[NFC] [HWASan] factor out debug record annotation (#90252)

This will also be used by stack MTE

Author: fmayer

llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h

@@ -86,6 +86,8 @@ Value *getFP(IRBuilder<> &IRB);
 Value *getPC(const Triple &TargetTriple, IRBuilder<> &IRB);
 Value *getAndroidSlotPtr(IRBuilder<> &IRB, int Slot);
 
+void annotateDebugRecords(AllocaInfo &Info, unsigned int Tag);
+
 } // namespace memtag
 } // namespace llvm
 

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

@@ -1385,14 +1385,6 @@ bool HWAddressSanitizer::instrumentLandingPads(
   return true;
 }
 
-static DbgAssignIntrinsic *DynCastToDbgAssign(DbgVariableIntrinsic *DVI) {
-  return dyn_cast<DbgAssignIntrinsic>(DVI);
-}
-
-static DbgVariableRecord *DynCastToDbgAssign(DbgVariableRecord *DVR) {
-  return DVR->isDbgAssign() ? DVR : nullptr;
-}
-
 bool HWAddressSanitizer::instrumentStack(memtag::StackInfo &SInfo,
                                          Value *StackTag, Value *UARTag,
                                          const DominatorTree &DT,
@@ -1448,28 +1440,7 @@ bool HWAddressSanitizer::instrumentStack(memtag::StackInfo &SInfo,
              !memtag::isLifetimeIntrinsic(User);
     });
 
-    // Helper utility for adding DW_OP_LLVM_tag_offset to debug-info records,
-    // abstracted over whether they're intrinsic-stored or DbgVariableRecord
-    // stored.
-    auto AnnotateDbgRecord = [&](auto *DPtr) {
-      // Prepend "tag_offset, N" to the dwarf expression.
-      // Tag offset logically applies to the alloca pointer, and it makes sense
-      // to put it at the beginning of the expression.
-      SmallVector<uint64_t, 8> NewOps = {dwarf::DW_OP_LLVM_tag_offset,
-                                         retagMask(N)};
-      for (size_t LocNo = 0; LocNo < DPtr->getNumVariableLocationOps(); ++LocNo)
-        if (DPtr->getVariableLocationOp(LocNo) == AI)
-          DPtr->setExpression(DIExpression::appendOpsToArg(
-              DPtr->getExpression(), NewOps, LocNo));
-      if (auto *DAI = DynCastToDbgAssign(DPtr)) {
-        if (DAI->getAddress() == AI)
-          DAI->setAddressExpression(DIExpression::prependOpcodes(
-              DAI->getAddressExpression(), NewOps));
-      }
-    };
-
-    llvm::for_each(Info.DbgVariableIntrinsics, AnnotateDbgRecord);
-    llvm::for_each(Info.DbgVariableRecords, AnnotateDbgRecord);
+    memtag::annotateDebugRecords(Info, retagMask(N));
 
     auto TagEnd = [&](Instruction *Node) {
       IRB.SetInsertPoint(Node);

llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp

@@ -17,6 +17,7 @@
 #include "llvm/Analysis/PostDominators.h"
 #include "llvm/Analysis/StackSafetyAnalysis.h"
 #include "llvm/Analysis/ValueTracking.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/IntrinsicInst.h"
@@ -283,5 +284,37 @@ Value *getAndroidSlotPtr(IRBuilder<> &IRB, int Slot) {
                                 IRB.CreateCall(ThreadPointerFunc), 8 * Slot);
 }
 
+static DbgAssignIntrinsic *DynCastToDbgAssign(DbgVariableIntrinsic *DVI) {
+  return dyn_cast<DbgAssignIntrinsic>(DVI);
+}
+
+static DbgVariableRecord *DynCastToDbgAssign(DbgVariableRecord *DVR) {
+  return DVR->isDbgAssign() ? DVR : nullptr;
+}
+
+void annotateDebugRecords(AllocaInfo &Info, unsigned int Tag) {
+  // Helper utility for adding DW_OP_LLVM_tag_offset to debug-info records,
+  // abstracted over whether they're intrinsic-stored or DbgVariableRecord
+  // stored.
+  auto AnnotateDbgRecord = [&](auto *DPtr) {
+    // Prepend "tag_offset, N" to the dwarf expression.
+    // Tag offset logically applies to the alloca pointer, and it makes sense
+    // to put it at the beginning of the expression.
+    SmallVector<uint64_t, 8> NewOps = {dwarf::DW_OP_LLVM_tag_offset, Tag};
+    for (size_t LocNo = 0; LocNo < DPtr->getNumVariableLocationOps(); ++LocNo)
+      if (DPtr->getVariableLocationOp(LocNo) == Info.AI)
+        DPtr->setExpression(
+            DIExpression::appendOpsToArg(DPtr->getExpression(), NewOps, LocNo));
+    if (auto *DAI = DynCastToDbgAssign(DPtr)) {
+      if (DAI->getAddress() == Info.AI)
+        DAI->setAddressExpression(
+            DIExpression::prependOpcodes(DAI->getAddressExpression(), NewOps));
+    }
+  };
+
+  llvm::for_each(Info.DbgVariableIntrinsics, AnnotateDbgRecord);
+  llvm::for_each(Info.DbgVariableRecords, AnnotateDbgRecord);
+}
+
 } // namespace memtag
 } // namespace llvm