGlobal:
case RecordStreamer::DefinedWeak:
IsDefined = true;
break;
case RecordStreamer::NeverSeen:
case RecordStreamer::Global:
case RecordStreamer::Used:
case RecordStreamer::UndefinedWeak:
break;
}
if (Attr == MCSA_Invalid || !IsDefined) {
const GlobalValue *GV = M.getNamedValue(Aliasee->getName());
if (!GV) {
auto MI = MangledNameMap.find(Aliasee->getName());
if (MI != MangledNameMap.end())
GV = MI->second;
}
if (GV) {
// If we don't have a symbol attribute from assembly, then check if
// the aliasee was defined in the IR.
if (Attr == MCSA_Invalid) {
if (GV->hasExternalLinkage())
Attr = MCSA_Global;
else if (GV->hasLocalLinkage())
Attr = MCSA_Local;
else if (GV->isWeakForLinker())
Attr = MCSA_Weak;
}
IsDefined = IsDefined || !GV->isDeclarationForLinker();
}
}
// Set the detected binding on each alias with this aliasee.
for (auto AliasName : Symver.second) {
std::pair<StringRef, StringRef> Split = AliasName.split("@@@");
SmallString<128> NewName;
if (!Split.second.empty() && !Split.second.startswith("@")) {
// Special processing for "@@@" according
// https://sourceware.org/binutils/docs/as/Symver.html
const char *Separator = IsDefined ? "@@" : "@";
AliasName =
(Split.first + Separator + Split.second).toStringRef(NewName);
}
MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
// TODO: Handle "@@@". Depending on SymbolAttribute value it needs to be
// converted into @ or @@.
const MCExpr *Value = MCSymbolRefExpr::create(Aliasee, getContext());
if (IsDefined)
markDefined(*Alias);
// Don't use EmitAssignment override as it always marks alias as defined.
MCStreamer::emitAssignment(Alias, Value);
if (Attr != MCSA_Invalid)
emitSymbolAttribute(Alias, Attr);
}
}
}
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