[llvm] [CodeGen] Allow `CodeGenPassBuilder` to add module pass after function pass (PR #77084)

[via llvm-commits]

================
@@ -0,0 +1,158 @@
+//===- llvm/unittest/CodeGen/CodeGenPassBuilderTest.cpp -------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/CodeGenPassBuilder.h"
+#include "llvm/CodeGen/MachinePassManager.h"
+#include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/TargetRegistry.h"
+#include "llvm/Passes/PassBuilder.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/TargetParser/Host.h"
+#include "gtest/gtest.h"
+#include <string>
+
+using namespace llvm;
+
+namespace {
+
+struct NoOpModulePass : PassInfoMixin<NoOpModulePass> {
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &) {
+    return PreservedAnalyses::all();
+  }
+
+  static StringRef name() { return "NoOpModulePass"; }
+};
+
+struct NoOpFunctionPass : PassInfoMixin<NoOpFunctionPass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &) {
+    return PreservedAnalyses::all();
+  }
+  static StringRef name() { return "NoOpFunctionPass"; }
+};
+
+class DummyCodeGenPassBuilder
+    : public CodeGenPassBuilder<DummyCodeGenPassBuilder> {
+public:
+  DummyCodeGenPassBuilder(LLVMTargetMachine &TM, CGPassBuilderOption Opts,
+                          PassInstrumentationCallbacks *PIC)
+      : CodeGenPassBuilder(TM, Opts, PIC){};
+
+  void addPreISel(AddIRPass &addPass) const {
+    addPass(NoOpModulePass());
+    addPass(NoOpFunctionPass());
+    addPass(NoOpFunctionPass());
+    addPass(NoOpFunctionPass());
+    addPass(NoOpModulePass());
+    addPass(NoOpFunctionPass());
+  }
+
+  void addAsmPrinter(AddMachinePass &, CreateMCStreamer) const {}
+
+  Error addInstSelector(AddMachinePass &) const { return Error::success(); }
+};
+
+class CodeGenPassBuilderTest : public testing::Test {
+public:
+  LLVMTargetMachine *TM;
+
+  static void SetUpTestCase() {
+    InitializeAllTargets();
+    InitializeAllTargetMCs();
+
+    static const char *argv[] = {
+        "test",
+        "-print-pipeline-passes",
+    };
+    int argc = std::size(argv);
+    cl::ParseCommandLineOptions(argc, argv);
+  }
+
+  void SetUp() override {
+    std::string TripleName = Triple::normalize(sys::getDefaultTargetTriple());
----------------
paperchalice wrote:

Yes, it will depend on the specific target, but I noticed there is a `BogusTargetMachine` in `unittests/CodeGen/MFCommon.inc`, will use it later.

https://github.com/llvm/llvm-project/pull/77084