Introduce enum values for previously defined metadata types. (NFC)

Our metadata scheme lazily assigns IDs to string metadata, but we have a mechanism to preassign them as well.  Using a preassigned ID is helpful since we get compile time type checking, and avoid some (minimal) string construction and comparison.  This change adds enum value for three existing metadata types:
+    MD_nontemporal = 9, // "nontemporal"
+    MD_mem_parallel_loop_access = 10, // "llvm.mem.parallel_loop_access"
+    MD_nonnull = 11 // "nonnull"

I went through an updated various uses as well.  I made no attempt to get all uses; I focused on the ones which were easily grepable and easily to translate.  For example, there were several items in LoopInfo.cpp I chose not to update.

llvm-svn: 220248
diff --git a/llvm/lib/IR/LLVMContext.cpp b/llvm/lib/IR/LLVMContext.cpp
index 73ddc8c..a1a4f63 100644
--- a/llvm/lib/IR/LLVMContext.cpp
+++ b/llvm/lib/IR/LLVMContext.cpp
@@ -76,6 +76,23 @@
   unsigned NoAliasID = getMDKindID("noalias");
   assert(NoAliasID == MD_noalias && "noalias kind id drifted");
   (void)NoAliasID;
+
+  // Create the 'nontemporal' metadata kind.
+  unsigned NonTemporalID = getMDKindID("nontemporal");
+  assert(NonTemporalID == MD_nontemporal && "nontemporal kind id drifted");
+  (void)NonTemporalID;
+
+  // Create the 'llvm.mem.parallel_loop_access' metadata kind.
+  unsigned MemParallelLoopAccessID = getMDKindID("llvm.mem.parallel_loop_access");
+  assert(MemParallelLoopAccessID == MD_mem_parallel_loop_access &&
+         "mem_parallel_loop_access kind id drifted");
+  (void)MemParallelLoopAccessID;
+
+
+  // Create the 'nonnull' metadata kind.
+  unsigned NonNullID = getMDKindID("nonnull");
+  assert(NonNullID == MD_nonnull && "nonnull kind id drifted");
+  (void)NonNullID;
 }
 LLVMContext::~LLVMContext() { delete pImpl; }