[llvm] Use hasSingleElement (NFC)

Author: kazutakahirata

llvm/include/llvm/CodeGen/MachineRegisterInfo.h

@@ -442,10 +442,7 @@ class MachineRegisterInfo {
  /// Return true if there is exactly one operand defining the specified
  /// register.
  bool hasOneDef(Register RegNo) const {
- def_iterator DI = def_begin(RegNo);
- if (DI == def_end())
- return false;
- return ++DI == def_end();
+ return hasSingleElement(def_operands(RegNo));
  }
 
  /// Returns the defining operand if there is exactly one operand defining the
@@ -511,10 +508,7 @@ class MachineRegisterInfo {
  /// hasOneUse - Return true if there is exactly one instruction using the
  /// specified register.
  bool hasOneUse(Register RegNo) const {
- use_iterator UI = use_begin(RegNo);
- if (UI == use_end())
- return false;
- return ++UI == use_end();
+ return hasSingleElement(use_operands(RegNo));
  }
 
  /// use_nodbg_iterator/use_nodbg_begin/use_nodbg_end - Walk all uses of the

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

@@ -689,9 +689,7 @@ END_TWO_BYTE_PACK()
  bool use_empty() const { return UseList == nullptr; }
 
  /// Return true if there is exactly one use of this node.
- bool hasOneUse() const {
- return !use_empty() && std::next(use_begin()) == use_end();
- }
+ bool hasOneUse() const { return hasSingleElement(uses()); }
 
  /// Return the number of uses of this node. This method takes
  /// time proportional to the number of uses.

llvm/include/llvm/IR/Value.h

@@ -434,11 +434,7 @@ class Value {
  ///
  /// This is specialized because it is a common request and does not require
  /// traversing the whole use list.
- bool hasOneUse() const {
- const_use_iterator I = use_begin(), E = use_end();
- if (I == E) return false;
- return ++I == E;
- }
+ bool hasOneUse() const { return hasSingleElement(uses()); }
 
  /// Return true if this Value has exactly N uses.
  bool hasNUses(unsigned N) const;

llvm/lib/CodeGen/MachineRegisterInfo.cpp

@@ -417,17 +417,11 @@ MachineInstr *MachineRegisterInfo::getUniqueVRegDef(Register Reg) const {
 }
 
 bool MachineRegisterInfo::hasOneNonDBGUse(Register RegNo) const {
- use_nodbg_iterator UI = use_nodbg_begin(RegNo);
- if (UI == use_nodbg_end())
- return false;
- return ++UI == use_nodbg_end();
+ return hasSingleElement(use_nodbg_operands(RegNo));
 }
 
 bool MachineRegisterInfo::hasOneNonDBGUser(Register RegNo) const {
- use_instr_nodbg_iterator UI = use_instr_nodbg_begin(RegNo);
- if (UI == use_instr_nodbg_end())
- return false;
- return ++UI == use_instr_nodbg_end();
+ return hasSingleElement(use_nodbg_instructions(RegNo));
 }
 
 /// clearKillFlags - Iterate over all the uses of the given register and

llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp

@@ -194,13 +194,12 @@ Optional<object::SectionedAddress>
 DWARFUnit::getAddrOffsetSectionItem(uint32_t Index) const {
  if (IsDWO) {
  auto R = Context.info_section_units();
- auto I = R.begin();
  // Surprising if a DWO file has more than one skeleton unit in it - this
  // probably shouldn't be valid, but if a use case is found, here's where to
  // support it (probably have to linearly search for the matching skeleton CU
  // here)
- if (I != R.end() && std::next(I) == R.end())
- return (*I)->getAddrOffsetSectionItem(Index);
+ if (hasSingleElement(R))
+ return (*R.begin())->getAddrOffsetSectionItem(Index);
  }
  if (!AddrOffsetSectionBase)
  return None;