Use llvm::reverse to make a bunch of loops use foreach. NFC.

In llvm commit r243581, a reverse range adapter was added which allows
us to change code such as

  for (auto I = Fields.rbegin(), E = Fields.rend(); I != E; ++I) {

in to

  for (const FieldDecl *I : llvm::reverse(Fields))

This commit changes a few of the places in clang which are eligible to use
this new adapter.

llvm-svn: 243663

clang/lib/ARCMigrate/TransformActions.cpp

@@ -505,11 +505,10 @@ void TransformActionsImpl::commitClearDiagnostic(ArrayRef<unsigned> IDs,
 void TransformActionsImpl::addInsertion(SourceLocation loc, StringRef text) {
   SourceManager &SM = Ctx.getSourceManager();
   loc = SM.getExpansionLoc(loc);
-  for (std::list<CharRange>::reverse_iterator
-         I = Removals.rbegin(), E = Removals.rend(); I != E; ++I) {
-    if (!SM.isBeforeInTranslationUnit(loc, I->End))
+  for (const CharRange &I : llvm::reverse(Removals)) {
+    if (!SM.isBeforeInTranslationUnit(loc, I.End))
       break;
-    if (I->Begin.isBeforeInTranslationUnitThan(loc))
+    if (I.Begin.isBeforeInTranslationUnitThan(loc))
       return;
   }
 

clang/lib/Analysis/CFG.cpp

@@ -994,9 +994,8 @@ std::unique_ptr<CFG> CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) {
 
   // For C++ constructor add initializers to CFG.
   if (const CXXConstructorDecl *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) {
-    for (CXXConstructorDecl::init_const_reverse_iterator I = CD->init_rbegin(),
-        E = CD->init_rend(); I != E; ++I) {
-      B = addInitializer(*I);
+    for (auto *I : llvm::reverse(CD->inits())) {
+      B = addInitializer(I);
       if (badCFG)
         return nullptr;
     }

clang/lib/CodeGen/CGCall.cpp

@@ -2614,10 +2614,9 @@ static void deactivateArgCleanupsBeforeCall(CodeGenFunction &CGF,
   ArrayRef<CallArgList::CallArgCleanup> Cleanups =
     CallArgs.getCleanupsToDeactivate();
   // Iterate in reverse to increase the likelihood of popping the cleanup.
-  for (ArrayRef<CallArgList::CallArgCleanup>::reverse_iterator
-         I = Cleanups.rbegin(), E = Cleanups.rend(); I != E; ++I) {
-    CGF.DeactivateCleanupBlock(I->Cleanup, I->IsActiveIP);
-    I->IsActiveIP->eraseFromParent();
+  for (const auto &I : llvm::reverse(Cleanups)) {
+    CGF.DeactivateCleanupBlock(I.Cleanup, I.IsActiveIP);
+    I.IsActiveIP->eraseFromParent();
   }
 }
 

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -496,12 +496,12 @@ struct CounterCoverageMappingBuilder
 
     llvm::SmallSet<SourceLocation, 8> StartLocs;
     Optional<Counter> ParentCounter;
-    for (auto I = RegionStack.rbegin(), E = RegionStack.rend(); I != E; ++I) {
-      if (!I->hasStartLoc())
+    for (SourceMappingRegion &I : llvm::reverse(RegionStack)) {
+      if (!I.hasStartLoc())
         continue;
-      SourceLocation Loc = I->getStartLoc();
+      SourceLocation Loc = I.getStartLoc();
       if (!isNestedIn(Loc, ParentFile)) {
-        ParentCounter = I->getCounter();
+        ParentCounter = I.getCounter();
         break;
       }
 
@@ -510,11 +510,11 @@ struct CounterCoverageMappingBuilder
         // correct count. We avoid creating redundant regions by stopping once
         // we've seen this region.
         if (StartLocs.insert(Loc).second)
-          SourceRegions.emplace_back(I->getCounter(), Loc,
+          SourceRegions.emplace_back(I.getCounter(), Loc,
                                      getEndOfFileOrMacro(Loc));
         Loc = getIncludeOrExpansionLoc(Loc);
       }
-      I->setStartLoc(getPreciseTokenLocEnd(Loc));
+      I.setStartLoc(getPreciseTokenLocEnd(Loc));
     }
 
     if (ParentCounter) {

clang/lib/Sema/AnalysisBasedWarnings.cpp

@@ -1098,8 +1098,7 @@ static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
 
   FM.fillReachableBlocks(Cfg);
 
-  for (CFG::reverse_iterator I = Cfg->rbegin(), E = Cfg->rend(); I != E; ++I) {
-    const CFGBlock *B = *I;
+  for (const CFGBlock *B : llvm::reverse(*Cfg)) {
     const Stmt *Label = B->getLabel();
 
     if (!Label || !isa<SwitchCase>(Label))

clang/lib/Sema/SemaDecl.cpp

@@ -8570,9 +8570,8 @@ namespace {
 
       // Convert FieldDecls to their index number.
       llvm::SmallVector<unsigned, 4> UsedFieldIndex;
-      for (auto I = Fields.rbegin(), E = Fields.rend(); I != E; ++I) {
-        UsedFieldIndex.push_back((*I)->getFieldIndex());
-      }
+      for (const FieldDecl *I : llvm::reverse(Fields))
+        UsedFieldIndex.push_back(I->getFieldIndex());
 
       // See if a warning is needed by checking the first difference in index
       // numbers.  If field being used has index less than the field being

clang/lib/Serialization/ASTReader.cpp

@@ -1592,16 +1592,15 @@ void ASTReader::ReadDefinedMacros() {
   // Note that we are loading defined macros.
   Deserializing Macros(this);
 
-  for (ModuleReverseIterator I = ModuleMgr.rbegin(),
-      E = ModuleMgr.rend(); I != E; ++I) {
-    BitstreamCursor &MacroCursor = (*I)->MacroCursor;
+  for (auto &I : llvm::reverse(ModuleMgr)) {
+    BitstreamCursor &MacroCursor = I->MacroCursor;
 
     // If there was no preprocessor block, skip this file.
     if (!MacroCursor.getBitStreamReader())
       continue;
 
     BitstreamCursor Cursor = MacroCursor;
-    Cursor.JumpToBit((*I)->MacroStartOffset);
+    Cursor.JumpToBit(I->MacroStartOffset);
 
     RecordData Record;
     while (true) {
@@ -1623,7 +1622,7 @@ void ASTReader::ReadDefinedMacros() {
           
         case PP_MACRO_OBJECT_LIKE:
         case PP_MACRO_FUNCTION_LIKE:
-          getLocalIdentifier(**I, Record[0]);
+          getLocalIdentifier(*I, Record[0]);
           break;
           
         case PP_TOKEN:

clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp

@@ -663,9 +663,7 @@ void ExprEngine::VisitGuardedExpr(const Expr *Ex,
   bool hasValue = false;
   SVal V;
 
-  for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(),
-                                        E = SrcBlock->rend(); I != E; ++I) {
-    CFGElement CE = *I;
+  for (CFGElement CE : llvm::reverse(*SrcBlock)) {
     if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
       const Expr *ValEx = cast<Expr>(CS->getStmt());
       ValEx = ValEx->IgnoreParens();

clang/tools/libclang/CIndex.cpp

@@ -2174,10 +2174,8 @@ void EnqueueVisitor::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
   AddTypeLoc(E->getTypeSourceInfo());
 }
 void EnqueueVisitor::VisitCompoundStmt(const CompoundStmt *S) {
-  for (CompoundStmt::const_reverse_body_iterator I = S->body_rbegin(),
-        E = S->body_rend(); I != E; ++I) {
-    AddStmt(*I);
-  }
+  for (auto &I : llvm::reverse(S->body()))
+    AddStmt(I);
 }
 void EnqueueVisitor::
 VisitMSDependentExistsStmt(const MSDependentExistsStmt *S) {