如何使用新的 Pass Manager 定义和读取 LLVM Pass 的 CLI 参数？

Question

如何使用新的 Pass Manager 定义和读取 LLVM Pass 的 CLI 参数？

Axe*_*noz 4 plugins llvm command-line-arguments

我想知道是否有一种方法可以在 LLVM pass 插件中定义和读取 CLI 参数的值？我的插件基于banach-space/llvm-tutor，特别是InjectFuncCall。假设我想传递一个参数-func=foo来表示仅注入名为的函数foo。我到底如何定义这个命令行参数？

我尝试使用CommandLine 2.0 Library。看到了这个答案，但我无法opt认可我的论点。

Answer 1

Lev*_*sov 6

我发现如果您使用opt -load yourLib.so. 在这种情况下，命令将如下所示：

opt -load ./build/libHelloWorld.so -load-pass-plugin=./build/libHelloWorld.so \ 
-passes="hello-world" -disable-output -lists MYARG1 -lists MYARG2 ./input_for_hello.ll

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下面是完整的可重现示例。

你好世界.cpp：

#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CommandLine.h"

using namespace llvm;

namespace {

// Here we register the pass arguments
cl::list<std::string> Lists("lists", cl::desc("Specify names"), cl::OneOrMore);

// This method implements what the pass does
void visitor(Function &F) {
    // using the pass arguments
      for(auto arg: Lists) {
        errs() << "arg: " << arg << "\n";
      }
    errs() << "(llvm-tutor) Hello from: "<< F.getName() << "\n";
    errs() << "(llvm-tutor)   number of arguments: " << F.arg_size() << "\n";
}

// New PM implementation
struct HelloWorld : PassInfoMixin<HelloWorld> {
  // Main entry point, takes IR unit to run the pass on (&F) and the
  // corresponding pass manager (to be queried if need be)
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &) {
    visitor(F);
    return PreservedAnalyses::all();
  }
};

} // namespace

//-----------------------------------------------------------------------------
// New PM Registration
//-----------------------------------------------------------------------------
llvm::PassPluginLibraryInfo getHelloWorldPluginInfo() {
  return {LLVM_PLUGIN_API_VERSION, "HelloWorld", LLVM_VERSION_STRING,
          [](PassBuilder &PB) {
            PB.registerPipelineParsingCallback(
                [](StringRef Name, FunctionPassManager &FPM,
                   ArrayRef<PassBuilder::PipelineElement>) {
                  if (Name == "hello-world") {
                    FPM.addPass(HelloWorld());
                    return true;
                  }
                  return false;
                });
          }};
}

// This is the core interface for pass plugins. It guarantees that 'opt' will
// be able to recognize HelloWorld when added to the pass pipeline on the
// command line, i.e. via '-passes=hello-world'
extern "C" LLVM_ATTRIBUTE_WEAK ::llvm::PassPluginLibraryInfo
llvmGetPassPluginInfo() {
  return getHelloWorldPluginInfo();
}

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CMakeLists.txt：

cmake_minimum_required(VERSION 3.13.4)
project(llvm-tutor-hello-world)

#===============================================================================
# 1. LOAD LLVM CONFIGURATION
#===============================================================================
# Set this to a valid LLVM installation dir
set(LT_LLVM_INSTALL_DIR "" CACHE PATH "LLVM installation directory")

# Add the location of LLVMConfig.cmake to CMake search paths (so that
# find_package can locate it)
list(APPEND CMAKE_PREFIX_PATH "${LT_LLVM_INSTALL_DIR}/lib/cmake/llvm/")

# FIXME: This is a warkaround for #25. Remove once resolved and use
# find_package(LLVM 11.0.0 REQUIRED CONFIG) instead.
find_package(LLVM REQUIRED CONFIG)

# HelloWorld includes headers from LLVM - update the include paths accordingly
include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})

#===============================================================================
# 2. LLVM-TUTOR BUILD CONFIGURATION
#===============================================================================
# Use the same C++ standard as LLVM does
set(CMAKE_CXX_STANDARD 14 CACHE STRING "")

# LLVM is normally built without RTTI. Be consistent with that.
if(NOT LLVM_ENABLE_RTTI)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti")
endif()

#===============================================================================
# 3. ADD THE TARGET
#===============================================================================
add_library(HelloWorld SHARED HelloWorld.cpp)

# Allow undefined symbols in shared objects on Darwin (this is the default
# behaviour on Linux)
target_link_libraries(HelloWorld
  "$<$<PLATFORM_ID:Darwin>:-undefined dynamic_lookup>")

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input_for_hello.ll：

; ModuleID = '../inputs/input_for_hello.c'
source_filename = "../inputs/input_for_hello.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @foo(i32 %0) local_unnamed_addr #0 {
  %2 = shl nsw i32 %0, 1
  ret i32 %2
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @bar(i32 %0, i32 %1) local_unnamed_addr #0 {
  %3 = shl i32 %1, 2
  %4 = add nsw i32 %3, %0
  ret i32 %4
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @fez(i32 %0, i32 %1, i32 %2) local_unnamed_addr #0 {
  %4 = shl i32 %1, 2
  %5 = add nsw i32 %4, %0
  %6 = shl nsw i32 %5, 1
  %7 = mul nsw i32 %2, 3
  %8 = add i32 %7, %0
  %9 = add i32 %8, %6
  ret i32 %9
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @main(i32 %0, i8** nocapture readnone %1) local_unnamed_addr #0 {
  ret i32 12915
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"uwtable", i32 1}
!2 = !{!"Ubuntu clang version 13.0.1-++20220120110924+75e33f71c2da-1~exp1~20220120231001.58"}

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构建步骤：

cmake_minimum_required(VERSION 3.13.4)
project(llvm-tutor-hello-world)

#===============================================================================
# 1. LOAD LLVM CONFIGURATION
#===============================================================================
# Set this to a valid LLVM installation dir
set(LT_LLVM_INSTALL_DIR "" CACHE PATH "LLVM installation directory")

# Add the location of LLVMConfig.cmake to CMake search paths (so that
# find_package can locate it)
list(APPEND CMAKE_PREFIX_PATH "${LT_LLVM_INSTALL_DIR}/lib/cmake/llvm/")

# FIXME: This is a warkaround for #25. Remove once resolved and use
# find_package(LLVM 11.0.0 REQUIRED CONFIG) instead.
find_package(LLVM REQUIRED CONFIG)

# HelloWorld includes headers from LLVM - update the include paths accordingly
include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})

#===============================================================================
# 2. LLVM-TUTOR BUILD CONFIGURATION
#===============================================================================
# Use the same C++ standard as LLVM does
set(CMAKE_CXX_STANDARD 14 CACHE STRING "")

# LLVM is normally built without RTTI. Be consistent with that.
if(NOT LLVM_ENABLE_RTTI)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti")
endif()

#===============================================================================
# 3. ADD THE TARGET
#===============================================================================
add_library(HelloWorld SHARED HelloWorld.cpp)

# Allow undefined symbols in shared objects on Darwin (this is the default
# behaviour on Linux)
target_link_libraries(HelloWorld
  "$<$<PLATFORM_ID:Darwin>:-undefined dynamic_lookup>")

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运行通行证：

; ModuleID = '../inputs/input_for_hello.c'
source_filename = "../inputs/input_for_hello.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @foo(i32 %0) local_unnamed_addr #0 {
  %2 = shl nsw i32 %0, 1
  ret i32 %2
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @bar(i32 %0, i32 %1) local_unnamed_addr #0 {
  %3 = shl i32 %1, 2
  %4 = add nsw i32 %3, %0
  ret i32 %4
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @fez(i32 %0, i32 %1, i32 %2) local_unnamed_addr #0 {
  %4 = shl i32 %1, 2
  %5 = add nsw i32 %4, %0
  %6 = shl nsw i32 %5, 1
  %7 = mul nsw i32 %2, 3
  %8 = add i32 %7, %0
  %9 = add i32 %8, %6
  ret i32 %9
}

; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn
define dso_local i32 @main(i32 %0, i8** nocapture readnone %1) local_unnamed_addr #0 {
  ret i32 12915
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind readnone uwtable willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"uwtable", i32 1}
!2 = !{!"Ubuntu clang version 13.0.1-++20220120110924+75e33f71c2da-1~exp1~20220120231001.58"}

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输出：

arg: MYARG1
arg: MYARG2
(llvm-tutor) Hello from: foo
(llvm-tutor)   number of arguments: 1
arg: MYARG1
arg: MYARG2
(llvm-tutor) Hello from: bar
(llvm-tutor)   number of arguments: 2
arg: MYARG1
arg: MYARG2
(llvm-tutor) Hello from: fez
(llvm-tutor)   number of arguments: 3
arg: MYARG1
arg: MYARG2
(llvm-tutor) Hello from: main
(llvm-tutor)   number of arguments: 2

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