Revert r224739: Debug info: Teach SROA how to update debug info for

fragmented variables.

This caused codegen to start crashing when we built somewhat large
programs with debug info and optimizations. 'check-msan' hit in, and
I suspect a bootstrap would as well. I mailed a test case to the
review thread.

llvm-svn: 224750

1 files changed, 1 insertions, 30 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 8fc9a94aefe..a7c1dc14713 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1220,10 +1220,6 @@ class SROA : public FunctionPass {
   /// currently in the promotable queue.
   SetVector<SelectInst *, SmallVector<SelectInst *, 2>> SpeculatableSelects;
 
-  /// Debug intrinsics do not show up as regular uses in the
-  /// IR. This side-table holds the missing use edges.
-  DenseMap<AllocaInst *, DbgDeclareInst *> DbgDeclares;
-
 public:
   SROA(bool RequiresDomTree = true)
       : FunctionPass(ID), RequiresDomTree(RequiresDomTree), C(nullptr),
@@ -3497,27 +3493,6 @@ bool SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
         SliceTy, nullptr, Alignment,
         AI.getName() + ".sroa." + Twine(P.begin() - AS.begin()), &AI);
     ++NumNewAllocas;
-
-    // Migrate debug information from the old alloca to the new alloca
-    // and the individial slices.
-    if (DbgDeclareInst *DbgDecl = DbgDeclares.lookup(&AI)) {
-      DIVariable Var(DbgDecl->getVariable());
-      DIExpression Piece;
-      DIBuilder DIB(*AI.getParent()->getParent()->getParent(),
-                    /*AllowUnresolved*/ false);
-      // Create a piece expression describing the slice, if the new slize is
-      // smaller than the old alloca or the old alloca already was described
-      // with a piece. It would be even better to just compare against the size
-      // of the type described in the debug info, but then we would need to
-      // build an expensive DIRefMap.
-      if (P.size() < DL->getTypeAllocSize(AI.getAllocatedType()) ||
-          DIExpression(DbgDecl->getExpression()).isVariablePiece())
-        Piece = DIB.createPieceExpression(P.beginOffset(), P.size());
-      Instruction *NewDDI = DIB.insertDeclare(NewAI, Var, Piece, &AI);
-      NewDDI->setDebugLoc(DbgDecl->getDebugLoc());
-      DbgDeclares.insert(std::make_pair(NewAI, cast<DbgDeclareInst>(NewDDI)));
-      DeadInsts.insert(DbgDecl);
-    }
   }
 
   DEBUG(dbgs() << "Rewriting alloca partition "
@@ -3851,13 +3826,9 @@ bool SROA::runOnFunction(Function &F) {
 
   BasicBlock &EntryBB = F.getEntryBlock();
   for (BasicBlock::iterator I = EntryBB.begin(), E = std::prev(EntryBB.end());
-       I != E; ++I) {
+       I != E; ++I)
     if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
       Worklist.insert(AI);
-    else if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I))
-      if (auto AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress()))
-        DbgDeclares.insert(std::make_pair(AI, DDI));
-  }
 
   bool Changed = false;
   // A set of deleted alloca instruction pointers which should be removed from