[Transforms] move copying of load metadata to helper function; NFC

There's another proposed load combine that can make use of this code
in D64432.

llvm-svn: 366949

llvm/include/llvm/Transforms/Utils/Local.h

@@ -427,6 +427,10 @@ void combineMetadata(Instruction *K, const Instruction *J,
 void combineMetadataForCSE(Instruction *K, const Instruction *J,
                            bool DoesKMove);
 
+/// Copy the metadata from the source instruction to the destination (the
+/// replacement for the source instruction).
+void copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source);
+
 /// Patch the replacement so that it is not more restrictive than the value
 /// being replaced. It assumes that the replacement does not get moved from
 /// its original position.

llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -455,9 +455,6 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT
 
   Value *Ptr = LI.getPointerOperand();
   unsigned AS = LI.getPointerAddressSpace();
-  SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
-  LI.getAllMetadata(MD);
-
   Value *NewPtr = nullptr;
   if (!(match(Ptr, m_BitCast(m_Value(NewPtr))) &&
         NewPtr->getType()->getPointerElementType() == NewTy &&
@@ -467,48 +464,7 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT
   LoadInst *NewLoad = IC.Builder.CreateAlignedLoad(
       NewTy, NewPtr, LI.getAlignment(), LI.isVolatile(), LI.getName() + Suffix);
   NewLoad->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-  MDBuilder MDB(NewLoad->getContext());
+  copyMetadataForLoad(*NewLoad, LI);
-  for (const auto &MDPair : MD) {
-    unsigned ID = MDPair.first;
-    MDNode *N = MDPair.second;
-    // Note, essentially every kind of metadata should be preserved here! This
-    // routine is supposed to clone a load instruction changing *only its type*.
-    // The only metadata it makes sense to drop is metadata which is invalidated
-    // when the pointer type changes. This should essentially never be the case
-    // in LLVM, but we explicitly switch over only known metadata to be
-    // conservatively correct. If you are adding metadata to LLVM which pertains
-    // to loads, you almost certainly want to add it here.
-    switch (ID) {
-    case LLVMContext::MD_dbg:
-    case LLVMContext::MD_tbaa:
-    case LLVMContext::MD_prof:
-    case LLVMContext::MD_fpmath:
-    case LLVMContext::MD_tbaa_struct:
-    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:
-    case LLVMContext::MD_access_group:
-      // All of these directly apply.
-      NewLoad->setMetadata(ID, N);
-      break;
-
-    case LLVMContext::MD_nonnull:
-      copyNonnullMetadata(LI, N, *NewLoad);
-      break;
-    case LLVMContext::MD_align:
-    case LLVMContext::MD_dereferenceable:
-    case LLVMContext::MD_dereferenceable_or_null:
-      // These only directly apply if the new type is also a pointer.
-      if (NewTy->isPointerTy())
-        NewLoad->setMetadata(ID, N);
-      break;
-    case LLVMContext::MD_range:
-      copyRangeMetadata(IC.getDataLayout(), LI, N, *NewLoad);
-      break;
-    }
-  }
   return NewLoad;
 }
 

llvm/lib/Transforms/Utils/Local.cpp

@@ -2390,6 +2390,57 @@ void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J,
   combineMetadata(K, J, KnownIDs, KDominatesJ);
 }
 
+void llvm::copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source) {
+  SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
+  Source.getAllMetadata(MD);
+  MDBuilder MDB(Dest.getContext());
+  Type *NewType = Dest.getType();
+  const DataLayout &DL = Source.getModule()->getDataLayout();
+  for (const auto &MDPair : MD) {
+    unsigned ID = MDPair.first;
+    MDNode *N = MDPair.second;
+    // Note, essentially every kind of metadata should be preserved here! This
+    // routine is supposed to clone a load instruction changing *only its type*.
+    // The only metadata it makes sense to drop is metadata which is invalidated
+    // when the pointer type changes. This should essentially never be the case
+    // in LLVM, but we explicitly switch over only known metadata to be
+    // conservatively correct. If you are adding metadata to LLVM which pertains
+    // to loads, you almost certainly want to add it here.
+    switch (ID) {
+    case LLVMContext::MD_dbg:
+    case LLVMContext::MD_tbaa:
+    case LLVMContext::MD_prof:
+    case LLVMContext::MD_fpmath:
+    case LLVMContext::MD_tbaa_struct:
+    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:
+    case LLVMContext::MD_access_group:
+      // All of these directly apply.
+      Dest.setMetadata(ID, N);
+      break;
+
+    case LLVMContext::MD_nonnull:
+      copyNonnullMetadata(Source, N, Dest);
+      break;
+
+    case LLVMContext::MD_align:
+    case LLVMContext::MD_dereferenceable:
+    case LLVMContext::MD_dereferenceable_or_null:
+      // These only directly apply if the new type is also a pointer.
+      if (NewType->isPointerTy())
+        Dest.setMetadata(ID, N);
+      break;
+
+    case LLVMContext::MD_range:
+      copyRangeMetadata(DL, Source, N, Dest);
+      break;
+    }
+  }
+}
+
 void llvm::patchReplacementInstruction(Instruction *I, Value *Repl) {
   auto *ReplInst = dyn_cast<Instruction>(Repl);
   if (!ReplInst)