Second attempt to add iterator_range::empty() (#174)

Doing this makes MSVC complain that `empty(someRange)` could refer to
either C++17's std::empty or LLVM's llvm::empty, which previously we
avoided via SFINAE because std::empty is defined in terms of an empty
member rather than begin and end. So, switch callers over to the new
method as it is added.

https://reviews.llvm.org/D68439

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373935 91177308-0d34-0410-b5e6-96231b3b80d8

Author: jrose-apple

include/llvm/ADT/iterator_range.h

@@ -44,6 +44,7 @@ class iterator_range {
 
   IteratorT begin() const { return begin_iterator; }
   IteratorT end() const { return end_iterator; }
+  bool empty() const { return begin_iterator == end_iterator; }
 };
 
 /// Convenience function for iterating over sub-ranges.

lib/Analysis/LazyCallGraph.cpp

@@ -631,7 +631,7 @@ LazyCallGraph::RefSCC::switchInternalEdgeToCall(
 
   // If the merge range is empty, then adding the edge didn't actually form any
   // new cycles. We're done.
-  if (empty(MergeRange)) {
+  if (MergeRange.empty()) {
     // Now that the SCC structure is finalized, flip the kind to call.
     SourceN->setEdgeKind(TargetN, Edge::Call);
     return false; // No new cycle.

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -902,7 +902,7 @@ void DwarfDebug::finalizeModuleInfo() {
     // If we're splitting the dwarf out now that we've got the entire
     // CU then add the dwo id to it.
     auto *SkCU = TheCU.getSkeleton();
-    if (useSplitDwarf() && !empty(TheCU.getUnitDie().children())) {
+    if (useSplitDwarf() && !TheCU.getUnitDie().children().empty()) {
       finishUnitAttributes(TheCU.getCUNode(), TheCU);
       TheCU.addString(TheCU.getUnitDie(), dwarf::DW_AT_GNU_dwo_name,
                       Asm->TM.Options.MCOptions.SplitDwarfFile);
@@ -954,7 +954,7 @@ void DwarfDebug::finalizeModuleInfo() {
     // is a bit pessimistic under LTO.
     if (!AddrPool.isEmpty() &&
         (getDwarfVersion() >= 5 ||
-         (SkCU && !empty(TheCU.getUnitDie().children()))))
+         (SkCU && !TheCU.getUnitDie().children().empty())))
       U.addAddrTableBase();
 
     if (getDwarfVersion() >= 5) {

lib/CodeGen/GlobalISel/InstructionSelector.cpp

@@ -79,5 +79,5 @@ bool InstructionSelector::isObviouslySafeToFold(MachineInstr &MI,
     return true;
 
   return !MI.mayLoadOrStore() && !MI.mayRaiseFPException() &&
-         !MI.hasUnmodeledSideEffects() && empty(MI.implicit_operands());
+         !MI.hasUnmodeledSideEffects() && MI.implicit_operands().empty();
 }

lib/CodeGen/GlobalISel/LegalizerInfo.cpp

@@ -412,7 +412,7 @@ LegalizeRuleSet &LegalizerInfo::getActionDefinitionsBuilder(
     std::initializer_list<unsigned> Opcodes) {
   unsigned Representative = *Opcodes.begin();
 
-  assert(!empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() &&
+  assert(!llvm::empty(Opcodes) && Opcodes.begin() + 1 != Opcodes.end() &&
          "Initializer list must have at least two opcodes");
 
   for (auto I = Opcodes.begin() + 1, E = Opcodes.end(); I != E; ++I)

lib/CodeGen/GlobalISel/RegBankSelect.cpp

@@ -139,7 +139,7 @@ bool RegBankSelect::repairReg(
          "need new vreg for each breakdown");
 
   // An empty range of new register means no repairing.
-  assert(!empty(NewVRegs) && "We should not have to repair");
+  assert(!NewVRegs.empty() && "We should not have to repair");
 
   MachineInstr *MI;
   if (ValMapping.NumBreakDowns == 1) {

lib/CodeGen/GlobalISel/RegisterBankInfo.cpp

@@ -456,7 +456,7 @@ void RegisterBankInfo::applyDefaultMapping(const OperandsMapper &OpdMapper) {
            "This mapping is too complex for this function");
     iterator_range<SmallVectorImpl<unsigned>::const_iterator> NewRegs =
         OpdMapper.getVRegs(OpIdx);
-    if (empty(NewRegs)) {
+    if (NewRegs.empty()) {
       LLVM_DEBUG(dbgs() << " has not been repaired, nothing to be done\n");
       continue;
     }

lib/ExecutionEngine/Orc/ExecutionUtils.cpp

@@ -87,7 +87,7 @@ iterator_range<CtorDtorIterator> getDestructors(const Module &M) {
 }
 
 void CtorDtorRunner::add(iterator_range<CtorDtorIterator> CtorDtors) {
-  if (empty(CtorDtors))
+  if (CtorDtors.empty())
     return;
 
   MangleAndInterner Mangle(

lib/IR/DebugInfo.cpp

@@ -279,7 +279,7 @@ bool DebugInfoFinder::addScope(DIScope *Scope) {
 }
 
 static MDNode *stripDebugLocFromLoopID(MDNode *N) {
-  assert(!empty(N->operands()) && "Missing self reference?");
+  assert(!N->operands().empty() && "Missing self reference?");
 
   // if there is no debug location, we do not have to rewrite this MDNode.
   if (std::none_of(N->op_begin() + 1, N->op_end(), [](const MDOperand &Op) {

lib/Target/BPF/BPFAsmPrinter.cpp

@@ -56,7 +56,7 @@ bool BPFAsmPrinter::doInitialization(Module &M) {
   AsmPrinter::doInitialization(M);
 
   // Only emit BTF when debuginfo available.
-  if (MAI->doesSupportDebugInformation() && !empty(M.debug_compile_units())) {
+  if (MAI->doesSupportDebugInformation() && !M.debug_compile_units().empty()) {
     Handlers.emplace_back(llvm::make_unique<BTFDebug>(this), "emit",
                           "Debug Info Emission", "BTF", "BTF Emission");
   }