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llvm-project/llvm/tools/bugpoint/Miscompilation.cpp

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//===- Miscompilation.cpp - Debug program miscompilations -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements optimizer and code generation miscompilation debugging
// support.
//
//===----------------------------------------------------------------------===//
#include "BugDriver.h"
#include "ListReducer.h"
#include "ToolRunner.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Linker.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Config/config.h" // for HAVE_LINK_R
using namespace llvm;
namespace llvm {
extern cl::opt<std::string> OutputPrefix;
extern cl::list<std::string> InputArgv;
}
namespace {
static llvm::cl::opt<bool>
DisableLoopExtraction("disable-loop-extraction",
cl::desc("Don't extract loops when searching for miscompilations"),
cl::init(false));
static llvm::cl::opt<bool>
DisableBlockExtraction("disable-block-extraction",
cl::desc("Don't extract blocks when searching for miscompilations"),
cl::init(false));
class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
BugDriver &BD;
public:
ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
std::vector<const PassInfo*> &Suffix);
};
}
/// TestResult - After passes have been split into a test group and a control
/// group, see if they still break the program.
///
ReduceMiscompilingPasses::TestResult
ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
std::vector<const PassInfo*> &Suffix) {
// First, run the program with just the Suffix passes. If it is still broken
// with JUST the kept passes, discard the prefix passes.
outs() << "Checking to see if '" << getPassesString(Suffix)
<< "' compiles correctly: ";
std::string BitcodeResult;
if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// Check to see if the finished program matches the reference output...
if (BD.diffProgram(BitcodeResult, "", true /*delete bitcode*/)) {
outs() << " nope.\n";
if (Suffix.empty()) {
errs() << BD.getToolName() << ": I'm confused: the test fails when "
<< "no passes are run, nondeterministic program?\n";
exit(1);
}
return KeepSuffix; // Miscompilation detected!
}
outs() << " yup.\n"; // No miscompilation!
if (Prefix.empty()) return NoFailure;
// Next, see if the program is broken if we run the "prefix" passes first,
// then separately run the "kept" passes.
outs() << "Checking to see if '" << getPassesString(Prefix)
<< "' compiles correctly: ";
// If it is not broken with the kept passes, it's possible that the prefix
// passes must be run before the kept passes to break it. If the program
// WORKS after the prefix passes, but then fails if running the prefix AND
// kept passes, we can update our bitcode file to include the result of the
// prefix passes, then discard the prefix passes.
//
if (BD.runPasses(Prefix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Prefix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// If the prefix maintains the predicate by itself, only keep the prefix!
if (BD.diffProgram(BitcodeResult)) {
outs() << " nope.\n";
sys::Path(BitcodeResult).eraseFromDisk();
return KeepPrefix;
}
outs() << " yup.\n"; // No miscompilation!
// Ok, so now we know that the prefix passes work, try running the suffix
// passes on the result of the prefix passes.
//
Module *PrefixOutput = ParseInputFile(BitcodeResult, BD.getContext());
if (PrefixOutput == 0) {
errs() << BD.getToolName() << ": Error reading bitcode file '"
<< BitcodeResult << "'!\n";
exit(1);
}
sys::Path(BitcodeResult).eraseFromDisk(); // No longer need the file on disk
// Don't check if there are no passes in the suffix.
if (Suffix.empty())
return NoFailure;
outs() << "Checking to see if '" << getPassesString(Suffix)
<< "' passes compile correctly after the '"
<< getPassesString(Prefix) << "' passes: ";
Module *OriginalInput = BD.swapProgramIn(PrefixOutput);
if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// Run the result...
if (BD.diffProgram(BitcodeResult, "", true/*delete bitcode*/)) {
outs() << " nope.\n";
delete OriginalInput; // We pruned down the original input...
return KeepSuffix;
}
// Otherwise, we must not be running the bad pass anymore.
outs() << " yup.\n"; // No miscompilation!
delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test
return NoFailure;
}
namespace {
class ReduceMiscompilingFunctions : public ListReducer<Function*> {
BugDriver &BD;
bool (*TestFn)(BugDriver &, Module *, Module *);
public:
ReduceMiscompilingFunctions(BugDriver &bd,
bool (*F)(BugDriver &, Module *, Module *))
: BD(bd), TestFn(F) {}
virtual TestResult doTest(std::vector<Function*> &Prefix,
std::vector<Function*> &Suffix) {
if (!Suffix.empty() && TestFuncs(Suffix))
return KeepSuffix;
if (!Prefix.empty() && TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(const std::vector<Function*> &Prefix);
};
}
/// TestMergedProgram - Given two modules, link them together and run the
/// program, checking to see if the program matches the diff. If the diff
/// matches, return false, otherwise return true. If the DeleteInputs argument
/// is set to true then this function deletes both input modules before it
/// returns.
///
static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2,
bool DeleteInputs) {
// Link the two portions of the program back to together.
std::string ErrorMsg;
if (!DeleteInputs) {
M1 = CloneModule(M1);
M2 = CloneModule(M2);
}
if (Linker::LinkModules(M1, M2, &ErrorMsg)) {
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete M2; // We are done with this module.
Module *OldProgram = BD.swapProgramIn(M1);
// Execute the program. If it does not match the expected output, we must
// return true.
bool Broken = BD.diffProgram();
// Delete the linked module & restore the original
BD.swapProgramIn(OldProgram);
delete M1;
return Broken;
}
/// TestFuncs - split functions in a Module into two groups: those that are
/// under consideration for miscompilation vs. those that are not, and test
/// accordingly. Each group of functions becomes a separate Module.
///
bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){
// Test to see if the function is misoptimized if we ONLY run it on the
// functions listed in Funcs.
outs() << "Checking to see if the program is misoptimized when "
<< (Funcs.size()==1 ? "this function is" : "these functions are")
<< " run through the pass"
<< (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
PrintFunctionList(Funcs);
outs() << '\n';
// Split the module into the two halves of the program we want.
DenseMap<const Value*, Value*> ValueMap;
Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs,
ValueMap);
// Run the predicate, note that the predicate will delete both input modules.
return TestFn(BD, ToOptimize, ToNotOptimize);
}
/// DisambiguateGlobalSymbols - Mangle symbols to guarantee uniqueness by
/// modifying predominantly internal symbols rather than external ones.
///
static void DisambiguateGlobalSymbols(Module *M) {
// Try not to cause collisions by minimizing chances of renaming an
// already-external symbol, so take in external globals and functions as-is.
// The code should work correctly without disambiguation (assuming the same
// mangler is used by the two code generators), but having symbols with the
// same name causes warnings to be emitted by the code generator.
Mangler Mang(*M);
// Agree with the CBE on symbol naming
Mang.markCharUnacceptable('.');
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I) {
// Don't mangle asm names.
if (!I->hasName() || I->getName()[0] != 1)
I->setName(Mang.getMangledName(I));
}
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
// Don't mangle asm names or intrinsics.
if ((!I->hasName() || I->getName()[0] != 1) &&
I->getIntrinsicID() == 0)
I->setName(Mang.getMangledName(I));
}
}
/// ExtractLoops - Given a reduced list of functions that still exposed the bug,
/// check to see if we can extract the loops in the region without obscuring the
/// bug. If so, it reduces the amount of code identified.
///
static bool ExtractLoops(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *),
std::vector<Function*> &MiscompiledFunctions) {
bool MadeChange = false;
while (1) {
if (BugpointIsInterrupted) return MadeChange;
DenseMap<const Value*, Value*> ValueMap;
Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
MiscompiledFunctions,
ValueMap);
Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize);
if (!ToOptimizeLoopExtracted) {
// If the loop extractor crashed or if there were no extractible loops,
// then this chapter of our odyssey is over with.
delete ToNotOptimize;
delete ToOptimize;
return MadeChange;
}
errs() << "Extracted a loop from the breaking portion of the program.\n";
// Bugpoint is intentionally not very trusting of LLVM transformations. In
// particular, we're not going to assume that the loop extractor works, so
// we're going to test the newly loop extracted program to make sure nothing
// has broken. If something broke, then we'll inform the user and stop
// extraction.
AbstractInterpreter *AI = BD.switchToSafeInterpreter();
if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) {
BD.switchToInterpreter(AI);
// Merged program doesn't work anymore!
errs() << " *** ERROR: Loop extraction broke the program. :("
<< " Please report a bug!\n";
errs() << " Continuing on with un-loop-extracted version.\n";
BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-tno.bc",
ToNotOptimize);
BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to.bc",
ToOptimize);
BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to-le.bc",
ToOptimizeLoopExtracted);
errs() << "Please submit the "
<< OutputPrefix << "-loop-extract-fail-*.bc files.\n";
delete ToOptimize;
delete ToNotOptimize;
delete ToOptimizeLoopExtracted;
return MadeChange;
}
delete ToOptimize;
BD.switchToInterpreter(AI);
outs() << " Testing after loop extraction:\n";
// Clone modules, the tester function will free them.
Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted);
Module *TNOBackup = CloneModule(ToNotOptimize);
if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) {
outs() << "*** Loop extraction masked the problem. Undoing.\n";
// If the program is not still broken, then loop extraction did something
// that masked the error. Stop loop extraction now.
delete TOLEBackup;
delete TNOBackup;
return MadeChange;
}
ToOptimizeLoopExtracted = TOLEBackup;
ToNotOptimize = TNOBackup;
outs() << "*** Loop extraction successful!\n";
std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
E = ToOptimizeLoopExtracted->end(); I != E; ++I)
if (!I->isDeclaration())
MisCompFunctions.push_back(std::make_pair(I->getName(),
I->getFunctionType()));
// Okay, great! Now we know that we extracted a loop and that loop
// extraction both didn't break the program, and didn't mask the problem.
// Replace the current program with the loop extracted version, and try to
// extract another loop.
std::string ErrorMsg;
if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete ToOptimizeLoopExtracted;
// All of the Function*'s in the MiscompiledFunctions list are in the old
// module. Update this list to include all of the functions in the
// optimized and loop extracted module.
MiscompiledFunctions.clear();
for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first);
assert(NewF && "Function not found??");
assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
"found wrong function type?");
MiscompiledFunctions.push_back(NewF);
}
BD.setNewProgram(ToNotOptimize);
MadeChange = true;
}
}
namespace {
class ReduceMiscompiledBlocks : public ListReducer<BasicBlock*> {
BugDriver &BD;
bool (*TestFn)(BugDriver &, Module *, Module *);
std::vector<Function*> FunctionsBeingTested;
public:
ReduceMiscompiledBlocks(BugDriver &bd,
bool (*F)(BugDriver &, Module *, Module *),
const std::vector<Function*> &Fns)
: BD(bd), TestFn(F), FunctionsBeingTested(Fns) {}
virtual TestResult doTest(std::vector<BasicBlock*> &Prefix,
std::vector<BasicBlock*> &Suffix) {
if (!Suffix.empty() && TestFuncs(Suffix))
return KeepSuffix;
if (TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(const std::vector<BasicBlock*> &Prefix);
};
}
/// TestFuncs - Extract all blocks for the miscompiled functions except for the
/// specified blocks. If the problem still exists, return true.
///
bool ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock*> &BBs) {
// Test to see if the function is misoptimized if we ONLY run it on the
// functions listed in Funcs.
outs() << "Checking to see if the program is misoptimized when all ";
if (!BBs.empty()) {
outs() << "but these " << BBs.size() << " blocks are extracted: ";
for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i)
outs() << BBs[i]->getName() << " ";
if (BBs.size() > 10) outs() << "...";
} else {
outs() << "blocks are extracted.";
}
outs() << '\n';
// Split the module into the two halves of the program we want.
DenseMap<const Value*, Value*> ValueMap;
Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
FunctionsBeingTested,
ValueMap);
// Try the extraction. If it doesn't work, then the block extractor crashed
// or something, in which case bugpoint can't chase down this possibility.
if (Module *New = BD.ExtractMappedBlocksFromModule(BBs, ToOptimize)) {
delete ToOptimize;
// Run the predicate, not that the predicate will delete both input modules.
return TestFn(BD, New, ToNotOptimize);
}
delete ToOptimize;
delete ToNotOptimize;
return false;
}
/// ExtractBlocks - Given a reduced list of functions that still expose the bug,
/// extract as many basic blocks from the region as possible without obscuring
/// the bug.
///
static bool ExtractBlocks(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *),
std::vector<Function*> &MiscompiledFunctions) {
if (BugpointIsInterrupted) return false;
std::vector<BasicBlock*> Blocks;
for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
for (Function::iterator I = MiscompiledFunctions[i]->begin(),
E = MiscompiledFunctions[i]->end(); I != E; ++I)
Blocks.push_back(I);
// Use the list reducer to identify blocks that can be extracted without
// obscuring the bug. The Blocks list will end up containing blocks that must
// be retained from the original program.
unsigned OldSize = Blocks.size();
// Check to see if all blocks are extractible first.
if (ReduceMiscompiledBlocks(BD, TestFn,
MiscompiledFunctions).TestFuncs(std::vector<BasicBlock*>())) {
Blocks.clear();
} else {
ReduceMiscompiledBlocks(BD, TestFn,MiscompiledFunctions).reduceList(Blocks);
if (Blocks.size() == OldSize)
return false;
}
DenseMap<const Value*, Value*> ValueMap;
Module *ProgClone = CloneModule(BD.getProgram(), ValueMap);
Module *ToExtract = SplitFunctionsOutOfModule(ProgClone,
MiscompiledFunctions,
ValueMap);
Module *Extracted = BD.ExtractMappedBlocksFromModule(Blocks, ToExtract);
if (Extracted == 0) {
// Weird, extraction should have worked.
errs() << "Nondeterministic problem extracting blocks??\n";
delete ProgClone;
delete ToExtract;
return false;
}
// Otherwise, block extraction succeeded. Link the two program fragments back
// together.
delete ToExtract;
std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
for (Module::iterator I = Extracted->begin(), E = Extracted->end();
I != E; ++I)
if (!I->isDeclaration())
MisCompFunctions.push_back(std::make_pair(I->getName(),
I->getFunctionType()));
std::string ErrorMsg;
if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) {
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete Extracted;
// Set the new program and delete the old one.
BD.setNewProgram(ProgClone);
// Update the list of miscompiled functions.
MiscompiledFunctions.clear();
for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first);
assert(NewF && "Function not found??");
assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
"Function has wrong type??");
MiscompiledFunctions.push_back(NewF);
}
return true;
}
/// DebugAMiscompilation - This is a generic driver to narrow down
/// miscompilations, either in an optimization or a code generator.
///
static std::vector<Function*>
DebugAMiscompilation(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *)) {
// Okay, now that we have reduced the list of passes which are causing the
// failure, see if we can pin down which functions are being
// miscompiled... first build a list of all of the non-external functions in
// the program.
std::vector<Function*> MiscompiledFunctions;
Module *Prog = BD.getProgram();
for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I)
if (!I->isDeclaration())
MiscompiledFunctions.push_back(I);
// Do the reduction...
if (!BugpointIsInterrupted)
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
outs() << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
outs() << '\n';
// See if we can rip any loops out of the miscompiled functions and still
// trigger the problem.
if (!BugpointIsInterrupted && !DisableLoopExtraction &&
ExtractLoops(BD, TestFn, MiscompiledFunctions)) {
// Okay, we extracted some loops and the problem still appears. See if we
// can eliminate some of the created functions from being candidates.
// Loop extraction can introduce functions with the same name (foo_code).
// Make sure to disambiguate the symbols so that when the program is split
// apart that we can link it back together again.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
if (!BugpointIsInterrupted)
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
outs() << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
outs() << '\n';
}
if (!BugpointIsInterrupted && !DisableBlockExtraction &&
ExtractBlocks(BD, TestFn, MiscompiledFunctions)) {
// Okay, we extracted some blocks and the problem still appears. See if we
// can eliminate some of the created functions from being candidates.
// Block extraction can introduce functions with the same name (foo_code).
// Make sure to disambiguate the symbols so that when the program is split
// apart that we can link it back together again.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
outs() << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
outs() << '\n';
}
return MiscompiledFunctions;
}
/// TestOptimizer - This is the predicate function used to check to see if the
/// "Test" portion of the program is misoptimized. If so, return true. In any
/// case, both module arguments are deleted.
///
static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) {
// Run the optimization passes on ToOptimize, producing a transformed version
// of the functions being tested.
outs() << " Optimizing functions being tested: ";
Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(),
/*AutoDebugCrashes*/true);
outs() << "done.\n";
delete Test;
outs() << " Checking to see if the merged program executes correctly: ";
bool Broken = TestMergedProgram(BD, Optimized, Safe, true);
outs() << (Broken ? " nope.\n" : " yup.\n");
return Broken;
}
/// debugMiscompilation - This method is used when the passes selected are not
/// crashing, but the generated output is semantically different from the
/// input.
///
bool BugDriver::debugMiscompilation() {
// Make sure something was miscompiled...
if (!BugpointIsInterrupted)
if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
errs() << "*** Optimized program matches reference output! No problem"
<< " detected...\nbugpoint can't help you with your problem!\n";
return false;
}
outs() << "\n*** Found miscompiling pass"
<< (getPassesToRun().size() == 1 ? "" : "es") << ": "
<< getPassesString(getPassesToRun()) << '\n';
EmitProgressBitcode("passinput");
std::vector<Function*> MiscompiledFunctions =
DebugAMiscompilation(*this, TestOptimizer);
// Output a bunch of bitcode files for the user...
outs() << "Outputting reduced bitcode files which expose the problem:\n";
DenseMap<const Value*, Value*> ValueMap;
Module *ToNotOptimize = CloneModule(getProgram(), ValueMap);
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
MiscompiledFunctions,
ValueMap);
outs() << " Non-optimized portion: ";
ToNotOptimize = swapProgramIn(ToNotOptimize);
EmitProgressBitcode("tonotoptimize", true);
setNewProgram(ToNotOptimize); // Delete hacked module.
outs() << " Portion that is input to optimizer: ";
ToOptimize = swapProgramIn(ToOptimize);
EmitProgressBitcode("tooptimize");
setNewProgram(ToOptimize); // Delete hacked module.
return false;
}
/// CleanupAndPrepareModules - Get the specified modules ready for code
/// generator testing.
///
static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test,
Module *Safe) {
// Clean up the modules, removing extra cruft that we don't need anymore...
Test = BD.performFinalCleanups(Test);
// If we are executing the JIT, we have several nasty issues to take care of.
if (!BD.isExecutingJIT()) return;
// First, if the main function is in the Safe module, we must add a stub to
// the Test module to call into it. Thus, we create a new function `main'
// which just calls the old one.
if (Function *oldMain = Safe->getFunction("main"))
if (!oldMain->isDeclaration()) {
// Rename it
oldMain->setName("llvm_bugpoint_old_main");
// Create a NEW `main' function with same type in the test module.
Function *newMain = Function::Create(oldMain->getFunctionType(),
GlobalValue::ExternalLinkage,
"main", Test);
// Create an `oldmain' prototype in the test module, which will
// corresponds to the real main function in the same module.
Function *oldMainProto = Function::Create(oldMain->getFunctionType(),
GlobalValue::ExternalLinkage,
oldMain->getName(), Test);
// Set up and remember the argument list for the main function.
std::vector<Value*> args;
for (Function::arg_iterator
I = newMain->arg_begin(), E = newMain->arg_end(),
OI = oldMain->arg_begin(); I != E; ++I, ++OI) {
I->setName(OI->getName()); // Copy argument names from oldMain
args.push_back(I);
}
// Call the old main function and return its result
BasicBlock *BB = BasicBlock::Create(Safe->getContext(), "entry", newMain);
CallInst *call = CallInst::Create(oldMainProto, args.begin(), args.end(),
"", BB);
// If the type of old function wasn't void, return value of call
ReturnInst::Create(Safe->getContext(), call, BB);
}
// The second nasty issue we must deal with in the JIT is that the Safe
// module cannot directly reference any functions defined in the test
// module. Instead, we use a JIT API call to dynamically resolve the
// symbol.
// Add the resolver to the Safe module.
// Prototype: void *getPointerToNamedFunction(const char* Name)
Constant *resolverFunc =
Safe->getOrInsertFunction("getPointerToNamedFunction",
PointerType::getUnqual(Type::getInt8Ty(Safe->getContext())),
PointerType::getUnqual(Type::getInt8Ty(Safe->getContext())),
(Type *)0);
// Use the function we just added to get addresses of functions we need.
for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) {
if (F->isDeclaration() && !F->use_empty() && &*F != resolverFunc &&
!F->isIntrinsic() /* ignore intrinsics */) {
Function *TestFn = Test->getFunction(F->getName());
// Don't forward functions which are external in the test module too.
if (TestFn && !TestFn->isDeclaration()) {
// 1. Add a string constant with its name to the global file
Constant *InitArray = ConstantArray::get(F->getContext(), F->getName());
GlobalVariable *funcName =
new GlobalVariable(*Safe, InitArray->getType(), true /*isConstant*/,
GlobalValue::InternalLinkage, InitArray,
F->getName() + "_name");
// 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
// sbyte* so it matches the signature of the resolver function.
// GetElementPtr *funcName, ulong 0, ulong 0
std::vector<Constant*> GEPargs(2,
Constant::getNullValue(Type::getInt32Ty(F->getContext())));
Value *GEP =
ConstantExpr::getGetElementPtr(funcName, &GEPargs[0], 2);
std::vector<Value*> ResolverArgs;
ResolverArgs.push_back(GEP);
// Rewrite uses of F in global initializers, etc. to uses of a wrapper
// function that dynamically resolves the calls to F via our JIT API
if (!F->use_empty()) {
// Create a new global to hold the cached function pointer.
Constant *NullPtr = ConstantPointerNull::get(F->getType());
GlobalVariable *Cache =
new GlobalVariable(*F->getParent(), F->getType(),
false, GlobalValue::InternalLinkage,
NullPtr,F->getName()+".fpcache");
// Construct a new stub function that will re-route calls to F
const FunctionType *FuncTy = F->getFunctionType();
Function *FuncWrapper = Function::Create(FuncTy,
GlobalValue::InternalLinkage,
F->getName() + "_wrapper",
F->getParent());
BasicBlock *EntryBB = BasicBlock::Create(F->getContext(),
"entry", FuncWrapper);
BasicBlock *DoCallBB = BasicBlock::Create(F->getContext(),
"usecache", FuncWrapper);
BasicBlock *LookupBB = BasicBlock::Create(F->getContext(),
"lookupfp", FuncWrapper);
// Check to see if we already looked up the value.
Value *CachedVal = new LoadInst(Cache, "fpcache", EntryBB);
Value *IsNull = new ICmpInst(*EntryBB, ICmpInst::ICMP_EQ, CachedVal,
NullPtr, "isNull");
BranchInst::Create(LookupBB, DoCallBB, IsNull, EntryBB);
// Resolve the call to function F via the JIT API:
//
// call resolver(GetElementPtr...)
CallInst *Resolver =
CallInst::Create(resolverFunc, ResolverArgs.begin(),
ResolverArgs.end(), "resolver", LookupBB);
// Cast the result from the resolver to correctly-typed function.
CastInst *CastedResolver =
new BitCastInst(Resolver,
PointerType::getUnqual(F->getFunctionType()),
"resolverCast", LookupBB);
// Save the value in our cache.
new StoreInst(CastedResolver, Cache, LookupBB);
BranchInst::Create(DoCallBB, LookupBB);
PHINode *FuncPtr = PHINode::Create(NullPtr->getType(),
"fp", DoCallBB);
FuncPtr->addIncoming(CastedResolver, LookupBB);
FuncPtr->addIncoming(CachedVal, EntryBB);
// Save the argument list.
std::vector<Value*> Args;
for (Function::arg_iterator i = FuncWrapper->arg_begin(),
e = FuncWrapper->arg_end(); i != e; ++i)
Args.push_back(i);
// Pass on the arguments to the real function, return its result
if (F->getReturnType() == Type::getVoidTy(F->getContext())) {
CallInst::Create(FuncPtr, Args.begin(), Args.end(), "", DoCallBB);
ReturnInst::Create(F->getContext(), DoCallBB);
} else {
CallInst *Call = CallInst::Create(FuncPtr, Args.begin(), Args.end(),
"retval", DoCallBB);
ReturnInst::Create(F->getContext(),Call, DoCallBB);
}
// Use the wrapper function instead of the old function
F->replaceAllUsesWith(FuncWrapper);
}
}
}
}
if (verifyModule(*Test) || verifyModule(*Safe)) {
errs() << "Bugpoint has a bug, which corrupted a module!!\n";
abort();
}
}
/// TestCodeGenerator - This is the predicate function used to check to see if
/// the "Test" portion of the program is miscompiled by the code generator under
/// test. If so, return true. In any case, both module arguments are deleted.
///
static bool TestCodeGenerator(BugDriver &BD, Module *Test, Module *Safe) {
CleanupAndPrepareModules(BD, Test, Safe);
sys::Path TestModuleBC("bugpoint.test.bc");
std::string ErrMsg;
if (TestModuleBC.makeUnique(true, &ErrMsg)) {
errs() << BD.getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (BD.writeProgramToFile(TestModuleBC.str(), Test)) {
errs() << "Error writing bitcode to `" << TestModuleBC.str()
<< "'\nExiting.";
exit(1);
}
delete Test;
// Make the shared library
sys::Path SafeModuleBC("bugpoint.safe.bc");
if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
errs() << BD.getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (BD.writeProgramToFile(SafeModuleBC.str(), Safe)) {
errs() << "Error writing bitcode to `" << SafeModuleBC.str()
<< "'\nExiting.";
exit(1);
}
std::string SharedObject = BD.compileSharedObject(SafeModuleBC.str());
delete Safe;
// Run the code generator on the `Test' code, loading the shared library.
// The function returns whether or not the new output differs from reference.
int Result = BD.diffProgram(TestModuleBC.str(), SharedObject, false);
if (Result)
errs() << ": still failing!\n";
else
errs() << ": didn't fail.\n";
TestModuleBC.eraseFromDisk();
SafeModuleBC.eraseFromDisk();
sys::Path(SharedObject).eraseFromDisk();
return Result;
}
/// debugCodeGenerator - debug errors in LLC, LLI, or CBE.
///
bool BugDriver::debugCodeGenerator() {
if ((void*)SafeInterpreter == (void*)Interpreter) {
std::string Result = executeProgramSafely("bugpoint.safe.out");
outs() << "\n*** The \"safe\" i.e. 'known good' backend cannot match "
<< "the reference diff. This may be due to a\n front-end "
<< "bug or a bug in the original program, but this can also "
<< "happen if bugpoint isn't running the program with the "
<< "right flags or input.\n I left the result of executing "
<< "the program with the \"safe\" backend in this file for "
<< "you: '"
<< Result << "'.\n";
return true;
}
DisambiguateGlobalSymbols(Program);
std::vector<Function*> Funcs = DebugAMiscompilation(*this, TestCodeGenerator);
// Split the module into the two halves of the program we want.
DenseMap<const Value*, Value*> ValueMap;
Module *ToNotCodeGen = CloneModule(getProgram(), ValueMap);
Module *ToCodeGen = SplitFunctionsOutOfModule(ToNotCodeGen, Funcs, ValueMap);
// Condition the modules
CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen);
sys::Path TestModuleBC("bugpoint.test.bc");
std::string ErrMsg;
if (TestModuleBC.makeUnique(true, &ErrMsg)) {
errs() << getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (writeProgramToFile(TestModuleBC.str(), ToCodeGen)) {
errs() << "Error writing bitcode to `" << TestModuleBC.str()
<< "'\nExiting.";
exit(1);
}
delete ToCodeGen;
// Make the shared library
sys::Path SafeModuleBC("bugpoint.safe.bc");
if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
errs() << getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (writeProgramToFile(SafeModuleBC.str(), ToNotCodeGen)) {
errs() << "Error writing bitcode to `" << SafeModuleBC.str()
<< "'\nExiting.";
exit(1);
}
std::string SharedObject = compileSharedObject(SafeModuleBC.str());
delete ToNotCodeGen;
outs() << "You can reproduce the problem with the command line: \n";
if (isExecutingJIT()) {
outs() << " lli -load " << SharedObject << " " << TestModuleBC.str();
} else {
outs() << " llc -f " << TestModuleBC.str() << " -o " << TestModuleBC.str()
<< ".s\n";
outs() << " gcc " << SharedObject << " " << TestModuleBC.str()
<< ".s -o " << TestModuleBC.str() << ".exe";
#if defined (HAVE_LINK_R)
outs() << " -Wl,-R.";
#endif
outs() << "\n";
outs() << " " << TestModuleBC.str() << ".exe";
}
for (unsigned i=0, e = InputArgv.size(); i != e; ++i)
outs() << " " << InputArgv[i];
outs() << '\n';
outs() << "The shared object was created with:\n llc -march=c "
<< SafeModuleBC.str() << " -o temporary.c\n"
<< " gcc -xc temporary.c -O2 -o " << SharedObject;
if (TargetTriple.getArch() == Triple::sparc)
outs() << " -G"; // Compile a shared library, `-G' for Sparc
else
outs() << " -fPIC -shared"; // `-shared' for Linux/X86, maybe others
outs() << " -fno-strict-aliasing\n";
return false;
}
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