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llvm-mirror/lib/MC/MCFragment.cpp
Chandler Carruth d4d44b30bf [ptr-traits] Split the MCFragment type hierarchy out of the MCAssembler 
header to its own header, allowing users of fragments to have a narrower
header file, and avoid circular header dependencies when getting the
definition of MCSection prior to inspecting traits on MCSection
pointers.

This is part of a series of patches to allow LLVM to check for complete
pointee types when computing its pointer traits. This is absolutely
necessary to get correct (or reproducible) results for things like how
many low bits are guaranteed to be zero.

Note that this doesn't in any way change the design of MC, it is just
moving code around to allow the *header files* to be more fine grained.
Without this, it is impossible to get a complete type for MCSection
where it is needed.

If anyone would prefer a different slicing of the header files, I'm
happy to oblige of course. =]

llvm-svn: 256548
2015-12-29 09:06:16 +00:00

459 lines
14 KiB
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//===- lib/MC/MCFragment.cpp - Assembler Fragment 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/MCFragment.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include <tuple>
using namespace llvm;
MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
: Assembler(Asm), LastValidFragment()
{
// Compute the section layout order. Virtual sections must go last.
for (MCSection &Sec : Asm)
if (!Sec.isVirtualSection())
SectionOrder.push_back(&Sec);
for (MCSection &Sec : Asm)
if (Sec.isVirtualSection())
SectionOrder.push_back(&Sec);
}
bool MCAsmLayout::isFragmentValid(const MCFragment *F) const {
const MCSection *Sec = F->getParent();
const MCFragment *LastValid = LastValidFragment.lookup(Sec);
if (!LastValid)
return false;
assert(LastValid->getParent() == Sec);
return F->getLayoutOrder() <= LastValid->getLayoutOrder();
}
void MCAsmLayout::invalidateFragmentsFrom(MCFragment *F) {
// If this fragment wasn't already valid, we don't need to do anything.
if (!isFragmentValid(F))
return;
// Otherwise, reset the last valid fragment to the previous fragment
// (if this is the first fragment, it will be NULL).
LastValidFragment[F->getParent()] = F->getPrevNode();
}
void MCAsmLayout::ensureValid(const MCFragment *F) const {
MCSection *Sec = F->getParent();
MCSection::iterator I;
if (MCFragment *Cur = LastValidFragment[Sec])
I = ++MCSection::iterator(Cur);
else
I = Sec->begin();
// Advance the layout position until the fragment is valid.
while (!isFragmentValid(F)) {
assert(I != Sec->end() && "Layout bookkeeping error");
const_cast<MCAsmLayout *>(this)->layoutFragment(&*I);
++I;
}
}
uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
ensureValid(F);
assert(F->Offset != ~UINT64_C(0) && "Address not set!");
return F->Offset;
}
// Simple getSymbolOffset helper for the non-varibale case.
static bool getLabelOffset(const MCAsmLayout &Layout, const MCSymbol &S,
bool ReportError, uint64_t &Val) {
if (!S.getFragment()) {
if (ReportError)
report_fatal_error("unable to evaluate offset to undefined symbol '" +
S.getName() + "'");
return false;
}
Val = Layout.getFragmentOffset(S.getFragment()) + S.getOffset();
return true;
}
static bool getSymbolOffsetImpl(const MCAsmLayout &Layout, const MCSymbol &S,
bool ReportError, uint64_t &Val) {
if (!S.isVariable())
return getLabelOffset(Layout, S, ReportError, Val);
// If SD is a variable, evaluate it.
MCValue Target;
if (!S.getVariableValue()->evaluateAsValue(Target, Layout))
report_fatal_error("unable to evaluate offset for variable '" +
S.getName() + "'");
uint64_t Offset = Target.getConstant();
const MCSymbolRefExpr *A = Target.getSymA();
if (A) {
uint64_t ValA;
if (!getLabelOffset(Layout, A->getSymbol(), ReportError, ValA))
return false;
Offset += ValA;
}
const MCSymbolRefExpr *B = Target.getSymB();
if (B) {
uint64_t ValB;
if (!getLabelOffset(Layout, B->getSymbol(), ReportError, ValB))
return false;
Offset -= ValB;
}
Val = Offset;
return true;
}
bool MCAsmLayout::getSymbolOffset(const MCSymbol &S, uint64_t &Val) const {
return getSymbolOffsetImpl(*this, S, false, Val);
}
uint64_t MCAsmLayout::getSymbolOffset(const MCSymbol &S) const {
uint64_t Val;
getSymbolOffsetImpl(*this, S, true, Val);
return Val;
}
const MCSymbol *MCAsmLayout::getBaseSymbol(const MCSymbol &Symbol) const {
if (!Symbol.isVariable())
return &Symbol;
const MCExpr *Expr = Symbol.getVariableValue();
MCValue Value;
if (!Expr->evaluateAsValue(Value, *this)) {
Assembler.getContext().reportError(
SMLoc(), "expression could not be evaluated");
return nullptr;
}
const MCSymbolRefExpr *RefB = Value.getSymB();
if (RefB) {
Assembler.getContext().reportError(
SMLoc(), Twine("symbol '") + RefB->getSymbol().getName() +
"' could not be evaluated in a subtraction expression");
return nullptr;
}
const MCSymbolRefExpr *A = Value.getSymA();
if (!A)
return nullptr;
const MCSymbol &ASym = A->getSymbol();
const MCAssembler &Asm = getAssembler();
if (ASym.isCommon()) {
// FIXME: we should probably add a SMLoc to MCExpr.
Asm.getContext().reportError(SMLoc(),
"Common symbol '" + ASym.getName() +
"' cannot be used in assignment expr");
return nullptr;
}
return &ASym;
}
uint64_t MCAsmLayout::getSectionAddressSize(const MCSection *Sec) const {
// The size is the last fragment's end offset.
const MCFragment &F = Sec->getFragmentList().back();
return getFragmentOffset(&F) + getAssembler().computeFragmentSize(*this, F);
}
uint64_t MCAsmLayout::getSectionFileSize(const MCSection *Sec) const {
// Virtual sections have no file size.
if (Sec->isVirtualSection())
return 0;
// Otherwise, the file size is the same as the address space size.
return getSectionAddressSize(Sec);
}
uint64_t llvm::computeBundlePadding(const MCAssembler &Assembler,
const MCFragment *F,
uint64_t FOffset, uint64_t FSize) {
uint64_t BundleSize = Assembler.getBundleAlignSize();
assert(BundleSize > 0 &&
"computeBundlePadding should only be called if bundling is enabled");
uint64_t BundleMask = BundleSize - 1;
uint64_t OffsetInBundle = FOffset & BundleMask;
uint64_t EndOfFragment = OffsetInBundle + FSize;
// There are two kinds of bundling restrictions:
//
// 1) For alignToBundleEnd(), add padding to ensure that the fragment will
// *end* on a bundle boundary.
// 2) Otherwise, check if the fragment would cross a bundle boundary. If it
// would, add padding until the end of the bundle so that the fragment
// will start in a new one.
if (F->alignToBundleEnd()) {
// Three possibilities here:
//
// A) The fragment just happens to end at a bundle boundary, so we're good.
// B) The fragment ends before the current bundle boundary: pad it just
// enough to reach the boundary.
// C) The fragment ends after the current bundle boundary: pad it until it
// reaches the end of the next bundle boundary.
//
// Note: this code could be made shorter with some modulo trickery, but it's
// intentionally kept in its more explicit form for simplicity.
if (EndOfFragment == BundleSize)
return 0;
else if (EndOfFragment < BundleSize)
return BundleSize - EndOfFragment;
else { // EndOfFragment > BundleSize
return 2 * BundleSize - EndOfFragment;
}
} else if (OffsetInBundle > 0 && EndOfFragment > BundleSize)
return BundleSize - OffsetInBundle;
else
return 0;
}
/* *** */
void ilist_node_traits<MCFragment>::deleteNode(MCFragment *V) {
V->destroy();
}
MCFragment::MCFragment() : Kind(FragmentType(~0)), HasInstructions(false),
AlignToBundleEnd(false), BundlePadding(0) {
}
MCFragment::~MCFragment() { }
MCFragment::MCFragment(FragmentType Kind, bool HasInstructions,
uint8_t BundlePadding, MCSection *Parent)
: Kind(Kind), HasInstructions(HasInstructions), AlignToBundleEnd(false),
BundlePadding(BundlePadding), Parent(Parent), Atom(nullptr),
Offset(~UINT64_C(0)) {
if (Parent && !isDummy())
Parent->getFragmentList().push_back(this);
}
void MCFragment::destroy() {
// First check if we are the sentinal.
if (Kind == FragmentType(~0)) {
delete this;
return;
}
switch (Kind) {
case FT_Align:
delete cast<MCAlignFragment>(this);
return;
case FT_Data:
delete cast<MCDataFragment>(this);
return;
case FT_CompactEncodedInst:
delete cast<MCCompactEncodedInstFragment>(this);
return;
case FT_Fill:
delete cast<MCFillFragment>(this);
return;
case FT_Relaxable:
delete cast<MCRelaxableFragment>(this);
return;
case FT_Org:
delete cast<MCOrgFragment>(this);
return;
case FT_Dwarf:
delete cast<MCDwarfLineAddrFragment>(this);
return;
case FT_DwarfFrame:
delete cast<MCDwarfCallFrameFragment>(this);
return;
case FT_LEB:
delete cast<MCLEBFragment>(this);
return;
case FT_SafeSEH:
delete cast<MCSafeSEHFragment>(this);
return;
case FT_Dummy:
delete cast<MCDummyFragment>(this);
return;
}
}
/* *** */
// Debugging methods
namespace llvm {
raw_ostream &operator<<(raw_ostream &OS, const MCFixup &AF) {
OS << "<MCFixup" << " Offset:" << AF.getOffset()
<< " Value:" << *AF.getValue()
<< " Kind:" << AF.getKind() << ">";
return OS;
}
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MCFragment::dump() {
raw_ostream &OS = llvm::errs();
OS << "<";
switch (getKind()) {
case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
case MCFragment::FT_Data: OS << "MCDataFragment"; break;
case MCFragment::FT_CompactEncodedInst:
OS << "MCCompactEncodedInstFragment"; break;
case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
case MCFragment::FT_Relaxable: OS << "MCRelaxableFragment"; break;
case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
case MCFragment::FT_LEB: OS << "MCLEBFragment"; break;
case MCFragment::FT_SafeSEH: OS << "MCSafeSEHFragment"; break;
case MCFragment::FT_Dummy:
OS << "MCDummyFragment";
break;
}
OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
<< " Offset:" << Offset
<< " HasInstructions:" << hasInstructions()
<< " BundlePadding:" << static_cast<unsigned>(getBundlePadding()) << ">";
switch (getKind()) {
case MCFragment::FT_Align: {
const MCAlignFragment *AF = cast<MCAlignFragment>(this);
if (AF->hasEmitNops())
OS << " (emit nops)";
OS << "\n ";
OS << " Alignment:" << AF->getAlignment()
<< " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
<< " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
break;
}
case MCFragment::FT_Data: {
const MCDataFragment *DF = cast<MCDataFragment>(this);
OS << "\n ";
OS << " Contents:[";
const SmallVectorImpl<char> &Contents = DF->getContents();
for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
if (i) OS << ",";
OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
}
OS << "] (" << Contents.size() << " bytes)";
if (DF->fixup_begin() != DF->fixup_end()) {
OS << ",\n ";
OS << " Fixups:[";
for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
ie = DF->fixup_end(); it != ie; ++it) {
if (it != DF->fixup_begin()) OS << ",\n ";
OS << *it;
}
OS << "]";
}
break;
}
case MCFragment::FT_CompactEncodedInst: {
const MCCompactEncodedInstFragment *CEIF =
cast<MCCompactEncodedInstFragment>(this);
OS << "\n ";
OS << " Contents:[";
const SmallVectorImpl<char> &Contents = CEIF->getContents();
for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
if (i) OS << ",";
OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
}
OS << "] (" << Contents.size() << " bytes)";
break;
}
case MCFragment::FT_Fill: {
const MCFillFragment *FF = cast<MCFillFragment>(this);
OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
<< " Size:" << FF->getSize();
break;
}
case MCFragment::FT_Relaxable: {
const MCRelaxableFragment *F = cast<MCRelaxableFragment>(this);
OS << "\n ";
OS << " Inst:";
F->getInst().dump_pretty(OS);
break;
}
case MCFragment::FT_Org: {
const MCOrgFragment *OF = cast<MCOrgFragment>(this);
OS << "\n ";
OS << " Offset:" << OF->getOffset() << " Value:" << OF->getValue();
break;
}
case MCFragment::FT_Dwarf: {
const MCDwarfLineAddrFragment *OF = cast<MCDwarfLineAddrFragment>(this);
OS << "\n ";
OS << " AddrDelta:" << OF->getAddrDelta()
<< " LineDelta:" << OF->getLineDelta();
break;
}
case MCFragment::FT_DwarfFrame: {
const MCDwarfCallFrameFragment *CF = cast<MCDwarfCallFrameFragment>(this);
OS << "\n ";
OS << " AddrDelta:" << CF->getAddrDelta();
break;
}
case MCFragment::FT_LEB: {
const MCLEBFragment *LF = cast<MCLEBFragment>(this);
OS << "\n ";
OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned();
break;
}
case MCFragment::FT_SafeSEH: {
const MCSafeSEHFragment *F = cast<MCSafeSEHFragment>(this);
OS << "\n ";
OS << " Sym:" << F->getSymbol();
break;
}
case MCFragment::FT_Dummy:
break;
}
OS << ">";
}
void MCAssembler::dump() {
raw_ostream &OS = llvm::errs();
OS << "<MCAssembler\n";
OS << " Sections:[\n ";
for (iterator it = begin(), ie = end(); it != ie; ++it) {
if (it != begin()) OS << ",\n ";
it->dump();
}
OS << "],\n";
OS << " Symbols:[";
for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
if (it != symbol_begin()) OS << ",\n ";
OS << "(";
it->dump();
OS << ", Index:" << it->getIndex() << ", ";
OS << ")";
}
OS << "]>\n";
}
#endif
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