CloneModule: Handling cloning ifuncs

[arsenm]

Summary

This is tested in a future llvm-reduce patch.

[aeubanks]

wrong patch uploaded? this is the same as D138524

[arsenm]

correct patch

[aeubanks]

looks fine, but even though the other patch indirectly tests this, can you add to llvm/unittests/Transforms/Utils/CloningTest.cpp?

[arsenm]

Add unit test

[arsenm]

f0693277c7cbe982bcfa5d1a8a9540807f6ec314

llvm/lib/Transforms/Utils/CloneModule.cpp

for (const GlobalAlias &I : M.aliases()) {
     }
     auto *GA = GlobalAlias::create(I.getValueType(),
                                    I.getType()->getPointerAddressSpace(),
                                    I.getLinkage(), I.getName(), New.get());
     GA->copyAttributesFrom(&I);
     VMap[&I] = GA;
   }
 
+  for (const GlobalIFunc &I : M.ifuncs()) {
+    // Defer setting the resolver function until after functions are cloned.
+    auto *GI =
+        GlobalIFunc::create(I.getValueType(), I.getAddressSpace(),
+                            I.getLinkage(), I.getName(), nullptr, New.get());
+    GI->copyAttributesFrom(&I);
+    VMap[&I] = GI;
+  }
+
   // Now that all of the things that global variable initializer can refer to
   // have been created, loop through and copy the global variable referrers
   // over...  We also set the attributes on the global now.
   //
   for (const GlobalVariable &G : M.globals()) {
     GlobalVariable *GV = cast<GlobalVariable>(VMap[&G]);
 
     SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
for (const GlobalAlias &I : M.aliases()) {
     // We already dealt with undefined aliases above.
     if (!ShouldCloneDefinition(&I))
       continue;
     GlobalAlias *GA = cast<GlobalAlias>(VMap[&I]);
     if (const Constant *C = I.getAliasee())
       GA->setAliasee(MapValue(C, VMap));
   }
 
+  for (const GlobalIFunc &I : M.ifuncs()) {
+    GlobalIFunc *GI = cast<GlobalIFunc>(VMap[&I]);
+    if (const Constant *Resolver = I.getResolver())
+      GI->setResolver(MapValue(Resolver, VMap));
+  }
+
   // And named metadata....
   for (const NamedMDNode &NMD : M.named_metadata()) {
     NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
     for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
       NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
   }
 
   return New;