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/test/tools/llvm-reduce/no-remove-ifunc-function.ll

+; RUN: llvm-reduce -abort-on-invalid-reduction --delta-passes=functions --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK-FINAL --input-file=%t %s
+
+; Test handling of ifunc. Make sure function reduction doesn't create
+; invalid ifunc
+
+
+; CHECK-INTERESTINGNESS: define void @no_ifunc_interesting
+
+; CHECK-FINAL: @ifunc1 = ifunc void (), ptr @has_ifunc
+; CHECK-FINAL: define void @no_ifunc_interesting() {
+; CHECK-FINAL-NOT: define
+
+@ifunc1 = ifunc void (), ptr @has_ifunc
+
+
+define void @has_ifunc() {
+  ret void
+}
+
+define void @no_ifunc_interesting() {
+  ret void
+}
+
+define void @no_ifunc_boring() {
+  ret void
+}

llvm/tools/llvm-reduce/deltas/Utils.cpp

 //===- Utils.cpp - llvm-reduce utility functions --------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains some utility functions supporting llvm-reduce.
 //
 //===----------------------------------------------------------------------===//
 
 #include "Utils.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalIFunc.h"
 
 using namespace llvm;
 
 extern cl::OptionCategory LLVMReduceOptions;
 
 cl::opt<bool> llvm::Verbose("verbose",
                             cl::desc("Print extra debugging information"),
                             cl::init(false), cl::cat(LLVMReduceOptions));
 
 Value *llvm::getDefaultValue(Type *T) {
   return T->isVoidTy() ? PoisonValue::get(T) : Constant::getNullValue(T);
 }
 
 bool llvm::hasAliasUse(Function &F) {
-  return any_of(F.users(), [](User *U) { return isa<GlobalAlias>(U); });
+  return any_of(F.users(), [](User *U) {
+      return isa<GlobalAlias>(U) || isa<GlobalIFunc>(U);
+    });
 }