[CIR] Handle expression with cleanups (#151600)

This adds code to handle expressions with cleanup, including
materializing a temporary object for the expression.

Author: andykaylor

clang/include/clang/CIR/MissingFeatures.h

@@ -223,6 +223,7 @@ struct MissingFeatures {
   static bool lowerAggregateLoadStore() { return false; }
   static bool lowerModeOptLevel() { return false; }
   static bool maybeHandleStaticInExternC() { return false; }
+  static bool mergeAllConstants() { return false; }
   static bool metaDataNode() { return false; }
   static bool moduleNameHash() { return false; }
   static bool msabi() { return false; }

clang/lib/CIR/CodeGen/Address.h

@@ -101,6 +101,17 @@ class Address {
   }
 
   clang::CharUnits getAlignment() const { return alignment; }
+
+  /// Get the operation which defines this address.
+  mlir::Operation *getDefiningOp() const {
+    if (!isValid())
+      return nullptr;
+    return getPointer().getDefiningOp();
+  }
+
+  template <typename OpTy> OpTy getDefiningOp() const {
+    return mlir::dyn_cast_or_null<OpTy>(getDefiningOp());
+  }
 };
 
 } // namespace clang::CIRGen

clang/lib/CIR/CodeGen/CIRGenDecl.cpp

@@ -653,6 +653,27 @@ void CIRGenFunction::emitNullabilityCheck(LValue lhs, mlir::Value rhs,
   assert(!cir::MissingFeatures::sanitizers());
 }
 
+namespace {
+struct DestroyObject final : EHScopeStack::Cleanup {
+  DestroyObject(Address addr, QualType type,
+                CIRGenFunction::Destroyer *destroyer)
+      : addr(addr), type(type), destroyer(destroyer) {}
+
+  Address addr;
+  QualType type;
+  CIRGenFunction::Destroyer *destroyer;
+
+  void emit(CIRGenFunction &cgf) override {
+    cgf.emitDestroy(addr, type, destroyer);
+  }
+};
+} // namespace
+
+void CIRGenFunction::pushDestroy(CleanupKind cleanupKind, Address addr,
+                                 QualType type, Destroyer *destroyer) {
+  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, destroyer);
+}
+
 /// Destroys all the elements of the given array, beginning from last to first.
 /// The array cannot be zero-length.
 ///
@@ -740,22 +761,6 @@ CIRGenFunction::getDestroyer(QualType::DestructionKind kind) {
   llvm_unreachable("Unknown DestructionKind");
 }
 
-namespace {
-struct DestroyObject final : EHScopeStack::Cleanup {
-  DestroyObject(Address addr, QualType type,
-                CIRGenFunction::Destroyer *destroyer)
-      : addr(addr), type(type), destroyer(destroyer) {}
-
-  Address addr;
-  QualType type;
-  CIRGenFunction::Destroyer *destroyer;
-
-  void emit(CIRGenFunction &cgf) override {
-    cgf.emitDestroy(addr, type, destroyer);
-  }
-};
-} // namespace
-
 /// Enter a destroy cleanup for the given local variable.
 void CIRGenFunction::emitAutoVarTypeCleanup(
     const CIRGenFunction::AutoVarEmission &emission,

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -1105,6 +1105,151 @@ void CIRGenFunction::emitAnyExprToMem(const Expr *e, Address ___location,
   llvm_unreachable("bad evaluation kind");
 }
 
+static Address createReferenceTemporary(CIRGenFunction &cgf,
+                                        const MaterializeTemporaryExpr *m,
+                                        const Expr *inner) {
+  // TODO(cir): cgf.getTargetHooks();
+  switch (m->getStorageDuration()) {
+  case SD_FullExpression:
+  case SD_Automatic: {
+    QualType ty = inner->getType();
+
+    assert(!cir::MissingFeatures::mergeAllConstants());
+
+    // The temporary memory should be created in the same scope as the extending
+    // declaration of the temporary materialization expression.
+    cir::AllocaOp extDeclAlloca;
+    if (const ValueDecl *extDecl = m->getExtendingDecl()) {
+      auto extDeclAddrIter = cgf.localDeclMap.find(extDecl);
+      if (extDeclAddrIter != cgf.localDeclMap.end())
+        extDeclAlloca = extDeclAddrIter->second.getDefiningOp<cir::AllocaOp>();
+    }
+    mlir::OpBuilder::InsertPoint ip;
+    if (extDeclAlloca)
+      ip = {extDeclAlloca->getBlock(), extDeclAlloca->getIterator()};
+    return cgf.createMemTemp(ty, cgf.getLoc(m->getSourceRange()),
+                             cgf.getCounterRefTmpAsString(), /*alloca=*/nullptr,
+                             ip);
+  }
+  case SD_Thread:
+  case SD_Static: {
+    cgf.cgm.errorNYI(
+        m->getSourceRange(),
+        "createReferenceTemporary: static/thread storage duration");
+    return Address::invalid();
+  }
+
+  case SD_Dynamic:
+    llvm_unreachable("temporary can't have dynamic storage duration");
+  }
+  llvm_unreachable("unknown storage duration");
+}
+
+static void pushTemporaryCleanup(CIRGenFunction &cgf,
+                                 const MaterializeTemporaryExpr *m,
+                                 const Expr *e, Address referenceTemporary) {
+  // Objective-C++ ARC:
+  //   If we are binding a reference to a temporary that has ownership, we
+  //   need to perform retain/release operations on the temporary.
+  //
+  // FIXME(ogcg): This should be looking at e, not m.
+  if (m->getType().getObjCLifetime()) {
+    cgf.cgm.errorNYI(e->getSourceRange(), "pushTemporaryCleanup: ObjCLifetime");
+    return;
+  }
+
+  CXXDestructorDecl *referenceTemporaryDtor = nullptr;
+  if (const clang::RecordType *rt = e->getType()
+                                        ->getBaseElementTypeUnsafe()
+                                        ->getAs<clang::RecordType>()) {
+    // Get the destructor for the reference temporary.
+    auto *classDecl = cast<CXXRecordDecl>(rt->getDecl());
+    if (!classDecl->hasTrivialDestructor())
+      referenceTemporaryDtor = classDecl->getDestructor();
+  }
+
+  if (!referenceTemporaryDtor)
+    return;
+
+  // Call the destructor for the temporary.
+  switch (m->getStorageDuration()) {
+  case SD_Static:
+  case SD_Thread:
+    cgf.cgm.errorNYI(e->getSourceRange(),
+                     "pushTemporaryCleanup: static/thread storage duration");
+    return;
+
+  case SD_FullExpression:
+    cgf.pushDestroy(NormalAndEHCleanup, referenceTemporary, e->getType(),
+                    CIRGenFunction::destroyCXXObject);
+    break;
+
+  case SD_Automatic:
+    cgf.cgm.errorNYI(e->getSourceRange(),
+                     "pushTemporaryCleanup: automatic storage duration");
+    break;
+
+  case SD_Dynamic:
+    llvm_unreachable("temporary cannot have dynamic storage duration");
+  }
+}
+
+LValue CIRGenFunction::emitMaterializeTemporaryExpr(
+    const MaterializeTemporaryExpr *m) {
+  const Expr *e = m->getSubExpr();
+
+  assert((!m->getExtendingDecl() || !isa<VarDecl>(m->getExtendingDecl()) ||
+          !cast<VarDecl>(m->getExtendingDecl())->isARCPseudoStrong()) &&
+         "Reference should never be pseudo-strong!");
+
+  // FIXME: ideally this would use emitAnyExprToMem, however, we cannot do so
+  // as that will cause the lifetime adjustment to be lost for ARC
+  auto ownership = m->getType().getObjCLifetime();
+  if (ownership != Qualifiers::OCL_None &&
+      ownership != Qualifiers::OCL_ExplicitNone) {
+    cgm.errorNYI(e->getSourceRange(),
+                 "emitMaterializeTemporaryExpr: ObjCLifetime");
+    return {};
+  }
+
+  SmallVector<const Expr *, 2> commaLHSs;
+  SmallVector<SubobjectAdjustment, 2> adjustments;
+  e = e->skipRValueSubobjectAdjustments(commaLHSs, adjustments);
+
+  for (const Expr *ignored : commaLHSs)
+    emitIgnoredExpr(ignored);
+
+  if (isa<OpaqueValueExpr>(e)) {
+    cgm.errorNYI(e->getSourceRange(),
+                 "emitMaterializeTemporaryExpr: OpaqueValueExpr");
+    return {};
+  }
+
+  // Create and initialize the reference temporary.
+  Address object = createReferenceTemporary(*this, m, e);
+
+  if (auto var = object.getPointer().getDefiningOp<cir::GlobalOp>()) {
+    // TODO(cir): add something akin to stripPointerCasts() to ptr above
+    cgm.errorNYI(e->getSourceRange(), "emitMaterializeTemporaryExpr: GlobalOp");
+    return {};
+  } else {
+    assert(!cir::MissingFeatures::emitLifetimeMarkers());
+    emitAnyExprToMem(e, object, Qualifiers(), /*isInitializer=*/true);
+  }
+  pushTemporaryCleanup(*this, m, e, object);
+
+  // Perform derived-to-base casts and/or field accesses, to get from the
+  // temporary object we created (and, potentially, for which we extended
+  // the lifetime) to the subobject we're binding the reference to.
+  if (!adjustments.empty()) {
+    cgm.errorNYI(e->getSourceRange(),
+                 "emitMaterializeTemporaryExpr: Adjustments");
+    return {};
+  }
+
+  return makeAddrLValue(object, m->getType(), AlignmentSource::Decl);
+}
+
 LValue CIRGenFunction::emitCompoundLiteralLValue(const CompoundLiteralExpr *e) {
   if (e->isFileScope()) {
     cgm.errorNYI(e->getSourceRange(), "emitCompoundLiteralLValue: FileScope");

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -626,6 +626,7 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
 
   mlir::Value VisitCXXThisExpr(CXXThisExpr *te) { return cgf.loadCXXThis(); }
 
+  mlir::Value VisitExprWithCleanups(ExprWithCleanups *e);
   mlir::Value VisitCXXNewExpr(const CXXNewExpr *e) {
     return cgf.emitCXXNewExpr(e);
   }
@@ -1217,6 +1218,29 @@ mlir::Value ScalarExprEmitter::emitCompoundAssign(
   return emitLoadOfLValue(lhs, e->getExprLoc());
 }
 
+mlir::Value ScalarExprEmitter::VisitExprWithCleanups(ExprWithCleanups *e) {
+  mlir::Location scopeLoc = cgf.getLoc(e->getSourceRange());
+  mlir::OpBuilder &builder = cgf.builder;
+
+  auto scope = cir::ScopeOp::create(
+      builder, scopeLoc,
+      /*scopeBuilder=*/
+      [&](mlir::OpBuilder &b, mlir::Type &yieldTy, mlir::Location loc) {
+        CIRGenFunction::LexicalScope lexScope{cgf, loc,
+                                              builder.getInsertionBlock()};
+        mlir::Value scopeYieldVal = Visit(e->getSubExpr());
+        if (scopeYieldVal) {
+          // Defend against dominance problems caused by jumps out of expression
+          // evaluation through the shared cleanup block.
+          lexScope.forceCleanup();
+          cir::YieldOp::create(builder, loc, scopeYieldVal);
+          yieldTy = scopeYieldVal.getType();
+        }
+      });
+
+  return scope.getNumResults() > 0 ? scope->getResult(0) : nullptr;
+}
+
 } // namespace
 
 LValue

clang/lib/CIR/CodeGen/CIRGenFunction.cpp

@@ -800,6 +800,8 @@ LValue CIRGenFunction::emitLValue(const Expr *e) {
   case Expr::CXXDynamicCastExprClass:
   case Expr::ImplicitCastExprClass:
     return emitCastLValue(cast<CastExpr>(e));
+  case Expr::MaterializeTemporaryExprClass:
+    return emitMaterializeTemporaryExpr(cast<MaterializeTemporaryExpr>(e));
   }
 }
 
@@ -810,6 +812,10 @@ static std::string getVersionedTmpName(llvm::StringRef name, unsigned cnt) {
   return std::string(out.str());
 }
 
+std::string CIRGenFunction::getCounterRefTmpAsString() {
+  return getVersionedTmpName("ref.tmp", counterRefTmp++);
+}
+
 std::string CIRGenFunction::getCounterAggTmpAsString() {
   return getVersionedTmpName("agg.tmp", counterAggTmp++);
 }

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -325,7 +325,9 @@ class CIRGenFunction : public CIRGenTypeCache {
   };
 
   /// Hold counters for incrementally naming temporaries
+  unsigned counterRefTmp = 0;
   unsigned counterAggTmp = 0;
+  std::string getCounterRefTmpAsString();
   std::string getCounterAggTmpAsString();
 
   /// Helpers to convert Clang's SourceLocation to a MLIR Location.
@@ -604,6 +606,19 @@ class CIRGenFunction : public CIRGenTypeCache {
   void popCleanupBlocks(size_t oldCleanupStackDepth);
   void popCleanupBlock();
 
+  /// Push a cleanup to be run at the end of the current full-expression.  Safe
+  /// against the possibility that we're currently inside a
+  /// conditionally-evaluated expression.
+  template <class T, class... As>
+  void pushFullExprCleanup(CleanupKind kind, As... a) {
+    // If we're not in a conditional branch, or if none of the
+    // arguments requires saving, then use the unconditional cleanup.
+    if (!isInConditionalBranch())
+      return ehStack.pushCleanup<T>(kind, a...);
+
+    cgm.errorNYI("pushFullExprCleanup in conditional branch");
+  }
+
   /// Enters a new scope for capturing cleanups, all of which
   /// will be executed once the scope is exited.
   class RunCleanupsScope {
@@ -619,6 +634,7 @@ class CIRGenFunction : public CIRGenTypeCache {
   protected:
     CIRGenFunction &cgf;
 
+  public:
     /// Enter a new cleanup scope.
     explicit RunCleanupsScope(CIRGenFunction &cgf)
         : performCleanup(true), cgf(cgf) {
@@ -801,6 +817,9 @@ class CIRGenFunction : public CIRGenTypeCache {
 
   static Destroyer destroyCXXObject;
 
+  void pushDestroy(CleanupKind kind, Address addr, QualType type,
+                   Destroyer *destroyer);
+
   Destroyer *getDestroyer(clang::QualType::DestructionKind kind);
 
   /// ----------------------
@@ -1139,6 +1158,8 @@ class CIRGenFunction : public CIRGenTypeCache {
                                           const clang::FieldDecl *field,
                                           llvm::StringRef fieldName);
 
+  LValue emitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *e);
+
   LValue emitMemberExpr(const MemberExpr *e);
 
   /// Given an expression with a pointer type, emit the value and compute our

clang/test/CIR/CodeGen/cleanup.cpp

@@ -81,3 +81,17 @@ void test_cleanup_nested() {
 // CHECK:   }
 // CHECK:   cir.call @_ZN5StrukD1Ev(%[[OUTER]]) nothrow : (!cir.ptr<!rec_Struk>) -> ()
 // CHECK:   cir.return
+
+void use_ref(const Struk &);
+
+void test_expr_with_cleanup() {
+  use_ref(Struk{});
+}
+
+// CHECK: cir.func{{.*}} @_Z22test_expr_with_cleanupv()
+// CHECK:   cir.scope {
+// CHECK:     %[[S:.*]] = cir.alloca !rec_Struk, !cir.ptr<!rec_Struk>
+// CHECK:     cir.call @_Z7use_refRK5Struk(%[[S]])
+// CHECK:     cir.call @_ZN5StrukD1Ev(%[[S]]) nothrow : (!cir.ptr<!rec_Struk>) -> ()
+// CHECK:   }
+// CHECK:   cir.return