ExecutionDriver.cpp

//===- ExecutionDriver.cpp - Allow execution of LLVM program --------------===//
//
// 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 code used to execute the program utilizing one of the
// various ways of running LLVM bitcode.
//
//===----------------------------------------------------------------------===//

#include"BugDriver.h"
#include"ToolRunner.h"
#include"llvm/Support/CommandLine.h"
#include"llvm/Support/Debug.h"
#include"llvm/Support/FileUtilities.h"
#include"llvm/Support/Program.h"
#include"llvm/Support/SystemUtils.h"
#include"llvm/Support/raw_ostream.h"
#include<fstream>

usingnamespacellvm;

namespace {
// OutputType - Allow the user to specify the way code should be run, to test
// for miscompilation.
//
enum OutputType {
 AutoPick,
 RunLLI,
 RunJIT,
 RunLLC,
 RunLLCIA,
 LLC_Safe,
 CompileCustom,
 Custom
};

cl::opt<double> AbsTolerance("abs-tolerance",
cl::desc("Absolute error tolerated"),
 cl::init(0.0));
cl::opt<double> RelTolerance("rel-tolerance",
cl::desc("Relative error tolerated"),
 cl::init(0.0));

cl::opt<OutputType> InterpreterSel(
cl::desc("Specify the \"test\" i.e. suspect back-end:"),
 cl::values(clEnumValN(AutoPick, "auto", "Use best guess"),
 clEnumValN(RunLLI, "run-int", "Execute with the interpreter"),
 clEnumValN(RunJIT, "run-jit", "Execute with JIT"),
 clEnumValN(RunLLC, "run-llc", "Compile with LLC"),
 clEnumValN(RunLLCIA, "run-llc-ia",
"Compile with LLC with integrated assembler"),
 clEnumValN(LLC_Safe, "llc-safe", "Use LLC for all"),
 clEnumValN(CompileCustom, "compile-custom",
"Use -compile-command to define a command to "
"compile the bitcode. Useful to avoid linking."),
 clEnumValN(Custom, "run-custom",
"Use -exec-command to define a command to execute "
"the bitcode. Useful for cross-compilation.")),
 cl::init(AutoPick));

cl::opt<OutputType> SafeInterpreterSel(
cl::desc("Specify \"safe\" i.e. known-good backend:"),
 cl::values(clEnumValN(AutoPick, "safe-auto", "Use best guess"),
 clEnumValN(RunLLC, "safe-run-llc", "Compile with LLC"),
 clEnumValN(Custom, "safe-run-custom",
"Use -exec-command to define a command to execute "
"the bitcode. Useful for cross-compilation.")),
 cl::init(AutoPick));

cl::opt<std::string> SafeInterpreterPath(
"safe-path", cl::desc("Specify the path to the \"safe\" backend program"),
 cl::init(""));

cl::opt<bool> AppendProgramExitCode(
"append-exit-code",
cl::desc("Append the exit code to the output so it gets diff'd too"),
 cl::init(false));

cl::opt<std::string>
InputFile("input", cl::init("/dev/null"),
 cl::desc("Filename to pipe in as stdin (default: /dev/null)"));

cl::list<std::string>
AdditionalSOs("additional-so", cl::desc("Additional shared objects to load "
"into executing programs"));

cl::list<std::string> AdditionalLinkerArgs(
"Xlinker", cl::desc("Additional arguments to pass to the linker"));

cl::opt<std::string> CustomCompileCommand(
"compile-command", cl::init("llc"),
 cl::desc("Command to compile the bitcode (use with -compile-custom) "
"(default: llc)"));

cl::opt<std::string> CustomExecCommand(
"exec-command", cl::init("simulate"),
 cl::desc("Command to execute the bitcode (use with -run-custom) "
"(default: simulate)"));
}

namespacellvm {
// Anything specified after the --args option are taken as arguments to the
// program being debugged.
cl::list<std::string> InputArgv("args", cl::Positional,
cl::desc("<program arguments>..."),
 cl::ZeroOrMore, cl::PositionalEatsArgs);

cl::opt<std::string>
OutputPrefix("output-prefix", cl::init("bugpoint"),
 cl::desc("Prefix to use for outputs (default: 'bugpoint')"));
}

namespace {
cl::list<std::string> ToolArgv("tool-args", cl::Positional,
cl::desc("<tool arguments>..."), cl::ZeroOrMore,
 cl::PositionalEatsArgs);

cl::list<std::string> SafeToolArgv("safe-tool-args", cl::Positional,
cl::desc("<safe-tool arguments>..."),
 cl::ZeroOrMore, cl::PositionalEatsArgs);

cl::opt<std::string> CCBinary("gcc", cl::init(""),
 cl::desc("The gcc binary to use."));

cl::list<std::string> CCToolArgv("gcc-tool-args", cl::Positional,
cl::desc("<gcc-tool arguments>..."),
 cl::ZeroOrMore, cl::PositionalEatsArgs);
}

//===----------------------------------------------------------------------===//
// BugDriver method implementation
//

/// initializeExecutionEnvironment - This method is used to set up the
/// environment for executing LLVM programs.
///
Error BugDriver::initializeExecutionEnvironment() {
outs() << "Initializing execution environment: ";

// Create an instance of the AbstractInterpreter interface as specified on
// the command line
 SafeInterpreter = nullptr;
 std::string Message;

if (CCBinary.empty()) {
if (ErrorOr<std::string> ClangPath =
FindProgramByName("clang", getToolName(), &AbsTolerance))
 CCBinary = *ClangPath;
else
 CCBinary = "gcc";
 }

switch (InterpreterSel) {
case AutoPick:
if (!Interpreter) {
 InterpreterSel = RunJIT;
 Interpreter =
AbstractInterpreter::createJIT(getToolName(), Message, &ToolArgv);
 }
if (!Interpreter) {
 InterpreterSel = RunLLC;
 Interpreter = AbstractInterpreter::createLLC(
getToolName(), Message, CCBinary, &ToolArgv, &CCToolArgv);
 }
if (!Interpreter) {
 InterpreterSel = RunLLI;
 Interpreter =
AbstractInterpreter::createLLI(getToolName(), Message, &ToolArgv);
 }
if (!Interpreter) {
 InterpreterSel = AutoPick;
 Message = "Sorry, I can't automatically select an interpreter!\n";
 }
break;
case RunLLI:
 Interpreter =
AbstractInterpreter::createLLI(getToolName(), Message, &ToolArgv);
break;
case RunLLC:
case RunLLCIA:
case LLC_Safe:
 Interpreter = AbstractInterpreter::createLLC(
getToolName(), Message, CCBinary, &ToolArgv, &CCToolArgv,
 InterpreterSel == RunLLCIA);
break;
case RunJIT:
 Interpreter =
AbstractInterpreter::createJIT(getToolName(), Message, &ToolArgv);
break;
case CompileCustom:
 Interpreter = AbstractInterpreter::createCustomCompiler(
getToolName(), Message, CustomCompileCommand);
break;
case Custom:
 Interpreter = AbstractInterpreter::createCustomExecutor(
getToolName(), Message, CustomExecCommand);
break;
 }
if (!Interpreter)
errs() << Message;
else// Display informational messages on stdout instead of stderr
outs() << Message;

 std::string Path = SafeInterpreterPath;
if (Path.empty())
 Path = getToolName();
 std::vector<std::string> SafeToolArgs = SafeToolArgv;
switch (SafeInterpreterSel) {
case AutoPick:
// In "llc-safe" mode, default to using LLC as the "safe" backend.
if (!SafeInterpreter && InterpreterSel == LLC_Safe) {
 SafeInterpreterSel = RunLLC;
 SafeToolArgs.push_back("--relocation-model=pic");
 SafeInterpreter = AbstractInterpreter::createLLC(
 Path.c_str(), Message, CCBinary, &SafeToolArgs, &CCToolArgv);
 }

if (!SafeInterpreter && InterpreterSel != RunLLC &&
 InterpreterSel != RunJIT) {
 SafeInterpreterSel = RunLLC;
 SafeToolArgs.push_back("--relocation-model=pic");
 SafeInterpreter = AbstractInterpreter::createLLC(
 Path.c_str(), Message, CCBinary, &SafeToolArgs, &CCToolArgv);
 }
if (!SafeInterpreter) {
 SafeInterpreterSel = AutoPick;
 Message = "Sorry, I can't automatically select a safe interpreter!\n";
 }
break;
case RunLLC:
case RunLLCIA:
 SafeToolArgs.push_back("--relocation-model=pic");
 SafeInterpreter = AbstractInterpreter::createLLC(
 Path.c_str(), Message, CCBinary, &SafeToolArgs, &CCToolArgv,
 SafeInterpreterSel == RunLLCIA);
break;
case Custom:
 SafeInterpreter = AbstractInterpreter::createCustomExecutor(
getToolName(), Message, CustomExecCommand);
break;
default:
 Message = "Sorry, this back-end is not supported by bugpoint as the "
"\"safe\" backend right now!\n";
break;
 }
if (!SafeInterpreter) {
outs() << Message << "\nExiting.\n";
exit(1);
 }

 cc = CC::create(getToolName(), Message, CCBinary, &CCToolArgv);
if (!cc) {
outs() << Message << "\nExiting.\n";
exit(1);
 }

// If there was an error creating the selected interpreter, quit with error.
if (Interpreter == nullptr)
return make_error<StringError>("Failed to init execution environment",
inconvertibleErrorCode());
returnError::success();
}

/// Try to compile the specified module, returning false and setting Error if an
/// error occurs. This is used for code generation crash testing.
Error BugDriver::compileProgram(Module &M) const {
// Emit the program to a bitcode file...
auto Temp =
sys::fs::TempFile::create(OutputPrefix + "-test-program-%%%%%%%.bc");
if (!Temp) {
errs() << ToolName
 << ": Error making unique filename: " << toString(Temp.takeError())
 << "\n";
exit(1);
 }
 DiscardTemp Discard{*Temp};
if (writeProgramToFile(Temp->FD, M)) {
errs() << ToolName << ": Error emitting bitcode to file '" << Temp->TmpName
 << "'!\n";
exit(1);
 }

// Actually compile the program!
return Interpreter->compileProgram(Temp->TmpName, Timeout, MemoryLimit);
}

/// This method runs "Program", capturing the output of the program to a file,
/// returning the filename of the file. A recommended filename may be
/// optionally specified.
Expected<std::string> BugDriver::executeProgram(const Module &Program,
 std::string OutputFile,
 std::string BitcodeFile,
const std::string &SharedObj,
 AbstractInterpreter *AI) const {
if (!AI)
 AI = Interpreter;
assert(AI && "Interpreter should have been created already!");
bool CreatedBitcode = false;
if (BitcodeFile.empty()) {
// Emit the program to a bitcode file...
 SmallString<128> UniqueFilename;
int UniqueFD;
 std::error_code EC = sys::fs::createUniqueFile(
 OutputPrefix + "-test-program-%%%%%%%.bc", UniqueFD, UniqueFilename);
if (EC) {
errs() << ToolName << ": Error making unique filename: " << EC.message()
 << "!\n";
exit(1);
 }
 BitcodeFile = UniqueFilename.str();

if (writeProgramToFile(BitcodeFile, UniqueFD, Program)) {
errs() << ToolName << ": Error emitting bitcode to file '" << BitcodeFile
 << "'!\n";
exit(1);
 }
 CreatedBitcode = true;
 }

// Remove the temporary bitcode file when we are done.
 std::string BitcodePath(BitcodeFile);
 FileRemover BitcodeFileRemover(BitcodePath, CreatedBitcode && !SaveTemps);

if (OutputFile.empty())
 OutputFile = OutputPrefix + "-execution-output-%%%%%%%";

// Check to see if this is a valid output filename...
 SmallString<128> UniqueFile;
 std::error_code EC = sys::fs::createUniqueFile(OutputFile, UniqueFile);
if (EC) {
errs() << ToolName << ": Error making unique filename: " << EC.message()
 << "\n";
exit(1);
 }
 OutputFile = UniqueFile.str();

// Figure out which shared objects to run, if any.
 std::vector<std::string> SharedObjs(AdditionalSOs);
if (!SharedObj.empty())
 SharedObjs.push_back(SharedObj);

 Expected<int> RetVal = AI->ExecuteProgram(BitcodeFile, InputArgv, InputFile,
 OutputFile, AdditionalLinkerArgs,
 SharedObjs, Timeout, MemoryLimit);
if (Error E = RetVal.takeError())
returnstd::move(E);

if (*RetVal == -1) {
errs() << "<timeout>";
staticbool FirstTimeout = true;
if (FirstTimeout) {
outs()
 << "\n"
"*** Program execution timed out! This mechanism is designed to "
"handle\n"
" programs stuck in infinite loops gracefully. The -timeout "
"option\n"
" can be used to change the timeout threshold or disable it "
"completely\n"
" (with -timeout=0). This message is only displayed once.\n";
 FirstTimeout = false;
 }
 }

if (AppendProgramExitCode) {
 std::ofstream outFile(OutputFile.c_str(), std::ios_base::app);
 outFile << "exit " << *RetVal << '\n';
 outFile.close();
 }

// Return the filename we captured the output to.
return OutputFile;
}

/// Used to create reference output with the "safe" backend, if reference output
/// is not provided.
Expected<std::string>
BugDriver::executeProgramSafely(const Module &Program,
const std::string &OutputFile) const {
returnexecuteProgram(Program, OutputFile, "", "", SafeInterpreter);
}

Expected<std::string>
BugDriver::compileSharedObject(const std::string &BitcodeFile) {
assert(Interpreter && "Interpreter should have been created already!");
 std::string OutputFile;

// Using the known-good backend.
 Expected<CC::FileType> FT =
 SafeInterpreter->OutputCode(BitcodeFile, OutputFile);
if (Error E = FT.takeError())
returnstd::move(E);

 std::string SharedObjectFile;
if (Error E = cc->MakeSharedObject(OutputFile, *FT, SharedObjectFile,
 AdditionalLinkerArgs))
returnstd::move(E);

// Remove the intermediate C file
sys::fs::remove(OutputFile);

return SharedObjectFile;
}

/// Calls compileProgram and then records the output into ReferenceOutputFile.
/// Returns true if reference file created, false otherwise. Note:
/// initializeExecutionEnvironment should be called BEFORE this function.
Error BugDriver::createReferenceFile(Module &M, const std::string &Filename) {
if (Error E = compileProgram(*Program))
return E;

 Expected<std::string> Result = executeProgramSafely(*Program, Filename);
if (Error E = Result.takeError()) {
if (Interpreter != SafeInterpreter) {
 E = joinErrors(
std::move(E),
 make_error<StringError>(
"*** There is a bug running the \"safe\" backend. Either"
" debug it (for example with the -run-jit bugpoint option,"
" if JIT is being used as the \"safe\" backend), or fix the"
" error some other way.\n",
inconvertibleErrorCode()));
 }
return E;
 }
 ReferenceOutputFile = *Result;
outs() << "\nReference output is: " << ReferenceOutputFile << "\n\n";
returnError::success();
}

/// This method executes the specified module and diffs the output against the
/// file specified by ReferenceOutputFile. If the output is different, 1 is
/// returned. If there is a problem with the code generator (e.g., llc
/// crashes), this will set ErrMsg.
Expected<bool> BugDriver::diffProgram(const Module &Program,
const std::string &BitcodeFile,
const std::string &SharedObject,
bool RemoveBitcode) const {
// Execute the program, generating an output file...
 Expected<std::string> Output =
executeProgram(Program, "", BitcodeFile, SharedObject, nullptr);
if (Error E = Output.takeError())
returnstd::move(E);

 std::string Error;
bool FilesDifferent = false;
if (int Diff = DiffFilesWithTolerance(ReferenceOutputFile, *Output,
 AbsTolerance, RelTolerance, &Error)) {
if (Diff == 2) {
errs() << "While diffing output: " << Error << '\n';
exit(1);
 }
 FilesDifferent = true;
 } else {
// Remove the generated output if there are no differences.
sys::fs::remove(*Output);
 }

// Remove the bitcode file if we are supposed to.
if (RemoveBitcode)
sys::fs::remove(BitcodeFile);
return FilesDifferent;
}

boolBugDriver::isExecutingJIT() { return InterpreterSel == RunJIT; }