[llvm] Use llvm::SmallVector::pop_back_val (NFC) (#136441)

Author: kazutakahirata

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

@@ -1793,8 +1793,7 @@ bool ComplexDeinterleavingGraph::checkNodes() {
   // Extract all instructions that are used by all XCMLA/XCADD/ADD/SUB/NEG
   // chains
   while (!Worklist.empty()) {
-    auto *I = Worklist.back();
-    Worklist.pop_back();
+    auto *I = Worklist.pop_back_val();
 
     if (!AllInstructions.insert(I).second)
       continue;
@@ -1828,8 +1827,7 @@ bool ComplexDeinterleavingGraph::checkNodes() {
   // that somehow connect to those instructions.
   SmallPtrSet<Instruction *, 16> Visited;
   while (!Worklist.empty()) {
-    auto *I = Worklist.back();
-    Worklist.pop_back();
+    auto *I = Worklist.pop_back_val();
     if (!Visited.insert(I).second)
       continue;
 

llvm/lib/CodeGen/TwoAddressInstructionPass.cpp

@@ -854,8 +854,7 @@ void TwoAddressInstructionImpl::scanUses(Register DstReg) {
   }
 
   if (!VirtRegPairs.empty()) {
-    Register ToReg = VirtRegPairs.back();
-    VirtRegPairs.pop_back();
+    Register ToReg = VirtRegPairs.pop_back_val();
     while (!VirtRegPairs.empty()) {
       Register FromReg = VirtRegPairs.pop_back_val();
       bool isNew = DstRegMap.insert(std::make_pair(FromReg, ToReg)).second;

llvm/lib/Support/SuffixTree.cpp

@@ -306,8 +306,7 @@ void SuffixTree::RepeatedSubstringIterator::advance() {
   // Continue visiting nodes until we find one which repeats more than once.
   while (!InternalNodesToVisit.empty()) {
     RepeatedSubstringStarts.clear();
-    auto *Curr = InternalNodesToVisit.back();
-    InternalNodesToVisit.pop_back();
+    auto *Curr = InternalNodesToVisit.pop_back_val();
 
     // Keep track of the length of the string associated with the node. If
     // it's too short, we'll quit.

llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp

@@ -1528,8 +1528,7 @@ bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
     Worklist.reserve(MaxUsesToExplore);
     SmallSet<const Use *, 20> Visited;
     while (!Worklist.empty()) {
-      Instruction *I = Worklist.back();
-      Worklist.pop_back();
+      Instruction *I = Worklist.pop_back_val();
       for (const Use &U : I->uses()) {
         auto *UI = cast<Instruction>(U.getUser());
         // If any use that isn't dominated by SrcAlloca exists, we move src

llvm/lib/Transforms/Utils/CodeMoverUtils.cpp

@@ -464,8 +464,7 @@ bool llvm::nonStrictlyPostDominate(const BasicBlock *ThisBlock,
   SmallPtrSet<const BasicBlock *, 8> Visited;
   WorkList.push_back(ThisBlock);
   while (!WorkList.empty()) {
-    const BasicBlock *CurBlock = WorkList.back();
-    WorkList.pop_back();
+    const BasicBlock *CurBlock = WorkList.pop_back_val();
     Visited.insert(CurBlock);
     if (PDT->dominates(CurBlock, OtherBlock))
       return true;