PR3281:crash00.ll: produce this diagnostic instead of crashing:

@t = global i8 0, align 3
                        ^



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61675 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index e44e650..1f08ca3 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -793,7 +793,11 @@
   Alignment = 0;
   if (!EatIfPresent(lltok::kw_align))
     return false;
-  return ParseUInt32(Alignment);
+  LocTy AlignLoc = Lex.getLoc();
+  if (ParseUInt32(Alignment)) return true;
+  if (!isPowerOf2_32(Alignment))
+    return Error(AlignLoc, "alignment is not a power of two");
+  return false;
 }
 
 /// ParseOptionalCommaAlignment