[llvm] r209698 - Change representation of instruction ranges where variable is accessible.
Alexey Samsonov
vonosmas at gmail.com
Tue May 27 16:09:50 PDT 2014
Author: samsonov
Date: Tue May 27 18:09:50 2014
New Revision: 209698
URL: http://llvm.org/viewvc/llvm-project?rev=209698&view=rev
Log:
Change representation of instruction ranges where variable is accessible.
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.
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp?rev=209698&r1=209697&r2=209698&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp Tue May 27 18:09:50 2014
@@ -20,11 +20,6 @@
namespace llvm {
-namespace {
-// Maps physreg numbers to the variables they describe.
-typedef std::map<unsigned, SmallVector<const MDNode *, 1>> RegDescribedVarsMap;
-}
-
// \brief If @MI is a DBG_VALUE with debug value described by a
// defined register, returns the number of this register.
// In the other case, returns 0.
@@ -36,6 +31,47 @@ static unsigned isDescribedByReg(const M
return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
}
+void DbgValueHistoryMap::startInstrRange(const MDNode *Var,
+ const MachineInstr &MI) {
+ // Instruction range should start with a DBG_VALUE instruction for the
+ // variable.
+ assert(MI.isDebugValue() && MI.getDebugVariable() == Var);
+ auto &Ranges = VarInstrRanges[Var];
+ if (!Ranges.empty() && Ranges.back().second == nullptr &&
+ Ranges.back().first->isIdenticalTo(&MI)) {
+ DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
+ << "\t" << Ranges.back().first << "\t" << MI << "\n");
+ return;
+ }
+ Ranges.push_back(std::make_pair(&MI, nullptr));
+}
+
+void DbgValueHistoryMap::endInstrRange(const MDNode *Var,
+ const MachineInstr &MI) {
+ auto &Ranges = VarInstrRanges[Var];
+ // Verify that the current instruction range is not yet closed.
+ assert(!Ranges.empty() && Ranges.back().second == nullptr);
+ // For now, instruction ranges are not allowed to cross basic block
+ // boundaries.
+ assert(Ranges.back().first->getParent() == MI.getParent());
+ Ranges.back().second = &MI;
+}
+
+unsigned DbgValueHistoryMap::getRegisterForVar(const MDNode *Var) const {
+ const auto &I = VarInstrRanges.find(Var);
+ if (I == VarInstrRanges.end())
+ return 0;
+ const auto &Ranges = I->second;
+ if (Ranges.empty() || Ranges.back().second != nullptr)
+ return 0;
+ return isDescribedByReg(*Ranges.back().first);
+}
+
+namespace {
+// Maps physreg numbers to the variables they describe.
+typedef std::map<unsigned, SmallVector<const MDNode *, 1>> RegDescribedVarsMap;
+}
+
// \brief Claim that @Var is not described by @RegNo anymore.
static void dropRegDescribedVar(RegDescribedVarsMap &RegVars,
unsigned RegNo, const MDNode *Var) {
@@ -54,16 +90,9 @@ static void dropRegDescribedVar(RegDescr
static void addRegDescribedVar(RegDescribedVarsMap &RegVars,
unsigned RegNo, const MDNode *Var) {
assert(RegNo != 0U);
- RegVars[RegNo].push_back(Var);
-}
-
-static void clobberVariableLocation(SmallVectorImpl<const MachineInstr *> &VarHistory,
- const MachineInstr &ClobberingInstr) {
- assert(!VarHistory.empty());
- // DBG_VALUE we're clobbering should belong to the same MBB.
- assert(VarHistory.back()->isDebugValue());
- assert(VarHistory.back()->getParent() == ClobberingInstr.getParent());
- VarHistory.push_back(&ClobberingInstr);
+ auto &VarSet = RegVars[RegNo];
+ assert(std::find(VarSet.begin(), VarSet.end(), Var) == VarSet.end());
+ VarSet.push_back(Var);
}
// \brief Terminate the location range for variables described by register
@@ -77,11 +106,11 @@ static void clobberRegisterUses(RegDescr
// Iterate over all variables described by this register and add this
// instruction to their history, clobbering it.
for (const auto &Var : I->second)
- clobberVariableLocation(HistMap[Var], ClobberingInstr);
+ HistMap.endInstrRange(Var, ClobberingInstr);
RegVars.erase(I);
}
-// \brief Terminate the location range for all variables, described by registers
+// \brief Terminate location ranges for all variables, described by registers
// clobbered by @MI.
static void clobberRegisterUses(RegDescribedVarsMap &RegVars,
const MachineInstr &MI,
@@ -105,31 +134,10 @@ static void clobberAllRegistersUses(RegD
const MachineInstr &ClobberingInstr) {
for (const auto &I : RegVars)
for (const auto &Var : I.second)
- clobberVariableLocation(HistMap[Var], ClobberingInstr);
+ HistMap.endInstrRange(Var, ClobberingInstr);
RegVars.clear();
}
-// \brief Update the register that describes location of @Var in @RegVars map.
-static void
-updateRegForVariable(RegDescribedVarsMap &RegVars, const MDNode *Var,
- const SmallVectorImpl<const MachineInstr *> &VarHistory,
- const MachineInstr &MI) {
- if (!VarHistory.empty()) {
- const MachineInstr &Prev = *VarHistory.back();
- // Check if Var is currently described by a register by instruction in the
- // same basic block.
- if (Prev.isDebugValue() && Prev.getDebugVariable() == Var &&
- Prev.getParent() == MI.getParent()) {
- if (unsigned PrevReg = isDescribedByReg(Prev))
- dropRegDescribedVar(RegVars, PrevReg, Var);
- }
- }
-
- assert(MI.getDebugVariable() == Var);
- if (unsigned MIReg = isDescribedByReg(MI))
- addRegDescribedVar(RegVars, MIReg, Var);
-}
-
void calculateDbgValueHistory(const MachineFunction *MF,
const TargetRegisterInfo *TRI,
DbgValueHistoryMap &Result) {
@@ -146,16 +154,14 @@ void calculateDbgValueHistory(const Mach
assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!");
const MDNode *Var = MI.getDebugVariable();
- auto &History = Result[Var];
- if (!History.empty() && History.back()->isIdenticalTo(&MI)) {
- DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
- << "\t" << History.back() << "\t" << MI << "\n");
- continue;
- }
+ if (unsigned PrevReg = Result.getRegisterForVar(Var))
+ dropRegDescribedVar(RegVars, PrevReg, Var);
+
+ Result.startInstrRange(Var, MI);
- updateRegForVariable(RegVars, Var, History, MI);
- History.push_back(&MI);
+ if (unsigned NewReg = isDescribedByReg(MI))
+ addRegDescribedVar(RegVars, NewReg, Var);
}
// Make sure locations for register-described variables are valid only
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h?rev=209698&r1=209697&r2=209698&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h Tue May 27 18:09:50 2014
@@ -20,12 +20,31 @@ class MachineInstr;
class MDNode;
class TargetRegisterInfo;
-// For each user variable, keep a list of DBG_VALUE instructions for it
-// in the order of appearance. The list can also contain another
-// instructions, which are assumed to clobber the previous DBG_VALUE.
-// The variables are listed in order of appearance.
-typedef MapVector<const MDNode *, SmallVector<const MachineInstr *, 4>>
-DbgValueHistoryMap;
+// For each user variable, keep a list of instruction ranges where this variable
+// is accessible. The variables are listed in order of appearance.
+class DbgValueHistoryMap {
+ // Each instruction range starts with a DBG_VALUE instruction, specifying the
+ // location of a variable, which is assumed to be valid until the end of the
+ // range. If end is not specified, location is valid until the start
+ // instruction of the next instruction range, or until the end of the
+ // function.
+ typedef std::pair<const MachineInstr *, const MachineInstr *> InstrRange;
+ typedef SmallVector<InstrRange, 4> InstrRanges;
+ typedef MapVector<const MDNode *, InstrRanges> InstrRangesMap;
+ InstrRangesMap VarInstrRanges;
+
+public:
+ void startInstrRange(const MDNode *Var, const MachineInstr &MI);
+ void endInstrRange(const MDNode *Var, const MachineInstr &MI);
+ // Returns register currently describing @Var. If @Var is currently
+ // unaccessible or is not described by a register, returns 0.
+ unsigned getRegisterForVar(const MDNode *Var) const;
+
+ bool empty() const { return VarInstrRanges.empty(); }
+ void clear() { VarInstrRanges.clear(); }
+ InstrRangesMap::const_iterator begin() const { return VarInstrRanges.begin(); }
+ InstrRangesMap::const_iterator end() const { return VarInstrRanges.end(); }
+};
void calculateDbgValueHistory(const MachineFunction *MF,
const TargetRegisterInfo *TRI,
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=209698&r1=209697&r2=209698&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Tue May 27 18:09:50 2014
@@ -1153,12 +1153,10 @@ DwarfDebug::collectVariableInfo(SmallPtr
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(SmallPtr
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(SmallPtr
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(SmallPtr
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;
-
- 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 *StartLabel = getLabelBeforeInsn(Begin);
+ assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
+
+ 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 Mac
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 Mac
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);
}
}
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