[llvm] [DebugInfo][RemoveDIs] Add local-utility plumbing for DPValues (PR #72276)

[Jeremy Morse via llvm-commits]

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@@ -1878,44 +2041,59 @@ bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
   return !DbgDeclares.empty();
 }
 
-static void replaceOneDbgValueForAlloca(DbgValueInst *DVI, Value *NewAddress,
+static void updateOneDbgValueForAlloca(const DebugLoc &Loc, DILocalVariable *DIVar, DIExpression *DIExpr,
+                                        Value *NewAddress, DbgValueInst *DVI, DPValue *DPV,
                                         DIBuilder &Builder, int Offset) {
-  const DebugLoc &Loc = DVI->getDebugLoc();
-  auto *DIVar = DVI->getVariable();
-  auto *DIExpr = DVI->getExpression();
   assert(DIVar && "Missing variable");
 
-  // This is an alloca-based llvm.dbg.value. The first thing it should do with
+  // This is an alloca-based dbg.value/DPValue. The first thing it should do with
   // the alloca pointer is dereference it. Otherwise we don't know how to handle
   // it and give up.
   if (!DIExpr || DIExpr->getNumElements() < 1 ||
       DIExpr->getElement(0) != dwarf::DW_OP_deref)
     return;
 
   // Insert the offset before the first deref.
-  // We could just change the offset argument of dbg.value, but it's unsigned...
   if (Offset)
     DIExpr = DIExpression::prepend(DIExpr, 0, Offset);
 
-  Builder.insertDbgValueIntrinsic(NewAddress, DIVar, DIExpr, Loc, DVI);
-  DVI->eraseFromParent();
+  if (DVI) {
+    DVI->setExpression(DIExpr);
+    DVI->replaceVariableLocationOp(0u, NewAddress);
+  } else {
+    assert(DPV);
+    DPV->setExpression(DIExpr);
+    DPV->replaceVariableLocationOp(0u, NewAddress);
+  }
 }
 
 void llvm::replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
                                     DIBuilder &Builder, int Offset) {
-  if (auto *L = LocalAsMetadata::getIfExists(AI))
-    if (auto *MDV = MetadataAsValue::getIfExists(AI->getContext(), L))
-      for (Use &U : llvm::make_early_inc_range(MDV->uses()))
-        if (auto *DVI = dyn_cast<DbgValueInst>(U.getUser()))
-          replaceOneDbgValueForAlloca(DVI, NewAllocaAddress, Builder, Offset);
+  SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
+  SmallVector<DPValue *, 1> DPUsers;
+  findDbgUsers(DbgUsers, AI, &DPUsers);
+
+  // Attempt to replace dbg.values that use this alloca.
+  for (auto *DV : DbgUsers) {
+    auto *DVI = dyn_cast<DbgValueInst>(DV);
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jmorse wrote:

Sounds like a plan, updated. On that basis, I haven't fiddled with the next comment, and will get findDbgValues to do the filtering in another patch.

https://github.com/llvm/llvm-project/pull/72276