[Cloning] Take another pass at properly cloning debug info

Summary:
In rL302576, DISubprograms gained the constraint that a !dbg attachments to functions must
have a 1:1 mapping to DISubprograms. As part of that change, the function cloning support
was adjusted to attempt to enforce this invariant during cloning. However, there
were several problems with the implementation. Part of these were fixed in rL304079.
However, there was a more fundamental problem with these changes, namely that it
bypasses the matadata value map, causing the cloned metadata to be a mix of metadata
pointing to the new suprogram (where manual code was added to fix those up) and the
old suprogram (where this was not the case). This mismatch could cause a number of
different assertion failures in the DWARF emitter. Some of these are given at
https://github.com/JuliaLang/julia/issues/22069, but some others have been observed
as well. Attempt to rectify this by partially reverting the manual DI metadata fixup,
and instead using the standard value map approach. To retain the desired semantics
of not duplicating the compilation unit and inlined subprograms, explicitly freeze
these in the value map.

Reviewers: dblaikie, aprantl, GorNishanov, echristo

Reviewed By: aprantl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33655

llvm-svn: 304226

1 files changed, 0 insertions, 81 deletions

diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
index b7e3f0c6779..0485fece7c4 100644
--- a/llvm/lib/IR/DebugLoc.cpp
+++ b/llvm/lib/IR/DebugLoc.cpp
@@ -99,87 +99,6 @@ 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)