[Alignment][NFC] Remove AllocaInst::setAlignment(unsigned)

Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: jholewinski, arsenm, jvesely, nhaehnle, eraman, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D68141

llvm-svn: 373207
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index c9823fa..74c6980 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -140,7 +140,7 @@
   }
 
   AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
-  New->setAlignment(AI.getAlignment());
+  New->setAlignment(MaybeAlign(AI.getAlignment()));
   New->takeName(&AI);
   New->setUsedWithInAlloca(AI.isUsedWithInAlloca());