static bool NoInterveningSideEffect(const MachineInstr *CopyMI,
const MachineInstr *MI) {
const MachineBasicBlock *MBB = CopyMI->getParent();
if (MI->getParent() != MBB)
return false;
MachineBasicBlock::const_iterator I = CopyMI;
MachineBasicBlock::const_iterator E = MBB->end();
MachineBasicBlock::const_iterator E2 = MI;
++I;
while (I != E && I != E2) {
if (I->hasUnmodeledSideEffects() || I->isCall() ||
I->isTerminator())
return false;
++I;
}
return true;
}
/// ComputeCallSiteTable - Compute the call-site table. The entry for an invoke
/// has a try-range containing the call, a non-zero landing pad, and an
/// appropriate action. The entry for an ordinary call has a try-range
/// containing the call and zero for the landing pad and the action. Calls
/// marked 'nounwind' have no entry and must not be contained in the try-range
/// of any entry - they form gaps in the table. Entries must be ordered by
/// try-range address.
void DwarfException::
ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
const RangeMapType &PadMap,
const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
const SmallVectorImpl<unsigned> &FirstActions) {
// The end label of the previous invoke or nounwind try-range.
MCSymbol *LastLabel = 0;
// Whether there is a potentially throwing instruction (currently this means
// an ordinary call) between the end of the previous try-range and now.
bool SawPotentiallyThrowing = false;
// Whether the last CallSite entry was for an invoke.
bool PreviousIsInvoke = false;
// Visit all instructions in order of address.
for (MachineFunction::const_iterator I = Asm->MF->begin(), E = Asm->MF->end();
I != E; ++I) {
for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
MI != E; ++MI) {
if (!MI->isLabel()) {
if (MI->isCall())
SawPotentiallyThrowing |= !CallToNoUnwindFunction(MI);
continue;
}
// End of the previous try-range?
MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
if (BeginLabel == LastLabel)
SawPotentiallyThrowing = false;
// Beginning of a new try-range?
RangeMapType::const_iterator L = PadMap.find(BeginLabel);
if (L == PadMap.end())
// Nope, it was just some random label.
continue;
const PadRange &P = L->second;
const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
"Inconsistent landing pad map!");
// For Dwarf exception handling (SjLj handling doesn't use this). If some
// instruction between the previous try-range and this one may throw,
// create a call-site entry with no landing pad for the region between the
// try-ranges.
if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
CallSiteEntry Site = { LastLabel, BeginLabel, 0, 0 };
CallSites.push_back(Site);
PreviousIsInvoke = false;
}
LastLabel = LandingPad->EndLabels[P.RangeIndex];
assert(BeginLabel && LastLabel && "Invalid landing pad!");
if (!LandingPad->LandingPadLabel) {
// Create a gap.
PreviousIsInvoke = false;
} else {
// This try-range is for an invoke.
CallSiteEntry Site = {
BeginLabel,
LastLabel,
LandingPad->LandingPadLabel,
FirstActions[P.PadIndex]
};
// Try to merge with the previous call-site. SJLJ doesn't do this
if (PreviousIsInvoke && Asm->MAI->isExceptionHandlingDwarf()) {
CallSiteEntry &Prev = CallSites.back();
if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
// Extend the range of the previous entry.
Prev.EndLabel = Site.EndLabel;
continue;
}
}
// Otherwise, create a new call-site.
if (Asm->MAI->isExceptionHandlingDwarf())
CallSites.push_back(Site);
else {
// SjLj EH must maintain the call sites in the order assigned
// to them by the SjLjPrepare pass.
unsigned SiteNo = MMI->getCallSiteBeginLabel(BeginLabel);
if (CallSites.size() < SiteNo)
CallSites.resize(SiteNo);
CallSites[SiteNo - 1] = Site;
}
PreviousIsInvoke = true;
}
}
}
// If some instruction between the previous try-range and the end of the
// function may throw, create a call-site entry with no landing pad for the
// region following the try-range.
if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
CallSiteEntry Site = { LastLabel, 0, 0, 0 };
CallSites.push_back(Site);
}
}
unsigned char* JITDwarfEmitter::EmitExceptionTable(MachineFunction* MF,
unsigned char* StartFunction,
unsigned char* EndFunction) const {
assert(MMI && "MachineModuleInfo not registered!");
// Map all labels and get rid of any dead landing pads.
MMI->TidyLandingPads(JCE->getLabelLocations());
const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
if (PadInfos.empty()) return 0;
// Sort the landing pads in order of their type ids. This is used to fold
// duplicate actions.
SmallVector<const LandingPadInfo *, 64> LandingPads;
LandingPads.reserve(PadInfos.size());
for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
LandingPads.push_back(&PadInfos[i]);
std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
// Negative type ids index into FilterIds, positive type ids index into
// TypeInfos. The value written for a positive type id is just the type
// id itself. For a negative type id, however, the value written is the
// (negative) byte offset of the corresponding FilterIds entry. The byte
// offset is usually equal to the type id, because the FilterIds entries
// are written using a variable width encoding which outputs one byte per
// entry as long as the value written is not too large, but can differ.
// This kind of complication does not occur for positive type ids because
// type infos are output using a fixed width encoding.
// FilterOffsets[i] holds the byte offset corresponding to FilterIds[i].
SmallVector<int, 16> FilterOffsets;
FilterOffsets.reserve(FilterIds.size());
int Offset = -1;
for(std::vector<unsigned>::const_iterator I = FilterIds.begin(),
E = FilterIds.end(); I != E; ++I) {
FilterOffsets.push_back(Offset);
Offset -= MCAsmInfo::getULEB128Size(*I);
}
// Compute the actions table and gather the first action index for each
// landing pad site.
SmallVector<ActionEntry, 32> Actions;
SmallVector<unsigned, 64> FirstActions;
FirstActions.reserve(LandingPads.size());
int FirstAction = 0;
unsigned SizeActions = 0;
for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
const LandingPadInfo *LP = LandingPads[i];
const std::vector<int> &TypeIds = LP->TypeIds;
const unsigned NumShared = i ? SharedTypeIds(LP, LandingPads[i-1]) : 0;
unsigned SizeSiteActions = 0;
if (NumShared < TypeIds.size()) {
unsigned SizeAction = 0;
ActionEntry *PrevAction = 0;
if (NumShared) {
const unsigned SizePrevIds = LandingPads[i-1]->TypeIds.size();
assert(Actions.size());
PrevAction = &Actions.back();
SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
for (unsigned j = NumShared; j != SizePrevIds; ++j) {
SizeAction -= MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
SizeAction += -PrevAction->NextAction;
PrevAction = PrevAction->Previous;
}
}
// Compute the actions.
for (unsigned I = NumShared, M = TypeIds.size(); I != M; ++I) {
int TypeID = TypeIds[I];
assert(-1-TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
SizeSiteActions += SizeAction;
ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
Actions.push_back(Action);
PrevAction = &Actions.back();
}
// Record the first action of the landing pad site.
FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
} // else identical - re-use previous FirstAction
FirstActions.push_back(FirstAction);
// Compute this sites contribution to size.
SizeActions += SizeSiteActions;
}
// Compute the call-site table. Entries must be ordered by address.
SmallVector<CallSiteEntry, 64> CallSites;
RangeMapType PadMap;
for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
const LandingPadInfo *LandingPad = LandingPads[i];
for (unsigned j=0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
PadRange P = { i, j };
PadMap[BeginLabel] = P;
}
}
bool MayThrow = false;
MCSymbol *LastLabel = 0;
for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
I != E; ++I) {
for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
MI != E; ++MI) {
if (!MI->isLabel()) {
MayThrow |= MI->isCall();
continue;
}
MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
assert(BeginLabel && "Invalid label!");
if (BeginLabel == LastLabel)
MayThrow = false;
RangeMapType::iterator L = PadMap.find(BeginLabel);
if (L == PadMap.end())
continue;
PadRange P = L->second;
const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
"Inconsistent landing pad map!");
// If some instruction between the previous try-range and this one may
// throw, create a call-site entry with no landing pad for the region
// between the try-ranges.
if (MayThrow) {
CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
CallSites.push_back(Site);
}
LastLabel = LandingPad->EndLabels[P.RangeIndex];
CallSiteEntry Site = {BeginLabel, LastLabel,
LandingPad->LandingPadLabel, FirstActions[P.PadIndex]};
assert(Site.BeginLabel && Site.EndLabel && Site.PadLabel &&
"Invalid landing pad!");
// Try to merge with the previous call-site.
if (CallSites.size()) {
CallSiteEntry &Prev = CallSites.back();
if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
// Extend the range of the previous entry.
Prev.EndLabel = Site.EndLabel;
continue;
}
}
// Otherwise, create a new call-site.
CallSites.push_back(Site);
}
}
// If some instruction between the previous try-range and the end of the
// function may throw, create a call-site entry with no landing pad for the
// region following the try-range.
if (MayThrow) {
CallSiteEntry Site = {LastLabel, 0, 0, 0};
CallSites.push_back(Site);
}
// Final tallies.
unsigned SizeSites = CallSites.size() * (sizeof(int32_t) + // Site start.
sizeof(int32_t) + // Site length.
sizeof(int32_t)); // Landing pad.
for (unsigned i = 0, e = CallSites.size(); i < e; ++i)
SizeSites += MCAsmInfo::getULEB128Size(CallSites[i].Action);
unsigned SizeTypes = TypeInfos.size() * TD->getPointerSize();
unsigned TypeOffset = sizeof(int8_t) + // Call site format
// Call-site table length
MCAsmInfo::getULEB128Size(SizeSites) +
SizeSites + SizeActions + SizeTypes;
// Begin the exception table.
JCE->emitAlignmentWithFill(4, 0);
// Asm->EOL("Padding");
unsigned char* DwarfExceptionTable = (unsigned char*)JCE->getCurrentPCValue();
// Emit the header.
JCE->emitByte(dwarf::DW_EH_PE_omit);
// Asm->EOL("LPStart format (DW_EH_PE_omit)");
JCE->emitByte(dwarf::DW_EH_PE_absptr);
// Asm->EOL("TType format (DW_EH_PE_absptr)");
JCE->emitULEB128Bytes(TypeOffset);
// Asm->EOL("TType base offset");
JCE->emitByte(dwarf::DW_EH_PE_udata4);
// Asm->EOL("Call site format (DW_EH_PE_udata4)");
JCE->emitULEB128Bytes(SizeSites);
// Asm->EOL("Call-site table length");
// Emit the landing pad site information.
for (unsigned i = 0; i < CallSites.size(); ++i) {
CallSiteEntry &S = CallSites[i];
intptr_t BeginLabelPtr = 0;
intptr_t EndLabelPtr = 0;
if (!S.BeginLabel) {
BeginLabelPtr = (intptr_t)StartFunction;
JCE->emitInt32(0);
} else {
BeginLabelPtr = JCE->getLabelAddress(S.BeginLabel);
JCE->emitInt32(BeginLabelPtr - (intptr_t)StartFunction);
}
// Asm->EOL("Region start");
if (!S.EndLabel)
EndLabelPtr = (intptr_t)EndFunction;
else
EndLabelPtr = JCE->getLabelAddress(S.EndLabel);
JCE->emitInt32(EndLabelPtr - BeginLabelPtr);
//Asm->EOL("Region length");
if (!S.PadLabel) {
JCE->emitInt32(0);
} else {
unsigned PadLabelPtr = JCE->getLabelAddress(S.PadLabel);
JCE->emitInt32(PadLabelPtr - (intptr_t)StartFunction);
}
// Asm->EOL("Landing pad");
JCE->emitULEB128Bytes(S.Action);
// Asm->EOL("Action");
}
// Emit the actions.
for (unsigned I = 0, N = Actions.size(); I != N; ++I) {
ActionEntry &Action = Actions[I];
JCE->emitSLEB128Bytes(Action.ValueForTypeID);
//Asm->EOL("TypeInfo index");
JCE->emitSLEB128Bytes(Action.NextAction);
//Asm->EOL("Next action");
}
// Emit the type ids.
for (unsigned M = TypeInfos.size(); M; --M) {
const GlobalVariable *GV = TypeInfos[M - 1];
if (GV) {
if (TD->getPointerSize() == sizeof(int32_t))
JCE->emitInt32((intptr_t)Jit.getOrEmitGlobalVariable(GV));
else
JCE->emitInt64((intptr_t)Jit.getOrEmitGlobalVariable(GV));
} else {
if (TD->getPointerSize() == sizeof(int32_t))
JCE->emitInt32(0);
else
JCE->emitInt64(0);
}
// Asm->EOL("TypeInfo");
}
// Emit the filter typeids.
for (unsigned j = 0, M = FilterIds.size(); j < M; ++j) {
unsigned TypeID = FilterIds[j];
JCE->emitULEB128Bytes(TypeID);
//Asm->EOL("Filter TypeInfo index");
}
JCE->emitAlignmentWithFill(4, 0);
return DwarfExceptionTable;
}