Add a unit test IsNoAliasForInstructions

Author: Chengjunp

llvm/unittests/Analysis/AliasAnalysisTest.cpp

@@ -364,6 +364,46 @@ TEST_F(AliasAnalysisTest, PartialAliasOffsetSign) {
   EXPECT_EQ(AR, AliasResult::PartialAlias);
   EXPECT_EQ(-1, AR.getOffset());
 }
+
+TEST_F(AliasAnalysisTest, IsNoAliasForInstructions) {
+  // Create global variable
+  auto *GlobalVar = new GlobalVariable(M, Type::getInt32Ty(C), false,
+                                     GlobalValue::ExternalLinkage, 
+                                     ConstantInt::get(Type::getInt32Ty(C), 0),
+                                     "g");
+  GlobalVar->setAlignment(Align(4));
+
+  // Create function declarations
+  FunctionType *VoidFnTy = FunctionType::get(Type::getVoidTy(C), false);
+  Function::Create(VoidFnTy, Function::ExternalLinkage, "foo", M);
+  Function::Create(VoidFnTy, Function::ExternalLinkage, "bar", M);
+
+  // Create test function
+  FunctionType *TestFnTy = FunctionType::get(Type::getInt32Ty(C), false);
+  Function *TestFn = Function::Create(TestFnTy, Function::ExternalLinkage, "test", M);
+  
+  // Create basic block
+  BasicBlock *BB = BasicBlock::Create(C, "entry", TestFn);
+  
+  // Create instructions
+  auto *Alloca = new AllocaInst(Type::getInt32Ty(C), 0, "p", BB);
+  auto *Store1 = new StoreInst(ConstantInt::get(Type::getInt32Ty(C), 42), Alloca, BB);
+  auto *Store2 = new StoreInst(ConstantInt::get(Type::getInt32Ty(C), 100), GlobalVar, BB);
+  auto *Call1 = CallInst::Create(M.getFunction("foo"), {}, BB);
+  auto *Call2 = CallInst::Create(M.getFunction("bar"), {}, BB);
+  auto *Load = new LoadInst(Type::getInt32Ty(C), Alloca, "val", BB);
+  ReturnInst::Create(C, Load, BB);
+
+  auto &AA = getAAResults(*TestFn);
+  EXPECT_EQ(true, AA.isNoAlias(Store1, Store2));
+  EXPECT_EQ(false, AA.isNoAlias(Store1, Call1));
+  EXPECT_EQ(false, AA.isNoAlias(Store1, Load));
+  EXPECT_EQ(false, AA.isNoAlias(Store2, Call1));
+  EXPECT_EQ(false, AA.isNoAlias(Call1, Call2));
+  EXPECT_EQ(true, AA.isNoAlias(Store2, Load));
+  
+}
+
 class AAPassInfraTest : public testing::Test {
 protected:
   LLVMContext C;