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Change representation of instruction ranges where variable is accessible.

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Use more straightforward way to represent the set of instruction
ranges where the location of a user variable is defined - vector of pairs
of instructions (defining start/end of each range),
instead of a flattened vector of instructions where some instructions
are supposed to start the range, and the rest are supposed to "clobber" it.

Simplify the code which generates actual .debug_loc entries.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209698 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexey Samsonov
2014-05-27 23:09:50 +00:00
parent f9e42bc162
commit a807d6783a
3 changed files with 109 additions and 98 deletions
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76
lib/CodeGen/AsmPrinter/DwarfDebug.cpp
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@ -1153,12 +1153,10 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
if (Processed.count(DV))
continue;
// History contains relevant DBG_VALUE instructions for DV and instructions
// clobbering it.
const SmallVectorImpl<const MachineInstr *> &History = I.second;
if (History.empty())
// Instruction ranges, specifying where DV is accessible.
const auto &Ranges = I.second;
if (Ranges.empty())
continue;
const MachineInstr *MInsn = History.front();
LexicalScope *Scope = nullptr;
if (DV.getTag() == dwarf::DW_TAG_arg_variable &&
@ -1175,6 +1173,7 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
continue;
Processed.insert(DV);
const MachineInstr *MInsn = Ranges.front().first;
assert(MInsn->isDebugValue() && "History must begin with debug value");
DbgVariable *AbsVar = findAbstractVariable(DV, MInsn->getDebugLoc());
DbgVariable *RegVar = new DbgVariable(DV, AbsVar, this);
@ -1183,9 +1182,8 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
if (AbsVar)
AbsVar->setMInsn(MInsn);
// Simplify ranges that are fully coalesced.
if (History.size() <= 1 ||
(History.size() == 2 && MInsn->isIdenticalTo(History.back()))) {
// Check if the first DBG_VALUE is valid for the rest of the function.
if (Ranges.size() == 1 && Ranges.front().second == nullptr) {
RegVar->setMInsn(MInsn);
continue;
}
@ -1198,42 +1196,31 @@ DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
LocList.Label =
Asm->GetTempSymbol("debug_loc", DotDebugLocEntries.size() - 1);
SmallVector<DebugLocEntry, 4> &DebugLoc = LocList.List;
for (SmallVectorImpl<const MachineInstr *>::const_iterator
HI = History.begin(),
HE = History.end();
HI != HE; ++HI) {
const MachineInstr *Begin = *HI;
for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
const MachineInstr *Begin = I->first;
const MachineInstr *End = I->second;
assert(Begin->isDebugValue() && "Invalid History entry");
// Check if DBG_VALUE is truncating a range.
// Check if a variable is unaccessible in this range.
if (Begin->getNumOperands() > 1 && Begin->getOperand(0).isReg() &&
!Begin->getOperand(0).getReg())
continue;
// Compute the range for a register location.
const MCSymbol *FLabel = getLabelBeforeInsn(Begin);
const MCSymbol *SLabel = nullptr;
const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
if (HI + 1 == HE)
// If Begin is the last instruction in History then its value is valid
// until the end of the function.
SLabel = FunctionEndSym;
else {
const MachineInstr *End = HI[1];
DEBUG(dbgs() << "DotDebugLoc Pair:\n"
<< "\t" << *Begin << "\t" << *End << "\n");
if (End->isDebugValue() && End->getDebugVariable() == DV)
SLabel = getLabelBeforeInsn(End);
else {
// End is clobbering the range.
SLabel = getLabelAfterInsn(End);
assert(SLabel && "Forgot label after clobber instruction");
++HI;
}
}
const MCSymbol *EndLabel;
if (End != nullptr)
EndLabel = getLabelAfterInsn(End);
else if (std::next(I) == Ranges.end())
EndLabel = FunctionEndSym;
else
EndLabel = getLabelBeforeInsn(std::next(I)->first);
assert(EndLabel && "Forgot label after instruction ending a range!");
// The value is valid until the next DBG_VALUE or clobber.
DebugLocEntry Loc(FLabel, SLabel, getDebugLocValue(Begin), TheCU);
DEBUG(dbgs() << "DotDebugLoc Pair:\n"
<< "\t" << *Begin << "\t" << *End << "\n");
DebugLocEntry Loc(StartLabel, EndLabel, getDebugLocValue(Begin), TheCU);
if (DebugLoc.empty() || !DebugLoc.back().Merge(Loc))
DebugLoc.push_back(std::move(Loc));
}
@ -1416,9 +1403,9 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
calculateDbgValueHistory(MF, Asm->TM.getRegisterInfo(), DbgValues);
// Request labels for the full history.
for (auto &I : DbgValues) {
const SmallVectorImpl<const MachineInstr *> &History = I.second;
if (History.empty())
for (const auto &I : DbgValues) {
const auto &Ranges = I.second;
if (Ranges.empty())
continue;
// The first mention of a function argument gets the FunctionBeginSym
@ -1426,13 +1413,12 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
DIVariable DV(I.first);
if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
getDISubprogram(DV.getContext()).describes(MF->getFunction()))
LabelsBeforeInsn[History.front()] = FunctionBeginSym;
LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
for (const MachineInstr *MI : History) {
if (MI->isDebugValue() && MI->getDebugVariable() == DV)
requestLabelBeforeInsn(MI);
else
requestLabelAfterInsn(MI);
for (const auto &Range : Ranges) {
requestLabelBeforeInsn(Range.first);
if (Range.second)
requestLabelAfterInsn(Range.second);
}
}