Revert "[LSV] Merge contiguous chains across scalar types (#154069)"

This reverts commit fbdf8ab.

Author: dakersnar

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

@@ -431,7 +431,7 @@ LLVM_ABI void combineAAMetadata(Instruction *K, const Instruction *J);
 
 /// Copy the metadata from the source instruction to the destination (the
 /// replacement for the source instruction).
-LLVM_ABI void copyMetadataForAccess(Instruction &Dest, Instruction &Source);
+LLVM_ABI 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

llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp

@@ -1035,7 +1035,7 @@ bool LegalizeBufferContentTypesVisitor::visitLoadImpl(
       LoadInst *NewLI = IRB.CreateAlignedLoad(
           LoadableType, NewPtr, commonAlignment(OrigLI.getAlign(), ByteOffset),
           Name + ".off." + Twine(ByteOffset));
-      copyMetadataForAccess(*NewLI, OrigLI);
+      copyMetadataForLoad(*NewLI, OrigLI);
       NewLI->setAAMetadata(
           AANodes.adjustForAccess(ByteOffset, LoadableType, DL));
       NewLI->setAtomic(OrigLI.getOrdering(), OrigLI.getSyncScopeID());

llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -415,7 +415,7 @@ void PointerReplacer::replace(Instruction *I) {
                               LT->getAlign(), LT->getOrdering(),
                               LT->getSyncScopeID());
     NewI->takeName(LT);
-    copyMetadataForAccess(*NewI, *LT);
+    copyMetadataForLoad(*NewI, *LT);
 
     IC.InsertNewInstWith(NewI, LT->getIterator());
     IC.replaceInstUsesWith(*LT, NewI);
@@ -606,7 +606,7 @@ LoadInst *InstCombinerImpl::combineLoadToNewType(LoadInst &LI, Type *NewTy,
       Builder.CreateAlignedLoad(NewTy, LI.getPointerOperand(), LI.getAlign(),
                                 LI.isVolatile(), LI.getName() + Suffix);
   NewLoad->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
-  copyMetadataForAccess(*NewLoad, LI);
+  copyMetadataForLoad(*NewLoad, LI);
   return NewLoad;
 }
 

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -3272,7 +3272,7 @@ class AllocaSliceRewriter : public InstVisitor<AllocaSliceRewriter, bool> {
       // Copy any metadata that is valid for the new load. This may require
       // conversion to a different kind of metadata, e.g. !nonnull might change
       // to !range or vice versa.
-      copyMetadataForAccess(*NewLI, LI);
+      copyMetadataForLoad(*NewLI, LI);
 
       // Do this after copyMetadataForLoad() to preserve the TBAA shift.
       if (AATags)

llvm/lib/Transforms/Utils/Local.cpp

@@ -3100,70 +3100,54 @@ void llvm::combineAAMetadata(Instruction *K, const Instruction *J) {
   combineMetadata(K, J, /*DoesKMove=*/true, /*AAOnly=*/true);
 }
 
-void llvm::copyMetadataForAccess(Instruction &DestI, Instruction &SourceI) {
+void llvm::copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source) {
   SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
-  SourceI.getAllMetadata(MD);
-  MDBuilder MDB(DestI.getContext());
-  Type *NewType = DestI.getType();
-
-  // Only needed for range metadata on loads.
-  const DataLayout *DL = nullptr;
-  const LoadInst *LSource = dyn_cast<LoadInst>(&SourceI);
-  if (LSource)
-    DL = &LSource->getDataLayout();
-
+  Source.getAllMetadata(MD);
+  MDBuilder MDB(Dest.getContext());
+  Type *NewType = Dest.getType();
+  const DataLayout &DL = Source.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) {
-    // Applies to both loads and stores as-is.
     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:
     case LLVMContext::MD_noundef:
     case LLVMContext::MD_noalias_addrspace:
-    case LLVMContext::MD_mem_parallel_loop_access:
-      DestI.setMetadata(ID, N);
-      break;
-
-    // Load-only metadata.
-    case LLVMContext::MD_fpmath:
-    case LLVMContext::MD_invariant_load:
-      if (isa<LoadInst>(DestI))
-        DestI.setMetadata(ID, N);
+      // All of these directly apply.
+      Dest.setMetadata(ID, N);
       break;
 
     case LLVMContext::MD_nonnull:
-      if (auto *LDest = dyn_cast<LoadInst>(&DestI)) {
-        if (LSource)
-          copyNonnullMetadata(*LSource, N, *LDest);
-      }
+      copyNonnullMetadata(Source, N, Dest);
       break;
 
     case LLVMContext::MD_align:
     case LLVMContext::MD_dereferenceable:
     case LLVMContext::MD_dereferenceable_or_null:
-      // Applies to both loads and stores only if the new type is also a
-      // pointer.
+      // These only directly apply if the new type is also a pointer.
       if (NewType->isPointerTy())
-        DestI.setMetadata(ID, N);
+        Dest.setMetadata(ID, N);
       break;
 
     case LLVMContext::MD_range:
-      if (auto *LDest = dyn_cast<LoadInst>(&DestI)) {
-        if (LSource && DL)
-          copyRangeMetadata(*DL, *LSource, N, *LDest);
-      }
-      break;
-
-    case LLVMContext::MD_tbaa:
-      if (isa<LoadInst>(DestI))
-        DestI.setMetadata(ID, N);
+      copyRangeMetadata(DL, Source, N, Dest);
       break;
     }
   }