[DebugInfo][RemoveDIs] Support cloning and remapping DPValues

llvm/include/llvm/Transforms/Utils/ValueMapper.h

@@ -15,21 +15,26 @@
 #define LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/simple_ilist.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/IR/ValueMap.h"
 
 namespace llvm {
 
 class Constant;
+class DIBuilder;
+class DPValue;
 class Function;
 class GlobalVariable;
 class Instruction;
 class MDNode;
 class Metadata;
+class Module;
 class Type;
 class Value;
 
 using ValueToValueMapTy = ValueMap<const Value *, WeakTrackingVH>;
+using DPValueIterator = simple_ilist<DPValue>::iterator;
 
 /// This is a class that can be implemented by clients to remap types when
 /// cloning constants and instructions.
@@ -175,6 +180,8 @@ class ValueMapper {
   Constant *mapConstant(const Constant &C);
 
   void remapInstruction(Instruction &I);
+  void remapDPValue(Module *M, DPValue &V);
+  void remapDPValueRange(Module *M, iterator_range<DPValueIterator> Range);
   void remapFunction(Function &F);
   void remapGlobalObjectMetadata(GlobalObject &GO);
 
@@ -260,6 +267,22 @@ inline void RemapInstruction(Instruction *I, ValueToValueMapTy &VM,
   ValueMapper(VM, Flags, TypeMapper, Materializer).remapInstruction(*I);
 }
 
+/// Remap the Values used in the DPValue \a V using the value map \a VM.
+inline void RemapDPValue(Module *M, DPValue *V, ValueToValueMapTy &VM,
+                         RemapFlags Flags = RF_None,
+                         ValueMapTypeRemapper *TypeMapper = nullptr,
+                         ValueMaterializer *Materializer = nullptr) {
+  ValueMapper(VM, Flags, TypeMapper, Materializer).remapDPValue(M, *V);
+}
+
+/// Remap the Values used in the DPValue \a V using the value map \a VM.
+inline void RemapDPValueRange(Module *M, iterator_range<DPValueIterator> Range,
+                              ValueToValueMapTy &VM, RemapFlags Flags = RF_None,
+                              ValueMapTypeRemapper *TypeMapper = nullptr,
+                              ValueMaterializer *Materializer = nullptr) {
+  ValueMapper(VM, Flags, TypeMapper, Materializer).remapDPValueRange(M, Range);
+}
+
 /// Remap the operands, metadata, arguments, and instructions of a function.
 ///
 /// Calls \a MapValue() on prefix data, prologue data, and personality

llvm/lib/IR/BasicBlock.cpp

@@ -39,8 +39,8 @@ cl::opt<bool>
 DPMarker *BasicBlock::createMarker(Instruction *I) {
   assert(IsNewDbgInfoFormat &&
          "Tried to create a marker in a non new debug-info block!");
-  assert(I->DbgMarker == nullptr &&
-         "Tried to create marker for instuction that already has one!");
+  if (I->DbgMarker)
+    return I->DbgMarker;
   DPMarker *Marker = new DPMarker();
   Marker->MarkedInstr = I;
   I->DbgMarker = Marker;
@@ -918,8 +918,8 @@ void BasicBlock::spliceDebugInfo(BasicBlock::iterator Dest, BasicBlock *Src,
   // move their markers onto Last. They remain in the Src block. No action
   // needed.
   if (!ReadFromHead) {
-    DPMarker *OntoLast = Src->getMarker(Last);
-    DPMarker *FromFirst = Src->getMarker(First);
+    DPMarker *OntoLast = Src->createMarker(Last);
+    DPMarker *FromFirst = Src->createMarker(First);
     OntoLast->absorbDebugValues(*FromFirst,
                                 true); // Always insert at head of it.
   }

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

@@ -1260,8 +1260,11 @@ static BasicBlock *buildClonedLoopBlocks(
   // everything available. Also, we have inserted new instructions which may
   // include assume intrinsics, so we update the assumption cache while
   // processing this.
+  Module *M = ClonedPH->getParent()->getParent();
   for (auto *ClonedBB : NewBlocks)
     for (Instruction &I : *ClonedBB) {
+      RemapDPValueRange(M, I.getDbgValueRange(), VMap,
+                        RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
       RemapInstruction(&I, VMap,
                        RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
       if (auto *II = dyn_cast<AssumeInst>(&I))

llvm/lib/Transforms/Utils/CloneFunction.cpp

@@ -59,7 +59,10 @@ BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
     Instruction *NewInst = I.clone();
     if (I.hasName())
       NewInst->setName(I.getName() + NameSuffix);
-    NewInst->insertInto(NewBB, NewBB->end());
+
+    NewInst->insertBefore(*NewBB, NewBB->end());
+    NewInst->cloneDebugInfoFrom(&I);
+
     VMap[&I] = NewInst; // Add instruction map to value.
 
     if (isa<CallInst>(I) && !I.isDebugOrPseudoInst()) {

llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp

@@ -913,9 +913,12 @@ bool llvm::UnrollRuntimeLoopRemainder(
   // Rewrite the cloned instruction operands to use the values created when the
   // clone is created.
   for (BasicBlock *BB : NewBlocks) {
+    Module *M = BB->getModule();
     for (Instruction &I : *BB) {
       RemapInstruction(&I, VMap,
                        RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
+      RemapDPValueRange(M, I.getDbgValueRange(), VMap,
+                        RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
     }
   }
 

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -1101,12 +1101,13 @@ static void CloneInstructionsIntoPredecessorBlockAndUpdateSSAUses(
   // Note that there may be multiple predecessor blocks, so we cannot move
   // bonus instructions to a predecessor block.
   for (Instruction &BonusInst : *BB) {
-    if (isa<DbgInfoIntrinsic>(BonusInst) || BonusInst.isTerminator())
+    if (BonusInst.isTerminator())
       continue;
 
     Instruction *NewBonusInst = BonusInst.clone();
 
-    if (PTI->getDebugLoc() != NewBonusInst->getDebugLoc()) {
+    if (!isa<DbgInfoIntrinsic>(BonusInst) &&
+        PTI->getDebugLoc() != NewBonusInst->getDebugLoc()) {
       // Unless the instruction has the same !dbg location as the original
       // branch, drop it. When we fold the bonus instructions we want to make
       // sure we reset their debug locations in order to avoid stepping on
@@ -1116,7 +1117,6 @@ static void CloneInstructionsIntoPredecessorBlockAndUpdateSSAUses(
 
     RemapInstruction(NewBonusInst, VMap,
                      RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
-    VMap[&BonusInst] = NewBonusInst;
 
     // If we speculated an instruction, we need to drop any metadata that may
     // result in undefined behavior, as the metadata might have been valid
@@ -1126,8 +1126,18 @@ static void CloneInstructionsIntoPredecessorBlockAndUpdateSSAUses(
     NewBonusInst->dropUBImplyingAttrsAndMetadata();
 
     NewBonusInst->insertInto(PredBlock, PTI->getIterator());
+    NewBonusInst->cloneDebugInfoFrom(&BonusInst);
+
+    for (DPValue &DPV : NewBonusInst->getDbgValueRange())
+      RemapDPValue(NewBonusInst->getModule(), &DPV, VMap,
+                   RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
+
+    if (isa<DbgInfoIntrinsic>(BonusInst))
+      continue;
+
     NewBonusInst->takeName(&BonusInst);
     BonusInst.setName(NewBonusInst->getName() + ".old");
+    VMap[&BonusInst] = NewBonusInst;
 
     // Update (liveout) uses of bonus instructions,
     // now that the bonus instruction has been cloned into predecessor.
@@ -3293,6 +3303,10 @@ FoldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
     BasicBlock::iterator InsertPt = EdgeBB->getFirstInsertionPt();
     DenseMap<Value *, Value *> TranslateMap; // Track translated values.
     TranslateMap[Cond] = CB;
+
+    // RemoveDIs: track instructions that we optimise away while folding, so
+    // that we can copy DPValues from them later.
+    BasicBlock::iterator SrcDbgCursor = BB->begin();
     for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) {
       if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
         TranslateMap[PN] = PN->getIncomingValueForBlock(EdgeBB);
@@ -3327,13 +3341,26 @@ FoldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
           TranslateMap[&*BBI] = N;
       }
       if (N) {
+        // Copy all debug-info attached to instructions from the last we
+        // successfully clone, up to this instruction (they might have been
+        // folded away).
+        for (; SrcDbgCursor != BBI; ++SrcDbgCursor)
+          N->cloneDebugInfoFrom(&*SrcDbgCursor);
+        SrcDbgCursor = std::next(BBI);
+        // Clone debug-info on this instruction too.
+        N->cloneDebugInfoFrom(&*BBI);
+
         // Register the new instruction with the assumption cache if necessary.
         if (auto *Assume = dyn_cast<AssumeInst>(N))
           if (AC)
             AC->registerAssumption(Assume);
       }
     }
 
+    for (; &*SrcDbgCursor != BI; ++SrcDbgCursor)
+      InsertPt->cloneDebugInfoFrom(&*SrcDbgCursor);
+    InsertPt->cloneDebugInfoFrom(BI);
+
     BB->removePredecessor(EdgeBB);
     BranchInst *EdgeBI = cast<BranchInst>(EdgeBB->getTerminator());
     EdgeBI->setSuccessor(0, RealDest);
@@ -3738,22 +3765,22 @@ static bool performBranchToCommonDestFolding(BranchInst *BI, BranchInst *PBI,
   ValueToValueMapTy VMap; // maps original values to cloned values
   CloneInstructionsIntoPredecessorBlockAndUpdateSSAUses(BB, PredBlock, VMap);
 
+  Module *M = BB->getModule();
+
+  if (PredBlock->IsNewDbgInfoFormat) {
+    PredBlock->getTerminator()->cloneDebugInfoFrom(BB->getTerminator());
+    for (DPValue &DPV : PredBlock->getTerminator()->getDbgValueRange()) {
+      RemapDPValue(M, &DPV, VMap,
+                   RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
+    }
+  }
+
   // Now that the Cond was cloned into the predecessor basic block,
   // or/and the two conditions together.
   Value *BICond = VMap[BI->getCondition()];
   PBI->setCondition(
       createLogicalOp(Builder, Opc, PBI->getCondition(), BICond, "or.cond"));
 
-  // Copy any debug value intrinsics into the end of PredBlock.
-  for (Instruction &I : *BB) {
-    if (isa<DbgInfoIntrinsic>(I)) {
-      Instruction *NewI = I.clone();
-      RemapInstruction(NewI, VMap,
-                       RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
-      NewI->insertBefore(PBI);
-    }
-  }
-
   ++NumFoldBranchToCommonDest;
   return true;
 }

llvm/lib/Transforms/Utils/ValueMapper.cpp

@@ -31,6 +31,7 @@
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Type.h"
@@ -145,6 +146,7 @@ class Mapper {
   Value *mapValue(const Value *V);
   void remapInstruction(Instruction *I);
   void remapFunction(Function &F);
+  void remapDPValue(DPValue &DPV);
 
   Constant *mapConstant(const Constant *C) {
     return cast_or_null<Constant>(mapValue(C));
@@ -535,6 +537,39 @@ Value *Mapper::mapValue(const Value *V) {
   return getVM()[V] = ConstantPointerNull::get(cast<PointerType>(NewTy));
 }
 
+void Mapper::remapDPValue(DPValue &V) {
+  // Remap variables and DILocations.
+  auto *MappedVar = mapMetadata(V.getVariable());
+  auto *MappedDILoc = mapMetadata(V.getDebugLoc());
+  V.setVariable(cast<DILocalVariable>(MappedVar));
+  V.setDebugLoc(DebugLoc(cast<DILocation>(MappedDILoc)));
+
+  // Find Value operands and remap those.
+  SmallVector<Value *, 4> Vals, NewVals;
+  for (Value *Val : V.location_ops())
+    Vals.push_back(Val);
+  for (Value *Val : Vals)
+    NewVals.push_back(mapValue(Val));
+
+  // If there are no changes to the Value operands, finished.
+  if (Vals == NewVals)
+    return;
+
+  bool IgnoreMissingLocals = Flags & RF_IgnoreMissingLocals;
+
+  // Otherwise, do some replacement.
+  if (!IgnoreMissingLocals &&
+      llvm::any_of(NewVals, [&](Value *V) { return V == nullptr; })) {
+    V.setKillLocation();
+  } else {
+    // Either we have all non-empty NewVals, or we're permitted to ignore
+    // missing locals.
+    for (unsigned int I = 0; I < Vals.size(); ++I)
+      if (NewVals[I])
+        V.replaceVariableLocationOp(I, NewVals[I]);
+  }
+}
+
 Value *Mapper::mapBlockAddress(const BlockAddress &BA) {
   Function *F = cast<Function>(mapValue(BA.getFunction()));
 
@@ -1179,6 +1214,17 @@ void ValueMapper::remapInstruction(Instruction &I) {
   FlushingMapper(pImpl)->remapInstruction(&I);
 }
 
+void ValueMapper::remapDPValue(Module *M, DPValue &V) {
+  FlushingMapper(pImpl)->remapDPValue(V);
+}
+
+void ValueMapper::remapDPValueRange(
+    Module *M, iterator_range<DPValue::self_iterator> Range) {
+  for (DPValue &DPV : Range) {
+    remapDPValue(M, DPV);
+  }
+}
+
 void ValueMapper::remapFunction(Function &F) {
   FlushingMapper(pImpl)->remapFunction(F);
 }

llvm/test/Transforms/LoopUnroll/runtime-epilog-debuginfo.ll

@@ -1,4 +1,5 @@
 ; RUN: opt -passes=loop-unroll -unroll-runtime -unroll-runtime-epilog -S %s | FileCheck %s
+; RUN: opt -passes=loop-unroll -unroll-runtime -unroll-runtime-epilog -S %s --try-experimental-debuginfo-iterators | FileCheck %s
 
 ; Test that epilogue is tagged with the same debug information as original loop body rather than original loop exit.
 
@@ -11,6 +12,18 @@
 ; CHECK:   br i1 %lcmp.mod, label %for.body.i.epil.preheader, label %lee1.exit.loopexit, !dbg ![[LOOP_LOC]]
 ; CHECK: for.body.i.epil.preheader:
 ; CHECK:   br label %for.body.i.epil, !dbg ![[LOOP_LOC]]
+; CHECK: for.body.i.epil:
+;; Ensure that when we clone the div/add/add and its following dbg.values,
+;; those dbg.values are remapped to the duplicated adds, not the originals.
+; CHECK:      %div.i.epil = sdiv i32 %t.08.i.epil, 2,
+; CHECK-NEXT: %add.i.epil = add i32 %t.08.i.epil, %a,
+; CHECK-NEXT: %add1.i.epil = add i32 %add.i.epil, %div.i.epil,
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %add1.i.epil,
+; CHECK-NEXT: %inc.i.epil = add nuw i32 %i.09.i.epil, 1, !dbg !36
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %inc.i.epil,
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %inc.i.epil,
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %add1.i.epil,
+
 ; CHECK: lee1.exit.loopexit:
 ; CHECK:   br label %lee1.exit, !dbg ![[EXIT_LOC:[0-9]+]]