Merge pull request #85120 from kavon/6.2-fspl-debuginfo-rdar163281183

[6.2] DebugInfo: fix FSPL SILLocation assertion issue

Author: kavon

lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp

@@ -434,10 +434,23 @@ void TypeTreeLeafTypeRange::constructFilteredProjections(
         callback) {
   auto *fn = insertPt->getFunction();
   SILType type = value->getType();
-  auto loc =
-      (insertPt->getLoc().getKind() != SILLocation::ArtificialUnreachableKind)
-          ? insertPt->getLoc()
-          : RegularLocation::getAutoGeneratedLocation();
+
+  // Create a debug location appropriate for synthesizing projection
+  // instructions that satisfy `SILInstruction::verifyDebugInfo`, while
+  // trying to preserve debug info when it's valid to do so.
+  auto projectionLocFrom = [](SILInstruction *orig) -> SILLocation {
+    auto loc = orig->getLoc();
+    switch (loc.getKind()) {
+    case SILLocation::ReturnKind:
+    case SILLocation::ImplicitReturnKind:
+    case SILLocation::ArtificialUnreachableKind:
+      return RegularLocation::getDebugOnlyLocation(loc, orig->getModule());
+
+    default:
+      return loc;
+    }
+  };
+  SILLocation loc = projectionLocFrom(insertPt);
 
   PRUNED_LIVENESS_LOG(llvm::dbgs() << "ConstructFilteredProjection. Bv: "
                           << filterBitVector << '\n');