1 files changed, 161 insertions, 0 deletions
diff --git a/clang/lib/ARCMigrate/TransEmptyStatements.cpp b/clang/lib/ARCMigrate/TransEmptyStatements.cpp
new file mode 100644
index 00000000000..1b62bbf0354
--- /dev/null
+++ b/clang/lib/ARCMigrate/TransEmptyStatements.cpp
@@ -0,0 +1,161 @@
+//===--- TransEmptyStatements.cpp - Tranformations to ARC mode ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// removeEmptyStatements:
+//
+// Removes empty statements that are leftovers from previous transformations.
+// e.g for
+//
+//  [x retain];
+//
+// removeRetainReleaseDealloc will leave an empty ";" that removeEmptyStatements
+// will remove.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Transforms.h"
+#include "Internals.h"
+#include "clang/AST/StmtVisitor.h"
+
+using namespace clang;
+using namespace arcmt;
+using namespace trans;
+using llvm::StringRef;
+
+namespace {
+
+class EmptyStatementsRemover :
+                            public RecursiveASTVisitor<EmptyStatementsRemover> {
+  MigrationPass &Pass;
+  llvm::DenseSet<unsigned> MacroLocs;
+
+public:
+  EmptyStatementsRemover(MigrationPass &pass) : Pass(pass) {
+    for (unsigned i = 0, e = Pass.ARCMTMacroLocs.size(); i != e; ++i)
+      MacroLocs.insert(Pass.ARCMTMacroLocs[i].getRawEncoding());
+  }
+
+  bool TraverseStmtExpr(StmtExpr *E) {
+    CompoundStmt *S = E->getSubStmt();
+    for (CompoundStmt::body_iterator
+           I = S->body_begin(), E = S->body_end(); I != E; ++I) {
+      if (I != E - 1)
+        check(*I);
+      TraverseStmt(*I);
+    }
+    return true;
+  }
+
+  bool VisitCompoundStmt(CompoundStmt *S) {
+    for (CompoundStmt::body_iterator
+           I = S->body_begin(), E = S->body_end(); I != E; ++I)
+      check(*I);
+    return true;
+  }
+
+  bool isMacroLoc(SourceLocation loc) {
+    if (loc.isInvalid()) return false;
+    return MacroLocs.count(loc.getRawEncoding());
+  }
+
+  ASTContext &getContext() { return Pass.Ctx; }
+
+private:
+  /// \brief Returns true if the statement became empty due to previous
+  /// transformations.
+  class EmptyChecker : public StmtVisitor<EmptyChecker, bool> {
+    EmptyStatementsRemover &Trans;
+
+  public:
+    EmptyChecker(EmptyStatementsRemover &trans) : Trans(trans) { }
+
+    bool VisitNullStmt(NullStmt *S) {
+      return Trans.isMacroLoc(S->getLeadingEmptyMacroLoc());
+    }
+    bool VisitCompoundStmt(CompoundStmt *S) {
+      if (S->body_empty())
+        return false; // was already empty, not because of transformations.
+      for (CompoundStmt::body_iterator
+             I = S->body_begin(), E = S->body_end(); I != E; ++I)
+        if (!Visit(*I))
+          return false;
+      return true;
+    }
+    bool VisitIfStmt(IfStmt *S) {
+      if (S->getConditionVariable())
+        return false;
+      Expr *condE = S->getCond();
+      if (!condE)
+        return false;
+      if (hasSideEffects(condE, Trans.getContext()))
+        return false;
+      if (!S->getThen() || !Visit(S->getThen()))
+        return false;
+      if (S->getElse() && !Visit(S->getElse()))
+        return false;
+      return true;
+    }
+    bool VisitWhileStmt(WhileStmt *S) {
+      if (S->getConditionVariable())
+        return false;
+      Expr *condE = S->getCond();
+      if (!condE)
+        return false;
+      if (hasSideEffects(condE, Trans.getContext()))
+        return false;
+      if (!S->getBody())
+        return false;
+      return Visit(S->getBody());
+    }
+    bool VisitDoStmt(DoStmt *S) {
+      Expr *condE = S->getCond();
+      if (!condE)
+        return false;
+      if (hasSideEffects(condE, Trans.getContext()))
+        return false;
+      if (!S->getBody())
+        return false;
+      return Visit(S->getBody());
+    }
+    bool VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
+      Expr *Exp = S->getCollection();
+      if (!Exp)
+        return false;
+      if (hasSideEffects(Exp, Trans.getContext()))
+        return false;
+      if (!S->getBody())
+        return false;
+      return Visit(S->getBody());
+    }
+    bool VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S) {
+      if (!S->getSubStmt())
+        return false;
+      return Visit(S->getSubStmt());
+    }
+  };
+
+  void check(Stmt *S) {
+    if (!S) return;
+    if (EmptyChecker(*this).Visit(S)) {
+      Transaction Trans(Pass.TA);
+      Pass.TA.removeStmt(S);
+    }
+  }
+};
+
+} // anonymous namespace
+
+void trans::removeEmptyStatements(MigrationPass &pass) {
+  EmptyStatementsRemover(pass).TraverseDecl(pass.Ctx.getTranslationUnitDecl());
+
+  for (unsigned i = 0, e = pass.ARCMTMacroLocs.size(); i != e; ++i) {
+    Transaction Trans(pass.TA);
+    pass.TA.remove(pass.ARCMTMacroLocs[i]);
+  }
+}