[NewPM][HelloWorld] Move HelloWorld to Utils

[aeubanks]

Summary

To prevent creating a new component, which creates a new library.

[aeubanks]

fix quoting

[ychen]

LGTM

[ychen]

llvm/docs/WritingAnLLVMNewPMPass.rst

51–55

creating a new directory involves messing around with more CMake files than we want

[aeubanks]

switch words around

llvm/docs/WritingAnLLVMNewPMPass.rst

 .. _writing-an-llvm-npm-pass-build:
 
 Setting up the build
 --------------------
 
 First, configure and build LLVM as described in :doc:`GettingStarted`.
 
 Next, we will reuse an existing directory (creating a new directory involves
-modifying more ``CMakeLists.txt``s than we want). For
-this example, we'll use ``llvm/lib/Transforms/HelloNew/HelloWorld.cpp``,
-which has already been created. If you'd like to create your own pass, add a
-new source file into ``llvm/lib/Transforms/HelloNew/CMakeLists.txt`` under
-``HelloWorld.cpp``:
-
-.. code-block:: cmake
-
-  add_llvm_component_library(LLVMHelloWorld
-    HelloWorld.cpp
-
-    DEPENDS
-    intrinsics_gen
-    )
+messing around with more CMake files than we want). For this example, we'll use
+``llvm/lib/Transforms/Utils/HelloWorld.cpp``, which has already been created.
+If you'd like to create your own pass, add a new source file into
+``llvm/lib/Transforms/Utils/CMakeLists.txt`` (assuming you want your pass in
+the ``Transforms/Utils`` directory.
 
 Now that we have the build set up for a new pass, we need to write the code
 for the pass itself.
 
 .. _writing-an-llvm-npm-pass-basiccode:
 
 Basic code required
 -------------------
 
 Now that the build is setup for a new pass, we just have to write it.
 
 First we need to define the pass in a header file. We'll create
-``llvm/include/llvm/Transforms/HelloNew/HelloWorld.h``. The file should
+``llvm/include/llvm/Transforms/Utils/HelloWorld.h``. The file should
 contain the following boilerplate:
 
 .. code-block:: c++
 
   #ifndef LLVM_TRANSFORMS_HELLONEW_HELLOWORLD_H
   #define LLVM_TRANSFORMS_HELLONEW_HELLOWORLD_H
 
   #include "llvm/IR/PassManager.h"

 
 This creates the class for the pass with a declaration of the ``run()``
 method which actually runs the pass. Inheriting from ``PassInfoMixin<PassT>``
 sets up some more boilerplate so that we don't have to write it ourselves.
 
 Our class is in the ``llvm`` namespace so that we don't pollute the global
 namespace.
 
-Next we'll create ``llvm/lib/Transforms/HelloNew/HelloWorld.cpp``, starting
+Next we'll create ``llvm/lib/Transforms/Utils/HelloWorld.cpp``, starting
 with
 
 .. code-block:: c++
 
-  #include "llvm/Transforms/HelloNew/HelloWorld.h"
+  #include "llvm/Transforms/Utils/HelloWorld.h"
 
 ... to include the header file we just created.
 
 .. code-block:: c++
 
   using namespace llvm;
 
 ... is required because the functions from the include files live in the llvm

 
 ... which simply prints out the name of the function to stderr. The pass
 manager will ensure that the pass will be run on every function in a module.
 The ``PreservedAnalyses`` return value says that all analyses (e.g. dominator
 tree) are still valid after this pass since we didn't modify any functions.
 
 That's it for the pass itself. Now in order to "register" the pass, we need
 to add it to a couple places. Add the following to
-``llvm\lib\Passes\PassRegistry.def`` in the ``FUNCTION_PASS`` section
+``llvm/lib/Passes/PassRegistry.def`` in the ``FUNCTION_PASS`` section
 
 .. code-block:: c++
 
   FUNCTION_PASS("helloworld", HelloWorldPass())
 
 ... which adds the pass under the name "helloworld".
 
-``llvm\lib\Passes\PassRegistry.def`` is #include'd into
-``llvm\lib\Passes\PassBuilder.cpp`` multiple times for various reasons. Since
+``llvm/lib/Passes/PassRegistry.def`` is #include'd into
+``llvm/lib/Passes/PassBuilder.cpp`` multiple times for various reasons. Since
 it constructs our pass, we need to also add the proper #include in
-``llvm\lib\Passes\PassBuilder.cpp``:
+``llvm/lib/Passes/PassBuilder.cpp``:
 
 .. code-block:: c++
 
-  #include "llvm/Transforms/HelloNew/HelloWorld.h"
+  #include "llvm/Transforms/Utils/HelloWorld.h"
 
 This should be all the code necessary for our pass, now it's time to compile
 and run it.
 
 Running a pass with ``opt``
 ---------------------------
 
 Now that you have a brand new shiny pass, we can build :program:`opt` and use
.. code-block:: console
   bar
 
 Our pass ran and printed the names of functions as expected!
 
 Testing a pass
 --------------
 
 Testing our pass is important to prevent future regressions. We'll add a lit
-test at ``llvm/test/Transforms/HelloNew/helloworld.ll``. See
+test at ``llvm/test/Transforms/Utils/helloworld.ll``. See
 :doc:`TestingGuide` for more information on testing.
 
 .. code-block:: llvm
 
-  $ cat llvm/test/Transforms/HelloNew/helloworld.ll
+  $ cat llvm/test/Transforms/Utils/helloworld.ll
   ; RUN: opt -disable-output -passes=helloworld %s 2>&1 | FileCheck %s
 
   ; CHECK: {{^}}foo{{$}}
   define i32 @foo() {
     %a = add i32 2, 3
     ret i32 %a
   }
 

llvm/lib/Passes/CMakeLists.txt

add_llvm_component_library(LLVMPasses
   DEPENDS
   intrinsics_gen
 
   LINK_COMPONENTS
   AggressiveInstCombine
   Analysis
   Core
   Coroutines
-  HelloNew
   IPO
   InstCombine
   ObjCARC
   Scalar
   Support
   Target
   TransformUtils
   Vectorize
   Instrumentation
   )

llvm/lib/Passes/PassBuilder.cpp

 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
 #include "llvm/Transforms/Coroutines/CoroCleanup.h"
 #include "llvm/Transforms/Coroutines/CoroEarly.h"
 #include "llvm/Transforms/Coroutines/CoroElide.h"
 #include "llvm/Transforms/Coroutines/CoroSplit.h"
-#include "llvm/Transforms/HelloNew/HelloWorld.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
 #include "llvm/Transforms/IPO/Annotation2Metadata.h"
 #include "llvm/Transforms/IPO/ArgumentPromotion.h"
 #include "llvm/Transforms/IPO/Attributor.h"
 #include "llvm/Transforms/IPO/BlockExtractor.h"
 #include "llvm/Transforms/IPO/CalledValuePropagation.h"
 #include "llvm/Transforms/IPO/ConstantMerge.h"
 #include "llvm/Transforms/IPO/CrossDSOCFI.h"

 #include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
 #include "llvm/Transforms/Utils/AddDiscriminators.h"
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/BreakCriticalEdges.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #include "llvm/Transforms/Utils/CanonicalizeFreezeInLoops.h"
 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
 #include "llvm/Transforms/Utils/FixIrreducible.h"
+#include "llvm/Transforms/Utils/HelloWorld.h"
 #include "llvm/Transforms/Utils/InjectTLIMappings.h"
 #include "llvm/Transforms/Utils/InstructionNamer.h"
 #include "llvm/Transforms/Utils/LCSSA.h"
 #include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
 #include "llvm/Transforms/Utils/LoopSimplify.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include "llvm/Transforms/Utils/LowerInvoke.h"
 #include "llvm/Transforms/Utils/LowerSwitch.h"

llvm/lib/Transforms/CMakeLists.txt

 add_subdirectory(Utils)
 add_subdirectory(Instrumentation)
 add_subdirectory(AggressiveInstCombine)
 add_subdirectory(InstCombine)
 add_subdirectory(Scalar)
 add_subdirectory(IPO)
 add_subdirectory(Vectorize)
 add_subdirectory(Hello)
-add_subdirectory(HelloNew)
 add_subdirectory(ObjCARC)
 add_subdirectory(Coroutines)
 add_subdirectory(CFGuard)

llvm/lib/Transforms/HelloNew/CMakeLists.txt

-add_llvm_component_library(LLVMHelloNew
-  HelloWorld.cpp
-
-  DEPENDS
-  intrinsics_gen
-
-  LINK_COMPONENTS
-  Core
-  Support
-  )

llvm/lib/Transforms/Utils/CMakeLists.txt

add_llvm_component_library(LLVMTransformUtils
   EscapeEnumerator.cpp
   Evaluator.cpp
   FixIrreducible.cpp
   FlattenCFG.cpp
   FunctionComparator.cpp
   FunctionImportUtils.cpp
   GlobalStatus.cpp
   GuardUtils.cpp
+  HelloWorld.cpp
   InlineFunction.cpp
   InjectTLIMappings.cpp
   InstructionNamer.cpp
   IntegerDivision.cpp
   LCSSA.cpp
   LibCallsShrinkWrap.cpp
   Local.cpp
   LoopPeel.cpp

llvm/lib/Transforms/Utils/HelloWorld.cpp

 //===-- HelloWorld.cpp - Example Transformations --------------------------===//
 //
 // 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/Transforms/HelloNew/HelloWorld.h"
+#include "llvm/Transforms/Utils/HelloWorld.h"
 
 using namespace llvm;
 
 PreservedAnalyses HelloWorldPass::run(Function &F,
                                       FunctionAnalysisManager &AM) {
   errs() << F.getName() << "\n";
   return PreservedAnalyses::all();
 }

llvm/utils/gn/secondary/llvm/lib/Passes/BUILD.gn

 static_library("Passes") {
   output_name = "LLVMPasses"
   deps = [
     "//llvm/lib/Analysis",
     "//llvm/lib/CodeGen",
     "//llvm/lib/IR",
     "//llvm/lib/Support",
     "//llvm/lib/Target",
     "//llvm/lib/Transforms/AggressiveInstCombine",
     "//llvm/lib/Transforms/Coroutines",
-    "//llvm/lib/Transforms/HelloNew",
     "//llvm/lib/Transforms/IPO",
     "//llvm/lib/Transforms/InstCombine",
     "//llvm/lib/Transforms/Instrumentation",
     "//llvm/lib/Transforms/ObjCARC",
     "//llvm/lib/Transforms/Scalar",
     "//llvm/lib/Transforms/Utils",
     "//llvm/lib/Transforms/Vectorize",
   ]
   sources = [
     "PassBuilder.cpp",
     "PassPlugin.cpp",
     "StandardInstrumentations.cpp",
   ]
 }

llvm/utils/gn/secondary/llvm/lib/Transforms/HelloNew/BUILD.gn

-static_library("HelloNew") {
-  output_name = "LLVMHelloNew"
-  deps = [
-    "//llvm/lib/Analysis",
-    "//llvm/lib/IR",
-    "//llvm/lib/Support",
-  ]
-  sources = [ "HelloWorld.cpp" ]
-}

llvm/utils/gn/secondary/llvm/lib/Transforms/Utils/BUILD.gn

sources = [
     "EscapeEnumerator.cpp",
     "Evaluator.cpp",
     "FixIrreducible.cpp",
     "FlattenCFG.cpp",
     "FunctionComparator.cpp",
     "FunctionImportUtils.cpp",
     "GlobalStatus.cpp",
     "GuardUtils.cpp",
+    "HelloWorld.cpp",
     "InjectTLIMappings.cpp",
     "InlineFunction.cpp",
     "InstructionNamer.cpp",
     "IntegerDivision.cpp",
     "LCSSA.cpp",
     "LibCallsShrinkWrap.cpp",
     "Local.cpp",
     "LoopPeel.cpp",