[DebugInfo][RemoveDIs][NFC] Split findDbgDeclares into two functions (#77478)

This patch follows on from comments on
https://github.com/llvm/llvm-project/pull/73498, implementing the
proposed split of findDbgDeclares into two separate functions for
DbgDeclareInsts and DPVDeclares, which return containers rather than
taking containers by reference.

6 files changed, 60 insertions, 48 deletions

diff --git a/llvm/include/llvm/IR/DebugInfo.h b/llvm/include/llvm/IR/DebugInfo.h
index 684bc7b..eb57286 100644
--- a/llvm/include/llvm/IR/DebugInfo.h
+++ b/llvm/include/llvm/IR/DebugInfo.h
@@ -40,8 +40,9 @@ class Module;
 
 /// Finds dbg.declare intrinsics declaring local variables as living in the
 /// memory that 'V' points to.
-void findDbgDeclares(SmallVectorImpl<DbgDeclareInst *> &DbgUsers, Value *V,
-                     SmallVectorImpl<DPValue *> *DPValues = nullptr);
+TinyPtrVector<DbgDeclareInst *> findDbgDeclares(Value *V);
+/// As above, for DPVDeclares.
+TinyPtrVector<DPValue *> findDPVDeclares(Value *V);
 
 /// Finds the llvm.dbg.value intrinsics describing a value.
 void findDbgValues(SmallVectorImpl<DbgValueInst *> &DbgValues,
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 316197a..6b7dd74 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -44,6 +44,42 @@ using namespace llvm;
 using namespace llvm::at;
 using namespace llvm::dwarf;
 
+TinyPtrVector<DbgDeclareInst *> llvm::findDbgDeclares(Value *V) {
+  // This function is hot. Check whether the value has any metadata to avoid a
+  // DenseMap lookup.
+  if (!V->isUsedByMetadata())
+    return {};
+  auto *L = LocalAsMetadata::getIfExists(V);
+  if (!L)
+    return {};
+  auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L);
+  if (!MDV)
+    return {};
+
+  TinyPtrVector<DbgDeclareInst *> Declares;
+  for (User *U : MDV->users())
+    if (auto *DDI = dyn_cast<DbgDeclareInst>(U))
+      Declares.push_back(DDI);
+
+  return Declares;
+}
+TinyPtrVector<DPValue *> llvm::findDPVDeclares(Value *V) {
+  // This function is hot. Check whether the value has any metadata to avoid a
+  // DenseMap lookup.
+  if (!V->isUsedByMetadata())
+    return {};
+  auto *L = LocalAsMetadata::getIfExists(V);
+  if (!L)
+    return {};
+
+  TinyPtrVector<DPValue *> Declares;
+  for (DPValue *DPV : L->getAllDPValueUsers())
+    if (DPV->getType() == DPValue::LocationType::Declare)
+      Declares.push_back(DPV);
+
+  return Declares;
+}
+
 template <typename IntrinsicT,
           DPValue::LocationType Type = DPValue::LocationType::Any>
 static void findDbgIntrinsics(SmallVectorImpl<IntrinsicT *> &Result, Value *V,
@@ -97,12 +133,6 @@ static void findDbgIntrinsics(SmallVectorImpl<IntrinsicT *> &Result, Value *V,
   }
 }
 
-void llvm::findDbgDeclares(SmallVectorImpl<DbgDeclareInst *> &DbgUsers,
-                           Value *V, SmallVectorImpl<DPValue *> *DPValues) {
-  findDbgIntrinsics<DbgDeclareInst, DPValue::LocationType::Declare>(DbgUsers, V,
-                                                                    DPValues);
-}
-
 void llvm::findDbgValues(SmallVectorImpl<DbgValueInst *> &DbgValues,
                          Value *V, SmallVectorImpl<DPValue *> *DPValues) {
   findDbgIntrinsics<DbgValueInst, DPValue::LocationType::Value>(DbgValues, V,
diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
index 4d2b31f..4293446 100644
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -963,18 +963,15 @@ static void cacheDIVar(FrameDataInfo &FrameData,
     if (DIVarCache.contains(V))
       continue;
 
-    SmallVector<DbgDeclareInst *, 1> DDIs;
-    SmallVector<DPValue *, 1> DPVs;
-    findDbgDeclares(DDIs, V, &DPVs);
-    auto CacheIt = [&DIVarCache, V](auto &Container) {
+    auto CacheIt = [&DIVarCache, V](auto Container) {
       auto *I = llvm::find_if(Container, [](auto *DDI) {
         return DDI->getExpression()->getNumElements() == 0;
       });
       if (I != Container.end())
         DIVarCache.insert({V, (*I)->getVariable()});
     };
-    CacheIt(DDIs);
-    CacheIt(DPVs);
+    CacheIt(findDbgDeclares(V));
+    CacheIt(findDPVDeclares(V));
   }
 }
 
@@ -1125,9 +1122,8 @@ static void buildFrameDebugInfo(Function &F, coro::Shape &Shape,
   assert(PromiseAlloca &&
          "Coroutine with switch ABI should own Promise alloca");
 
-  SmallVector<DbgDeclareInst *, 1> DIs;
-  SmallVector<DPValue *, 1> DPVs;
-  findDbgDeclares(DIs, PromiseAlloca, &DPVs);
+  TinyPtrVector<DbgDeclareInst *> DIs = findDbgDeclares(PromiseAlloca);
+  TinyPtrVector<DPValue *> DPVs = findDPVDeclares(PromiseAlloca);
 
   DILocalVariable *PromiseDIVariable = nullptr;
   DILocation *DILoc = nullptr;
@@ -1865,9 +1861,8 @@ static void insertSpills(const FrameDataInfo &FrameData, coro::Shape &Shape) {
               FrameTy->getElementType(FrameData.getFieldIndex(E.first)), GEP,
               SpillAlignment, E.first->getName() + Twine(".reload"));
 
-        SmallVector<DbgDeclareInst *, 1> DIs;
-        SmallVector<DPValue *, 1> DPVs;
-        findDbgDeclares(DIs, Def, &DPVs);
+        TinyPtrVector<DbgDeclareInst *> DIs = findDbgDeclares(Def);
+        TinyPtrVector<DPValue *> DPVs = findDPVDeclares(Def);
         // Try best to find dbg.declare. If the spill is a temp, there may not
         // be a direct dbg.declare. Walk up the load chain to find one from an
         // alias.
@@ -1881,9 +1876,8 @@ static void insertSpills(const FrameDataInfo &FrameData, coro::Shape &Shape) {
             CurDef = LdInst->getPointerOperand();
             if (!isa<AllocaInst, LoadInst>(CurDef))
               break;
-            DIs.clear();
-            DPVs.clear();
-            findDbgDeclares(DIs, CurDef, &DPVs);
+            DIs = findDbgDeclares(CurDef);
+            DPVs = findDPVDeclares(CurDef);
           }
         }
 
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index a40ca7f..adf87eb 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -5021,9 +5021,6 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
 
       // Remove any existing intrinsics on the new alloca describing
       // the variable fragment.
-      SmallVector<DbgDeclareInst *, 1> FragDbgDeclares;
-      SmallVector<DPValue *, 1> FragDPVs;
-      findDbgDeclares(FragDbgDeclares, Fragment.Alloca, &FragDPVs);
       auto RemoveOne = [DbgVariable](auto *OldDII) {
         auto SameVariableFragment = [](const auto *LHS, const auto *RHS) {
           return LHS->getVariable() == RHS->getVariable() &&
@@ -5033,8 +5030,8 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
         if (SameVariableFragment(OldDII, DbgVariable))
           OldDII->eraseFromParent();
       };
-      for_each(FragDbgDeclares, RemoveOne);
-      for_each(FragDPVs, RemoveOne);
+      for_each(findDbgDeclares(Fragment.Alloca), RemoveOne);
+      for_each(findDPVDeclares(Fragment.Alloca), RemoveOne);
 
       insertNewDbgInst(DIB, DbgVariable, Fragment.Alloca, FragmentExpr, &AI);
     }
@@ -5042,11 +5039,8 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
 
   // Migrate debug information from the old alloca to the new alloca(s)
   // and the individual partitions.
-  SmallVector<DbgDeclareInst *, 1> DbgDeclares;
-  SmallVector<DPValue *, 1> DPValues;
-  findDbgDeclares(DbgDeclares, &AI, &DPValues);
-  for_each(DbgDeclares, MigrateOne);
-  for_each(DPValues, MigrateOne);
+  for_each(findDbgDeclares(&AI), MigrateOne);
+  for_each(findDPVDeclares(&AI), MigrateOne);
   for_each(at::getAssignmentMarkers(&AI), MigrateOne);
 
   return Changed;
@@ -5169,12 +5163,9 @@ bool SROA::deleteDeadInstructions(
     // not be able to find it.
     if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
       DeletedAllocas.insert(AI);
-      SmallVector<DbgDeclareInst *, 1> DbgDeclares;
-      SmallVector<DPValue *, 1> DPValues;
-      findDbgDeclares(DbgDeclares, AI, &DPValues);
-      for (DbgDeclareInst *OldDII : DbgDeclares)
+      for (DbgDeclareInst *OldDII : findDbgDeclares(AI))
         OldDII->eraseFromParent();
-      for (DPValue *OldDII : DPValues)
+      for (DPValue *OldDII : findDPVDeclares(AI))
         OldDII->eraseFromParent();
     }
 
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index b9cad76..d1b42f2 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -2130,9 +2130,8 @@ void llvm::insertDebugValuesForPHIs(BasicBlock *BB,
 bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
                              DIBuilder &Builder, uint8_t DIExprFlags,
                              int Offset) {
-  SmallVector<DbgDeclareInst *, 1> DbgDeclares;
-  SmallVector<DPValue *, 1> DPValues;
-  findDbgDeclares(DbgDeclares, Address, &DPValues);
+  TinyPtrVector<DbgDeclareInst *> DbgDeclares = findDbgDeclares(Address);
+  TinyPtrVector<DPValue *> DPVDeclares = findDPVDeclares(Address);
 
   auto ReplaceOne = [&](auto *DII) {
     assert(DII->getVariable() && "Missing variable");
@@ -2143,9 +2142,9 @@ bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
   };
 
   for_each(DbgDeclares, ReplaceOne);
-  for_each(DPValues, ReplaceOne);
+  for_each(DPVDeclares, ReplaceOne);
 
-  return !DbgDeclares.empty() || !DPValues.empty();
+  return !DbgDeclares.empty() || !DPVDeclares.empty();
 }
 
 static void updateOneDbgValueForAlloca(const DebugLoc &Loc,
diff --git a/llvm/lib/Transforms/Utils/MemoryOpRemark.cpp b/llvm/lib/Transforms/Utils/MemoryOpRemark.cpp
index 47c6bcb..d671a93 100644
--- a/llvm/lib/Transforms/Utils/MemoryOpRemark.cpp
+++ b/llvm/lib/Transforms/Utils/MemoryOpRemark.cpp
@@ -321,9 +321,6 @@ void MemoryOpRemark::visitVariable(const Value *V,
   bool FoundDI = false;
   // Try to get an llvm.dbg.declare, which has a DILocalVariable giving us the
   // real debug info name and size of the variable.
-  SmallVector<DbgDeclareInst *, 1> DbgDeclares;
-  SmallVector<DPValue *, 1> DPValues;
-  findDbgDeclares(DbgDeclares, const_cast<Value *>(V), &DPValues);
   auto FindDI = [&](const auto *DVI) {
     if (DILocalVariable *DILV = DVI->getVariable()) {
       std::optional<uint64_t> DISize = getSizeInBytes(DILV->getSizeInBits());
@@ -334,8 +331,8 @@ void MemoryOpRemark::visitVariable(const Value *V,
       }
     }
   };
-  for_each(DbgDeclares, FindDI);
-  for_each(DPValues, FindDI);
+  for_each(findDbgDeclares(const_cast<Value *>(V)), FindDI);
+  for_each(findDPVDeclares(const_cast<Value *>(V)), FindDI);
 
   if (FoundDI) {
     assert(!Result.empty());