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llvm-6502/tools/bugpoint/CrashDebugger.cpp
Duncan P. N. Exon Smith facdfc6781 Revert "[C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ranges." 
This reverts commit r213474 (and r213475), which causes a miscompile on
a stage2 LTO build.  I'll reply on the list in a moment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213562 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-21 17:06:51 +00:00

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//===- CrashDebugger.cpp - Debug compilation crashes ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the bugpoint internals that narrow down compilation crashes
//
//===----------------------------------------------------------------------===//
#include "BugDriver.h"
#include "ListReducer.h"
#include "ToolRunner.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Pass.h"
#include "llvm/PassManager.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <set>
using namespace llvm;
namespace {
cl::opt<bool>
KeepMain("keep-main",
cl::desc("Force function reduction to keep main"),
cl::init(false));
cl::opt<bool>
NoGlobalRM ("disable-global-remove",
cl::desc("Do not remove global variables"),
cl::init(false));
}
namespace llvm {
class ReducePassList : public ListReducer<std::string> {
BugDriver &BD;
public:
ReducePassList(BugDriver &bd) : BD(bd) {}
// doTest - Return true iff running the "removed" passes succeeds, and
// running the "Kept" passes fail when run on the output of the "removed"
// passes. If we return true, we update the current module of bugpoint.
//
TestResult doTest(std::vector<std::string> &Removed,
std::vector<std::string> &Kept,
std::string &Error) override;
};
}
ReducePassList::TestResult
ReducePassList::doTest(std::vector<std::string> &Prefix,
std::vector<std::string> &Suffix,
std::string &Error) {
std::string PrefixOutput;
Module *OrigProgram = nullptr;
if (!Prefix.empty()) {
outs() << "Checking to see if these passes crash: "
<< getPassesString(Prefix) << ": ";
if (BD.runPasses(BD.getProgram(), Prefix, PrefixOutput))
return KeepPrefix;
OrigProgram = BD.Program;
BD.Program = ParseInputFile(PrefixOutput, BD.getContext());
if (BD.Program == nullptr) {
errs() << BD.getToolName() << ": Error reading bitcode file '"
<< PrefixOutput << "'!\n";
exit(1);
}
sys::fs::remove(PrefixOutput);
}
outs() << "Checking to see if these passes crash: "
<< getPassesString(Suffix) << ": ";
if (BD.runPasses(BD.getProgram(), Suffix)) {
delete OrigProgram; // The suffix crashes alone...
return KeepSuffix;
}
// Nothing failed, restore state...
if (OrigProgram) {
delete BD.Program;
BD.Program = OrigProgram;
}
return NoFailure;
}
namespace {
/// ReduceCrashingGlobalVariables - This works by removing the global
/// variable's initializer and seeing if the program still crashes. If it
/// does, then we keep that program and try again.
///
class ReduceCrashingGlobalVariables : public ListReducer<GlobalVariable*> {
BugDriver &BD;
bool (*TestFn)(const BugDriver &, Module *);
public:
ReduceCrashingGlobalVariables(BugDriver &bd,
bool (*testFn)(const BugDriver &, Module *))
: BD(bd), TestFn(testFn) {}
TestResult doTest(std::vector<GlobalVariable*> &Prefix,
std::vector<GlobalVariable*> &Kept,
std::string &Error) override {
if (!Kept.empty() && TestGlobalVariables(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestGlobalVariables(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestGlobalVariables(std::vector<GlobalVariable*> &GVs);
};
}
bool
ReduceCrashingGlobalVariables::TestGlobalVariables(
std::vector<GlobalVariable*> &GVs) {
// Clone the program to try hacking it apart...
ValueToValueMapTy VMap;
Module *M = CloneModule(BD.getProgram(), VMap);
// Convert list to set for fast lookup...
std::set<GlobalVariable*> GVSet;
for (unsigned i = 0, e = GVs.size(); i != e; ++i) {
GlobalVariable* CMGV = cast<GlobalVariable>(VMap[GVs[i]]);
assert(CMGV && "Global Variable not in module?!");
GVSet.insert(CMGV);
}
outs() << "Checking for crash with only these global variables: ";
PrintGlobalVariableList(GVs);
outs() << ": ";
// Loop over and delete any global variables which we aren't supposed to be
// playing with...
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I)
if (I->hasInitializer() && !GVSet.count(I)) {
I->setInitializer(nullptr);
I->setLinkage(GlobalValue::ExternalLinkage);
}
// Try running the hacked up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // It crashed, keep the trimmed version...
// Make sure to use global variable pointers that point into the now-current
// module.
GVs.assign(GVSet.begin(), GVSet.end());
return true;
}
delete M;
return false;
}
namespace {
/// ReduceCrashingFunctions reducer - This works by removing functions and
/// seeing if the program still crashes. If it does, then keep the newer,
/// smaller program.
///
class ReduceCrashingFunctions : public ListReducer<Function*> {
BugDriver &BD;
bool (*TestFn)(const BugDriver &, Module *);
public:
ReduceCrashingFunctions(BugDriver &bd,
bool (*testFn)(const BugDriver &, Module *))
: BD(bd), TestFn(testFn) {}
TestResult doTest(std::vector<Function*> &Prefix,
std::vector<Function*> &Kept,
std::string &Error) override {
if (!Kept.empty() && TestFuncs(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(std::vector<Function*> &Prefix);
};
}
bool ReduceCrashingFunctions::TestFuncs(std::vector<Function*> &Funcs) {
// If main isn't present, claim there is no problem.
if (KeepMain && std::find(Funcs.begin(), Funcs.end(),
BD.getProgram()->getFunction("main")) ==
Funcs.end())
return false;
// Clone the program to try hacking it apart...
ValueToValueMapTy VMap;
Module *M = CloneModule(BD.getProgram(), VMap);
// Convert list to set for fast lookup...
std::set<Function*> Functions;
for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
Function *CMF = cast<Function>(VMap[Funcs[i]]);
assert(CMF && "Function not in module?!");
assert(CMF->getFunctionType() == Funcs[i]->getFunctionType() && "wrong ty");
assert(CMF->getName() == Funcs[i]->getName() && "wrong name");
Functions.insert(CMF);
}
outs() << "Checking for crash with only these functions: ";
PrintFunctionList(Funcs);
outs() << ": ";
// Loop over and delete any functions which we aren't supposed to be playing
// with...
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->isDeclaration() && !Functions.count(I))
DeleteFunctionBody(I);
// Try running the hacked up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // It crashed, keep the trimmed version...
// Make sure to use function pointers that point into the now-current
// module.
Funcs.assign(Functions.begin(), Functions.end());
return true;
}
delete M;
return false;
}
namespace {
/// ReduceCrashingBlocks reducer - This works by setting the terminators of
/// all terminators except the specified basic blocks to a 'ret' instruction,
/// then running the simplify-cfg pass. This has the effect of chopping up
/// the CFG really fast which can reduce large functions quickly.
///
class ReduceCrashingBlocks : public ListReducer<const BasicBlock*> {
BugDriver &BD;
bool (*TestFn)(const BugDriver &, Module *);
public:
ReduceCrashingBlocks(BugDriver &bd,
bool (*testFn)(const BugDriver &, Module *))
: BD(bd), TestFn(testFn) {}
TestResult doTest(std::vector<const BasicBlock*> &Prefix,
std::vector<const BasicBlock*> &Kept,
std::string &Error) override {
if (!Kept.empty() && TestBlocks(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestBlocks(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestBlocks(std::vector<const BasicBlock*> &Prefix);
};
}
bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
// Clone the program to try hacking it apart...
ValueToValueMapTy VMap;
Module *M = CloneModule(BD.getProgram(), VMap);
// Convert list to set for fast lookup...
SmallPtrSet<BasicBlock*, 8> Blocks;
for (unsigned i = 0, e = BBs.size(); i != e; ++i)
Blocks.insert(cast<BasicBlock>(VMap[BBs[i]]));
outs() << "Checking for crash with only these blocks:";
unsigned NumPrint = Blocks.size();
if (NumPrint > 10) NumPrint = 10;
for (unsigned i = 0, e = NumPrint; i != e; ++i)
outs() << " " << BBs[i]->getName();
if (NumPrint < Blocks.size())
outs() << "... <" << Blocks.size() << " total>";
outs() << ": ";
// Loop over and delete any hack up any blocks that are not listed...
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
if (!Blocks.count(BB) && BB->getTerminator()->getNumSuccessors()) {
// Loop over all of the successors of this block, deleting any PHI nodes
// that might include it.
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
(*SI)->removePredecessor(BB);
TerminatorInst *BBTerm = BB->getTerminator();
if (!BB->getTerminator()->getType()->isVoidTy())
BBTerm->replaceAllUsesWith(Constant::getNullValue(BBTerm->getType()));
// Replace the old terminator instruction.
BB->getInstList().pop_back();
new UnreachableInst(BB->getContext(), BB);
}
// The CFG Simplifier pass may delete one of the basic blocks we are
// interested in. If it does we need to take the block out of the list. Make
// a "persistent mapping" by turning basic blocks into <function, name> pairs.
// This won't work well if blocks are unnamed, but that is just the risk we
// have to take.
std::vector<std::pair<std::string, std::string> > BlockInfo;
for (SmallPtrSet<BasicBlock*, 8>::iterator I = Blocks.begin(),
E = Blocks.end(); I != E; ++I)
BlockInfo.push_back(std::make_pair((*I)->getParent()->getName(),
(*I)->getName()));
// Now run the CFG simplify pass on the function...
std::vector<std::string> Passes;
Passes.push_back("simplifycfg");
Passes.push_back("verify");
Module *New = BD.runPassesOn(M, Passes);
delete M;
if (!New) {
errs() << "simplifycfg failed!\n";
exit(1);
}
M = New;
// Try running on the hacked up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // It crashed, keep the trimmed version...
// Make sure to use basic block pointers that point into the now-current
// module, and that they don't include any deleted blocks.
BBs.clear();
const ValueSymbolTable &GST = M->getValueSymbolTable();
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
Function *F = cast<Function>(GST.lookup(BlockInfo[i].first));
ValueSymbolTable &ST = F->getValueSymbolTable();
Value* V = ST.lookup(BlockInfo[i].second);
if (V && V->getType() == Type::getLabelTy(V->getContext()))
BBs.push_back(cast<BasicBlock>(V));
}
return true;
}
delete M; // It didn't crash, try something else.
return false;
}
namespace {
/// ReduceCrashingInstructions reducer - This works by removing the specified
/// non-terminator instructions and replacing them with undef.
///
class ReduceCrashingInstructions : public ListReducer<const Instruction*> {
BugDriver &BD;
bool (*TestFn)(const BugDriver &, Module *);
public:
ReduceCrashingInstructions(BugDriver &bd,
bool (*testFn)(const BugDriver &, Module *))
: BD(bd), TestFn(testFn) {}
TestResult doTest(std::vector<const Instruction*> &Prefix,
std::vector<const Instruction*> &Kept,
std::string &Error) override {
if (!Kept.empty() && TestInsts(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestInsts(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestInsts(std::vector<const Instruction*> &Prefix);
};
}
bool ReduceCrashingInstructions::TestInsts(std::vector<const Instruction*>
&Insts) {
// Clone the program to try hacking it apart...
ValueToValueMapTy VMap;
Module *M = CloneModule(BD.getProgram(), VMap);
// Convert list to set for fast lookup...
SmallPtrSet<Instruction*, 64> Instructions;
for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
assert(!isa<TerminatorInst>(Insts[i]));
Instructions.insert(cast<Instruction>(VMap[Insts[i]]));
}
outs() << "Checking for crash with only " << Instructions.size();
if (Instructions.size() == 1)
outs() << " instruction: ";
else
outs() << " instructions: ";
for (Module::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI)
for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE; ++FI)
for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E;) {
Instruction *Inst = I++;
if (!Instructions.count(Inst) && !isa<TerminatorInst>(Inst) &&
!isa<LandingPadInst>(Inst)) {
if (!Inst->getType()->isVoidTy())
Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
Inst->eraseFromParent();
}
}
// Verify that this is still valid.
PassManager Passes;
Passes.add(createVerifierPass());
Passes.add(createDebugInfoVerifierPass());
Passes.run(*M);
// Try running on the hacked up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // It crashed, keep the trimmed version...
// Make sure to use instruction pointers that point into the now-current
// module, and that they don't include any deleted blocks.
Insts.clear();
for (SmallPtrSet<Instruction*, 64>::const_iterator I = Instructions.begin(),
E = Instructions.end(); I != E; ++I)
Insts.push_back(*I);
return true;
}
delete M; // It didn't crash, try something else.
return false;
}
/// DebugACrash - Given a predicate that determines whether a component crashes
/// on a program, try to destructively reduce the program while still keeping
/// the predicate true.
static bool DebugACrash(BugDriver &BD,
bool (*TestFn)(const BugDriver &, Module *),
std::string &Error) {
// See if we can get away with nuking some of the global variable initializers
// in the program...
if (!NoGlobalRM &&
BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
// Now try to reduce the number of global variable initializers in the
// module to something small.
Module *M = CloneModule(BD.getProgram());
bool DeletedInit = false;
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I)
if (I->hasInitializer()) {
I->setInitializer(nullptr);
I->setLinkage(GlobalValue::ExternalLinkage);
DeletedInit = true;
}
if (!DeletedInit) {
delete M; // No change made...
} else {
// See if the program still causes a crash...
outs() << "\nChecking to see if we can delete global inits: ";
if (TestFn(BD, M)) { // Still crashes?
BD.setNewProgram(M);
outs() << "\n*** Able to remove all global initializers!\n";
} else { // No longer crashes?
outs() << " - Removing all global inits hides problem!\n";
delete M;
std::vector<GlobalVariable*> GVs;
for (Module::global_iterator I = BD.getProgram()->global_begin(),
E = BD.getProgram()->global_end(); I != E; ++I)
if (I->hasInitializer())
GVs.push_back(I);
if (GVs.size() > 1 && !BugpointIsInterrupted) {
outs() << "\n*** Attempting to reduce the number of global "
<< "variables in the testcase\n";
unsigned OldSize = GVs.size();
ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs, Error);
if (!Error.empty())
return true;
if (GVs.size() < OldSize)
BD.EmitProgressBitcode(BD.getProgram(), "reduced-global-variables");
}
}
}
}
// Now try to reduce the number of functions in the module to something small.
std::vector<Function*> Functions;
for (Module::iterator I = BD.getProgram()->begin(),
E = BD.getProgram()->end(); I != E; ++I)
if (!I->isDeclaration())
Functions.push_back(I);
if (Functions.size() > 1 && !BugpointIsInterrupted) {
outs() << "\n*** Attempting to reduce the number of functions "
"in the testcase\n";
unsigned OldSize = Functions.size();
ReduceCrashingFunctions(BD, TestFn).reduceList(Functions, Error);
if (Functions.size() < OldSize)
BD.EmitProgressBitcode(BD.getProgram(), "reduced-function");
}
// Attempt to delete entire basic blocks at a time to speed up
// convergence... this actually works by setting the terminator of the blocks
// to a return instruction then running simplifycfg, which can potentially
// shrinks the code dramatically quickly
//
if (!DisableSimplifyCFG && !BugpointIsInterrupted) {
std::vector<const BasicBlock*> Blocks;
for (Module::const_iterator I = BD.getProgram()->begin(),
E = BD.getProgram()->end(); I != E; ++I)
for (Function::const_iterator FI = I->begin(), E = I->end(); FI !=E; ++FI)
Blocks.push_back(FI);
unsigned OldSize = Blocks.size();
ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks, Error);
if (Blocks.size() < OldSize)
BD.EmitProgressBitcode(BD.getProgram(), "reduced-blocks");
}
// Attempt to delete instructions using bisection. This should help out nasty
// cases with large basic blocks where the problem is at one end.
if (!BugpointIsInterrupted) {
std::vector<const Instruction*> Insts;
for (Module::const_iterator MI = BD.getProgram()->begin(),
ME = BD.getProgram()->end(); MI != ME; ++MI)
for (Function::const_iterator FI = MI->begin(), FE = MI->end(); FI != FE;
++FI)
for (BasicBlock::const_iterator I = FI->begin(), E = FI->end();
I != E; ++I)
if (!isa<TerminatorInst>(I))
Insts.push_back(I);
ReduceCrashingInstructions(BD, TestFn).reduceList(Insts, Error);
}
// FIXME: This should use the list reducer to converge faster by deleting
// larger chunks of instructions at a time!
unsigned Simplification = 2;
do {
if (BugpointIsInterrupted) break;
--Simplification;
outs() << "\n*** Attempting to reduce testcase by deleting instruc"
<< "tions: Simplification Level #" << Simplification << '\n';
// Now that we have deleted the functions that are unnecessary for the
// program, try to remove instructions that are not necessary to cause the
// crash. To do this, we loop through all of the instructions in the
// remaining functions, deleting them (replacing any values produced with
// nulls), and then running ADCE and SimplifyCFG. If the transformed input
// still triggers failure, keep deleting until we cannot trigger failure
// anymore.
//
unsigned InstructionsToSkipBeforeDeleting = 0;
TryAgain:
// Loop over all of the (non-terminator) instructions remaining in the
// function, attempting to delete them.
unsigned CurInstructionNum = 0;
for (Module::const_iterator FI = BD.getProgram()->begin(),
E = BD.getProgram()->end(); FI != E; ++FI)
if (!FI->isDeclaration())
for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
++BI)
for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
I != E; ++I, ++CurInstructionNum) {
if (InstructionsToSkipBeforeDeleting) {
--InstructionsToSkipBeforeDeleting;
} else {
if (BugpointIsInterrupted) goto ExitLoops;
if (isa<LandingPadInst>(I))
continue;
outs() << "Checking instruction: " << *I;
Module *M = BD.deleteInstructionFromProgram(I, Simplification);
// Find out if the pass still crashes on this pass...
if (TestFn(BD, M)) {
// Yup, it does, we delete the old module, and continue trying
// to reduce the testcase...
BD.setNewProgram(M);
InstructionsToSkipBeforeDeleting = CurInstructionNum;
goto TryAgain; // I wish I had a multi-level break here!
}
// This pass didn't crash without this instruction, try the next
// one.
delete M;
}
}
if (InstructionsToSkipBeforeDeleting) {
InstructionsToSkipBeforeDeleting = 0;
goto TryAgain;
}
} while (Simplification);
ExitLoops:
// Try to clean up the testcase by running funcresolve and globaldce...
if (!BugpointIsInterrupted) {
outs() << "\n*** Attempting to perform final cleanups: ";
Module *M = CloneModule(BD.getProgram());
M = BD.performFinalCleanups(M, true);
// Find out if the pass still crashes on the cleaned up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // Yup, it does, keep the reduced version...
} else {
delete M;
}
}
BD.EmitProgressBitcode(BD.getProgram(), "reduced-simplified");
return false;
}
static bool TestForOptimizerCrash(const BugDriver &BD, Module *M) {
return BD.runPasses(M);
}
/// debugOptimizerCrash - This method is called when some pass crashes on input.
/// It attempts to prune down the testcase to something reasonable, and figure
/// out exactly which pass is crashing.
///
bool BugDriver::debugOptimizerCrash(const std::string &ID) {
outs() << "\n*** Debugging optimizer crash!\n";
std::string Error;
// Reduce the list of passes which causes the optimizer to crash...
if (!BugpointIsInterrupted)
ReducePassList(*this).reduceList(PassesToRun, Error);
assert(Error.empty());
outs() << "\n*** Found crashing pass"
<< (PassesToRun.size() == 1 ? ": " : "es: ")
<< getPassesString(PassesToRun) << '\n';
EmitProgressBitcode(Program, ID);
bool Success = DebugACrash(*this, TestForOptimizerCrash, Error);
assert(Error.empty());
return Success;
}
static bool TestForCodeGenCrash(const BugDriver &BD, Module *M) {
std::string Error;
BD.compileProgram(M, &Error);
if (!Error.empty()) {
errs() << "<crash>\n";
return true; // Tool is still crashing.
}
errs() << '\n';
return false;
}
/// debugCodeGeneratorCrash - This method is called when the code generator
/// crashes on an input. It attempts to reduce the input as much as possible
/// while still causing the code generator to crash.
bool BugDriver::debugCodeGeneratorCrash(std::string &Error) {
errs() << "*** Debugging code generator crash!\n";
return DebugACrash(*this, TestForCodeGenCrash, Error);
}
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