Reapplying r281895 (and follow-up r281964) after fixing pr30468.

The additional fix is:

When adding debug information to a lowered phi node in mem2reg
check that we have a valid insertion point after the phi for adding
the debug information.

This change addresses the issue in pr30468 where a lowered phi was
added before a catchswitch and no debug information should be added
after the phi in this case.

Differential Revision: https://reviews.llvm.org/D24797

llvm-svn: 282155

llvm/include/llvm/Transforms/Utils/Local.h

@@ -32,6 +32,7 @@ class BranchInst;
 class Instruction;
 class CallInst;
 class DbgDeclareInst;
+class DbgValueInst;
 class StoreInst;
 class LoadInst;
 class Value;
@@ -48,6 +49,8 @@ class LazyValueInfo;
 
 template<typename T> class SmallVectorImpl;
 
+typedef SmallVector<DbgValueInst *, 1> DbgValueList;
+
 //===----------------------------------------------------------------------===//
 //  Local constant propagation.
 //
@@ -255,14 +258,19 @@ Value *EmitGEPOffset(IRBuilderTy *Builder, const DataLayout &DL, User *GEP,
 
 /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
 /// that has an associated llvm.dbg.decl intrinsic.
-bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+void ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                      StoreInst *SI, DIBuilder &Builder);
 
 /// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
 /// that has an associated llvm.dbg.decl intrinsic.
-bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+void ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                      LoadInst *LI, DIBuilder &Builder);
 
+/// Inserts a llvm.dbg.value intrinsic after a phi of an alloca'd value
+/// that has an associated llvm.dbg.decl intrinsic.
+void ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+                                     PHINode *LI, DIBuilder &Builder);
+
 /// Lowers llvm.dbg.declare intrinsics into appropriate set of
 /// llvm.dbg.value intrinsics.
 bool LowerDbgDeclare(Function &F);
@@ -270,6 +278,9 @@ bool LowerDbgDeclare(Function &F);
 /// Finds the llvm.dbg.declare intrinsic corresponding to an alloca, if any.
 DbgDeclareInst *FindAllocaDbgDeclare(Value *V);
 
+/// Finds the llvm.dbg.value intrinsics corresponding to an alloca, if any.
+void FindAllocaDbgValues(DbgValueList &DbgValues, Value *V);
+
 /// Replaces llvm.dbg.declare instruction when the address it describes
 /// is replaced with a new value. If Deref is true, an additional DW_OP_deref is
 /// prepended to the expression. If Offset is non-zero, a constant displacement

llvm/lib/Transforms/Utils/Local.cpp

@@ -1053,9 +1053,27 @@ static bool LdStHasDebugValue(DILocalVariable *DIVar, DIExpression *DIExpr,
   return false;
 }
 
+/// See if there is a dbg.value intrinsic for DIVar for the PHI node.
+static bool PhiHasDebugValue(DILocalVariable *DIVar, 
+                             DIExpression *DIExpr,
+                             PHINode *APN) {
+  // Since we can't guarantee that the original dbg.declare instrinsic
+  // is removed by LowerDbgDeclare(), we need to make sure that we are
+  // not inserting the same dbg.value intrinsic over and over.
+  DbgValueList DbgValues;
+  FindAllocaDbgValues(DbgValues, APN);
+  for (auto DVI : DbgValues) {
+    assert (DVI->getValue() == APN);
+    assert (DVI->getOffset() == 0);
+    if ((DVI->getVariable() == DIVar) && (DVI->getExpression() == DIExpr))
+      return true;
+  }
+  return false;
+}
+
 /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
 /// that has an associated llvm.dbg.decl intrinsic.
-bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                            StoreInst *SI, DIBuilder &Builder) {
   auto *DIVar = DDI->getVariable();
   auto *DIExpr = DDI->getExpression();
@@ -1096,19 +1114,18 @@ bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
   } else if (!LdStHasDebugValue(DIVar, DIExpr, SI))
     Builder.insertDbgValueIntrinsic(SI->getOperand(0), 0, DIVar, DIExpr,
                                     DDI->getDebugLoc(), SI);
-  return true;
 }
 
 /// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
 /// that has an associated llvm.dbg.decl intrinsic.
-bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                            LoadInst *LI, DIBuilder &Builder) {
   auto *DIVar = DDI->getVariable();
   auto *DIExpr = DDI->getExpression();
   assert(DIVar && "Missing variable");
 
   if (LdStHasDebugValue(DIVar, DIExpr, LI))
-    return true;
+    return;
 
   // We are now tracking the loaded value instead of the address. In the
   // future if multi-location support is added to the IR, it might be
@@ -1117,7 +1134,26 @@ bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
   Instruction *DbgValue = Builder.insertDbgValueIntrinsic(
       LI, 0, DIVar, DIExpr, DDI->getDebugLoc(), (Instruction *)nullptr);
   DbgValue->insertAfter(LI);
-  return true;
+}
+
+/// Inserts a llvm.dbg.value intrinsic after a phi 
+/// that has an associated llvm.dbg.decl intrinsic.
+void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
+                                           PHINode *APN, DIBuilder &Builder) {
+  auto *DIVar = DDI->getVariable();
+  auto *DIExpr = DDI->getExpression();
+  assert(DIVar && "Missing variable");
+
+  if (PhiHasDebugValue(DIVar, DIExpr, APN))
+    return;
+
+  auto BB = APN->getParent();
+  auto InsertionPt = BB->getFirstInsertionPt();
+  if (InsertionPt != BB->end()) {
+    Instruction *DbgValue = Builder.insertDbgValueIntrinsic(
+        APN, 0, DIVar, DIExpr, DDI->getDebugLoc(), (Instruction *)nullptr);
+    DbgValue->insertBefore(&*InsertionPt);
+  }
 }
 
 /// Determine whether this alloca is either a VLA or an array.
@@ -1187,6 +1223,16 @@ DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
   return nullptr;
 }
 
+/// FindAllocaDbgValues - Finds the llvm.dbg.value intrinsics describing the
+/// alloca 'V', if any.
+void llvm::FindAllocaDbgValues(DbgValueList &DbgValues, Value *V) {
+  if (auto *L = LocalAsMetadata::getIfExists(V))
+    if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L))
+      for (User *U : MDV->users())
+        if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(U))
+          DbgValues.push_back(DVI);
+}
+
 static void DIExprAddDeref(SmallVectorImpl<uint64_t> &Expr) {
   Expr.push_back(dwarf::DW_OP_deref);
 }

llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp

@@ -907,6 +907,8 @@ NextIteration:
 
         // The currently active variable for this block is now the PHI.
         IncomingVals[AllocaNo] = APN;
+        if (DbgDeclareInst *DDI = AllocaDbgDeclares[AllocaNo])
+          ConvertDebugDeclareToDebugValue(DDI, APN, DIB);
 
         // Get the next phi node.
         ++PNI;