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AsmPrinter: Rewrite initialization of DbgVariable, NFC

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There are three types of `DbgVariable`:
  - alloca variables, created based on the MMI table,
  - register variables, created based on DBG_VALUE instructions, and
  - optimized-out variables.

This commit reconfigures `DbgVariable` to make it easier to tell which
kind we have, and make initialization a little clearer.

For MMI/alloca variables, `FrameIndex.size()` must always equal
`Expr.size()`, and there shouldn't be an `MInsn`.  For register
variables (with a `MInsn`), `FrameIndex` must be empty, and `Expr`
should have 0 or 1 element depending on whether it has a complex
expression (registers with multiple locations use `DebugLocListIndex`).
Optimized-out variables shouldn't have any of these fields.

Moreover, this separates DBG_VALUE initialization until after the
variable is created, simplifying logic in a future commit that changes
`collectVariableInfo()` to stop creating empty .debug_loc entries/lists.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240243 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith 2015-06-21 16:50:43 +00:00
parent 87f860c737
commit 01a8dc8ca6
3 changed files with 85 additions and 64 deletions
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6
lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
View File

@ -508,7 +508,7 @@ DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
}
// .. else use frame index.
if (DV.getFrameIndex().back() == ~0)
if (DV.getFrameIndex().empty())
return VariableDie;
auto Expr = DV.getExpression().begin();
@ -686,7 +686,7 @@ void DwarfCompileUnit::collectDeadVariables(const DISubprogram *SP) {
SPDIE = getDIE(SP);
assert(SPDIE);
for (const DILocalVariable *DV : Variables) {
DbgVariable NewVar(DV, /* IA */ nullptr, /* Expr */ nullptr, DD);
DbgVariable NewVar(DV, /* IA */ nullptr, DD);
auto VariableDie = constructVariableDIE(NewVar);
applyVariableAttributes(NewVar, *VariableDie);
SPDIE->addChild(std::move(VariableDie));
@ -725,7 +725,7 @@ void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
/// DbgVariable based on provided MachineLocation.
void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
MachineLocation Location) {
if (DV.variableHasComplexAddress())
if (DV.hasComplexAddress())
addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
else if (DV.isBlockByrefVariable())
addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);

35
lib/CodeGen/AsmPrinter/DwarfDebug.cpp
View File

@ -678,8 +678,7 @@ DbgVariable *DwarfDebug::getExistingAbstractVariable(InlinedVariable IV) {
void DwarfDebug::createAbstractVariable(const DILocalVariable *Var,
LexicalScope *Scope) {
auto AbsDbgVariable =
make_unique<DbgVariable>(Var, /* IA */ nullptr, /* Expr */ nullptr, this);
auto AbsDbgVariable = make_unique<DbgVariable>(Var, /* IA */ nullptr, this);
InfoHolder.addScopeVariable(Scope, AbsDbgVariable.get());
AbstractVariables[Var] = std::move(AbsDbgVariable);
}
@ -722,10 +721,9 @@ void DwarfDebug::collectVariableInfoFromMMITable(
if (!Scope)
continue;
const DIExpression *Expr = cast_or_null<DIExpression>(VI.Expr);
ensureAbstractVariableIsCreatedIfScoped(Var, Scope->getScopeNode());
auto RegVar =
make_unique<DbgVariable>(Var.first, Var.second, Expr, this, VI.Slot);
auto RegVar = make_unique<DbgVariable>(Var.first, Var.second, this);
RegVar->initializeMMI(VI.Expr, VI.Slot);
if (InfoHolder.addScopeVariable(Scope, RegVar.get()))
ConcreteVariables.push_back(std::move(RegVar));
}
@ -870,6 +868,14 @@ DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
}
}
DbgVariable *DwarfDebug::createConcreteVariable(LexicalScope &Scope,
InlinedVariable IV) {
ensureAbstractVariableIsCreatedIfScoped(IV, Scope.getScopeNode());
ConcreteVariables.push_back(
make_unique<DbgVariable>(IV.first, IV.second, this));
InfoHolder.addScopeVariable(&Scope, ConcreteVariables.back().get());
return ConcreteVariables.back().get();
}
// Find variables for each lexical scope.
void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
@ -898,12 +904,11 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
continue;
Processed.insert(IV);
DbgVariable *RegVar = createConcreteVariable(*Scope, IV);
const MachineInstr *MInsn = Ranges.front().first;
assert(MInsn->isDebugValue() && "History must begin with debug value");
ensureAbstractVariableIsCreatedIfScoped(IV, Scope->getScopeNode());
ConcreteVariables.push_back(make_unique<DbgVariable>(MInsn, this));
DbgVariable *RegVar = ConcreteVariables.back().get();
InfoHolder.addScopeVariable(Scope, RegVar);
RegVar->initializeDbgValue(MInsn);
// Check if the first DBG_VALUE is valid for the rest of the function.
if (Ranges.size() == 1 && Ranges.front().second == nullptr)
@ -930,15 +935,9 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
// Collect info for variables that were optimized out.
for (const DILocalVariable *DV : SP->getVariables()) {
if (!Processed.insert(InlinedVariable(DV, nullptr)).second)
continue;
if (LexicalScope *Scope = LScopes.findLexicalScope(DV->getScope())) {
ensureAbstractVariableIsCreatedIfScoped(InlinedVariable(DV, nullptr),
Scope->getScopeNode());
ConcreteVariables.push_back(make_unique<DbgVariable>(
DV, /* IA */ nullptr, /* Expr */ nullptr, this));
InfoHolder.addScopeVariable(Scope, ConcreteVariables.back().get());
}
if (Processed.insert(InlinedVariable(DV, nullptr)).second)
if (LexicalScope *Scope = LScopes.findLexicalScope(DV->getScope()))
createConcreteVariable(*Scope, InlinedVariable(DV, nullptr));
}
}

108
lib/CodeGen/AsmPrinter/DwarfDebug.h
View File

@ -67,42 +67,61 @@ public:
};
//===----------------------------------------------------------------------===//
/// \brief This class is used to track local variable information.
/// This class is used to track local variable information.
///
/// - Variables whose location changes over time have a DebugLocListIndex and
/// the other fields are not used.
/// Variables can be created from allocas, in which case they're generated from
/// the MMI table. Such variables can have multiple expressions and frame
/// indices. The \a Expr and \a FrameIndices array must match.
///
/// - Variables that are described by multiple MMI table entries have multiple
/// expressions and frame indices.
/// Variables can be created from \c DBG_VALUE instructions. Those whose
/// location changes over time use \a DebugLocListIndex, while those with a
/// single instruction use \a MInsn and (optionally) a single entry of \a Expr.
///
/// Variables that have been optimized out use none of these fields.
class DbgVariable {
const DILocalVariable *Var; /// Variable Descriptor.
const DILocation *IA; /// Inlined at location.
SmallVector<const DIExpression *, 1>
Expr; /// Complex address location expression.
DIE *TheDIE; /// Variable DIE.
unsigned DebugLocListIndex; /// Offset in DebugLocs.
const MachineInstr *MInsn; /// DBG_VALUE instruction of the variable.
SmallVector<int, 1> FrameIndex; /// Frame index of the variable.
const DILocalVariable *Var; /// Variable Descriptor.
const DILocation *IA; /// Inlined at location.
SmallVector<const DIExpression *, 1> Expr; /// Complex address.
DIE *TheDIE = nullptr; /// Variable DIE.
unsigned DebugLocListIndex = ~0u; /// Offset in DebugLocs.
const MachineInstr *MInsn = nullptr; /// DBG_VALUE instruction.
SmallVector<int, 1> FrameIndex; /// Frame index.
DwarfDebug *DD;
public:
/// Construct a DbgVariable from a variable.
DbgVariable(const DILocalVariable *V, const DILocation *IA,
const DIExpression *E, DwarfDebug *DD, int FI = ~0)
: Var(V), IA(IA), Expr(1, E), TheDIE(nullptr), DebugLocListIndex(~0U),
MInsn(nullptr), DD(DD) {
/// Construct a DbgVariable.
///
/// Creates a variable without any DW_AT_location. Call \a initializeMMI()
/// for MMI entries, or \a initializeDbgValue() for DBG_VALUE instructions.
DbgVariable(const DILocalVariable *V, const DILocation *IA, DwarfDebug *DD)
: Var(V), IA(IA), DD(DD) {}
/// Initialize from the MMI table.
void initializeMMI(const DIExpression *E, int FI) {
assert(Expr.empty() && "Already initialized?");
assert(FrameIndex.empty() && "Already initialized?");
assert(!MInsn && "Already initialized?");
assert((!E || E->isValid()) && "Expected valid expression");
assert(~FI && "Expected valid index");
Expr.push_back(E);
FrameIndex.push_back(FI);
assert(!E || E->isValid());
}
/// Construct a DbgVariable from a DEBUG_VALUE.
/// AbstractVar may be NULL.
DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
: Var(DbgValue->getDebugVariable()),
IA(DbgValue->getDebugLoc()->getInlinedAt()),
Expr(1, DbgValue->getDebugExpression()), TheDIE(nullptr),
DebugLocListIndex(~0U), MInsn(DbgValue), DD(DD) {
FrameIndex.push_back(~0);
/// Initialize from a DBG_VALUE instruction.
void initializeDbgValue(const MachineInstr *DbgValue) {
assert(Expr.empty() && "Already initialized?");
assert(FrameIndex.empty() && "Already initialized?");
assert(!MInsn && "Already initialized?");
assert(Var == DbgValue->getDebugVariable() && "Wrong variable");
assert(IA == DbgValue->getDebugLoc()->getInlinedAt() && "Wrong inlined-at");
MInsn = DbgValue;
if (auto *E = DbgValue->getDebugExpression())
if (E->getNumElements())
Expr.push_back(E);
}
// Accessors.
@ -123,17 +142,16 @@ public:
assert(V.Var == Var && "conflicting variable");
assert(V.IA == IA && "conflicting inlined-at location");
if (V.getFrameIndex().back() != ~0) {
auto E = V.getExpression();
auto FI = V.getFrameIndex();
Expr.append(E.begin(), E.end());
FrameIndex.append(FI.begin(), FI.end());
}
assert(Expr.size() > 1 ? std::all_of(Expr.begin(), Expr.end(),
[](const DIExpression *E) {
return E->isBitPiece();
})
: (true && "conflicting locations for variable"));
assert(!FrameIndex.empty() && "Expected an MMI entry");
assert(!V.FrameIndex.empty() && "Expected an MMI entry");
assert(Expr.size() == FrameIndex.size() && "Mismatched expressions");
assert(V.Expr.size() == V.FrameIndex.size() && "Mismatched expressions");
Expr.append(V.Expr.begin(), V.Expr.end());
FrameIndex.append(V.FrameIndex.begin(), V.FrameIndex.end());
assert(std::all_of(Expr.begin(), Expr.end(), [](const DIExpression *E) {
return E && E->isBitPiece();
}) && "conflicting locations for variable");
}
// Translate tag to proper Dwarf tag.
@ -160,11 +178,13 @@ public:
return false;
}
bool variableHasComplexAddress() const {
assert(Var && "Invalid complex DbgVariable!");
assert(Expr.size() == 1 &&
"variableHasComplexAddress() invoked on multi-FI variable");
return Expr.back()->getNumElements() > 0;
bool hasComplexAddress() const {
assert(MInsn && "Expected DBG_VALUE, not MMI variable");
assert(FrameIndex.empty() && "Expected DBG_VALUE, not MMI variable");
assert(
(Expr.empty() || (Expr.size() == 1 && Expr.back()->getNumElements())) &&
"Invalid Expr for DBG_VALUE");
return !Expr.empty();
}
bool isBlockByrefVariable() const;
const DIType *getType() const;
@ -344,6 +364,8 @@ class DwarfDebug : public AsmPrinterHandler {
void ensureAbstractVariableIsCreatedIfScoped(InlinedVariable Var,
const MDNode *Scope);
DbgVariable *createConcreteVariable(LexicalScope &Scope, InlinedVariable IV);
/// \brief Construct a DIE for this abstract scope.
void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);