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llvm-mirror/lib/MC/MCSection.cpp
Eric Christopher c2b29240e0 The initial .text section generated in object files was missing the
SHF_ARM_PURECODE flag when being built with the -mexecute-only flag.
All code sections of an ELF must have the flag set for the final .text
section to be execute-only, otherwise the flag gets removed.

A HasData flag is added to MCSection to aid in the determination that
the section is empty. A virtual setTargetSectionFlags is added to
MCELFObjectTargetWriter to allow subclasses to set target specific
section flags to be added to sections which we then use in the ARM
backend to set SHF_ARM_PURECODE.

Patch by Ivan Lozano!

Reviewed By: echristo

Differential Revision: https://reviews.llvm.org/D48792

llvm-svn: 341593
2018-09-06 22:09:31 +00:00

104 lines
3.1 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/ADT/SmallVector.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCFragment.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <utility>
using namespace llvm;
MCSection::MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin)
: Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
HasData(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() = default;
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->getIterator();
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)
LLVM_DUMP_METHOD void MCSection::dump() const {
raw_ostream &OS = errs();
OS << "<MCSection";
OS << " Fragments:[\n ";
for (auto it = begin(), ie = end(); it != ie; ++it) {
if (it != begin())
OS << ",\n ";
it->dump();
}
OS << "]>";
}
#endif