[SILVerifier] Add detection of conflicting debug variables

(cherry picked from commit fed03cc)

Author: Snowy1803

include/swift/SIL/SILLocation.h

@@ -773,4 +773,26 @@ class SILDebugLocation {
 
 } // end swift namespace
 
+namespace llvm {
+
+template<>
+struct DenseMapInfo<swift::SILLocation> {
+  static inline swift::SILLocation getEmptyKey() {
+    return swift::SILLocation::invalid();
+  }
+  static inline swift::SILLocation getTombstoneKey() {
+    return swift::SILLocation::invalid().asAutoGenerated();
+  }
+  static inline unsigned getHashValue(swift::SILLocation id) {
+    if (id.isFilenameAndLocation())
+      return hash_value(id);
+    return 0;
+  }
+  static bool isEqual(swift::SILLocation a, swift::SILLocation b) {
+    return a == b;
+  }
+};
+
+} // end namespace llvm
+
 #endif

lib/SIL/Verifier/SILVerifier.cpp

@@ -820,6 +820,11 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
   /// fix this for each of its uses.
   llvm::DenseSet<std::pair<SILValue, const Operand *>> isOperandInValueUsesCache;
 
+  /// Used for checking all equivalent variables have the same type
+  using VarID = std::tuple<const SILDebugScope *, llvm::StringRef, SILLocation>;
+  llvm::DenseMap<VarID, SILType> DebugVarTypes;
+  llvm::StringSet<> VarNames;
+
   /// Check that this operand appears in the use-chain of the value it uses.
   bool isOperandInValueUses(const Operand *operand) {
     SILValue value = operand->get();
@@ -1520,6 +1525,26 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
               "Scope of the debug variable should have the same parent function"
               " as that of instruction.");
 
+    // Check that every var info with the same name, scope and location, refer
+    // to a variable of the same type
+    llvm::StringRef UniqueName = VarNames.insert(varInfo->Name).first->getKey();
+    if (!varInfo->Loc)
+      varInfo->Loc = inst->getLoc();
+    if (!varInfo->Loc)
+      varInfo->Loc = SILLocation::invalid();
+    VarID Key(varInfo->Scope ? varInfo->Scope : debugScope,
+              UniqueName, *varInfo->Loc);
+    auto CachedVar = DebugVarTypes.insert({Key, DebugVarTy});
+    if (!CachedVar.second) {
+      auto lhs = CachedVar.first->second.removingMoveOnlyWrapper();
+      auto rhs = DebugVarTy.removingMoveOnlyWrapper();
+
+      require(lhs == rhs ||
+              (lhs.isAddress() && lhs.getObjectType() == rhs) ||
+              (DebugVarTy.isAddress() && lhs == rhs.getObjectType()),
+              "Two variables with different type but same scope!");
+    }
+
     // Check debug info expression
     if (const auto &DIExpr = varInfo->DIExpr) {
       bool HasFragment = false;