[Polly] Align copied load/store instructions as the original.

[jdoerfert]

dup

[dpeixott]

LGTM. Could also fold the alignment setting into the creation.

lib/CodeGen/BlockGenerators.cpp

226

You could use Builder.CreateAlignedLoad here.

241

Could use Builder.CreateAlignedStore here.

lib/CodeGen/BlockGenerators.cpp

 Value *BlockGenerator::generateScalarLoad(const LoadInst *Load,
                                           ValueMapT &BBMap,
                                           ValueMapT &GlobalMap,
                                           LoopToScevMapT &LTS) {
   const Value *Pointer = Load->getPointerOperand();
   const Instruction *Inst = dyn_cast<Instruction>(Load);
   Value *NewPointer =
       generateLocationAccessed(Inst, Pointer, BBMap, GlobalMap, LTS);
-  Value *ScalarLoad =
+  LoadInst *ScalarLoad =
       Builder.CreateLoad(NewPointer, Load->getName() + "_p_scalar_");
+  ScalarLoad->setAlignment(Load->getAlignment());
   return ScalarLoad;
 }
 
 Value *BlockGenerator::generateScalarStore(const StoreInst *Store,
                                            ValueMapT &BBMap,
                                            ValueMapT &GlobalMap,
                                            LoopToScevMapT &LTS) {
   const Value *Pointer = Store->getPointerOperand();
   Value *NewPointer =
       generateLocationAccessed(Store, Pointer, BBMap, GlobalMap, LTS);
   Value *ValueOperand = getNewValue(Store->getValueOperand(), BBMap, GlobalMap,
                                     LTS, getLoopForInst(Store));
 
-  return Builder.CreateStore(ValueOperand, NewPointer);
+  StoreInst *NewStore = Builder.CreateStore(ValueOperand, NewPointer);
+  NewStore->setAlignment(Store->getAlignment());
+  return NewStore;
 }
 
 void BlockGenerator::copyInstruction(const Instruction *Inst, ValueMapT &BBMap,
                                      ValueMapT &GlobalMap,
                                      LoopToScevMapT &LTS) {
   // Terminator instructions control the control flow. They are explicitly
   // expressed in the clast and do not need to be copied.
   if (Inst->isTerminator())