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llvm-mirror/lib/MC/MCSymbol.cpp
Rafael Espindola d32e304f9c Fix pr24486.
This extends the work done in r233995 so that now getFragment (in addition to
getSection) also works for variable symbols.

With that the existing logic to decide if a-b can be computed works even if
a or b are variables. Given that, the expression evaluation can avoid expanding
variables as aggressively and that in turn lets the relocation code see the
original variable.

In order for this to work with the asm streamer, there is now a dummy fragment
per section. It is used to assign a section to a symbol when no other fragment
exists.

This patch is a joint work by Maxim Ostapenko andy myself.

llvm-svn: 249303
2015-10-05 12:07:05 +00:00

80 lines
2.7 KiB
C++

//===- lib/MC/MCSymbol.cpp - MCSymbol implementation ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
// Sentinel value for the absolute pseudo fragment.
MCFragment *MCSymbol::AbsolutePseudoFragment =
reinterpret_cast<MCFragment *>(4);
void *MCSymbol::operator new(size_t s, const StringMapEntry<bool> *Name,
MCContext &Ctx) {
// We may need more space for a Name to account for alignment. So allocate
// space for the storage type and not the name pointer.
size_t Size = s + (Name ? sizeof(NameEntryStorageTy) : 0);
// For safety, ensure that the alignment of a pointer is enough for an
// MCSymbol. This also ensures we don't need padding between the name and
// symbol.
static_assert((unsigned)AlignOf<MCSymbol>::Alignment <=
AlignOf<NameEntryStorageTy>::Alignment,
"Bad alignment of MCSymbol");
void *Storage = Ctx.allocate(Size, alignOf<NameEntryStorageTy>());
NameEntryStorageTy *Start = static_cast<NameEntryStorageTy*>(Storage);
NameEntryStorageTy *End = Start + (Name ? 1 : 0);
return End;
}
void MCSymbol::setVariableValue(const MCExpr *Value) {
assert(!IsUsed && "Cannot set a variable that has already been used.");
assert(Value && "Invalid variable value!");
assert((SymbolContents == SymContentsUnset ||
SymbolContents == SymContentsVariable) &&
"Cannot give common/offset symbol a variable value");
this->Value = Value;
SymbolContents = SymContentsVariable;
setUndefined();
}
void MCSymbol::print(raw_ostream &OS, const MCAsmInfo *MAI) const {
// The name for this MCSymbol is required to be a valid target name. However,
// some targets support quoting names with funny characters. If the name
// contains a funny character, then print it quoted.
StringRef Name = getName();
if (!MAI || MAI->isValidUnquotedName(Name)) {
OS << Name;
return;
}
if (MAI && !MAI->supportsNameQuoting())
report_fatal_error("Symbol name with unsupported characters");
OS << '"';
for (char C : Name) {
if (C == '\n')
OS << "\\n";
else if (C == '"')
OS << "\\\"";
else
OS << C;
}
OS << '"';
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MCSymbol::dump() const { dbgs() << *this; }
#endif