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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/Config/config.h" // for HAVE_LINK_R
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Linker/Linker.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Transforms/Utils/Cloning.h"
using namespace llvm;
namespace llvm {
extern cl::opt<std::string> OutputPrefix;
extern cl::list<std::string> InputArgv;
} // end namespace llvm
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<std::string> {
BugDriver &BD;
public:
ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
Expected<TestResult> doTest(std::vector<std::string> &Prefix,
std::vector<std::string> &Suffix) override;
};
} // end anonymous namespace
/// TestResult - After passes have been split into a test group and a control
/// group, see if they still break the program.
///
Expected<ReduceMiscompilingPasses::TestResult>
ReduceMiscompilingPasses::doTest(std::vector<std::string> &Prefix,
std::vector<std::string> &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(BD.getProgram(), Suffix, BitcodeResult, false /*delete*/,
true /*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false);
// TODO: This should propagate the error instead of exiting.
if (Error E = BD.debugOptimizerCrash())
exit(1);
exit(0);
}
// Check to see if the finished program matches the reference output...
Expected<bool> Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "",
true /*delete bitcode*/);
if (Error E = Diff.takeError())
return std::move(E);
if (*Diff) {
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(BD.getProgram(), Prefix, BitcodeResult, false /*delete*/,
true /*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Prefix);
BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false);
// TODO: This should propagate the error instead of exiting.
if (Error E = BD.debugOptimizerCrash())
exit(1);
exit(0);
}
// If the prefix maintains the predicate by itself, only keep the prefix!
Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "", false);
if (Error E = Diff.takeError())
return std::move(E);
if (*Diff) {
outs() << " nope.\n";
sys::fs::remove(BitcodeResult);
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.
//
std::unique_ptr<Module> PrefixOutput =
parseInputFile(BitcodeResult, BD.getContext());
if (!PrefixOutput) {
errs() << BD.getToolName() << ": Error reading bitcode file '"
<< BitcodeResult << "'!\n";
exit(1);
}
sys::fs::remove(BitcodeResult);
// 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: ";
std::unique_ptr<Module> OriginalInput(
BD.swapProgramIn(PrefixOutput.release()));
if (BD.runPasses(BD.getProgram(), Suffix, BitcodeResult, false /*delete*/,
true /*quiet*/)) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false);
// TODO: This should propagate the error instead of exiting.
if (Error E = BD.debugOptimizerCrash())
exit(1);
exit(0);
}
// Run the result...
Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "",
true /*delete bitcode*/);
if (Error E = Diff.takeError())
return std::move(E);
if (*Diff) {
outs() << " nope.\n";
return KeepSuffix;
}
// Otherwise, we must not be running the bad pass anymore.
outs() << " yup.\n"; // No miscompilation!
// Restore orig program & free test.
delete BD.swapProgramIn(OriginalInput.release());
return NoFailure;
}
namespace {
class ReduceMiscompilingFunctions : public ListReducer<Function *> {
BugDriver &BD;
Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
std::unique_ptr<Module>);
public:
ReduceMiscompilingFunctions(BugDriver &bd,
Expected<bool> (*F)(BugDriver &,
std::unique_ptr<Module>,
std::unique_ptr<Module>))
: BD(bd), TestFn(F) {}
Expected<TestResult> doTest(std::vector<Function *> &Prefix,
std::vector<Function *> &Suffix) override {
if (!Suffix.empty()) {
Expected<bool> Ret = TestFuncs(Suffix);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret)
return KeepSuffix;
}
if (!Prefix.empty()) {
Expected<bool> Ret = TestFuncs(Prefix);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret)
return KeepPrefix;
}
return NoFailure;
}
Expected<bool> TestFuncs(const std::vector<Function *> &Prefix);
};
} // end anonymous namespace
/// Given two modules, link them together and run the program, checking to see
/// if the program matches the diff. If there is an error, return NULL. If not,
/// return the merged module. The Broken argument will be set to true if the
/// output is different. If the DeleteInputs argument is set to true then this
/// function deletes both input modules before it returns.
///
static Expected<std::unique_ptr<Module>> testMergedProgram(const BugDriver &BD,
const Module &M1,
const Module &M2,
bool &Broken) {
// Resulting merge of M1 and M2.
auto Merged = CloneModule(M1);
if (Linker::linkModules(*Merged, CloneModule(M2)))
// TODO: Shouldn't we thread the error up instead of exiting?
exit(1);
// Execute the program.
Expected<bool> Diff = BD.diffProgram(Merged.get(), "", "", false);
if (Error E = Diff.takeError())
return std::move(E);
Broken = *Diff;
return std::move(Merged);
}
/// 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.
///
Expected<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';
// Create a clone for two reasons:
// * If the optimization passes delete any function, the deleted function
// will be in the clone and Funcs will still point to valid memory
// * If the optimization passes use interprocedural information to break
// a function, we want to continue with the original function. Otherwise
// we can conclude that a function triggers the bug when in fact one
// needs a larger set of original functions to do so.
ValueToValueMapTy VMap;
Module *Clone = CloneModule(*BD.getProgram(), VMap).release();
Module *Orig = BD.swapProgramIn(Clone);
std::vector<Function *> FuncsOnClone;
for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
Function *F = cast<Function>(VMap[Funcs[i]]);
FuncsOnClone.push_back(F);
}
// Split the module into the two halves of the program we want.
VMap.clear();
std::unique_ptr<Module> ToNotOptimize = CloneModule(*BD.getProgram(), VMap);
std::unique_ptr<Module> ToOptimize =
SplitFunctionsOutOfModule(ToNotOptimize.get(), FuncsOnClone, VMap);
Expected<bool> Broken =
TestFn(BD, std::move(ToOptimize), std::move(ToNotOptimize));
delete BD.swapProgramIn(Orig);
return Broken;
}
/// DisambiguateGlobalSymbols - Give anonymous global values names.
///
static void DisambiguateGlobalSymbols(Module *M) {
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I)
if (!I->hasName())
I->setName("anon_global");
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->hasName())
I->setName("anon_fn");
}
/// 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 Expected<bool>
ExtractLoops(BugDriver &BD,
Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
std::unique_ptr<Module>),
std::vector<Function *> &MiscompiledFunctions) {
bool MadeChange = false;
while (1) {
if (BugpointIsInterrupted)
return MadeChange;
ValueToValueMapTy VMap;
std::unique_ptr<Module> ToNotOptimize = CloneModule(*BD.getProgram(), VMap);
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize.get(),
MiscompiledFunctions, VMap)
.release();
std::unique_ptr<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 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();
bool Failure;
Expected<std::unique_ptr<Module>> New = testMergedProgram(
BD, *ToOptimizeLoopExtracted, *ToNotOptimize, Failure);
if (Error E = New.takeError())
return std::move(E);
if (!*New)
return false;
// Delete the original and set the new program.
Module *Old = BD.swapProgramIn(New->release());
for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
MiscompiledFunctions[i] = cast<Function>(VMap[MiscompiledFunctions[i]]);
delete Old;
if (Failure) {
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.get());
BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to.bc",
ToOptimize);
BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to-le.bc",
ToOptimizeLoopExtracted.get());
errs() << "Please submit the " << OutputPrefix
<< "-loop-extract-fail-*.bc files.\n";
delete ToOptimize;
return MadeChange;
}
delete ToOptimize;
BD.switchToInterpreter(AI);
outs() << " Testing after loop extraction:\n";
// Clone modules, the tester function will free them.
std::unique_ptr<Module> TOLEBackup =
CloneModule(*ToOptimizeLoopExtracted, VMap);
std::unique_ptr<Module> TNOBackup = CloneModule(*ToNotOptimize, VMap);
for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
MiscompiledFunctions[i] = cast<Function>(VMap[MiscompiledFunctions[i]]);
Expected<bool> Result = TestFn(BD, std::move(ToOptimizeLoopExtracted),
std::move(ToNotOptimize));
if (Error E = Result.takeError())
return std::move(E);
ToOptimizeLoopExtracted = std::move(TOLEBackup);
ToNotOptimize = std::move(TNOBackup);
if (!*Result) {
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.
std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions;
for (Function *F : MiscompiledFunctions) {
MisCompFunctions.emplace_back(F->getName(), F->getFunctionType());
}
if (Linker::linkModules(*ToNotOptimize,
std::move(ToOptimizeLoopExtracted)))
exit(1);
MiscompiledFunctions.clear();
for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first);
assert(NewF && "Function not found??");
MiscompiledFunctions.push_back(NewF);
}
BD.setNewProgram(ToNotOptimize.release());
return MadeChange;
}
outs() << "*** Loop extraction successful!\n";
std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions;
for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
E = ToOptimizeLoopExtracted->end();
I != E; ++I)
if (!I->isDeclaration())
MisCompFunctions.emplace_back(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.
if (Linker::linkModules(*ToNotOptimize, std::move(ToOptimizeLoopExtracted)))
exit(1);
// 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??");
MiscompiledFunctions.push_back(NewF);
}
BD.setNewProgram(ToNotOptimize.release());
MadeChange = true;
}
}
namespace {
class ReduceMiscompiledBlocks : public ListReducer<BasicBlock *> {
BugDriver &BD;
Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
std::unique_ptr<Module>);
std::vector<Function *> FunctionsBeingTested;
public:
ReduceMiscompiledBlocks(BugDriver &bd,
Expected<bool> (*F)(BugDriver &,
std::unique_ptr<Module>,
std::unique_ptr<Module>),
const std::vector<Function *> &Fns)
: BD(bd), TestFn(F), FunctionsBeingTested(Fns) {}
Expected<TestResult> doTest(std::vector<BasicBlock *> &Prefix,
std::vector<BasicBlock *> &Suffix) override {
if (!Suffix.empty()) {
Expected<bool> Ret = TestFuncs(Suffix);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret)
return KeepSuffix;
}
if (!Prefix.empty()) {
Expected<bool> Ret = TestFuncs(Prefix);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret)
return KeepPrefix;
}
return NoFailure;
}
Expected<bool> TestFuncs(const std::vector<BasicBlock *> &BBs);
};
} // end anonymous namespace
/// TestFuncs - Extract all blocks for the miscompiled functions except for the
/// specified blocks. If the problem still exists, return true.
///
Expected<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.
ValueToValueMapTy VMap;
Module *Clone = CloneModule(*BD.getProgram(), VMap).release();
Module *Orig = BD.swapProgramIn(Clone);
std::vector<Function *> FuncsOnClone;
std::vector<BasicBlock *> BBsOnClone;
for (unsigned i = 0, e = FunctionsBeingTested.size(); i != e; ++i) {
Function *F = cast<Function>(VMap[FunctionsBeingTested[i]]);
FuncsOnClone.push_back(F);
}
for (unsigned i = 0, e = BBs.size(); i != e; ++i) {
BasicBlock *BB = cast<BasicBlock>(VMap[BBs[i]]);
BBsOnClone.push_back(BB);
}
VMap.clear();
std::unique_ptr<Module> ToNotOptimize = CloneModule(*BD.getProgram(), VMap);
std::unique_ptr<Module> ToOptimize =
SplitFunctionsOutOfModule(ToNotOptimize.get(), FuncsOnClone, VMap);
// 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 (std::unique_ptr<Module> New =
BD.extractMappedBlocksFromModule(BBsOnClone, ToOptimize.get())) {
Expected<bool> Ret = TestFn(BD, std::move(New), std::move(ToNotOptimize));
delete BD.swapProgramIn(Orig);
return Ret;
}
delete BD.swapProgramIn(Orig);
return false;
}
/// 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 Expected<bool>
ExtractBlocks(BugDriver &BD,
Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
std::unique_ptr<Module>),
std::vector<Function *> &MiscompiledFunctions) {
if (BugpointIsInterrupted)
return false;
std::vector<BasicBlock *> Blocks;
for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
for (BasicBlock &BB : *MiscompiledFunctions[i])
Blocks.push_back(&BB);
// 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.
Expected<bool> Ret = ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions)
.TestFuncs(std::vector<BasicBlock *>());
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret) {
Blocks.clear();
} else {
Expected<bool> Ret =
ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions)
.reduceList(Blocks);
if (Error E = Ret.takeError())
return std::move(E);
if (Blocks.size() == OldSize)
return false;
}
ValueToValueMapTy VMap;
Module *ProgClone = CloneModule(*BD.getProgram(), VMap).release();
Module *ToExtract =
SplitFunctionsOutOfModule(ProgClone, MiscompiledFunctions, VMap)
.release();
std::unique_ptr<Module> Extracted =
BD.extractMappedBlocksFromModule(Blocks, ToExtract);
if (!Extracted) {
// 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, FunctionType *>> MisCompFunctions;
for (Module::iterator I = Extracted->begin(), E = Extracted->end(); I != E;
++I)
if (!I->isDeclaration())
MisCompFunctions.emplace_back(I->getName(), I->getFunctionType());
if (Linker::linkModules(*ProgClone, std::move(Extracted)))
exit(1);
// 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??");
MiscompiledFunctions.push_back(NewF);
}
return true;
}
/// This is a generic driver to narrow down miscompilations, either in an
/// optimization or a code generator.
///
static Expected<std::vector<Function *>> DebugAMiscompilation(
BugDriver &BD,
Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
std::unique_ptr<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 (Function &F : *Prog)
if (!F.isDeclaration())
MiscompiledFunctions.push_back(&F);
// Do the reduction...
if (!BugpointIsInterrupted) {
Expected<bool> Ret = ReduceMiscompilingFunctions(BD, TestFn)
.reduceList(MiscompiledFunctions);
if (Error E = Ret.takeError()) {
errs() << "\n***Cannot reduce functions: ";
return std::move(E);
}
}
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) {
Expected<bool> Ret = ExtractLoops(BD, TestFn, MiscompiledFunctions);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret) {
// Okay, we extracted some loops and the problem still appears. See if
// we can eliminate some of the created functions from being candidates.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
if (!BugpointIsInterrupted)
Ret = ReduceMiscompilingFunctions(BD, TestFn)
.reduceList(MiscompiledFunctions);
if (Error E = Ret.takeError())
return std::move(E);
outs() << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
outs() << '\n';
}
}
if (!BugpointIsInterrupted && !DisableBlockExtraction) {
Expected<bool> Ret = ExtractBlocks(BD, TestFn, MiscompiledFunctions);
if (Error E = Ret.takeError())
return std::move(E);
if (*Ret) {
// Okay, we extracted some blocks and the problem still appears. See if
// we can eliminate some of the created functions from being candidates.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
Ret = ReduceMiscompilingFunctions(BD, TestFn)
.reduceList(MiscompiledFunctions);
if (Error E = Ret.takeError())
return std::move(E);
outs() << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
outs() << '\n';
}
}
return MiscompiledFunctions;
}
/// 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 Expected<bool> TestOptimizer(BugDriver &BD, std::unique_ptr<Module> Test,
std::unique_ptr<Module> Safe) {
// Run the optimization passes on ToOptimize, producing a transformed version
// of the functions being tested.
outs() << " Optimizing functions being tested: ";
std::unique_ptr<Module> Optimized =
BD.runPassesOn(Test.get(), BD.getPassesToRun());
if (!Optimized) {
errs() << " Error running this sequence of passes"
<< " on the input program!\n";
delete BD.swapProgramIn(Test.get());
BD.EmitProgressBitcode(Test.get(), "pass-error", false);
if (Error E = BD.debugOptimizerCrash())
return std::move(E);
return false;
}
outs() << "done.\n";
outs() << " Checking to see if the merged program executes correctly: ";
bool Broken;
auto Result = testMergedProgram(BD, *Optimized, *Safe, Broken);
if (Error E = Result.takeError())
return std::move(E);
if (auto New = std::move(*Result)) {
outs() << (Broken ? " nope.\n" : " yup.\n");
// Delete the original and set the new program.
delete BD.swapProgramIn(New.release());
}
return Broken;
}
/// debugMiscompilation - This method is used when the passes selected are not
/// crashing, but the generated output is semantically different from the
/// input.
///
Error BugDriver::debugMiscompilation() {
// Make sure something was miscompiled...
if (!BugpointIsInterrupted) {
Expected<bool> Result =
ReduceMiscompilingPasses(*this).reduceList(PassesToRun);
if (Error E = Result.takeError())
return E;
if (!*Result)
return make_error<StringError>(
"*** Optimized program matches reference output! No problem"
" detected...\nbugpoint can't help you with your problem!\n",
inconvertibleErrorCode());
}
outs() << "\n*** Found miscompiling pass"
<< (getPassesToRun().size() == 1 ? "" : "es") << ": "
<< getPassesString(getPassesToRun()) << '\n';
EmitProgressBitcode(Program, "passinput");
Expected<std::vector<Function *>> MiscompiledFunctions =
DebugAMiscompilation(*this, TestOptimizer);
if (Error E = MiscompiledFunctions.takeError())
return E;
// Output a bunch of bitcode files for the user...
outs() << "Outputting reduced bitcode files which expose the problem:\n";
ValueToValueMapTy VMap;
Module *ToNotOptimize = CloneModule(*getProgram(), VMap).release();
Module *ToOptimize =
SplitFunctionsOutOfModule(ToNotOptimize, *MiscompiledFunctions, VMap)
.release();
outs() << " Non-optimized portion: ";
EmitProgressBitcode(ToNotOptimize, "tonotoptimize", true);
delete ToNotOptimize; // Delete hacked module.
outs() << " Portion that is input to optimizer: ";
EmitProgressBitcode(ToOptimize, "tooptimize");
delete ToOptimize; // Delete hacked module.
return Error::success();
}
/// Get the specified modules ready for code generator testing.
///
static void CleanupAndPrepareModules(BugDriver &BD,
std::unique_ptr<Module> &Test,
Module *Safe) {
// Clean up the modules, removing extra cruft that we don't need anymore...
Test = BD.performFinalCleanups(Test.get());
// 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.get());
// 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.get());
// 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, "", 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", Type::getInt8PtrTy(Safe->getContext()),
Type::getInt8PtrTy(Safe->getContext()));
// 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 =
ConstantDataArray::getString(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(InitArray->getType(),
funcName, GEPargs);
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
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,
"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(), 2, "fp", DoCallBB);
FuncPtr->addIncoming(CastedResolver, LookupBB);
FuncPtr->addIncoming(CachedVal, EntryBB);
// Save the argument list.
std::vector<Value *> Args;
for (Argument &A : FuncWrapper->args())
Args.push_back(&A);
// Pass on the arguments to the real function, return its result
if (F->getReturnType()->isVoidTy()) {
CallInst::Create(FuncPtr, Args, "", DoCallBB);
ReturnInst::Create(F->getContext(), DoCallBB);
} else {
CallInst *Call =
CallInst::Create(FuncPtr, Args, "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();
}
}
/// 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 Expected<bool> TestCodeGenerator(BugDriver &BD,
std::unique_ptr<Module> Test,
std::unique_ptr<Module> Safe) {
CleanupAndPrepareModules(BD, Test, Safe.get());
SmallString<128> TestModuleBC;
int TestModuleFD;
std::error_code EC = sys::fs::createTemporaryFile("bugpoint.test", "bc",
TestModuleFD, TestModuleBC);
if (EC) {
errs() << BD.getToolName()
<< "Error making unique filename: " << EC.message() << "\n";
exit(1);
}
if (BD.writeProgramToFile(TestModuleBC.str(), TestModuleFD, Test.get())) {
errs() << "Error writing bitcode to `" << TestModuleBC.str()
<< "'\nExiting.";
exit(1);
}
FileRemover TestModuleBCRemover(TestModuleBC.str(), !SaveTemps);
// Make the shared library
SmallString<128> SafeModuleBC;
int SafeModuleFD;
EC = sys::fs::createTemporaryFile("bugpoint.safe", "bc", SafeModuleFD,
SafeModuleBC);
if (EC) {
errs() << BD.getToolName()
<< "Error making unique filename: " << EC.message() << "\n";
exit(1);
}
if (BD.writeProgramToFile(SafeModuleBC.str(), SafeModuleFD, Safe.get())) {
errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
exit(1);
}
FileRemover SafeModuleBCRemover(SafeModuleBC.str(), !SaveTemps);
Expected<std::string> SharedObject =
BD.compileSharedObject(SafeModuleBC.str());
if (Error E = SharedObject.takeError())
return std::move(E);
FileRemover SharedObjectRemover(*SharedObject, !SaveTemps);
// Run the code generator on the `Test' code, loading the shared library.
// The function returns whether or not the new output differs from reference.
Expected<bool> Result =
BD.diffProgram(BD.getProgram(), TestModuleBC.str(), *SharedObject, false);
if (Error E = Result.takeError())
return std::move(E);
if (*Result)
errs() << ": still failing!\n";
else
errs() << ": didn't fail.\n";
return Result;
}
/// debugCodeGenerator - debug errors in LLC, LLI, or CBE.
///
Error BugDriver::debugCodeGenerator() {
if ((void *)SafeInterpreter == (void *)Interpreter) {
Expected<std::string> Result =
executeProgramSafely(Program, "bugpoint.safe.out");
if (Result) {
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 Error::success();
}
DisambiguateGlobalSymbols(Program);
Expected<std::vector<Function *>> Funcs =
DebugAMiscompilation(*this, TestCodeGenerator);
if (Error E = Funcs.takeError())
return E;
// Split the module into the two halves of the program we want.
ValueToValueMapTy VMap;
std::unique_ptr<Module> ToNotCodeGen = CloneModule(*getProgram(), VMap);
std::unique_ptr<Module> ToCodeGen =
SplitFunctionsOutOfModule(ToNotCodeGen.get(), *Funcs, VMap);
// Condition the modules
CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen.get());
SmallString<128> TestModuleBC;
int TestModuleFD;
std::error_code EC = sys::fs::createTemporaryFile("bugpoint.test", "bc",
TestModuleFD, TestModuleBC);
if (EC) {
errs() << getToolName() << "Error making unique filename: " << EC.message()
<< "\n";
exit(1);
}
if (writeProgramToFile(TestModuleBC.str(), TestModuleFD, ToCodeGen.get())) {
errs() << "Error writing bitcode to `" << TestModuleBC << "'\nExiting.";
exit(1);
}
// Make the shared library
SmallString<128> SafeModuleBC;
int SafeModuleFD;
EC = sys::fs::createTemporaryFile("bugpoint.safe", "bc", SafeModuleFD,
SafeModuleBC);
if (EC) {
errs() << getToolName() << "Error making unique filename: " << EC.message()
<< "\n";
exit(1);
}
if (writeProgramToFile(SafeModuleBC.str(), SafeModuleFD,
ToNotCodeGen.get())) {
errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
exit(1);
}
Expected<std::string> SharedObject = compileSharedObject(SafeModuleBC.str());
if (Error E = SharedObject.takeError())
return E;
outs() << "You can reproduce the problem with the command line: \n";
if (isExecutingJIT()) {
outs() << " lli -load " << *SharedObject << " " << TestModuleBC;
} else {
outs() << " llc " << TestModuleBC << " -o " << TestModuleBC << ".s\n";
outs() << " cc " << *SharedObject << " " << TestModuleBC.str() << ".s -o "
<< TestModuleBC << ".exe\n";
outs() << " ./" << TestModuleBC << ".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"
<< " cc -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 Error::success();
}
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