llvm-mirror/lib/MC/MCSection.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

110 lines
3.3 KiB
C++

//===- lib/MC/MCSection.cpp - Machine Code Section Representation ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// MCSection
//===----------------------------------------------------------------------===//
MCSection::MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin)
: Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
IsRegistered(false), DummyFragment(this), Variant(V), Kind(K) {}
MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
if (!End)
End = Ctx.createTempSymbol("sec_end", true);
return End;
}
bool MCSection::hasEnded() const { return End && End->isInSection(); }
MCSection::~MCSection() {
}
void MCSection::setBundleLockState(BundleLockStateType NewState) {
if (NewState == NotBundleLocked) {
if (BundleLockNestingDepth == 0) {
report_fatal_error("Mismatched bundle_lock/unlock directives");
}
if (--BundleLockNestingDepth == 0) {
BundleLockState = NotBundleLocked;
}
return;
}
// If any of the directives is an align_to_end directive, the whole nested
// group is align_to_end. So don't downgrade from align_to_end to just locked.
if (BundleLockState != BundleLockedAlignToEnd) {
BundleLockState = NewState;
}
++BundleLockNestingDepth;
}
MCSection::iterator
MCSection::getSubsectionInsertionPoint(unsigned Subsection) {
if (Subsection == 0 && SubsectionFragmentMap.empty())
return end();
SmallVectorImpl<std::pair<unsigned, MCFragment *>>::iterator MI =
std::lower_bound(SubsectionFragmentMap.begin(),
SubsectionFragmentMap.end(),
std::make_pair(Subsection, (MCFragment *)nullptr));
bool ExactMatch = false;
if (MI != SubsectionFragmentMap.end()) {
ExactMatch = MI->first == Subsection;
if (ExactMatch)
++MI;
}
iterator IP;
if (MI == SubsectionFragmentMap.end())
IP = end();
else
IP = MI->second;
if (!ExactMatch && Subsection != 0) {
// The GNU as documentation claims that subsections have an alignment of 4,
// although this appears not to be the case.
MCFragment *F = new MCDataFragment();
SubsectionFragmentMap.insert(MI, std::make_pair(Subsection, F));
getFragmentList().insert(IP, F);
F->setParent(this);
}
return IP;
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MCSection::dump() {
raw_ostream &OS = llvm::errs();
OS << "<MCSection";
OS << " Fragments:[\n ";
for (auto it = begin(), ie = end(); it != ie; ++it) {
if (it != begin())
OS << ",\n ";
it->dump();
}
OS << "]>";
}
#endif
MCSection::iterator MCSection::begin() { return Fragments.begin(); }
MCSection::iterator MCSection::end() { return Fragments.end(); }
MCSection::reverse_iterator MCSection::rbegin() { return Fragments.rbegin(); }
MCSection::reverse_iterator MCSection::rend() { return Fragments.rend(); }