Revert "[DebugInfo][RemoveDIs] Remove a swathe of debug-intrinsic code (llvm#144389)"

This reverts commit 9eb0020.

Author: ronlieb

llvm/include/llvm/Analysis/IRSimilarityIdentifier.h

@@ -545,6 +545,10 @@ struct IRInstructionMapper {
     // dependent.
     InstrType visitLandingPadInst(LandingPadInst &LPI) { return Illegal; }
     InstrType visitFuncletPadInst(FuncletPadInst &FPI) { return Illegal; }
+    // DebugInfo should be included in the regions, but should not be
+    // analyzed for similarity as it has no bearing on the outcome of the
+    // program.
+    InstrType visitDbgInfoIntrinsic(DbgInfoIntrinsic &DII) { return Invisible; }
     InstrType visitIntrinsicInst(IntrinsicInst &II) {
       // These are disabled due to complications in the CodeExtractor when
       // outlining these instructions.  For instance, It is unclear what we

llvm/include/llvm/Analysis/PtrUseVisitor.h

@@ -285,6 +285,7 @@ class PtrUseVisitor : protected InstVisitor<DerivedT>,
 
   // No-op intrinsics which we know don't escape the pointer to logic in
   // some other function.
+  void visitDbgInfoIntrinsic(DbgInfoIntrinsic &I) {}
   void visitMemIntrinsic(MemIntrinsic &I) {}
   void visitIntrinsicInst(IntrinsicInst &II) {
     switch (II.getIntrinsicID()) {

llvm/include/llvm/Transforms/Utils/Local.h

@@ -394,9 +394,12 @@ handleUnreachableTerminator(Instruction *I,
                             SmallVectorImpl<Value *> &PoisonedValues);
 
 /// Remove all instructions from a basic block other than its terminator
-/// and any present EH pad instructions. Returns the number of instructions
+/// and any present EH pad instructions. Returns a pair where the first element
+/// is the number of instructions (excluding debug info intrinsics) that have
+/// been removed, and the second element is the number of debug info intrinsics
 /// that have been removed.
-LLVM_ABI unsigned removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB);
+LLVM_ABI std::pair<unsigned, unsigned>
+removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB);
 
 /// Insert an unreachable instruction before the specified
 /// instruction, making it and the rest of the code in the block dead.

llvm/lib/Analysis/AliasSetTracker.cpp

@@ -343,6 +343,9 @@ void AliasSetTracker::add(AnyMemTransferInst *MTI) {
 }
 
 void AliasSetTracker::addUnknown(Instruction *Inst) {
+  if (isa<DbgInfoIntrinsic>(Inst))
+    return; // Ignore DbgInfo Intrinsics.
+
   if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
     // These intrinsics will show up as affecting memory, but they are just
     // markers.

llvm/lib/Analysis/CallGraph.cpp

@@ -34,7 +34,8 @@ CallGraph::CallGraph(Module &M)
       CallsExternalNode(std::make_unique<CallGraphNode>(this, nullptr)) {
   // Add every interesting function to the call graph.
   for (Function &F : M)
-    addToCallGraph(&F);
+    if (!isDbgInfoIntrinsic(F.getIntrinsicID()))
+      addToCallGraph(&F);
 }
 
 CallGraph::CallGraph(CallGraph &&Arg)
@@ -100,7 +101,7 @@ void CallGraph::populateCallGraphNode(CallGraphNode *Node) {
         const Function *Callee = Call->getCalledFunction();
         if (!Callee)
           Node->addCalledFunction(Call, CallsExternalNode.get());
-        else
+        else if (!isDbgInfoIntrinsic(Callee->getIntrinsicID()))
           Node->addCalledFunction(Call, getOrInsertFunction(Callee));
 
         // Add reference to callback functions.

llvm/lib/Analysis/DemandedBits.cpp

@@ -46,7 +46,8 @@ using namespace llvm::PatternMatch;
 #define DEBUG_TYPE "demanded-bits"
 
 static bool isAlwaysLive(Instruction *I) {
-  return I->isTerminator() || I->isEHPad() || I->mayHaveSideEffects();
+  return I->isTerminator() || isa<DbgInfoIntrinsic>(I) || I->isEHPad() ||
+         I->mayHaveSideEffects();
 }
 
 void DemandedBits::determineLiveOperandBits(

llvm/lib/Analysis/Loads.cpp

@@ -434,7 +434,7 @@ bool llvm::isSafeToLoadUnconditionally(Value *V, Align Alignment, const APInt &S
     // If we see a free or a call which may write to memory (i.e. which might do
     // a free) the pointer could be marked invalid.
     if (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
-        !isa<LifetimeIntrinsic>(BBI))
+        !isa<LifetimeIntrinsic>(BBI) && !isa<DbgInfoIntrinsic>(BBI))
       return false;
 
     Value *AccessedPtr;

llvm/lib/Analysis/MemoryDependenceAnalysis.cpp

@@ -188,6 +188,9 @@ MemDepResult MemoryDependenceResults::getCallDependencyFrom(
   // Walk backwards through the block, looking for dependencies.
   while (ScanIt != BB->begin()) {
     Instruction *Inst = &*--ScanIt;
+    // Debug intrinsics don't cause dependences and should not affect Limit
+    if (isa<DbgInfoIntrinsic>(Inst))
+      continue;
 
     // Limit the amount of scanning we do so we don't end up with quadratic
     // running time on extreme testcases.
@@ -429,6 +432,11 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
   while (ScanIt != BB->begin()) {
     Instruction *Inst = &*--ScanIt;
 
+    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+      // Debug intrinsics don't (and can't) cause dependencies.
+      if (isa<DbgInfoIntrinsic>(II))
+        continue;
+
     // Limit the amount of scanning we do so we don't end up with quadratic
     // running time on extreme testcases.
     --*Limit;

llvm/lib/Analysis/ValueTracking.cpp

@@ -7846,6 +7846,8 @@ bool llvm::isGuaranteedToTransferExecutionToSuccessor(
    iterator_range<BasicBlock::const_iterator> Range, unsigned ScanLimit) {
   assert(ScanLimit && "scan limit must be non-zero");
   for (const Instruction &I : Range) {
+    if (isa<DbgInfoIntrinsic>(I))
+        continue;
     if (--ScanLimit == 0)
       return false;
     if (!isGuaranteedToTransferExecutionToSuccessor(&I))
@@ -8048,6 +8050,8 @@ static bool programUndefinedIfUndefOrPoison(const Value *V,
     // well-defined operands.
 
     for (const auto &I : make_range(Begin, End)) {
+      if (isa<DbgInfoIntrinsic>(I))
+        continue;
       if (--ScanLimit == 0)
         break;
 
@@ -8072,6 +8076,8 @@ static bool programUndefinedIfUndefOrPoison(const Value *V,
 
   while (true) {
     for (const auto &I : make_range(Begin, End)) {
+      if (isa<DbgInfoIntrinsic>(I))
+        continue;
       if (--ScanLimit == 0)
         return false;
       if (mustTriggerUB(&I, YieldsPoison))

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -896,7 +896,12 @@ BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
   BasicBlock::iterator BBI = BI->getIterator();
   if (BBI != BB->begin()) {
     --BBI;
-    if (!isa<PHINode>(BBI))
+    while (isa<DbgInfoIntrinsic>(BBI)) {
+      if (BBI == BB->begin())
+        break;
+      --BBI;
+    }
+    if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
       return nullptr;
   }
 
@@ -2976,9 +2981,10 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB,
   // Make sure there are no instructions between the first instruction
   // and return.
   BasicBlock::const_iterator BI = BB->getFirstNonPHIIt();
-  // Skip over pseudo-probes and the bitcast.
-  while (&*BI == BCI || &*BI == EVI || isa<PseudoProbeInst>(BI) ||
-         isLifetimeEndOrBitCastFor(&*BI) || isFakeUse(&*BI))
+  // Skip over debug and the bitcast.
+  while (isa<DbgInfoIntrinsic>(BI) || &*BI == BCI || &*BI == EVI ||
+         isa<PseudoProbeInst>(BI) || isLifetimeEndOrBitCastFor(&*BI) ||
+         isFakeUse(&*BI))
     BI = std::next(BI);
   if (&*BI != RetI)
     return false;