Copy Elementtype Attribute to IR at Link step

[chenyang.liu]

Summary

Copying IR during linking causes a type mismatch due to the field being missing in IRMover/Valuemapper. Adds the full range of typed attributes including elementtype attribute in the copy functions.

[nikic]

llvm/lib/Linker/IRMover.cpp

652–654

You can use FirstTypeAttr and LastTypeAttr to generalize this.

[chenyang.liu]

llvm/lib/Linker/IRMover.cpp

652–654

I can do it like this if you think it's ok:

for (unsigned i = 0; i < Attrs.getNumAttrSets(); ++i) {
  auto Attr = Attrs.getAttribute(i);
  if (Attr.isTypeAttribute()) {
    auto TypedAttr = Attr.getKindAsEnum();
    if (Type *Ty = Attrs.getAttribute(i, TypedAttr).getValueAsType()) {
      Attrs = Attrs.replaceAttributeType(C, i, TypedAttr, TypeMap.get(Ty));
      break;

[chenyang.liu]

llvm/lib/Linker/IRMover.cpp

652–654

Nvm, the existing Attributes API doesn't allow get/set without specifying the specific attribute itself. I wouldn't be able to generalize the attributes with only the firsttype/lasttype as there isn't a way to get the set of attributes of specific type. It's also out of the scope of this change that I want to make.

[nikic]

llvm/lib/Linker/IRMover.cpp

652–654

To be clear, what I'm suggesting is that you replace the hardcoded list of type attributes with something like for (Attribute::AttrKind TypedAttr = Attribute::FirstTypeAttr; TypedAttr <= Attribute::LastTypeAttr; TypedAttr++).

[chenyang.liu]

Updated the loop to use FirstTypeAttr and LastTypeAttr.

[chenyang.liu]

Rebased to fix conflicts

[chenyang.liu]

Generate new diff.

[nikic]

LGTM

[chenyang.liu]

I don't see any issues locally. Is there something else required to get the automated build passing?

[nikic]

@chenyang.liu You can ignore test failures that don't look related to your change.

llvm/lib/Linker/IRMover.cpp

GlobalVariable *NewDGV =
                          SGVar->getAddressSpace());
   NewDGV->setAlignment(MaybeAlign(SGVar->getAlignment()));
   NewDGV->copyAttributesFrom(SGVar);
   return NewDGV;
 }
 
 AttributeList IRLinker::mapAttributeTypes(LLVMContext &C, AttributeList Attrs) {
   for (unsigned i = 0; i < Attrs.getNumAttrSets(); ++i) {
-    for (Attribute::AttrKind TypedAttr :
-         {Attribute::ByVal, Attribute::StructRet, Attribute::ByRef,
-          Attribute::InAlloca}) {
+    for (int AttrIdx = Attribute::FirstTypeAttr;
+         AttrIdx <= Attribute::LastTypeAttr; AttrIdx++) {
+      Attribute::AttrKind TypedAttr = (Attribute::AttrKind)AttrIdx;
       if (Attrs.hasAttributeAtIndex(i, TypedAttr)) {
         if (Type *Ty =
                 Attrs.getAttributeAtIndex(i, TypedAttr).getValueAsType()) {
           Attrs = Attrs.replaceAttributeTypeAtIndex(C, i, TypedAttr,
                                                     TypeMap.get(Ty));
           break;
         }
       }

llvm/lib/Transforms/Utils/ValueMapper.cpp

if (auto *CB = dyn_cast<CallBase>(I)) {
     for (Type *Ty : FTy->params())
       Tys.push_back(TypeMapper->remapType(Ty));
     CB->mutateFunctionType(FunctionType::get(
         TypeMapper->remapType(I->getType()), Tys, FTy->isVarArg()));
 
     LLVMContext &C = CB->getContext();
     AttributeList Attrs = CB->getAttributes();
     for (unsigned i = 0; i < Attrs.getNumAttrSets(); ++i) {
-      for (Attribute::AttrKind TypedAttr :
-             {Attribute::ByVal, Attribute::StructRet, Attribute::ByRef,
-              Attribute::InAlloca}) {
+      for (int AttrIdx = Attribute::FirstTypeAttr;
+           AttrIdx <= Attribute::LastTypeAttr; AttrIdx++) {
+        Attribute::AttrKind TypedAttr = (Attribute::AttrKind)AttrIdx;
         if (Type *Ty =
                 Attrs.getAttributeAtIndex(i, TypedAttr).getValueAsType()) {
           Attrs = Attrs.replaceAttributeTypeAtIndex(C, i, TypedAttr,
                                                     TypeMapper->remapType(Ty));
           break;
         }
       }
     }

llvm/test/Linker/Inputs/elementtype-struct-2.ll

+%struct = type {i32, i8}
+
+define void @struct_elementtype_2() {
+  call %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct* elementtype(%struct) null, i32 0, i32 0)
+  ret void
+}
+
+declare %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct*, i32, i32)

llvm/test/Linker/elementtype-struct-1.ll

+; RUN: llvm-link %S/Inputs/elementtype-struct-2.ll %s -S | FileCheck %s
+
+; Check that the attribute for elementtype matches when linking.
+
+; CHECK: define void @struct_elementtype_2
+; CHECK: call %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct* elementtype(%struct) null, i32 0, i32 0)
+; CHECK: define void @struct_elementtype
+; CHECK: call %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct* elementtype(%struct) null, i32 0, i32 0)
+
+%struct = type {i32, i8}
+
+define void @struct_elementtype() {
+  call %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct* elementtype(%struct) null, i32 0, i32 0)
+  ret void
+}
+
+declare %struct* @llvm.preserve.array.access.index.p0s_structs.p0s_structs(%struct*, i32, i32)