[SLPVectorizer] minor tweaks around lambdas for compatibility with older compilers (#122348)

Older version of msvc do not have great lambda support and are not able
to handle uses of class data or lambdas with implicit return types in
some cases. These minor changes improve the sources compatibility with
older msvc and don't hurt readability either.

Author: AlexMaclean

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -6908,7 +6908,7 @@ void BoUpSLP::tryToVectorizeGatheredLoads(
     return L1.second > L2.second;
   };
 
-  auto IsMaskedGatherSupported = [&](ArrayRef<LoadInst *> Loads) {
+  auto IsMaskedGatherSupported = [&, TTI = TTI](ArrayRef<LoadInst *> Loads) {
     ArrayRef<Value *> Values(reinterpret_cast<Value *const *>(Loads.begin()),
                              Loads.size());
     Align Alignment = computeCommonAlignment<LoadInst>(Values);
@@ -7075,9 +7075,10 @@ void BoUpSLP::tryToVectorizeGatheredLoads(
           }
           SmallVector<std::pair<LoadInst *, int>> LocalLoadsDists(LoadsDists);
           SmallVector<LoadInst *> OriginalLoads(LocalLoadsDists.size());
-          transform(
-              LoadsDists, OriginalLoads.begin(),
-              [](const std::pair<LoadInst *, int> &L) { return L.first; });
+          transform(LoadsDists, OriginalLoads.begin(),
+                    [](const std::pair<LoadInst *, int> &L) -> LoadInst * {
+                      return L.first;
+                    });
           stable_sort(LocalLoadsDists, LoadSorter);
           SmallVector<LoadInst *> Loads;
           unsigned MaxConsecutiveDistance = 0;
@@ -7304,7 +7305,8 @@ void BoUpSLP::tryToVectorizeGatheredLoads(
     if (!Ref.empty() && !NonVectorized.empty() &&
         std::accumulate(
             Ref.begin(), Ref.end(), 0u,
-            [](unsigned S, ArrayRef<std::pair<LoadInst *, int>> LoadsDists) {
+            [](unsigned S,
+               ArrayRef<std::pair<LoadInst *, int>> LoadsDists) -> unsigned {
               return S + LoadsDists.size();
             }) != NonVectorized.size() &&
         IsMaskedGatherSupported(NonVectorized)) {
@@ -16979,8 +16981,9 @@ void BoUpSLP::optimizeGatherSequence() {
   // and its mask indeces are the same as in the first one or undefs. E.g.
   // shuffle %0, poison, <0, 0, 0, undef> is less defined than shuffle %0,
   // poison, <0, 0, 0, 0>.
-  auto &&IsIdenticalOrLessDefined = [this](Instruction *I1, Instruction *I2,
-                                           SmallVectorImpl<int> &NewMask) {
+  auto &&IsIdenticalOrLessDefined = [TTI = TTI](Instruction *I1,
+                                                Instruction *I2,
+                                                SmallVectorImpl<int> &NewMask) {
     if (I1->getType() != I2->getType())
       return false;
     auto *SI1 = dyn_cast<ShuffleVectorInst>(I1);
@@ -17774,7 +17777,7 @@ bool BoUpSLP::collectValuesToDemote(
     BitWidth = std::max(BitWidth, BitWidth1);
     return BitWidth > 0 && OrigBitWidth >= (BitWidth * 2);
   };
-  auto FinalAnalysis = [&]() {
+  auto FinalAnalysis = [&, TTI = TTI]() {
     if (!IsProfitableToDemote)
       return false;
     bool Res = all_of(