void LineNumberAnnotatedWriter::emitInstructionAnnot(
const Instruction *I, formatted_raw_ostream &Out)
{
DILocation *NewInstrLoc = I->getDebugLoc();
if (!NewInstrLoc) {
auto Loc = DebugLoc.find(I);
if (Loc != DebugLoc.end())
NewInstrLoc = Loc->second;
}
if (!NewInstrLoc || NewInstrLoc == InstrLoc)
return;
InstrLoc = NewInstrLoc;
std::vector<DILineInfo> DIvec;
do {
DIvec.emplace_back();
DILineInfo &DI = DIvec.back();
DIScope *scope = NewInstrLoc->getScope();
if (scope)
DI.FunctionName = scope->getName();
DI.FileName = NewInstrLoc->getFilename();
DI.Line = NewInstrLoc->getLine();
NewInstrLoc = NewInstrLoc->getInlinedAt();
} while (NewInstrLoc);
LinePrinter.emit_lineinfo(Out, DIvec);
}
const DILocation *DILocation::getMergedLocation(const DILocation *LocA,
const DILocation *LocB) {
if (!LocA || !LocB)
return nullptr;
if (LocA == LocB)
return LocA;
SmallPtrSet<DILocation *, 5> InlinedLocationsA;
for (DILocation *L = LocA->getInlinedAt(); L; L = L->getInlinedAt())
InlinedLocationsA.insert(L);
SmallSet<std::pair<DIScope *, DILocation *>, 5> Locations;
DIScope *S = LocA->getScope();
DILocation *L = LocA->getInlinedAt();
while (S) {
Locations.insert(std::make_pair(S, L));
S = S->getScope().resolve();
if (!S && L) {
S = L->getScope();
L = L->getInlinedAt();
}
}
const DILocation *Result = LocB;
S = LocB->getScope();
L = LocB->getInlinedAt();
while (S) {
if (Locations.count(std::make_pair(S, L)))
break;
S = S->getScope().resolve();
if (!S && L) {
S = L->getScope();
L = L->getInlinedAt();
}
}
// If the two locations are irreconsilable, just pick one. This is misleading,
// but on the other hand, it's a "line 0" location.
if (!S || !isa<DILocalScope>(S))
S = LocA->getScope();
return DILocation::get(Result->getContext(), 0, 0, S, L);
}
const DILocation *DILocation::getMergedLocation(const DILocation *LocA,
const DILocation *LocB,
bool GenerateLocation) {
if (!LocA || !LocB)
return nullptr;
if (LocA == LocB || !LocA->canDiscriminate(*LocB))
return LocA;
if (!GenerateLocation)
return nullptr;
SmallPtrSet<DILocation *, 5> InlinedLocationsA;
for (DILocation *L = LocA->getInlinedAt(); L; L = L->getInlinedAt())
InlinedLocationsA.insert(L);
const DILocation *Result = LocB;
for (DILocation *L = LocB->getInlinedAt(); L; L = L->getInlinedAt()) {
Result = L;
if (InlinedLocationsA.count(L))
break;
}
return DILocation::get(Result->getContext(), 0, 0, Result->getScope(),
Result->getInlinedAt());
}
/// \brief Assign DWARF discriminators.
///
/// To assign discriminators, we examine the boundaries of every
/// basic block and its successors. Suppose there is a basic block B1
/// with successor B2. The last instruction I1 in B1 and the first
/// instruction I2 in B2 are located at the same file and line number.
/// This situation is illustrated in the following code snippet:
///
/// if (i < 10) x = i;
///
/// entry:
/// br i1 %cmp, label %if.then, label %if.end, !dbg !10
/// if.then:
/// %1 = load i32* %i.addr, align 4, !dbg !10
/// store i32 %1, i32* %x, align 4, !dbg !10
/// br label %if.end, !dbg !10
/// if.end:
/// ret void, !dbg !12
///
/// Notice how the branch instruction in block 'entry' and all the
/// instructions in block 'if.then' have the exact same debug location
/// information (!dbg !10).
///
/// To distinguish instructions in block 'entry' from instructions in
/// block 'if.then', we generate a new lexical block for all the
/// instruction in block 'if.then' that share the same file and line
/// location with the last instruction of block 'entry'.
///
/// This new lexical block will have the same location information as
/// the previous one, but with a new DWARF discriminator value.
///
/// One of the main uses of this discriminator value is in runtime
/// sample profilers. It allows the profiler to distinguish instructions
/// at location !dbg !10 that execute on different basic blocks. This is
/// important because while the predicate 'if (x < 10)' may have been
/// executed millions of times, the assignment 'x = i' may have only
/// executed a handful of times (meaning that the entry->if.then edge is
/// seldom taken).
///
/// If we did not have discriminator information, the profiler would
/// assign the same weight to both blocks 'entry' and 'if.then', which
/// in turn will make it conclude that the entry->if.then edge is very
/// hot.
///
/// To decide where to create new discriminator values, this function
/// traverses the CFG and examines instruction at basic block boundaries.
/// If the last instruction I1 of a block B1 is at the same file and line
/// location as instruction I2 of successor B2, then it creates a new
/// lexical block for I2 and all the instruction in B2 that share the same
/// file and line location as I2. This new lexical block will have a
/// different discriminator number than I1.
bool AddDiscriminators::runOnFunction(Function &F) {
// If the function has debug information, but the user has disabled
// discriminators, do nothing.
// Simlarly, if the function has no debug info, do nothing.
// Finally, if this module is built with dwarf versions earlier than 4,
// do nothing (discriminator support is a DWARF 4 feature).
if (NoDiscriminators || !hasDebugInfo(F) ||
F.getParent()->getDwarfVersion() < 4)
return false;
bool Changed = false;
Module *M = F.getParent();
LLVMContext &Ctx = M->getContext();
DIBuilder Builder(*M, /*AllowUnresolved*/ false);
typedef std::pair<StringRef, unsigned> Location;
typedef DenseMap<const BasicBlock *, Metadata *> BBScopeMap;
typedef DenseMap<Location, BBScopeMap> LocationBBMap;
typedef DenseMap<Location, unsigned> LocationDiscriminatorMap;
LocationBBMap LBM;
LocationDiscriminatorMap LDM;
// Traverse all instructions in the function. If the source line location
// of the instruction appears in other basic block, assign a new
// discriminator for this instruction.
for (BasicBlock &B : F) {
for (auto &I : B.getInstList()) {
if (isa<DbgInfoIntrinsic>(&I))
continue;
const DILocation *DIL = I.getDebugLoc();
if (!DIL)
continue;
Location L = std::make_pair(DIL->getFilename(), DIL->getLine());
auto &BBMap = LBM[L];
auto R = BBMap.insert(std::make_pair(&B, (Metadata *)nullptr));
if (BBMap.size() == 1)
continue;
bool InsertSuccess = R.second;
Metadata *&NewScope = R.first->second;
// If we could insert a different block in the same location, a
// discriminator is needed to distinguish both instructions.
if (InsertSuccess) {
auto *Scope = DIL->getScope();
auto *File =
Builder.createFile(DIL->getFilename(), Scope->getDirectory());
NewScope = Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
}
I.setDebugLoc(DILocation::get(Ctx, DIL->getLine(), DIL->getColumn(),
NewScope, DIL->getInlinedAt()));
DEBUG(dbgs() << DIL->getFilename() << ":" << DIL->getLine() << ":"
<< DIL->getColumn() << ":"
<< dyn_cast<DILexicalBlockFile>(NewScope)->getDiscriminator()
<< I << "\n");
Changed = true;
}
}
// Traverse all instructions and assign new discriminators to call
// instructions with the same lineno that are in the same basic block.
// Sample base profile needs to distinguish different function calls within
// a same source line for correct profile annotation.
for (BasicBlock &B : F) {
const DILocation *FirstDIL = nullptr;
for (auto &I : B.getInstList()) {
CallInst *Current = dyn_cast<CallInst>(&I);
if (!Current || isa<DbgInfoIntrinsic>(&I))
continue;
DILocation *CurrentDIL = Current->getDebugLoc();
if (FirstDIL) {
if (CurrentDIL && CurrentDIL->getLine() == FirstDIL->getLine() &&
CurrentDIL->getFilename() == FirstDIL->getFilename()) {
auto *Scope = FirstDIL->getScope();
auto *File = Builder.createFile(FirstDIL->getFilename(),
Scope->getDirectory());
Location L =
std::make_pair(FirstDIL->getFilename(), FirstDIL->getLine());
auto *NewScope =
Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
Current->setDebugLoc(DILocation::get(
Ctx, CurrentDIL->getLine(), CurrentDIL->getColumn(), NewScope,
CurrentDIL->getInlinedAt()));
Changed = true;
} else {
FirstDIL = CurrentDIL;
}
} else {
FirstDIL = CurrentDIL;
}
}
}
return Changed;
}
/// \brief Assign DWARF discriminators.
///
/// To assign discriminators, we examine the boundaries of every
/// basic block and its successors. Suppose there is a basic block B1
/// with successor B2. The last instruction I1 in B1 and the first
/// instruction I2 in B2 are located at the same file and line number.
/// This situation is illustrated in the following code snippet:
///
/// if (i < 10) x = i;
///
/// entry:
/// br i1 %cmp, label %if.then, label %if.end, !dbg !10
/// if.then:
/// %1 = load i32* %i.addr, align 4, !dbg !10
/// store i32 %1, i32* %x, align 4, !dbg !10
/// br label %if.end, !dbg !10
/// if.end:
/// ret void, !dbg !12
///
/// Notice how the branch instruction in block 'entry' and all the
/// instructions in block 'if.then' have the exact same debug location
/// information (!dbg !10).
///
/// To distinguish instructions in block 'entry' from instructions in
/// block 'if.then', we generate a new lexical block for all the
/// instruction in block 'if.then' that share the same file and line
/// location with the last instruction of block 'entry'.
///
/// This new lexical block will have the same location information as
/// the previous one, but with a new DWARF discriminator value.
///
/// One of the main uses of this discriminator value is in runtime
/// sample profilers. It allows the profiler to distinguish instructions
/// at location !dbg !10 that execute on different basic blocks. This is
/// important because while the predicate 'if (x < 10)' may have been
/// executed millions of times, the assignment 'x = i' may have only
/// executed a handful of times (meaning that the entry->if.then edge is
/// seldom taken).
///
/// If we did not have discriminator information, the profiler would
/// assign the same weight to both blocks 'entry' and 'if.then', which
/// in turn will make it conclude that the entry->if.then edge is very
/// hot.
///
/// To decide where to create new discriminator values, this function
/// traverses the CFG and examines instruction at basic block boundaries.
/// If the last instruction I1 of a block B1 is at the same file and line
/// location as instruction I2 of successor B2, then it creates a new
/// lexical block for I2 and all the instruction in B2 that share the same
/// file and line location as I2. This new lexical block will have a
/// different discriminator number than I1.
bool AddDiscriminators::runOnFunction(Function &F) {
// If the function has debug information, but the user has disabled
// discriminators, do nothing.
// Simlarly, if the function has no debug info, do nothing.
// Finally, if this module is built with dwarf versions earlier than 4,
// do nothing (discriminator support is a DWARF 4 feature).
if (NoDiscriminators ||
!hasDebugInfo(F) ||
F.getParent()->getDwarfVersion() < 4)
return false;
bool Changed = false;
Module *M = F.getParent();
LLVMContext &Ctx = M->getContext();
DIBuilder Builder(*M, /*AllowUnresolved*/ false);
// Traverse all the blocks looking for instructions in different
// blocks that are at the same file:line location.
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
BasicBlock *B = I;
TerminatorInst *Last = B->getTerminator();
DILocation LastDIL = Last->getDebugLoc().get();
if (!LastDIL)
continue;
for (unsigned I = 0; I < Last->getNumSuccessors(); ++I) {
BasicBlock *Succ = Last->getSuccessor(I);
Instruction *First = Succ->getFirstNonPHIOrDbgOrLifetime();
DILocation FirstDIL = First->getDebugLoc().get();
if (!FirstDIL)
continue;
// If the first instruction (First) of Succ is at the same file
// location as B's last instruction (Last), add a new
// discriminator for First's location and all the instructions
// in Succ that share the same location with First.
if (!FirstDIL->canDiscriminate(*LastDIL)) {
// Create a new lexical scope and compute a new discriminator
// number for it.
StringRef Filename = FirstDIL->getFilename();
auto *Scope = FirstDIL->getScope();
auto *File = Builder.createFile(Filename, Scope->getDirectory());
// FIXME: Calculate the discriminator here, based on local information,
// and delete MDLocation::computeNewDiscriminator(). The current
// solution gives different results depending on other modules in the
// same context. All we really need is to discriminate between
// FirstDIL and LastDIL -- a local map would suffice.
unsigned Discriminator = FirstDIL->computeNewDiscriminator();
auto *NewScope =
Builder.createLexicalBlockFile(Scope, File, Discriminator);
auto *NewDIL =
MDLocation::get(Ctx, FirstDIL->getLine(), FirstDIL->getColumn(),
NewScope, FirstDIL->getInlinedAt());
DebugLoc newDebugLoc = NewDIL;
// Attach this new debug location to First and every
// instruction following First that shares the same location.
for (BasicBlock::iterator I1(*First), E1 = Succ->end(); I1 != E1;
++I1) {
if (I1->getDebugLoc().get() != FirstDIL)
break;
I1->setDebugLoc(newDebugLoc);
DEBUG(dbgs() << NewDIL->getFilename() << ":" << NewDIL->getLine()
<< ":" << NewDIL->getColumn() << ":"
<< NewDIL->getDiscriminator() << *I1 << "\n");
}
DEBUG(dbgs() << "\n");
Changed = true;
}
}
}
return Changed;
}
