[DebugInfo][RemoveDIs] Prevent duplicate DPValues from being returned by findDbgIntrinsics (#82764)

Fixes the error described here:
https://github.com/llvm/llvm-project/commit/a93a4ec7dd205b965ee5597314bb376520cd736c#commitcomment-138965199

The function `findDbgIntrinsics` is used to return a list of debug
intrinsics and DPValues that use a given value, with the intent that no
duplicates are returned in either list. For DPValues, we've guarded
against DPValues that use a value multiple times as part of a DIArgList,
but we have not guarded against DPValues that use a value multiple times
as separate operands (currently only possible for `dbg_assign`s,
something I missed in my implementation of that type!). This patch adds
a guard, and also updates a test to cover this case.

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index e044ab3..1f3ff22 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -99,8 +99,8 @@ static void findDbgIntrinsics(SmallVectorImpl<IntrinsicT *> &Result, Value *V,
   SmallPtrSet<DPValue *, 4> EncounteredDPValues;
 
   /// Append IntrinsicT users of MetadataAsValue(MD).
-  auto AppendUsers = [&Ctx, &EncounteredIntrinsics, &Result,
-                      DPValues](Metadata *MD) {
+  auto AppendUsers = [&Ctx, &EncounteredIntrinsics, &EncounteredDPValues,
+                      &Result, DPValues](Metadata *MD) {
     if (auto *MDV = MetadataAsValue::getIfExists(Ctx, MD)) {
       for (User *U : MDV->users())
         if (IntrinsicT *DVI = dyn_cast<IntrinsicT>(U))
@@ -113,7 +113,8 @@ static void findDbgIntrinsics(SmallVectorImpl<IntrinsicT *> &Result, Value *V,
     if (LocalAsMetadata *L = dyn_cast<LocalAsMetadata>(MD)) {
       for (DPValue *DPV : L->getAllDPValueUsers()) {
         if (Type == DPValue::LocationType::Any || DPV->getType() == Type)
-          DPValues->push_back(DPV);
+          if (EncounteredDPValues.insert(DPV).second)
+            DPValues->push_back(DPV);
       }
     }
   };