llvm · nikic · Jul 23, 2025 · Jul 22, 2025
diff --git a/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h b/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h
@@ -57,7 +57,6 @@ struct AllocaInfo {
 
 struct StackInfo {
   MapVector<AllocaInst *, AllocaInfo> AllocasToInstrument;
-  SmallVector<Instruction *, 4> UnrecognizedLifetimes;
   SmallVector<Instruction *, 8> RetVec;
   bool CallsReturnTwice = false;
 };

diff --git a/llvm/lib/Analysis/StackLifetime.cpp b/llvm/lib/Analysis/StackLifetime.cpp
@@ -63,10 +63,7 @@ bool StackLifetime::isAliveAfter(const AllocaInst *AI,
 // markers has the same size and points to the alloca start.
 static const AllocaInst *findMatchingAlloca(const IntrinsicInst &II,
                                             const DataLayout &DL) {
-  const AllocaInst *AI = findAllocaForValue(II.getArgOperand(1), true);
-  if (!AI)
-    return nullptr;
-
+  const AllocaInst *AI = cast<AllocaInst>(II.getArgOperand(1));
   auto AllocaSize = AI->getAllocationSize(DL);
   if (!AllocaSize)
     return nullptr;

diff --git a/llvm/lib/Target/AArch64/AArch64StackTagging.cpp b/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
@@ -581,7 +581,6 @@ bool AArch64StackTagging::runOnFunction(Function &Fn) {
     // statement if return_twice functions are called.
     bool StandardLifetime =
         !SInfo.CallsReturnTwice &&
-        SInfo.UnrecognizedLifetimes.empty() &&
         memtag::isStandardLifetime(Info.LifetimeStart, Info.LifetimeEnd, DT, LI,
                                    ClMaxLifetimes);
     if (StandardLifetime) {
@@ -616,10 +615,5 @@ bool AArch64StackTagging::runOnFunction(Function &Fn) {
     memtag::annotateDebugRecords(Info, Tag);
   }
 
-  // If we have instrumented at least one alloca, all unrecognized lifetime
-  // intrinsics have to go.
-  for (auto *I : SInfo.UnrecognizedLifetimes)
-    I->eraseFromParent();
-
   return true;
 }
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1063,7 +1063,6 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
   };
   SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
   SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
-  bool HasUntracedLifetimeIntrinsic = false;
 
   SmallVector<AllocaInst *, 1> DynamicAllocaVec;
   SmallVector<IntrinsicInst *, 1> StackRestoreVec;
@@ -1097,14 +1096,6 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
 
     initializeCallbacks(*F.getParent());
 
-    if (HasUntracedLifetimeIntrinsic) {
-      // If there are lifetime intrinsics which couldn't be traced back to an
-      // alloca, we may not know exactly when a variable enters scope, and
-      // therefore should "fail safe" by not poisoning them.
-      StaticAllocaPoisonCallVec.clear();
-      DynamicAllocaPoisonCallVec.clear();
-    }
-
     processDynamicAllocas();
     processStaticAllocas();
 
@@ -1231,13 +1222,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
         !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
       return;
     // Find alloca instruction that corresponds to llvm.lifetime argument.
-    // Currently we can only handle lifetime markers pointing to the
-    // beginning of the alloca.
-    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1), true);
-    if (!AI) {
-      HasUntracedLifetimeIntrinsic = true;
-      return;
-    }
+    AllocaInst *AI = cast<AllocaInst>(II.getArgOperand(1));
     // We're interested only in allocas we can handle.
     if (!ASan.isInterestingAlloca(*AI))
       return;

diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1500,7 +1500,6 @@ bool HWAddressSanitizer::instrumentStack(memtag::StackInfo &SInfo,
     // statement if return_twice functions are called.
     bool StandardLifetime =
         !SInfo.CallsReturnTwice &&
-        SInfo.UnrecognizedLifetimes.empty() &&
         memtag::isStandardLifetime(Info.LifetimeStart, Info.LifetimeEnd, &DT,
                                    &LI, ClMaxLifetimes);
     if (DetectUseAfterScope && StandardLifetime) {
@@ -1525,8 +1524,6 @@ bool HWAddressSanitizer::instrumentStack(memtag::StackInfo &SInfo,
     }
     memtag::alignAndPadAlloca(Info, Mapping.getObjectAlignment());
   }
-  for (auto &I : SInfo.UnrecognizedLifetimes)
-    I->eraseFromParent();
   return true;
 }
 

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1216,7 +1216,6 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
   };
   SmallVector<ShadowOriginAndInsertPoint, 16> InstrumentationList;
   DenseMap<const DILocation *, int> LazyWarningDebugLocationCount;
-  bool InstrumentLifetimeStart = ClHandleLifetimeIntrinsics;
   SmallSetVector<AllocaInst *, 16> AllocaSet;
   SmallVector<std::pair<IntrinsicInst *, AllocaInst *>, 16> LifetimeStartList;
   SmallVector<StoreInst *, 16> StoreList;
@@ -1623,7 +1622,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
 
     // Poison llvm.lifetime.start intrinsics, if we haven't fallen back to
     // instrumenting only allocas.
-    if (InstrumentLifetimeStart) {
+    if (ClHandleLifetimeIntrinsics) {
       for (auto Item : LifetimeStartList) {
         instrumentAlloca(*Item.second, Item.first);
         AllocaSet.remove(Item.second);
@@ -3303,9 +3302,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
   void handleLifetimeStart(IntrinsicInst &I) {
     if (!PoisonStack)
       return;
-    AllocaInst *AI = llvm::findAllocaForValue(I.getArgOperand(1));
-    if (!AI)
-      InstrumentLifetimeStart = false;
+    AllocaInst *AI = cast<AllocaInst>(I.getArgOperand(1));
     LifetimeStartList.push_back(std::make_pair(&I, AI));
   }
 

diff --git a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -343,8 +343,7 @@ static bool markTails(Function &F, OptimizationRemarkEmitter *ORE) {
 ///
 static bool canMoveAboveCall(Instruction *I, CallInst *CI, AliasAnalysis *AA) {
   if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
-    if (II->getIntrinsicID() == Intrinsic::lifetime_end &&
-        llvm::findAllocaForValue(II->getArgOperand(1)))
+    if (II->getIntrinsicID() == Intrinsic::lifetime_end)
       return true;
 
   // FIXME: We can move load/store/call/free instructions above the call if the

diff --git a/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp b/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
@@ -155,11 +155,7 @@ void StackInfoBuilder::visit(OptimizationRemarkEmitter &ORE,
     return;
   }
   if (auto *II = dyn_cast<LifetimeIntrinsic>(&Inst)) {
-    AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
-    if (!AI) {
-      Info.UnrecognizedLifetimes.push_back(&Inst);
-      return;
-    }
+    AllocaInst *AI = cast<AllocaInst>(II->getArgOperand(1));
     if (getAllocaInterestingness(*AI) != AllocaInterestingness::kInteresting)
       return;
     if (II->getIntrinsicID() == Intrinsic::lifetime_start)