Add DebugSSAUpdater class to track debug value liveness #134055
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This patch adds a class that uses SSA construction, with debug values as definitions, to determine whether and which debug values for a particular variable are live at each point in an IR function. This will be used by the IR reader of llvm-debuginfo-analyzer to compute variable ranges and coverage, although it may be applicable to other debug info IR analyses.
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-debuginfo Author: Stephen Tozer (SLTozer) ChangesThis patch adds a class that uses SSA construction, with debug values as definitions, to determine whether and which debug values for a particular variable are live at each point in an IR function. This will be used by the IR reader of llvm-debuginfo-analyzer to compute variable ranges and coverage, although it may be applicable to other debug info IR analyses. Patch is 37.69 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/134055.diff 8 Files Affected:
diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 174ff09f56bdf..43246d3615b24 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -4349,6 +4349,7 @@ template <> struct DenseMapInfo<DebugVariable> {
class DebugVariableAggregate : public DebugVariable {
public:
DebugVariableAggregate(const DbgVariableIntrinsic *DVI);
+ DebugVariableAggregate(const DbgVariableRecord *DVR);
DebugVariableAggregate(const DebugVariable &V)
: DebugVariable(V.getVariable(), std::nullopt, V.getInlinedAt()) {}
};
diff --git a/llvm/include/llvm/Transforms/Utils/DebugSSAUpdater.h b/llvm/include/llvm/Transforms/Utils/DebugSSAUpdater.h
new file mode 100644
index 0000000000000..27a56274cd3d9
--- /dev/null
+++ b/llvm/include/llvm/Transforms/Utils/DebugSSAUpdater.h
@@ -0,0 +1,351 @@
+//===- DebugSSAUpdater.h - Debug SSA Update Tool ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the DebugSSAUpdater class, which is used to evaluate the
+// live values of debug variables in IR. This uses SSA construction, treating
+// debug value records as definitions, to determine at each point in the program
+// which definition(s) are live at a given point. This is useful for analysis of
+// the state of debug variables, such as measuring the change in values of a
+// variable over time, or calculating coverage stats.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_DEBUGSSAUPDATER_H
+#define LLVM_TRANSFORMS_UTILS_DEBUGSSAUPDATER_H
+
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/DebugProgramInstruction.h"
+#include "llvm/IR/Instruction.h"
+
+namespace llvm {
+
+////////////////////////////////////////
+// SSAUpdater specialization classes
+
+class DbgSSAPhi;
+template <typename T> class SmallVectorImpl;
+template <typename T> class SSAUpdaterTraits;
+
+/// A definition of a variable; can represent either a debug value, no
+/// definition (the variable has not yet been defined), or a phi value*.
+/// *Meaning multiple definitions that are live-in to a block from different
+/// predecessors, not a debug value that uses an IR PHINode.
+struct DbgValueDef {
+ DbgSSAPhi *Phi;
+ bool IsUndef;
+ bool IsMemory;
+ Metadata *Locations;
+ DIExpression *Expression;
+
+ DbgValueDef()
+ : Phi(nullptr), IsUndef(true), IsMemory(false), Locations(nullptr),
+ Expression(nullptr) {}
+ DbgValueDef(int)
+ : Phi(nullptr), IsUndef(true), IsMemory(false), Locations(nullptr),
+ Expression(nullptr) {}
+ DbgValueDef(bool IsMemory, Metadata *Locations, DIExpression *Expression)
+ : Phi(nullptr), IsUndef(false), IsMemory(IsMemory), Locations(Locations),
+ Expression(Expression) {}
+ DbgValueDef(DbgVariableRecord *DVR) : Phi(nullptr) {
+ assert(!DVR->isDbgAssign() && "#dbg_assign not yet supported");
+ IsUndef = DVR->isKillLocation();
+ IsMemory = DVR->isAddressOfVariable();
+ Locations = DVR->getRawLocation();
+ Expression = DVR->getExpression();
+ }
+ DbgValueDef(DbgSSAPhi *Phi)
+ : Phi(Phi), IsUndef(false), IsMemory(false), Locations(nullptr),
+ Expression(nullptr) {}
+
+ bool agreesWith(DbgValueDef Other) const {
+ if (IsUndef && Other.IsUndef)
+ return true;
+ return std::tie(Phi, IsUndef, IsMemory, Locations, Expression) ==
+ std::tie(Other.Phi, Other.IsUndef, Other.IsMemory, Other.Locations,
+ Other.Expression);
+ }
+
+ operator bool() const { return !IsUndef; }
+ bool operator==(DbgValueDef Other) const { return agreesWith(Other); }
+ bool operator!=(DbgValueDef Other) const { return !agreesWith(Other); }
+
+ void print(raw_ostream &OS) const;
+};
+
+class DbgSSABlock;
+class DebugSSAUpdater;
+
+/// Represents the live-in definitions of a variable to a block with multiple
+/// predecessors.
+class DbgSSAPhi {
+public:
+ SmallVector<std::pair<DbgSSABlock *, DbgValueDef>, 4> IncomingValues;
+ DbgSSABlock *ParentBlock;
+ DbgSSAPhi(DbgSSABlock *ParentBlock) : ParentBlock(ParentBlock) {}
+
+ DbgSSABlock *getParent() { return ParentBlock; }
+ unsigned getNumIncomingValues() const { return IncomingValues.size(); }
+ DbgSSABlock *getIncomingBlock(size_t Idx) {
+ return IncomingValues[Idx].first;
+ }
+ DbgValueDef getIncomingValue(size_t Idx) {
+ return IncomingValues[Idx].second;
+ }
+ void addIncoming(DbgSSABlock *BB, DbgValueDef DV) {
+ IncomingValues.push_back({BB, DV});
+ }
+
+ void print(raw_ostream &OS) const;
+};
+
+inline raw_ostream &operator<<(raw_ostream &OS, const DbgValueDef &DV) {
+ DV.print(OS);
+ return OS;
+}
+inline raw_ostream &operator<<(raw_ostream &OS, const DbgSSAPhi &PHI) {
+ PHI.print(OS);
+ return OS;
+}
+
+/// Thin wrapper around a block successor iterator.
+class DbgSSABlockSuccIterator {
+public:
+ succ_iterator SuccIt;
+ DebugSSAUpdater &Updater;
+
+ DbgSSABlockSuccIterator(succ_iterator SuccIt, DebugSSAUpdater &Updater)
+ : SuccIt(SuccIt), Updater(Updater) {}
+
+ bool operator!=(const DbgSSABlockSuccIterator &OtherIt) const {
+ return OtherIt.SuccIt != SuccIt;
+ }
+
+ DbgSSABlockSuccIterator &operator++() {
+ ++SuccIt;
+ return *this;
+ }
+
+ DbgSSABlock *operator*();
+};
+
+/// Thin wrapper around a block successor iterator.
+class DbgSSABlockPredIterator {
+public:
+ pred_iterator PredIt;
+ DebugSSAUpdater &Updater;
+
+ DbgSSABlockPredIterator(pred_iterator PredIt, DebugSSAUpdater &Updater)
+ : PredIt(PredIt), Updater(Updater) {}
+
+ bool operator!=(const DbgSSABlockPredIterator &OtherIt) const {
+ return OtherIt.PredIt != PredIt;
+ }
+
+ DbgSSABlockPredIterator &operator++() {
+ ++PredIt;
+ return *this;
+ }
+
+ DbgSSABlock *operator*();
+};
+
+class DbgSSABlock {
+public:
+ BasicBlock &BB;
+ DebugSSAUpdater &Updater;
+ using PHIListT = SmallVector<DbgSSAPhi, 1>;
+ /// List of PHIs in this block. There should only ever be one, but this needs
+ /// to be a list for the SSAUpdater.
+ PHIListT PHIList;
+
+ DbgSSABlock(BasicBlock &BB, DebugSSAUpdater &Updater)
+ : BB(BB), Updater(Updater) {}
+
+ DbgSSABlockPredIterator pred_begin() {
+ return DbgSSABlockPredIterator(llvm::pred_begin(&BB), Updater);
+ }
+
+ DbgSSABlockPredIterator pred_end() {
+ return DbgSSABlockPredIterator(llvm::pred_end(&BB), Updater);
+ }
+
+ iterator_range<DbgSSABlockPredIterator> predecessors() {
+ return iterator_range(pred_begin(), pred_end());
+ }
+
+ DbgSSABlockSuccIterator succ_begin() {
+ return DbgSSABlockSuccIterator(llvm::succ_begin(&BB), Updater);
+ }
+
+ DbgSSABlockSuccIterator succ_end() {
+ return DbgSSABlockSuccIterator(llvm::succ_end(&BB), Updater);
+ }
+
+ iterator_range<DbgSSABlockSuccIterator> successors() {
+ return iterator_range(succ_begin(), succ_end());
+ }
+
+ /// SSAUpdater has requested a PHI: create that within this block record.
+ DbgSSAPhi *newPHI() {
+ assert(PHIList.empty() &&
+ "Only one PHI should exist per-block per-variable");
+ PHIList.emplace_back(this);
+ return &PHIList.back();
+ }
+
+ /// SSAUpdater wishes to know what PHIs already exist in this block.
+ PHIListT &phis() { return PHIList; }
+};
+
+/// Class used to determine the live ranges of debug variables in IR using
+/// SSA construction (via the SSAUpdaterImpl class), used for analysis purposes.
+class DebugSSAUpdater {
+ friend class SSAUpdaterTraits<DebugSSAUpdater>;
+
+private:
+ /// This keeps track of which value to use on a per-block basis. When we
+ /// insert PHI nodes, we keep track of them here.
+ void *AV = nullptr;
+
+ SmallVectorImpl<DbgSSAPhi *> *InsertedPHIs;
+
+ DenseMap<BasicBlock *, DbgSSABlock *> BlockMap;
+
+public:
+ /// If InsertedPHIs is specified, it will be filled
+ /// in with all PHI Nodes created by rewriting.
+ explicit DebugSSAUpdater(
+ SmallVectorImpl<DbgSSAPhi *> *InsertedPHIs = nullptr);
+ DebugSSAUpdater(const DebugSSAUpdater &) = delete;
+ DebugSSAUpdater &operator=(const DebugSSAUpdater &) = delete;
+ ~DebugSSAUpdater();
+
+ void reset() {
+ for (auto &Block : BlockMap)
+ delete Block.second;
+
+ if (InsertedPHIs)
+ InsertedPHIs->clear();
+ BlockMap.clear();
+ }
+
+ void initialize();
+
+ /// For a given BB, create a wrapper block for it. Stores it in the
+ /// DebugSSAUpdater block map.
+ DbgSSABlock *getDbgSSABlock(BasicBlock *BB) {
+ auto it = BlockMap.find(BB);
+ if (it == BlockMap.end()) {
+ BlockMap[BB] = new DbgSSABlock(*BB, *this);
+ it = BlockMap.find(BB);
+ }
+ return it->second;
+ }
+
+ /// Indicate that a rewritten value is available in the specified block
+ /// with the specified value.
+ void addAvailableValue(DbgSSABlock *BB, DbgValueDef DV);
+
+ /// Return true if the DebugSSAUpdater already has a value for the specified
+ /// block.
+ bool hasValueForBlock(DbgSSABlock *BB) const;
+
+ /// Return the value for the specified block if the DebugSSAUpdater has one,
+ /// otherwise return nullptr.
+ DbgValueDef findValueForBlock(DbgSSABlock *BB) const;
+
+ /// Construct SSA form, materializing a value that is live at the end
+ /// of the specified block.
+ DbgValueDef getValueAtEndOfBlock(DbgSSABlock *BB);
+
+ /// Construct SSA form, materializing a value that is live in the
+ /// middle of the specified block.
+ ///
+ /// \c getValueInMiddleOfBlock is the same as \c GetValueAtEndOfBlock except
+ /// in one important case: if there is a definition of the rewritten value
+ /// after the 'use' in BB. Consider code like this:
+ ///
+ /// \code
+ /// X1 = ...
+ /// SomeBB:
+ /// use(X)
+ /// X2 = ...
+ /// br Cond, SomeBB, OutBB
+ /// \endcode
+ ///
+ /// In this case, there are two values (X1 and X2) added to the AvailableVals
+ /// set by the client of the rewriter, and those values are both live out of
+ /// their respective blocks. However, the use of X happens in the *middle* of
+ /// a block. Because of this, we need to insert a new PHI node in SomeBB to
+ /// merge the appropriate values, and this value isn't live out of the block.
+ DbgValueDef getValueInMiddleOfBlock(DbgSSABlock *BB);
+
+private:
+ DbgValueDef getValueAtEndOfBlockInternal(DbgSSABlock *BB);
+};
+
+struct DbgRangeEntry {
+ BasicBlock::iterator Start;
+ BasicBlock::iterator End;
+ // Should be non-PHI.
+ DbgValueDef Value;
+};
+
+class DbgValueRangeTable {
+ DenseMap<DebugVariableAggregate, SmallVector<DbgRangeEntry>>
+ OrigVariableValueRangeTable;
+ DenseMap<DebugVariableAggregate, DbgValueDef> OrigSingleLocVariableValueTable;
+ // For the only initial user of this class, the mappings below are useful and
+ // are used in conjunction with the variable value ranges above, thus we track
+ // them as part of the same class. If we have more uses for variable value
+ // range tracking, then the line/variable name mapping should be moved out to
+ // a separate class.
+ DenseMap<BasicBlock::iterator, uint64_t> LineMapping;
+ DenseMap<uint64_t, std::string> VariableNameMapping;
+
+ using VarMapping = DenseMap<Value *, uint64_t>;
+ VarMapping VariableMapping;
+ uint64_t KeyIndex = 0;
+
+public:
+ void addVariable(Function *F, DebugVariableAggregate DVA);
+ bool hasVariableEntry(DebugVariableAggregate DVA) const {
+ return OrigVariableValueRangeTable.contains(DVA) ||
+ OrigSingleLocVariableValueTable.contains(DVA);
+ }
+ bool hasSingleLocEntry(DebugVariableAggregate DVA) const {
+ return OrigSingleLocVariableValueTable.contains(DVA);
+ }
+ ArrayRef<DbgRangeEntry> getVariableRanges(DebugVariableAggregate DVA) {
+ return OrigVariableValueRangeTable[DVA];
+ }
+ DbgValueDef getSingleLoc(DebugVariableAggregate DVA) {
+ return OrigSingleLocVariableValueTable[DVA];
+ }
+
+ void addLine(BasicBlock::iterator I, uint64_t LineAddr) {
+ LineMapping[I] = LineAddr;
+ }
+ uint64_t getLine(BasicBlock::iterator I) {
+ return LineMapping.contains(I) ? LineMapping[I] : (uint64_t)-1;
+ }
+
+ uint64_t addVariableName(Value *V, uint64_t Size);
+ std::string getVariableName(uint64_t Key) {
+ assert(VariableNameMapping.contains(Key) && "Why not here?");
+ return VariableNameMapping[Key];
+ }
+
+ void printValues(DebugVariableAggregate DVA, raw_ostream &OS);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_DEBUGSSAUPDATER_H
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index f8c24d896df32..e7e79cd64c954 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -55,6 +55,10 @@ DebugVariableAggregate::DebugVariableAggregate(const DbgVariableIntrinsic *DVI)
: DebugVariable(DVI->getVariable(), std::nullopt,
DVI->getDebugLoc()->getInlinedAt()) {}
+DebugVariableAggregate::DebugVariableAggregate(const DbgVariableRecord *DVR)
+ : DebugVariable(DVR->getVariable(), std::nullopt,
+ DVR->getDebugLoc()->getInlinedAt()) {}
+
DILocation::DILocation(LLVMContext &C, StorageType Storage, unsigned Line,
unsigned Column, ArrayRef<Metadata *> MDs,
bool ImplicitCode)
diff --git a/llvm/lib/Transforms/Utils/CMakeLists.txt b/llvm/lib/Transforms/Utils/CMakeLists.txt
index 78cad0d253be8..7e61f47094151 100644
--- a/llvm/lib/Transforms/Utils/CMakeLists.txt
+++ b/llvm/lib/Transforms/Utils/CMakeLists.txt
@@ -20,6 +20,7 @@ add_llvm_component_library(LLVMTransformUtils
CtorUtils.cpp
CountVisits.cpp
Debugify.cpp
+ DebugSSAUpdater.cpp
DemoteRegToStack.cpp
DXILUpgrade.cpp
EntryExitInstrumenter.cpp
diff --git a/llvm/lib/Transforms/Utils/DebugSSAUpdater.cpp b/llvm/lib/Transforms/Utils/DebugSSAUpdater.cpp
new file mode 100644
index 0000000000000..f646fdea90968
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/DebugSSAUpdater.cpp
@@ -0,0 +1,415 @@
+//===- DebugSSAUpdater.cpp - Debug Variable SSA Update Tool ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the DebugSSAUpdater class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/DebugSSAUpdater.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/Transforms/Utils/SSAUpdaterImpl.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "debug-ssa-updater"
+
+void DbgValueDef::print(raw_ostream &OS) const {
+ OS << "DbgVal{ ";
+ if (IsUndef) {
+ OS << "undef }";
+ return;
+ }
+ if (Phi) {
+ OS << *Phi << "}";
+ return;
+ }
+ OS << (IsMemory ? "Mem: " : "Def: ") << *Locations << " - " << *Expression
+ << " }";
+}
+
+void DbgSSAPhi::print(raw_ostream &OS) const {
+ OS << "DbgPhi ";
+ for (auto &[BB, DV] : IncomingValues)
+ OS << "[" << BB->BB.getName() << ", " << DV << "] ";
+}
+
+using AvailableValsTy = DenseMap<DbgSSABlock *, DbgValueDef>;
+
+static AvailableValsTy &getAvailableVals(void *AV) {
+ return *static_cast<AvailableValsTy *>(AV);
+}
+
+DebugSSAUpdater::DebugSSAUpdater(SmallVectorImpl<DbgSSAPhi *> *NewPHI)
+ : InsertedPHIs(NewPHI) {}
+
+DebugSSAUpdater::~DebugSSAUpdater() {
+ delete static_cast<AvailableValsTy *>(AV);
+}
+
+void DebugSSAUpdater::initialize() {
+ if (!AV)
+ AV = new AvailableValsTy();
+ else
+ getAvailableVals(AV).clear();
+}
+
+bool DebugSSAUpdater::hasValueForBlock(DbgSSABlock *BB) const {
+ return getAvailableVals(AV).count(BB);
+}
+
+DbgValueDef DebugSSAUpdater::findValueForBlock(DbgSSABlock *BB) const {
+ return getAvailableVals(AV).lookup(BB);
+}
+
+void DebugSSAUpdater::addAvailableValue(DbgSSABlock *BB, DbgValueDef DV) {
+ getAvailableVals(AV)[BB] = DV;
+}
+
+DbgValueDef DebugSSAUpdater::getValueAtEndOfBlock(DbgSSABlock *BB) {
+ DbgValueDef Res = getValueAtEndOfBlockInternal(BB);
+ return Res;
+}
+
+DbgValueDef DebugSSAUpdater::getValueInMiddleOfBlock(DbgSSABlock *BB) {
+ // If there is no definition of the renamed variable in this block, just use
+ // 'getValueAtEndOfBlock' to do our work.
+ if (!hasValueForBlock(BB))
+ return getValueAtEndOfBlock(BB);
+
+ // Otherwise, we have the hard case. Get the live-in values for each
+ // predecessor.
+ SmallVector<std::pair<DbgSSABlock *, DbgValueDef>, 8> PredValues;
+ DbgValueDef SingularValue;
+
+ bool IsFirstPred = true;
+ for (DbgSSABlock *PredBB : BB->predecessors()) {
+ DbgValueDef PredVal = getValueAtEndOfBlock(PredBB);
+ PredValues.push_back(std::make_pair(PredBB, PredVal));
+
+ // Compute SingularValue.
+ if (IsFirstPred) {
+ SingularValue = PredVal;
+ IsFirstPred = false;
+ } else if (!PredVal.agreesWith(SingularValue))
+ SingularValue = DbgValueDef();
+ }
+
+ // If there are no predecessors, just return undef.
+ if (PredValues.empty())
+ return DbgValueDef();
+
+ // Otherwise, if all the merged values are the same, just use it.
+ if (!SingularValue.IsUndef)
+ return SingularValue;
+
+ // Ok, we have no way out, insert a new one now.
+ DbgSSAPhi *InsertedPHI = BB->newPHI();
+
+ // Fill in all the predecessors of the PHI.
+ for (const auto &PredValue : PredValues)
+ InsertedPHI->addIncoming(PredValue.first, PredValue.second);
+
+ // See if the PHI node can be merged to a single value. This can happen in
+ // loop cases when we get a PHI of itself and one other value.
+
+ // If the client wants to know about all new instructions, tell it.
+ if (InsertedPHIs)
+ InsertedPHIs->push_back(InsertedPHI);
+
+ LLVM_DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n");
+ return InsertedPHI;
+}
+
+DbgSSABlock *DbgSSABlockSuccIterator::operator*() {
+ return Updater.getDbgSSABlock(*SuccIt);
+}
+DbgSSABlock *DbgSSABlockPredIterator::operator*() {
+ return Updater.getDbgSSABlock(*PredIt);
+}
+
+namespace llvm {
+
+template <> class SSAUpdaterTraits<DebugSSAUpdater> {
+public:
+ using BlkT = DbgSSABlock;
+ using ValT = DbgValueDef;
+ using PhiT = DbgSSAPhi;
+ using BlkSucc_iterator = DbgSSABlockSuccIterator;
+
+ static BlkSucc_iterator BlkSucc_begin(BlkT *BB) { return BB->succ_begin(); }
+ static BlkSucc_iterator BlkSucc_end(BlkT *BB) { return BB->succ_end(); }
+
+ class PHI_iterator {
+ private:
+ DbgSSAPhi *PHI;
+ unsigned Idx;
+
+ public:
+ explicit PHI_iterator(DbgSSAPhi *P) // begin iterator
+ : PHI(P), Idx(0) {}
+ PHI_iterator(DbgSSAPhi *P, bool) // end iterator
+ : PHI(P), Idx(PHI->getNumIncomingValues()) {}
+
+ PHI_iterator &operator++() {
+ ++Idx;
+ return *this;
+ }
+ bool operator==(const PHI_iterator &X) const { return Idx == X.Idx; }
+ bool operator!=(const PHI_iterator &X) const { return !operator==(X); }
+
+ DbgValueDef getIncomingValue() { return PHI->getIncomingValue(Idx); }
+ DbgSSABlock *getIncomingBlock() { return PHI->getIncomingBlock(Idx); }
+ };
+
+ static PHI_iterator PHI_begin(PhiT *PHI) { return PHI_iterator(PHI); }
+ static PHI_iterator PHI_end(PhiT *PHI) { return PHI_iterator(PHI, true); }
+
+ /// FindPredecessorBlocks - Put the predecessors of Info->BB into the Preds
+ /// vector, set Info->NumPreds, and allocate space in Info->Preds.
+ static void FindPredecessorBlocks(DbgSSABlock *BB,
+ SmallVectorImpl<DbgSSABlock *> *Preds) {
+ for (auto PredIt = BB->pred_begin(); PredIt != BB->pred_end(); ++PredIt)
+ Preds->push_back(*PredIt);
+ }
+
+ /// GetPoisonVal - Get an undefined value of the same type as the value
+ /// being handled.
+ static DbgValueDef GetPoisonVal(DbgSSABlock *BB, DebugSSAUpdater *Updater) {
+ return DbgValueDef();
+ }
+
+ /// CreateEmptyPHI - Create a new PHI instruction in the specified block.
+ /// Reserve space for the operands (?) but do not fill them in yet.
+ static DbgSSAPhi *CreateEmptyPHI(DbgSSABloc...
[truncated]
|
You can test this locally with the following command:git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' 'HEAD~1' HEAD llvm/include/llvm/Transforms/Utils/DebugSSAUpdater.h llvm/lib/Transforms/Utils/DebugSSAUpdater.cpp llvm/unittests/Transforms/Utils/DebugSSAUpdaterTest.cpp llvm/include/llvm/IR/DebugInfoMetadata.h llvm/lib/IR/DebugInfoMetadata.cppThe following files introduce new uses of undef:
Undef is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields In tests, avoid using For example, this is considered a bad practice: define void @fn() {
...
br i1 undef, ...
}Please use the following instead: define void @fn(i1 %cond) {
...
br i1 %cond, ...
}Please refer to the Undefined Behavior Manual for more information. |
|
Just noting that the undef deprecator comment above is incorrect - this code doesn't contain instances of |
|
I would suggest to change the text; may be to |
|
Reopened as: #135349 |
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This patch adds a class that uses SSA construction, with debug values as definitions, to determine whether and which debug values for a particular variable are live at each point in an IR function. This will be used by the IR reader of llvm-debuginfo-analyzer to compute variable ranges and coverage, although it may be applicable to other debug info IR analyses.