Add IR and codegen support for deactivation symbols.

pcc · pcc · commit be7ef9ac392a · 2025-07-14T13:09:07.000-07:00
Deactivation symbols are a mechanism for allowing object files to disable specific instructions in other object files at link time. The initial use case is for pointer field protection. For more information, see the RFC: https://discourse.llvm.org/t/rfc-deactivation-symbols/85556 TODO: - Add tests. Pull Request: llvm#133536
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -162,6 +162,8 @@ class LLVM_ABI CallLowering {
 
     /// True if this call results in convergent operations.
     bool IsConvergent = true;
+
+    GlobalValue *DeactivationSymbol = nullptr;
   };
 
   /// Argument handling is mostly uniform between the four places that
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h b/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
@@ -56,6 +56,7 @@ struct MachineIRBuilderState {
   MDNode *PCSections = nullptr;
   /// MMRA Metadata to be set on any instruction we create.
   MDNode *MMRA = nullptr;
+  Value *DS = nullptr;
 
   /// \name Fields describing the insertion point.
   /// @{
@@ -369,6 +370,7 @@ class LLVM_ABI MachineIRBuilder {
     State.II = MI.getIterator();
     setPCSections(MI.getPCSections());
     setMMRAMetadata(MI.getMMRAMetadata());
+    setDeactivationSymbol(MI.getDeactivationSymbol());
   }
   /// @}
 
@@ -405,6 +407,9 @@ class LLVM_ABI MachineIRBuilder {
   /// Set the PC sections metadata to \p MD for all the next build instructions.
   void setMMRAMetadata(MDNode *MMRA) { State.MMRA = MMRA; }
 
+  Value *getDeactivationSymbol() { return State.DS; }
+  void setDeactivationSymbol(Value *DS) { State.DS = DS; }
+
   /// Get the current instruction's MMRA metadata.
   MDNode *getMMRAMetadata() { return State.MMRA; }
 
diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -1563,6 +1563,8 @@ enum NodeType {
   // Outputs: Output Chain
   CLEAR_CACHE,
 
+  DEACTIVATION_SYMBOL,
+
   /// BUILTIN_OP_END - This must be the last enum value in this list.
   /// The target-specific pre-isel opcode values start here.
   BUILTIN_OP_END
diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -866,6 +866,15 @@ class MachineInstr
     return nullptr;
   }
 
+  // FIXME: Move to Info.
+  Value *DeactivationSymbol = nullptr;
+  Value *getDeactivationSymbol() const {
+    return DeactivationSymbol;
+  }
+  void setDeactivationSymbol(MachineFunction &MF, Value *DeactivationSymbol) {
+    this->DeactivationSymbol = DeactivationSymbol;
+  }
+
   /// Helper to extract a CFI type hash if one has been added.
   uint32_t getCFIType() const {
     if (!Info)
diff --git a/llvm/include/llvm/CodeGen/MachineInstrBuilder.h b/llvm/include/llvm/CodeGen/MachineInstrBuilder.h
@@ -70,29 +70,44 @@ enum {
 } // end namespace RegState
 
 /// Set of metadata that should be preserved when using BuildMI(). This provides
-/// a more convenient way of preserving DebugLoc, PCSections and MMRA.
+/// a more convenient way of preserving certain data from the original
+/// instruction.
 class MIMetadata {
 public:
   MIMetadata() = default;
-  MIMetadata(DebugLoc DL, MDNode *PCSections = nullptr, MDNode *MMRA = nullptr)
-      : DL(std::move(DL)), PCSections(PCSections), MMRA(MMRA) {}
+  MIMetadata(DebugLoc DL, MDNode *PCSections = nullptr, MDNode *MMRA = nullptr,
+             Value *DeactivationSymbol = nullptr)
+      : DL(std::move(DL)), PCSections(PCSections), MMRA(MMRA),
+        DeactivationSymbol(DeactivationSymbol) {}
   MIMetadata(const DILocation *DI, MDNode *PCSections = nullptr,
              MDNode *MMRA = nullptr)
       : DL(DI), PCSections(PCSections), MMRA(MMRA) {}
   explicit MIMetadata(const Instruction &From)
       : DL(From.getDebugLoc()),
-        PCSections(From.getMetadata(LLVMContext::MD_pcsections)) {}
+        PCSections(From.getMetadata(LLVMContext::MD_pcsections)),
+        DeactivationSymbol(getDeactivationSymbol(&From)) {}
   explicit MIMetadata(const MachineInstr &From)
-      : DL(From.getDebugLoc()), PCSections(From.getPCSections()) {}
+      : DL(From.getDebugLoc()), PCSections(From.getPCSections()),
+        DeactivationSymbol(From.getDeactivationSymbol()) {}
 
   const DebugLoc &getDL() const { return DL; }
   MDNode *getPCSections() const { return PCSections; }
   MDNode *getMMRAMetadata() const { return MMRA; }
+  Value *getDeactivationSymbol() const { return DeactivationSymbol; }
 
 private:
   DebugLoc DL;
   MDNode *PCSections = nullptr;
   MDNode *MMRA = nullptr;
+  Value *DeactivationSymbol = nullptr;
+
+  static inline Value *getDeactivationSymbol(const Instruction *I) {
+    if (auto *CB = dyn_cast<CallBase>(I))
+      if (auto Bundle =
+              CB->getOperandBundle(llvm::LLVMContext::OB_deactivation_symbol))
+        return Bundle->Inputs[0].get();
+    return nullptr;
+  }
 };
 
 class MachineInstrBuilder {
@@ -348,6 +363,8 @@ class MachineInstrBuilder {
       MI->setPCSections(*MF, MIMD.getPCSections());
     if (MIMD.getMMRAMetadata())
       MI->setMMRAMetadata(*MF, MIMD.getMMRAMetadata());
+    if (MIMD.getDeactivationSymbol())
+      MI->setDeactivationSymbol(*MF, MIMD.getDeactivationSymbol());
     return *this;
   }
 
diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -763,6 +763,7 @@ class SelectionDAG {
                                  int64_t offset = 0, unsigned TargetFlags = 0) {
     return getGlobalAddress(GV, DL, VT, offset, true, TargetFlags);
   }
+  LLVM_ABI SDValue getDeactivationSymbol(const GlobalValue *GV);
   LLVM_ABI SDValue getFrameIndex(int FI, EVT VT, bool isTarget = false);
   SDValue getTargetFrameIndex(int FI, EVT VT) {
     return getFrameIndex(FI, VT, true);
diff --git a/llvm/include/llvm/CodeGen/SelectionDAGISel.h b/llvm/include/llvm/CodeGen/SelectionDAGISel.h
@@ -150,6 +150,7 @@ class SelectionDAGISel {
     OPC_RecordChild7,
     OPC_RecordMemRef,
     OPC_CaptureGlueInput,
+    OPC_CaptureDeactivationSymbol,
     OPC_MoveChild,
     OPC_MoveChild0,
     OPC_MoveChild1,
diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -1980,6 +1980,23 @@ class GlobalAddressSDNode : public SDNode {
   }
 };
 
+class DeactivationSymbolSDNode : public SDNode {
+  friend class SelectionDAG;
+
+  const GlobalValue *TheGlobal;
+
+  DeactivationSymbolSDNode(const GlobalValue *GV, SDVTList VTs)
+      : SDNode(ISD::DEACTIVATION_SYMBOL, 0, DebugLoc(), VTs),
+        TheGlobal(GV) {}
+
+public:
+  const GlobalValue *getGlobal() const { return TheGlobal; }
+
+  static bool classof(const SDNode *N) {
+    return N->getOpcode() == ISD::DEACTIVATION_SYMBOL;
+  }
+};
+
 class FrameIndexSDNode : public SDNode {
   friend class SelectionDAG;
 
diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -4716,6 +4716,7 @@ class LLVM_ABI TargetLowering : public TargetLoweringBase {
     SmallVector<SDValue, 4> InVals;
     const ConstantInt *CFIType = nullptr;
     SDValue ConvergenceControlToken;
+    GlobalValue *DeactivationSymbol = nullptr;
 
     std::optional<PtrAuthInfo> PAI;
 
@@ -4861,6 +4862,11 @@ class LLVM_ABI TargetLowering : public TargetLoweringBase {
       return *this;
     }
 
+    CallLoweringInfo &setDeactivationSymbol(GlobalValue *Sym) {
+      DeactivationSymbol = Sym;
+      return *this;
+    }
+
     ArgListTy &getArgs() {
       return Args;
     }
diff --git a/llvm/include/llvm/IR/LLVMContext.h b/llvm/include/llvm/IR/LLVMContext.h
@@ -97,6 +97,7 @@ class LLVMContext {
     OB_ptrauth = 7,                // "ptrauth"
     OB_kcfi = 8,                   // "kcfi"
     OB_convergencectrl = 9,        // "convergencectrl"
+    OB_deactivation_symbol = 10,   // "deactivation-symbol"
   };
 
   /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
diff --git a/llvm/include/llvm/Target/Target.td b/llvm/include/llvm/Target/Target.td
@@ -682,6 +682,7 @@ class Instruction : InstructionEncoding {
                                 // If so, make sure to override
                                 // TargetInstrInfo::getInsertSubregLikeInputs.
   bit variadicOpsAreDefs = false; // Are variadic operands definitions?
+  bit supportsDeactivationSymbol = false;
 
   // Does the instruction have side effects that are not captured by any
   // operands of the instruction or other flags?
diff --git a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
@@ -195,6 +195,10 @@ bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
     assert(Info.CFIType->getType()->isIntegerTy(32) && "Invalid CFI type");
   }
 
+  if (auto Bundle = CB.getOperandBundle(LLVMContext::OB_deactivation_symbol)) {
+    Info.DeactivationSymbol = cast<GlobalValue>(Bundle->Inputs[0]);
+  }
+
   Info.CB = &CB;
   Info.KnownCallees = CB.getMetadata(LLVMContext::MD_callees);
   Info.CallConv = CallConv;
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -2857,6 +2857,9 @@ bool IRTranslator::translateCall(const User &U, MachineIRBuilder &MIRBuilder) {
     }
   }
 
+  if (auto Bundle = CI.getOperandBundle(LLVMContext::OB_deactivation_symbol))
+    MIB->setDeactivationSymbol(*MF, Bundle->Inputs[0].get());
+
   return true;
 }
 
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -38,8 +38,10 @@ void MachineIRBuilder::setMF(MachineFunction &MF) {
 //------------------------------------------------------------------------------
 
 MachineInstrBuilder MachineIRBuilder::buildInstrNoInsert(unsigned Opcode) {
-  return BuildMI(getMF(), {getDL(), getPCSections(), getMMRAMetadata()},
-                 getTII().get(Opcode));
+  return BuildMI(
+      getMF(),
+      {getDL(), getPCSections(), getMMRAMetadata(), getDeactivationSymbol()},
+      getTII().get(Opcode));
 }
 
 MachineInstrBuilder MachineIRBuilder::insertInstr(MachineInstrBuilder MIB) {
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -120,7 +120,7 @@ MachineInstr::MachineInstr(MachineFunction &MF, const MCInstrDesc &TID,
 MachineInstr::MachineInstr(MachineFunction &MF, const MachineInstr &MI)
     : MCID(&MI.getDesc()), NumOperands(0), Flags(0), AsmPrinterFlags(0),
       Info(MI.Info), DbgLoc(MI.getDebugLoc()), DebugInstrNum(0),
-      Opcode(MI.getOpcode()) {
+      Opcode(MI.getOpcode()), DeactivationSymbol(MI.getDeactivationSymbol()) {
   assert(DbgLoc.hasTrivialDestructor() && "Expected trivial destructor");
 
   CapOperands = OperandCapacity::get(MI.getNumOperands());
@@ -728,6 +728,8 @@ bool MachineInstr::isIdenticalTo(const MachineInstr &Other,
   // Call instructions with different CFI types are not identical.
   if (isCall() && getCFIType() != Other.getCFIType())
     return false;
+  if (getDeactivationSymbol() != Other.getDeactivationSymbol())
+    return false;
 
   return true;
 }
@@ -2029,6 +2031,8 @@ void MachineInstr::print(raw_ostream &OS, ModuleSlotTracker &MST,
       OS << ',';
     OS << " cfi-type " << CFIType;
   }
+  if (getDeactivationSymbol())
+    OS << ", deactivation-symbol " << getDeactivationSymbol()->getName();
 
   if (DebugInstrNum) {
     if (!FirstOp)
diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -15,10 +15,12 @@
 #include "InstrEmitter.h"
 #include "SDNodeDbgValue.h"
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/CodeGen/ISDOpcodes.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/StackMaps.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/CodeGen/TargetLowering.h"
@@ -61,6 +63,8 @@ static unsigned countOperands(SDNode *Node, unsigned NumExpUses,
   unsigned N = Node->getNumOperands();
   while (N && Node->getOperand(N - 1).getValueType() == MVT::Glue)
     --N;
+  if (N && Node->getOperand(N - 1).getOpcode() == ISD::DEACTIVATION_SYMBOL)
+    --N; // Ignore deactivation symbol if it exists.
   if (N && Node->getOperand(N - 1).getValueType() == MVT::Other)
     --N; // Ignore chain if it exists.
 
@@ -1219,15 +1223,23 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
     }
   }
 
-  if (SDNode *GluedNode = Node->getGluedNode()) {
-    // FIXME: Possibly iterate over multiple glue nodes?
-    if (GluedNode->getOpcode() ==
-        ~(unsigned)TargetOpcode::CONVERGENCECTRL_GLUE) {
-      Register VReg = getVR(GluedNode->getOperand(0), VRBaseMap);
-      MachineOperand MO = MachineOperand::CreateReg(VReg, /*isDef=*/false,
-                                                    /*isImp=*/true);
-      MIB->addOperand(MO);
-    }
+  unsigned Op = Node->getNumOperands();
+  if (Op != 0 && Node->getOperand(Op - 1)->getOpcode() ==
+                     ~(unsigned)TargetOpcode::CONVERGENCECTRL_GLUE) {
+    Register VReg = getVR(Node->getOperand(Op - 1)->getOperand(0), VRBaseMap);
+    MachineOperand MO = MachineOperand::CreateReg(VReg, /*isDef=*/false,
+                                                  /*isImp=*/true);
+    MIB->addOperand(MO);
+    Op--;
+  }
+
+  if (Op != 0 &&
+      Node->getOperand(Op - 1)->getOpcode() == ISD::DEACTIVATION_SYMBOL) {
+    MI->setDeactivationSymbol(
+        *MF, const_cast<GlobalValue *>(
+                 cast<DeactivationSymbolSDNode>(Node->getOperand(Op - 1))
+                     ->getGlobal()));
+    Op--;
   }
 
   // Run post-isel target hook to adjust this instruction if needed.
@@ -1248,7 +1260,8 @@ EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned,
     llvm_unreachable("This target-independent node should have been selected!");
   case ISD::EntryToken:
   case ISD::MERGE_VALUES:
-  case ISD::TokenFactor: // fall thru
+  case ISD::TokenFactor:
+  case ISD::DEACTIVATION_SYMBOL:
     break;
   case ISD::CopyToReg: {
     Register DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1917,6 +1917,21 @@ SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV, const SDLoc &DL,
   return SDValue(N, 0);
 }
 
+SDValue SelectionDAG::getDeactivationSymbol(const GlobalValue *GV) {
+  SDVTList VTs = getVTList(MVT::Untyped);
+  FoldingSetNodeID ID;
+  AddNodeIDNode(ID, ISD::DEACTIVATION_SYMBOL, VTs, {});
+  ID.AddPointer(GV);
+  void *IP = nullptr;
+  if (SDNode *E = FindNodeOrInsertPos(ID, SDLoc(), IP))
+    return SDValue(E, 0);
+
+  auto *N = newSDNode<DeactivationSymbolSDNode>(GV, VTs);
+  CSEMap.InsertNode(N, IP);
+  InsertNode(N);
+  return SDValue(N, 0);
+}
+
 SDValue SelectionDAG::getFrameIndex(int FI, EVT VT, bool isTarget) {
   unsigned Opc = isTarget ? ISD::TargetFrameIndex : ISD::FrameIndex;
   SDVTList VTs = getVTList(VT);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -45,6 +45,7 @@
 #include "llvm/CodeGen/MachineOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/SelectionDAGTargetInfo.h"
 #include "llvm/CodeGen/StackMaps.h"
 #include "llvm/CodeGen/SwiftErrorValueTracking.h"
@@ -5360,6 +5361,13 @@ void SelectionDAGBuilder::visitTargetIntrinsic(const CallInst &I,
   // Create the node.
   SDValue Result;
 
+  if (auto Bundle = I.getOperandBundle(LLVMContext::OB_deactivation_symbol)) {
+    auto *Sym = Bundle->Inputs[0].get();
+    SDValue SDSym = getValue(Sym);
+    SDSym = DAG.getDeactivationSymbol(cast<GlobalValue>(Sym));
+    Ops.push_back(SDSym);
+  }
+
   if (auto Bundle = I.getOperandBundle(LLVMContext::OB_convergencectrl)) {
     auto *Token = Bundle->Inputs[0].get();
     SDValue ConvControlToken = getValue(Token);
@@ -8947,6 +8955,11 @@ void SelectionDAGBuilder::LowerCallTo(const CallBase &CB, SDValue Callee,
     ConvControlToken = getValue(Token);
   }
 
+  GlobalValue *DeactivationSymbol = nullptr;
+  if (auto Bundle = CB.getOperandBundle(LLVMContext::OB_deactivation_symbol)) {
+    DeactivationSymbol = cast<GlobalValue>(Bundle->Inputs[0].get());
+  }
+
   TargetLowering::CallLoweringInfo CLI(DAG);
   CLI.setDebugLoc(getCurSDLoc())
       .setChain(getRoot())
@@ -8956,7 +8969,8 @@ void SelectionDAGBuilder::LowerCallTo(const CallBase &CB, SDValue Callee,
       .setIsPreallocated(
           CB.countOperandBundlesOfType(LLVMContext::OB_preallocated) != 0)
       .setCFIType(CFIType)
-      .setConvergenceControlToken(ConvControlToken);
+      .setConvergenceControlToken(ConvControlToken)
+      .setDeactivationSymbol(DeactivationSymbol);
 
   // Set the pointer authentication info if we have it.
   if (PAI) {
@@ -9572,7 +9586,8 @@ void SelectionDAGBuilder::visitCall(const CallInst &I) {
           {LLVMContext::OB_deopt, LLVMContext::OB_funclet,
            LLVMContext::OB_cfguardtarget, LLVMContext::OB_preallocated,
            LLVMContext::OB_clang_arc_attachedcall, LLVMContext::OB_kcfi,
-           LLVMContext::OB_convergencectrl}))
+           LLVMContext::OB_convergencectrl,
+           LLVMContext::OB_deactivation_symbol}))
     reportFatalUsageError("cannot lower calls with arbitrary operand bundles!");
 
   SDValue Callee = getValue(I.getCalledOperand());
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
diff --git a/llvm/lib/IR/LLVMContext.cpp b/llvm/lib/IR/LLVMContext.cpp
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
diff --git a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
diff --git a/llvm/lib/Target/AArch64/AArch64InstrFormats.td b/llvm/lib/Target/AArch64/AArch64InstrFormats.td
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp b/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
diff --git a/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp b/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp

Original file line number	Diff line number	Diff line change
`@@ -763,6 +763,7 @@ class SelectionDAG {`
`763`	`763`	`int64_t offset = 0, unsigned TargetFlags = 0) {`
`764`	`764`	`return getGlobalAddress(GV, DL, VT, offset, true, TargetFlags);`
`765`	`765`	`}`
	`766`	`+ LLVM_ABI SDValue getDeactivationSymbol(const GlobalValue *GV);`
`766`	`767`	`LLVM_ABI SDValue getFrameIndex(int FI, EVT VT, bool isTarget = false);`
`767`	`768`	`SDValue getTargetFrameIndex(int FI, EVT VT) {`
`768`	`769`	`return getFrameIndex(FI, VT, true);`