1 files changed, 81 insertions, 0 deletions
diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
index 0485fece7c4..b7e3f0c6779 100644
--- a/llvm/lib/IR/DebugLoc.cpp
+++ b/llvm/lib/IR/DebugLoc.cpp
@@ -99,6 +99,87 @@ DebugLoc DebugLoc::appendInlinedAt(DebugLoc DL, DILocation *InlinedAt,
   return Last;
 }
 
+/// Reparent \c Scope from \c OrigSP to \c NewSP.
+static DIScope *reparentScope(LLVMContext &Ctx, DIScope *Scope,
+                              DISubprogram *OrigSP, DISubprogram *NewSP,
+                              DenseMap<const MDNode *, MDNode *> &Cache) {
+  SmallVector<DIScope *, 3> ScopeChain;
+  DIScope *Last = NewSP;
+  DIScope *CurScope = Scope;
+  do {
+    if (auto *SP = dyn_cast<DISubprogram>(CurScope)) {
+      // Don't rewrite this scope chain if it doesn't lead to the replaced SP.
+      if (SP != OrigSP)
+        return Scope;
+      Cache.insert({OrigSP, NewSP});
+      break;
+    }
+    if (auto *Found = Cache[CurScope]) {
+      Last = cast<DIScope>(Found);
+      break;
+    }
+    ScopeChain.push_back(CurScope);
+  } while ((CurScope = CurScope->getScope().resolve()));
+
+  // Starting from the top, rebuild the nodes to point to the new inlined-at
+  // location (then rebuilding the rest of the chain behind it) and update the
+  // map of already-constructed inlined-at nodes.
+  for (const DIScope *MD : reverse(ScopeChain)) {
+    if (auto *LB = dyn_cast<DILexicalBlock>(MD))
+      Cache[MD] = Last = DILexicalBlock::getDistinct(
+          Ctx, Last, LB->getFile(), LB->getLine(), LB->getColumn());
+    else if (auto *LB = dyn_cast<DILexicalBlockFile>(MD))
+      Cache[MD] = Last = DILexicalBlockFile::getDistinct(
+          Ctx, Last, LB->getFile(), LB->getDiscriminator());
+    else
+      llvm_unreachable("illegal parent scope");
+  }
+  return Last;
+}
+
+void DebugLoc::reparentDebugInfo(Instruction &I, DISubprogram *OrigSP,
+                                 DISubprogram *NewSP,
+                                 DenseMap<const MDNode *, MDNode *> &Cache) {
+  auto DL = I.getDebugLoc();
+  if (!OrigSP || !NewSP || OrigSP == NewSP || !DL)
+    return;
+
+  // Reparent the debug location.
+  auto &Ctx = I.getContext();
+  DILocation *InlinedAt = DL->getInlinedAt();
+  if (InlinedAt) {
+    while (auto *IA = InlinedAt->getInlinedAt())
+      InlinedAt = IA;
+    auto NewScope =
+        reparentScope(Ctx, InlinedAt->getScope(), OrigSP, NewSP, Cache);
+    InlinedAt =
+        DebugLoc::get(InlinedAt->getLine(), InlinedAt->getColumn(), NewScope);
+  }
+  I.setDebugLoc(
+      DebugLoc::get(DL.getLine(), DL.getCol(),
+                    reparentScope(Ctx, DL->getScope(), OrigSP, NewSP, Cache),
+                    DebugLoc::appendInlinedAt(DL, InlinedAt, Ctx, Cache,
+                                              ReplaceLastInlinedAt)));
+
+  // Fix up debug variables to point to NewSP.
+  auto reparentVar = [&](DILocalVariable *Var) {
+    return DILocalVariable::get(
+        Ctx,
+        cast<DILocalScope>(
+            reparentScope(Ctx, Var->getScope(), OrigSP, NewSP, Cache)),
+        Var->getName(), Var->getFile(), Var->getLine(), Var->getType(),
+        Var->getArg(), Var->getFlags(), Var->getAlignInBits());
+  };
+  if (auto *DbgValue = dyn_cast<DbgValueInst>(&I)) {
+    auto *Var = DbgValue->getVariable();
+    I.setOperand(2, MetadataAsValue::get(Ctx, reparentVar(Var)));
+  } else if (auto *DbgDeclare = dyn_cast<DbgDeclareInst>(&I)) {
+    auto *Var = DbgDeclare->getVariable();
+    I.setOperand(1, MetadataAsValue::get(Ctx, reparentVar(Var)));
+  }
+}
+
+
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD void DebugLoc::dump() const {
   if (!Loc)