[DebugInfo] [AutoDiff] Strip var info for tangents

Author: Snowy1803

lib/SILOptimizer/Differentiation/JVPCloner.cpp

@@ -1000,9 +1000,16 @@ class JVPCloner::Implementation final
   ///    Tangent: tan[y] = alloc_stack $T.Tangent
   CLONE_AND_EMIT_TANGENT(AllocStack, asi) {
     auto &diffBuilder = getDifferentialBuilder();
+    auto varInfo = asi->getVarInfo();
+    if (varInfo) {
+      // This is a new variable, it shouldn't keep the old scope, type, etc.
+      varInfo->Type = {};
+      varInfo->DIExpr = {};
+      varInfo->Loc = {};
+      varInfo->Scope = nullptr;
+    }
     auto *mappedAllocStackInst = diffBuilder.createAllocStack(
-        asi->getLoc(), getRemappedTangentType(asi->getElementType()),
-        asi->getVarInfo());
+        asi->getLoc(), getRemappedTangentType(asi->getElementType()), varInfo);
     setTangentBuffer(asi->getParent(), asi, mappedAllocStackInst);
   }
 

lib/SILOptimizer/Differentiation/PullbackCloner.cpp

@@ -665,6 +665,11 @@ class PullbackCloner::Implementation final
             }
             adjNameStream << " (scope #" << origBB->getDebugID() << ")";
             dv.Name = adjName;
+            // We have no meaningful debug location, and the type is different.
+            dv.Scope = nullptr;
+            dv.Loc = {};
+            dv.Type = {};
+            dv.DIExpr = {};
             return dv;
           }));
     return (insertion.first->getSecond() = newBuf);