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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220248 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/LLVMContext.h

@@ -55,7 +55,10 @@ public:
     MD_tbaa_struct = 5, // "tbaa.struct"
     MD_invariant_load = 6, // "invariant.load"
     MD_alias_scope = 7, // "alias.scope"
-    MD_noalias = 8 // "noalias"
+    MD_noalias = 8, // "noalias",
+    MD_nontemporal = 9, // "nontemporal"
+    MD_mem_parallel_loop_access = 10, // "llvm.mem.parallel_loop_access"
+    MD_nonnull = 11 // "nonnull"
   };
 
   /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.

lib/Analysis/LoopInfo.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
@@ -307,7 +308,8 @@ bool Loop::isAnnotatedParallel() const {
       // directly or indirectly through another list metadata (in case of
       // nested parallel loops). The loop identifier metadata refers to
       // itself so we can check both cases with the same routine.
-      MDNode *loopIdMD = II->getMetadata("llvm.mem.parallel_loop_access");
+      MDNode *loopIdMD =
+        II->getMetadata(LLVMContext::MD_mem_parallel_loop_access);
 
       if (!loopIdMD)
         return false;

lib/Analysis/ValueTracking.cpp

@@ -2624,7 +2624,7 @@ bool llvm::isKnownNonNull(const Value *V, const TargetLibraryInfo *TLI) {
 
   // A Load tagged w/nonnull metadata is never null. 
   if (const LoadInst *LI = dyn_cast<LoadInst>(V))
-    return LI->getMetadata("nonnull");
+    return LI->getMetadata(LLVMContext::MD_nonnull);
 
   if (ImmutableCallSite CS = V)
     if (CS.isReturnNonNull())

lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -2122,8 +2122,8 @@ FastISel::createMachineMemOperandFor(const Instruction *I) const {
   } else
     return nullptr;
 
-  bool IsNonTemporal = I->getMetadata("nontemporal") != nullptr;
-  bool IsInvariant = I->getMetadata("invariant.load") != nullptr;
+  bool IsNonTemporal = I->getMetadata(LLVMContext::MD_nontemporal) != nullptr;
+  bool IsInvariant = I->getMetadata(LLVMContext::MD_invariant_load) != nullptr;
   const MDNode *Ranges = I->getMetadata(LLVMContext::MD_range);
 
   AAMDNodes AAInfo;

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -3480,8 +3480,8 @@ void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
   Type *Ty = I.getType();
 
   bool isVolatile = I.isVolatile();
-  bool isNonTemporal = I.getMetadata("nontemporal") != nullptr;
-  bool isInvariant = I.getMetadata("invariant.load") != nullptr;
+  bool isNonTemporal = I.getMetadata(LLVMContext::MD_nontemporal) != nullptr;
+  bool isInvariant = I.getMetadata(LLVMContext::MD_invariant_load) != nullptr;
   unsigned Alignment = I.getAlignment();
 
   AAMDNodes AAInfo;
@@ -3584,7 +3584,7 @@ void SelectionDAGBuilder::visitStore(const StoreInst &I) {
                                           NumValues));
   EVT PtrVT = Ptr.getValueType();
   bool isVolatile = I.isVolatile();
-  bool isNonTemporal = I.getMetadata("nontemporal") != nullptr;
+  bool isNonTemporal = I.getMetadata(LLVMContext::MD_nontemporal) != nullptr;
   unsigned Alignment = I.getAlignment();
 
   AAMDNodes AAInfo;

lib/IR/LLVMContext.cpp

@@ -76,6 +76,23 @@ LLVMContext::LLVMContext() : pImpl(new LLVMContextImpl(*this)) {
   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; }
 

lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -329,6 +329,8 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT
     case LLVMContext::MD_invariant_load:
     case LLVMContext::MD_alias_scope:
     case LLVMContext::MD_noalias:
+    case LLVMContext::MD_nontemporal:
+    case LLVMContext::MD_mem_parallel_loop_access:
       // All of these directly apply.
       NewLoad->setMetadata(ID, N);
       break;
@@ -339,12 +341,6 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT
       break;
     }
   }
-  // FIXME: These metadata nodes should really have enumerators and be handled
-  // above.
-  if (MDNode *N = LI.getMetadata("nontemporal"))
-    NewLoad->setMetadata("nontemporal", N);
-  if (MDNode *N = LI.getMetadata("llvm.mem.parallel_loop_access"))
-    NewLoad->setMetadata("llvm.mem.parallel_loop_access", N);
   return NewLoad;
 }
 

lib/Transforms/Scalar/LICM.cpp

@@ -444,7 +444,7 @@ bool LICM::canSinkOrHoistInst(Instruction &I) {
     // in the same alias set as something that ends up being modified.
     if (AA->pointsToConstantMemory(LI->getOperand(0)))
       return true;
-    if (LI->getMetadata("invariant.load"))
+    if (LI->getMetadata(LLVMContext::MD_invariant_load))
       return true;
 
     // Don't hoist loads which have may-aliased stores in loop.