uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
const MCFragment &F) const {
switch (F.getKind()) {
case MCFragment::FT_Data:
case MCFragment::FT_Relaxable:
case MCFragment::FT_CompactEncodedInst:
return cast<MCEncodedFragment>(F).getContents().size();
case MCFragment::FT_Fill:
return cast<MCFillFragment>(F).getSize();
case MCFragment::FT_LEB:
return cast<MCLEBFragment>(F).getContents().size();
case MCFragment::FT_Align: {
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
unsigned Offset = Layout.getFragmentOffset(&AF);
unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
// If we are padding with nops, force the padding to be larger than the
// minimum nop size.
if (Size > 0 && AF.hasEmitNops()) {
while (Size % getBackend().getMinimumNopSize())
Size += AF.getAlignment();
}
if (Size > AF.getMaxBytesToEmit())
return 0;
return Size;
}
case MCFragment::FT_Org: {
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
int64_t TargetLocation;
if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, Layout))
report_fatal_error("expected assembly-time absolute expression");
// FIXME: We need a way to communicate this error.
uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
int64_t Size = TargetLocation - FragmentOffset;
if (Size < 0 || Size >= 0x40000000)
report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
"' (at offset '" + Twine(FragmentOffset) + "')");
return Size;
}
case MCFragment::FT_Dwarf:
return cast<MCDwarfLineAddrFragment>(F).getContents().size();
case MCFragment::FT_DwarfFrame:
return cast<MCDwarfCallFrameFragment>(F).getContents().size();
}
llvm_unreachable("invalid fragment kind");
}
uint64_t MCAssembler::ComputeFragmentSize(MCAsmLayout &Layout,
const MCFragment &F,
uint64_t SectionAddress,
uint64_t FragmentOffset) const {
switch (F.getKind()) {
case MCFragment::FT_Data:
return cast<MCDataFragment>(F).getContents().size();
case MCFragment::FT_Fill:
return cast<MCFillFragment>(F).getSize();
case MCFragment::FT_Inst:
return cast<MCInstFragment>(F).getInstSize();
case MCFragment::FT_Align: {
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
assert((!AF.hasOnlyAlignAddress() || !AF.getNextNode()) &&
"Invalid OnlyAlignAddress bit, not the last fragment!");
uint64_t Size = OffsetToAlignment(SectionAddress + FragmentOffset,
AF.getAlignment());
// Honor MaxBytesToEmit.
if (Size > AF.getMaxBytesToEmit())
return 0;
return Size;
}
case MCFragment::FT_Org: {
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
// FIXME: We should compute this sooner, we don't want to recurse here, and
// we would like to be more functional.
int64_t TargetLocation;
if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, &Layout))
report_fatal_error("expected assembly-time absolute expression");
// FIXME: We need a way to communicate this error.
int64_t Offset = TargetLocation - FragmentOffset;
if (Offset < 0)
report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
"' (at offset '" + Twine(FragmentOffset) + "'");
return Offset;
}
}
assert(0 && "invalid fragment kind");
return 0;
}
void MCCodePadder::handleInstructionBegin(const MCInst &Inst) {
if (!OS)
return; // instruction was emitted outside a function
assert(CurrHandledInstFragment == nullptr && "Can't start handling an "
"instruction while still "
"handling another instruction");
bool InsertionPoint = instructionRequiresInsertionPoint(Inst);
assert((!InsertionPoint ||
OS->getCurrentFragment()->getKind() != MCFragment::FT_Align) &&
"Cannot insert padding nops right after an alignment fragment as it "
"will ruin the alignment");
uint64_t PoliciesMask = MCPaddingFragment::PFK_None;
if (ArePoliciesActive) {
PoliciesMask = std::accumulate(
CodePaddingPolicies.begin(), CodePaddingPolicies.end(),
MCPaddingFragment::PFK_None,
[&Inst](uint64_t Mask, const MCCodePaddingPolicy *Policy) -> uint64_t {
return Policy->instructionRequiresPaddingFragment(Inst)
? (Mask | Policy->getKindMask())
: Mask;
});
}
MCFragment *CurrFragment = OS->getCurrentFragment();
// CurrFragment can be a previously created MCPaddingFragment. If so, let's
// update it with the information we have, such as the instruction that it
// should point to.
bool needToUpdateCurrFragment =
CurrFragment != nullptr &&
CurrFragment->getKind() == MCFragment::FT_Padding;
if (InsertionPoint || PoliciesMask != MCPaddingFragment::PFK_None ||
needToUpdateCurrFragment) {
// temporarily holding the fragment as CurrHandledInstFragment, to be
// updated after the instruction will be written
CurrHandledInstFragment = OS->getOrCreatePaddingFragment();
if (InsertionPoint)
CurrHandledInstFragment->setAsInsertionPoint();
CurrHandledInstFragment->setPaddingPoliciesMask(
CurrHandledInstFragment->getPaddingPoliciesMask() | PoliciesMask);
}
}
/// \brief Write the fragment \p F to the output file.
static void writeFragment(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment &F) {
MCObjectWriter *OW = &Asm.getWriter();
// FIXME: Embed in fragments instead?
uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
Asm.writeFragmentPadding(F, FragmentSize, OW);
// This variable (and its dummy usage) is to participate in the assert at
// the end of the function.
uint64_t Start = OW->getStream().tell();
(void) Start;
++stats::EmittedFragments;
switch (F.getKind()) {
case MCFragment::FT_Align: {
++stats::EmittedAlignFragments;
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
uint64_t Count = FragmentSize / AF.getValueSize();
// FIXME: This error shouldn't actually occur (the front end should emit
// multiple .align directives to enforce the semantics it wants), but is
// severe enough that we want to report it. How to handle this?
if (Count * AF.getValueSize() != FragmentSize)
report_fatal_error("undefined .align directive, value size '" +
Twine(AF.getValueSize()) +
"' is not a divisor of padding size '" +
Twine(FragmentSize) + "'");
// See if we are aligning with nops, and if so do that first to try to fill
// the Count bytes. Then if that did not fill any bytes or there are any
// bytes left to fill use the Value and ValueSize to fill the rest.
// If we are aligning with nops, ask that target to emit the right data.
if (AF.hasEmitNops()) {
if (!Asm.getBackend().writeNopData(Count, OW))
report_fatal_error("unable to write nop sequence of " +
Twine(Count) + " bytes");
break;
}
// Otherwise, write out in multiples of the value size.
for (uint64_t i = 0; i != Count; ++i) {
switch (AF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->write8 (uint8_t (AF.getValue())); break;
case 2: OW->write16(uint16_t(AF.getValue())); break;
case 4: OW->write32(uint32_t(AF.getValue())); break;
case 8: OW->write64(uint64_t(AF.getValue())); break;
}
}
break;
}
case MCFragment::FT_Data:
++stats::EmittedDataFragments;
OW->writeBytes(cast<MCDataFragment>(F).getContents());
break;
case MCFragment::FT_Relaxable:
++stats::EmittedRelaxableFragments;
OW->writeBytes(cast<MCRelaxableFragment>(F).getContents());
break;
case MCFragment::FT_CompactEncodedInst:
++stats::EmittedCompactEncodedInstFragments;
OW->writeBytes(cast<MCCompactEncodedInstFragment>(F).getContents());
break;
case MCFragment::FT_Fill: {
++stats::EmittedFillFragments;
const MCFillFragment &FF = cast<MCFillFragment>(F);
assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
switch (FF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->write8 (uint8_t (FF.getValue())); break;
case 2: OW->write16(uint16_t(FF.getValue())); break;
case 4: OW->write32(uint32_t(FF.getValue())); break;
case 8: OW->write64(uint64_t(FF.getValue())); break;
}
}
break;
}
case MCFragment::FT_LEB: {
const MCLEBFragment &LF = cast<MCLEBFragment>(F);
OW->writeBytes(LF.getContents());
break;
}
case MCFragment::FT_SafeSEH: {
const MCSafeSEHFragment &SF = cast<MCSafeSEHFragment>(F);
OW->write32(SF.getSymbol()->getIndex());
break;
}
case MCFragment::FT_Org: {
++stats::EmittedOrgFragments;
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
OW->write8(uint8_t(OF.getValue()));
break;
}
case MCFragment::FT_Dwarf: {
const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
OW->writeBytes(OF.getContents());
break;
}
case MCFragment::FT_DwarfFrame: {
const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
OW->writeBytes(CF.getContents());
break;
}
case MCFragment::FT_Dummy:
llvm_unreachable("Should not have been added");
}
assert(OW->getStream().tell() - Start == FragmentSize &&
"The stream should advance by fragment size");
}
/// \brief Write the fragment \p F to the output file.
static void writeFragment(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment &F) {
MCObjectWriter *OW = &Asm.getWriter();
// FIXME: Embed in fragments instead?
uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
// Should NOP padding be written out before this fragment?
unsigned BundlePadding = F.getBundlePadding();
if (BundlePadding > 0) {
assert(Asm.isBundlingEnabled() &&
"Writing bundle padding with disabled bundling");
assert(F.hasInstructions() &&
"Writing bundle padding for a fragment without instructions");
unsigned TotalLength = BundlePadding + static_cast<unsigned>(FragmentSize);
if (F.alignToBundleEnd() && TotalLength > Asm.getBundleAlignSize()) {
// If the padding itself crosses a bundle boundary, it must be emitted
// in 2 pieces, since even nop instructions must not cross boundaries.
// v--------------v <- BundleAlignSize
// v---------v <- BundlePadding
// ----------------------------
// | Prev |####|####| F |
// ----------------------------
// ^-------------------^ <- TotalLength
unsigned DistanceToBoundary = TotalLength - Asm.getBundleAlignSize();
if (!Asm.getBackend().writeNopData(DistanceToBoundary, OW))
report_fatal_error("unable to write NOP sequence of " +
Twine(DistanceToBoundary) + " bytes");
BundlePadding -= DistanceToBoundary;
}
if (!Asm.getBackend().writeNopData(BundlePadding, OW))
report_fatal_error("unable to write NOP sequence of " +
Twine(BundlePadding) + " bytes");
}
// This variable (and its dummy usage) is to participate in the assert at
// the end of the function.
uint64_t Start = OW->getStream().tell();
(void) Start;
++stats::EmittedFragments;
switch (F.getKind()) {
case MCFragment::FT_Align: {
++stats::EmittedAlignFragments;
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
uint64_t Count = FragmentSize / AF.getValueSize();
// FIXME: This error shouldn't actually occur (the front end should emit
// multiple .align directives to enforce the semantics it wants), but is
// severe enough that we want to report it. How to handle this?
if (Count * AF.getValueSize() != FragmentSize)
report_fatal_error("undefined .align directive, value size '" +
Twine(AF.getValueSize()) +
"' is not a divisor of padding size '" +
Twine(FragmentSize) + "'");
// See if we are aligning with nops, and if so do that first to try to fill
// the Count bytes. Then if that did not fill any bytes or there are any
// bytes left to fill use the Value and ValueSize to fill the rest.
// If we are aligning with nops, ask that target to emit the right data.
if (AF.hasEmitNops()) {
if (!Asm.getBackend().writeNopData(Count, OW))
report_fatal_error("unable to write nop sequence of " +
Twine(Count) + " bytes");
break;
}
// Otherwise, write out in multiples of the value size.
for (uint64_t i = 0; i != Count; ++i) {
switch (AF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->Write8 (uint8_t (AF.getValue())); break;
case 2: OW->Write16(uint16_t(AF.getValue())); break;
case 4: OW->Write32(uint32_t(AF.getValue())); break;
case 8: OW->Write64(uint64_t(AF.getValue())); break;
}
}
break;
}
case MCFragment::FT_Data:
++stats::EmittedDataFragments;
writeFragmentContents(F, OW);
break;
case MCFragment::FT_Relaxable:
++stats::EmittedRelaxableFragments;
writeFragmentContents(F, OW);
break;
case MCFragment::FT_CompactEncodedInst:
++stats::EmittedCompactEncodedInstFragments;
writeFragmentContents(F, OW);
break;
case MCFragment::FT_Fill: {
++stats::EmittedFillFragments;
const MCFillFragment &FF = cast<MCFillFragment>(F);
assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
switch (FF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->Write8 (uint8_t (FF.getValue())); break;
case 2: OW->Write16(uint16_t(FF.getValue())); break;
case 4: OW->Write32(uint32_t(FF.getValue())); break;
case 8: OW->Write64(uint64_t(FF.getValue())); break;
}
}
break;
}
case MCFragment::FT_LEB: {
const MCLEBFragment &LF = cast<MCLEBFragment>(F);
OW->WriteBytes(LF.getContents().str());
break;
}
case MCFragment::FT_Org: {
++stats::EmittedOrgFragments;
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
OW->Write8(uint8_t(OF.getValue()));
break;
}
case MCFragment::FT_Dwarf: {
const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
OW->WriteBytes(OF.getContents().str());
break;
}
case MCFragment::FT_DwarfFrame: {
const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
OW->WriteBytes(CF.getContents().str());
break;
}
}
assert(OW->getStream().tell() - Start == FragmentSize &&
"The stream should advance by fragment size");
}
/// WriteFragmentData - Write the \p F data to the output file.
static void WriteFragmentData(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment &F) {
MCObjectWriter *OW = &Asm.getWriter();
uint64_t Start = OW->getStream().tell();
(void) Start;
++stats::EmittedFragments;
// FIXME: Embed in fragments instead?
uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
switch (F.getKind()) {
case MCFragment::FT_Align: {
MCAlignFragment &AF = cast<MCAlignFragment>(F);
uint64_t Count = FragmentSize / AF.getValueSize();
assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
// FIXME: This error shouldn't actually occur (the front end should emit
// multiple .align directives to enforce the semantics it wants), but is
// severe enough that we want to report it. How to handle this?
if (Count * AF.getValueSize() != FragmentSize)
report_fatal_error("undefined .align directive, value size '" +
Twine(AF.getValueSize()) +
"' is not a divisor of padding size '" +
Twine(FragmentSize) + "'");
// See if we are aligning with nops, and if so do that first to try to fill
// the Count bytes. Then if that did not fill any bytes or there are any
// bytes left to fill use the Value and ValueSize to fill the rest.
// If we are aligning with nops, ask that target to emit the right data.
if (AF.hasEmitNops()) {
if (!Asm.getBackend().writeNopData(Count, OW))
report_fatal_error("unable to write nop sequence of " +
Twine(Count) + " bytes");
break;
}
// Otherwise, write out in multiples of the value size.
for (uint64_t i = 0; i != Count; ++i) {
switch (AF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->Write8 (uint8_t (AF.getValue())); break;
case 2: OW->Write16(uint16_t(AF.getValue())); break;
case 4: OW->Write32(uint32_t(AF.getValue())); break;
case 8: OW->Write64(uint64_t(AF.getValue())); break;
}
}
break;
}
case MCFragment::FT_Data: {
MCDataFragment &DF = cast<MCDataFragment>(F);
assert(FragmentSize == DF.getContents().size() && "Invalid size!");
OW->WriteBytes(DF.getContents().str());
break;
}
case MCFragment::FT_Fill: {
MCFillFragment &FF = cast<MCFillFragment>(F);
assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
switch (FF.getValueSize()) {
default: llvm_unreachable("Invalid size!");
case 1: OW->Write8 (uint8_t (FF.getValue())); break;
case 2: OW->Write16(uint16_t(FF.getValue())); break;
case 4: OW->Write32(uint32_t(FF.getValue())); break;
case 8: OW->Write64(uint64_t(FF.getValue())); break;
}
}
break;
}
case MCFragment::FT_Inst: {
MCInstFragment &IF = cast<MCInstFragment>(F);
OW->WriteBytes(StringRef(IF.getCode().begin(), IF.getCode().size()));
break;
}
case MCFragment::FT_LEB: {
MCLEBFragment &LF = cast<MCLEBFragment>(F);
OW->WriteBytes(LF.getContents().str());
break;
}
case MCFragment::FT_Org: {
MCOrgFragment &OF = cast<MCOrgFragment>(F);
for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
OW->Write8(uint8_t(OF.getValue()));
break;
}
case MCFragment::FT_Dwarf: {
const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
OW->WriteBytes(OF.getContents().str());
break;
}
case MCFragment::FT_DwarfFrame: {
const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
OW->WriteBytes(CF.getContents().str());
break;
}
}
assert(OW->getStream().tell() - Start == FragmentSize);
}
uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
const MCFragment &F) const {
switch (F.getKind()) {
case MCFragment::FT_Data:
return cast<MCDataFragment>(F).getContents().size();
case MCFragment::FT_Relaxable:
return cast<MCRelaxableFragment>(F).getContents().size();
case MCFragment::FT_CompactEncodedInst:
return cast<MCCompactEncodedInstFragment>(F).getContents().size();
case MCFragment::FT_Fill:
return cast<MCFillFragment>(F).getSize();
case MCFragment::FT_LEB:
return cast<MCLEBFragment>(F).getContents().size();
case MCFragment::FT_SafeSEH:
return 4;
case MCFragment::FT_Align: {
const MCAlignFragment &AF = cast<MCAlignFragment>(F);
unsigned Offset = Layout.getFragmentOffset(&AF);
unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
// If we are padding with nops, force the padding to be larger than the
// minimum nop size.
if (Size > 0 && AF.hasEmitNops()) {
while (Size % getBackend().getMinimumNopSize())
Size += AF.getAlignment();
}
if (Size > AF.getMaxBytesToEmit())
return 0;
return Size;
}
case MCFragment::FT_Org: {
const MCOrgFragment &OF = cast<MCOrgFragment>(F);
MCValue Value;
if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
getContext().reportError(OF.getLoc(),
"expected assembly-time absolute expression");
return 0;
}
uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
int64_t TargetLocation = Value.getConstant();
if (const MCSymbolRefExpr *A = Value.getSymA()) {
uint64_t Val;
if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
getContext().reportError(OF.getLoc(), "expected absolute expression");
return 0;
}
TargetLocation += Val;
}
int64_t Size = TargetLocation - FragmentOffset;
if (Size < 0 || Size >= 0x40000000) {
getContext().reportError(
OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
"' (at offset '" + Twine(FragmentOffset) + "')");
return 0;
}
return Size;
}
case MCFragment::FT_Dwarf:
return cast<MCDwarfLineAddrFragment>(F).getContents().size();
case MCFragment::FT_DwarfFrame:
return cast<MCDwarfCallFrameFragment>(F).getContents().size();
case MCFragment::FT_CVInlineLines:
return cast<MCCVInlineLineTableFragment>(F).getContents().size();
case MCFragment::FT_CVDefRange:
return cast<MCCVDefRangeFragment>(F).getContents().size();
case MCFragment::FT_Dummy:
llvm_unreachable("Should not have been added");
}
llvm_unreachable("invalid fragment kind");
}