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//===- CrashDebugger.cpp - Debug compilation crashes ----------------------===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file defines the bugpoint internals that narrow down compilation crashes
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//===----------------------------------------------------------------------===//
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#include "BugDriver.h"
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#include "ListReducer.h"
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#include "ToolRunner.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/ValueSymbolTable.h"
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#include "llvm/IR/Verifier.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/FileUtilities.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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cl::desc("Force function reduction to keep main"),
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NoGlobalRM ("disable-global-remove",
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cl::desc("Do not remove global variables"),
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ReplaceFuncsWithNull("replace-funcs-with-null",
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cl::desc("When stubbing functions, replace all uses will null"),
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DontReducePassList("disable-pass-list-reduction",
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cl::desc("Skip pass list reduction steps"),
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class ReducePassList : public ListReducer<std::string> {
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ReducePassList(BugDriver &bd) : BD(bd) {}
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// doTest - Return true iff running the "removed" passes succeeds, and
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// running the "Kept" passes fail when run on the output of the "removed"
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// passes. If we return true, we update the current module of bugpoint.
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TestResult doTest(std::vector<std::string> &Removed,
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std::vector<std::string> &Kept,
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std::string &Error) override;
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ReducePassList::TestResult
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ReducePassList::doTest(std::vector<std::string> &Prefix,
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std::vector<std::string> &Suffix,
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std::string PrefixOutput;
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Module *OrigProgram = nullptr;
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if (!Prefix.empty()) {
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outs() << "Checking to see if these passes crash: "
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<< getPassesString(Prefix) << ": ";
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if (BD.runPasses(BD.getProgram(), Prefix, PrefixOutput))
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OrigProgram = BD.Program;
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BD.Program = parseInputFile(PrefixOutput, BD.getContext()).release();
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if (BD.Program == nullptr) {
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errs() << BD.getToolName() << ": Error reading bitcode file '"
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<< PrefixOutput << "'!\n";
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sys::fs::remove(PrefixOutput);
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outs() << "Checking to see if these passes crash: "
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<< getPassesString(Suffix) << ": ";
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if (BD.runPasses(BD.getProgram(), Suffix)) {
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delete OrigProgram; // The suffix crashes alone...
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// Nothing failed, restore state...
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BD.Program = OrigProgram;
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/// ReduceCrashingGlobalVariables - This works by removing the global
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/// variable's initializer and seeing if the program still crashes. If it
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/// does, then we keep that program and try again.
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class ReduceCrashingGlobalVariables : public ListReducer<GlobalVariable*> {
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bool (*TestFn)(const BugDriver &, Module *);
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ReduceCrashingGlobalVariables(BugDriver &bd,
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bool (*testFn)(const BugDriver &, Module *))
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: BD(bd), TestFn(testFn) {}
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TestResult doTest(std::vector<GlobalVariable*> &Prefix,
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std::vector<GlobalVariable*> &Kept,
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std::string &Error) override {
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if (!Kept.empty() && TestGlobalVariables(Kept))
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if (!Prefix.empty() && TestGlobalVariables(Prefix))
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bool TestGlobalVariables(std::vector<GlobalVariable*> &GVs);
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ReduceCrashingGlobalVariables::TestGlobalVariables(
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std::vector<GlobalVariable*> &GVs) {
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// Clone the program to try hacking it apart...
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ValueToValueMapTy VMap;
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Module *M = CloneModule(BD.getProgram(), VMap);
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// Convert list to set for fast lookup...
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std::set<GlobalVariable*> GVSet;
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for (unsigned i = 0, e = GVs.size(); i != e; ++i) {
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GlobalVariable* CMGV = cast<GlobalVariable>(VMap[GVs[i]]);
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assert(CMGV && "Global Variable not in module?!");
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outs() << "Checking for crash with only these global variables: ";
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PrintGlobalVariableList(GVs);
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// Loop over and delete any global variables which we aren't supposed to be
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for (Module::global_iterator I = M->global_begin(), E = M->global_end();
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if (I->hasInitializer() && !GVSet.count(I)) {
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I->setInitializer(nullptr);
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I->setLinkage(GlobalValue::ExternalLinkage);
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// Try running the hacked up program...
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BD.setNewProgram(M); // It crashed, keep the trimmed version...
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// Make sure to use global variable pointers that point into the now-current
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GVs.assign(GVSet.begin(), GVSet.end());
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/// ReduceCrashingFunctions reducer - This works by removing functions and
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/// seeing if the program still crashes. If it does, then keep the newer,
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class ReduceCrashingFunctions : public ListReducer<Function*> {
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bool (*TestFn)(const BugDriver &, Module *);
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ReduceCrashingFunctions(BugDriver &bd,
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bool (*testFn)(const BugDriver &, Module *))
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: BD(bd), TestFn(testFn) {}
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TestResult doTest(std::vector<Function*> &Prefix,
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std::vector<Function*> &Kept,
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std::string &Error) override {
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if (!Kept.empty() && TestFuncs(Kept))
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if (!Prefix.empty() && TestFuncs(Prefix))
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bool TestFuncs(std::vector<Function*> &Prefix);
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static void RemoveFunctionReferences(Module *M, const char* Name) {
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auto *UsedVar = M->getGlobalVariable(Name, true);
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if (!UsedVar || !UsedVar->hasInitializer()) return;
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if (isa<ConstantAggregateZero>(UsedVar->getInitializer())) {
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assert(UsedVar->use_empty());
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UsedVar->eraseFromParent();
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auto *OldUsedVal = cast<ConstantArray>(UsedVar->getInitializer());
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std::vector<Constant*> Used;
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for(Value *V : OldUsedVal->operand_values()) {
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Constant *Op = cast<Constant>(V->stripPointerCasts());
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if(!Op->isNullValue()) {
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Used.push_back(cast<Constant>(V));
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auto *NewValElemTy = OldUsedVal->getType()->getElementType();
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auto *NewValTy = ArrayType::get(NewValElemTy, Used.size());
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auto *NewUsedVal = ConstantArray::get(NewValTy, Used);
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UsedVar->mutateType(NewUsedVal->getType()->getPointerTo());
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UsedVar->setInitializer(NewUsedVal);
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bool ReduceCrashingFunctions::TestFuncs(std::vector<Function*> &Funcs) {
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// If main isn't present, claim there is no problem.
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if (KeepMain && std::find(Funcs.begin(), Funcs.end(),
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BD.getProgram()->getFunction("main")) ==
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// Clone the program to try hacking it apart...
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ValueToValueMapTy VMap;
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Module *M = CloneModule(BD.getProgram(), VMap);
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// Convert list to set for fast lookup...
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std::set<Function*> Functions;
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for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
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Function *CMF = cast<Function>(VMap[Funcs[i]]);
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assert(CMF && "Function not in module?!");
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assert(CMF->getFunctionType() == Funcs[i]->getFunctionType() && "wrong ty");
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assert(CMF->getName() == Funcs[i]->getName() && "wrong name");
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Functions.insert(CMF);
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outs() << "Checking for crash with only these functions: ";
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PrintFunctionList(Funcs);
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if (!ReplaceFuncsWithNull) {
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// Loop over and delete any functions which we aren't supposed to be playing
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for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
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if (!I->isDeclaration() && !Functions.count(I))
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DeleteFunctionBody(I);
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std::vector<GlobalValue*> ToRemove;
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// First, remove aliases to functions we're about to purge.
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for (GlobalAlias &Alias : M->aliases()) {
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Constant *Root = Alias.getAliasee()->stripPointerCasts();
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Function *F = dyn_cast<Function>(Root);
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if (Functions.count(F))
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// We're keeping this function.
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} else if (Root->isNullValue()) {
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// This referenced a globalalias that we've already replaced,
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// so we still need to replace this alias.
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// Not a function, therefore not something we mess with.
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PointerType *Ty = cast<PointerType>(Alias.getType());
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Constant *Replacement = ConstantPointerNull::get(Ty);
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Alias.replaceAllUsesWith(Replacement);
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ToRemove.push_back(&Alias);
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for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
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if (!I->isDeclaration() && !Functions.count(I)) {
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PointerType *Ty = cast<PointerType>(I->getType());
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Constant *Replacement = ConstantPointerNull::get(Ty);
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I->replaceAllUsesWith(Replacement);
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ToRemove.push_back(I);
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for (auto *F : ToRemove) {
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F->eraseFromParent();
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// Finally, remove any null members from any global intrinsic.
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RemoveFunctionReferences(M, "llvm.used");
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RemoveFunctionReferences(M, "llvm.compiler.used");
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// Try running the hacked up program...
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BD.setNewProgram(M); // It crashed, keep the trimmed version...
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// Make sure to use function pointers that point into the now-current
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Funcs.assign(Functions.begin(), Functions.end());
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/// ReduceCrashingBlocks reducer - This works by setting the terminators of
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/// all terminators except the specified basic blocks to a 'ret' instruction,
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/// then running the simplify-cfg pass. This has the effect of chopping up
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/// the CFG really fast which can reduce large functions quickly.
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class ReduceCrashingBlocks : public ListReducer<const BasicBlock*> {
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bool (*TestFn)(const BugDriver &, Module *);
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ReduceCrashingBlocks(BugDriver &bd,
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bool (*testFn)(const BugDriver &, Module *))
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: BD(bd), TestFn(testFn) {}
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TestResult doTest(std::vector<const BasicBlock*> &Prefix,
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std::vector<const BasicBlock*> &Kept,
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std::string &Error) override {
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if (!Kept.empty() && TestBlocks(Kept))
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if (!Prefix.empty() && TestBlocks(Prefix))
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bool TestBlocks(std::vector<const BasicBlock*> &Prefix);
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bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
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// Clone the program to try hacking it apart...
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ValueToValueMapTy VMap;
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Module *M = CloneModule(BD.getProgram(), VMap);
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// Convert list to set for fast lookup...
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SmallPtrSet<BasicBlock*, 8> Blocks;
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for (unsigned i = 0, e = BBs.size(); i != e; ++i)
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Blocks.insert(cast<BasicBlock>(VMap[BBs[i]]));
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outs() << "Checking for crash with only these blocks:";
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unsigned NumPrint = Blocks.size();
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if (NumPrint > 10) NumPrint = 10;
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for (unsigned i = 0, e = NumPrint; i != e; ++i)
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outs() << " " << BBs[i]->getName();
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if (NumPrint < Blocks.size())
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outs() << "... <" << Blocks.size() << " total>";
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// Loop over and delete any hack up any blocks that are not listed...
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for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
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for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
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if (!Blocks.count(BB) && BB->getTerminator()->getNumSuccessors()) {
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// Loop over all of the successors of this block, deleting any PHI nodes
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// that might include it.
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for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
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(*SI)->removePredecessor(BB);
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TerminatorInst *BBTerm = BB->getTerminator();
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if (!BB->getTerminator()->getType()->isVoidTy())
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BBTerm->replaceAllUsesWith(Constant::getNullValue(BBTerm->getType()));
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// Replace the old terminator instruction.
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BB->getInstList().pop_back();
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new UnreachableInst(BB->getContext(), BB);
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// The CFG Simplifier pass may delete one of the basic blocks we are
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// interested in. If it does we need to take the block out of the list. Make
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// a "persistent mapping" by turning basic blocks into <function, name> pairs.
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// This won't work well if blocks are unnamed, but that is just the risk we
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std::vector<std::pair<std::string, std::string> > BlockInfo;
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for (BasicBlock *BB : Blocks)
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BlockInfo.emplace_back(BB->getParent()->getName(), BB->getName());
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// Now run the CFG simplify pass on the function...
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std::vector<std::string> Passes;
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Passes.push_back("simplifycfg");
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Passes.push_back("verify");
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std::unique_ptr<Module> New = BD.runPassesOn(M, Passes);
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errs() << "simplifycfg failed!\n";
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// Try running on the hacked up program...
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BD.setNewProgram(M); // It crashed, keep the trimmed version...
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// Make sure to use basic block pointers that point into the now-current
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// module, and that they don't include any deleted blocks.
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const ValueSymbolTable &GST = M->getValueSymbolTable();
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for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
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Function *F = cast<Function>(GST.lookup(BlockInfo[i].first));
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ValueSymbolTable &ST = F->getValueSymbolTable();
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Value* V = ST.lookup(BlockInfo[i].second);
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if (V && V->getType() == Type::getLabelTy(V->getContext()))
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BBs.push_back(cast<BasicBlock>(V));
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delete M; // It didn't crash, try something else.
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/// ReduceCrashingInstructions reducer - This works by removing the specified
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/// non-terminator instructions and replacing them with undef.
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class ReduceCrashingInstructions : public ListReducer<const Instruction*> {
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bool (*TestFn)(const BugDriver &, Module *);
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ReduceCrashingInstructions(BugDriver &bd,
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bool (*testFn)(const BugDriver &, Module *))
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: BD(bd), TestFn(testFn) {}
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TestResult doTest(std::vector<const Instruction*> &Prefix,
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std::vector<const Instruction*> &Kept,
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std::string &Error) override {
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if (!Kept.empty() && TestInsts(Kept))
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if (!Prefix.empty() && TestInsts(Prefix))
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bool TestInsts(std::vector<const Instruction*> &Prefix);
449
bool ReduceCrashingInstructions::TestInsts(std::vector<const Instruction*>
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// Clone the program to try hacking it apart...
452
ValueToValueMapTy VMap;
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Module *M = CloneModule(BD.getProgram(), VMap);
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// Convert list to set for fast lookup...
456
SmallPtrSet<Instruction*, 64> Instructions;
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for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
458
assert(!isa<TerminatorInst>(Insts[i]));
459
Instructions.insert(cast<Instruction>(VMap[Insts[i]]));
462
outs() << "Checking for crash with only " << Instructions.size();
463
if (Instructions.size() == 1)
464
outs() << " instruction: ";
466
outs() << " instructions: ";
468
for (Module::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI)
469
for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE; ++FI)
470
for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E;) {
471
Instruction *Inst = I++;
472
if (!Instructions.count(Inst) && !isa<TerminatorInst>(Inst) &&
473
!isa<LandingPadInst>(Inst)) {
474
if (!Inst->getType()->isVoidTy())
475
Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
476
Inst->eraseFromParent();
480
// Verify that this is still valid.
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legacy::PassManager Passes;
482
Passes.add(createVerifierPass());
485
// Try running on the hacked up program...
487
BD.setNewProgram(M); // It crashed, keep the trimmed version...
489
// Make sure to use instruction pointers that point into the now-current
490
// module, and that they don't include any deleted blocks.
492
for (Instruction *Inst : Instructions)
493
Insts.push_back(Inst);
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delete M; // It didn't crash, try something else.
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/// DebugACrash - Given a predicate that determines whether a component crashes
501
/// on a program, try to destructively reduce the program while still keeping
502
/// the predicate true.
503
static bool DebugACrash(BugDriver &BD,
504
bool (*TestFn)(const BugDriver &, Module *),
505
std::string &Error) {
506
// See if we can get away with nuking some of the global variable initializers
509
BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
510
// Now try to reduce the number of global variable initializers in the
511
// module to something small.
512
Module *M = CloneModule(BD.getProgram());
513
bool DeletedInit = false;
515
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
517
if (I->hasInitializer()) {
518
I->setInitializer(nullptr);
519
I->setLinkage(GlobalValue::ExternalLinkage);
524
delete M; // No change made...
526
// See if the program still causes a crash...
527
outs() << "\nChecking to see if we can delete global inits: ";
529
if (TestFn(BD, M)) { // Still crashes?
531
outs() << "\n*** Able to remove all global initializers!\n";
532
} else { // No longer crashes?
533
outs() << " - Removing all global inits hides problem!\n";
536
std::vector<GlobalVariable*> GVs;
538
for (Module::global_iterator I = BD.getProgram()->global_begin(),
539
E = BD.getProgram()->global_end(); I != E; ++I)
540
if (I->hasInitializer())
543
if (GVs.size() > 1 && !BugpointIsInterrupted) {
544
outs() << "\n*** Attempting to reduce the number of global "
545
<< "variables in the testcase\n";
547
unsigned OldSize = GVs.size();
548
ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs, Error);
552
if (GVs.size() < OldSize)
553
BD.EmitProgressBitcode(BD.getProgram(), "reduced-global-variables");
559
// Now try to reduce the number of functions in the module to something small.
560
std::vector<Function*> Functions;
561
for (Module::iterator I = BD.getProgram()->begin(),
562
E = BD.getProgram()->end(); I != E; ++I)
563
if (!I->isDeclaration())
564
Functions.push_back(I);
566
if (Functions.size() > 1 && !BugpointIsInterrupted) {
567
outs() << "\n*** Attempting to reduce the number of functions "
570
unsigned OldSize = Functions.size();
571
ReduceCrashingFunctions(BD, TestFn).reduceList(Functions, Error);
573
if (Functions.size() < OldSize)
574
BD.EmitProgressBitcode(BD.getProgram(), "reduced-function");
577
// Attempt to delete entire basic blocks at a time to speed up
578
// convergence... this actually works by setting the terminator of the blocks
579
// to a return instruction then running simplifycfg, which can potentially
580
// shrinks the code dramatically quickly
582
if (!DisableSimplifyCFG && !BugpointIsInterrupted) {
583
std::vector<const BasicBlock*> Blocks;
584
for (Module::const_iterator I = BD.getProgram()->begin(),
585
E = BD.getProgram()->end(); I != E; ++I)
586
for (Function::const_iterator FI = I->begin(), E = I->end(); FI !=E; ++FI)
587
Blocks.push_back(FI);
588
unsigned OldSize = Blocks.size();
589
ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks, Error);
590
if (Blocks.size() < OldSize)
591
BD.EmitProgressBitcode(BD.getProgram(), "reduced-blocks");
594
// Attempt to delete instructions using bisection. This should help out nasty
595
// cases with large basic blocks where the problem is at one end.
596
if (!BugpointIsInterrupted) {
597
std::vector<const Instruction*> Insts;
598
for (Module::const_iterator MI = BD.getProgram()->begin(),
599
ME = BD.getProgram()->end(); MI != ME; ++MI)
600
for (Function::const_iterator FI = MI->begin(), FE = MI->end(); FI != FE;
602
for (BasicBlock::const_iterator I = FI->begin(), E = FI->end();
604
if (!isa<TerminatorInst>(I))
607
ReduceCrashingInstructions(BD, TestFn).reduceList(Insts, Error);
610
// FIXME: This should use the list reducer to converge faster by deleting
611
// larger chunks of instructions at a time!
612
unsigned Simplification = 2;
614
if (BugpointIsInterrupted) break;
616
outs() << "\n*** Attempting to reduce testcase by deleting instruc"
617
<< "tions: Simplification Level #" << Simplification << '\n';
619
// Now that we have deleted the functions that are unnecessary for the
620
// program, try to remove instructions that are not necessary to cause the
621
// crash. To do this, we loop through all of the instructions in the
622
// remaining functions, deleting them (replacing any values produced with
623
// nulls), and then running ADCE and SimplifyCFG. If the transformed input
624
// still triggers failure, keep deleting until we cannot trigger failure
627
unsigned InstructionsToSkipBeforeDeleting = 0;
630
// Loop over all of the (non-terminator) instructions remaining in the
631
// function, attempting to delete them.
632
unsigned CurInstructionNum = 0;
633
for (Module::const_iterator FI = BD.getProgram()->begin(),
634
E = BD.getProgram()->end(); FI != E; ++FI)
635
if (!FI->isDeclaration())
636
for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
638
for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
639
I != E; ++I, ++CurInstructionNum) {
640
if (InstructionsToSkipBeforeDeleting) {
641
--InstructionsToSkipBeforeDeleting;
643
if (BugpointIsInterrupted) goto ExitLoops;
645
if (isa<LandingPadInst>(I))
648
outs() << "Checking instruction: " << *I;
649
std::unique_ptr<Module> M =
650
BD.deleteInstructionFromProgram(I, Simplification);
652
// Find out if the pass still crashes on this pass...
653
if (TestFn(BD, M.get())) {
654
// Yup, it does, we delete the old module, and continue trying
655
// to reduce the testcase...
656
BD.setNewProgram(M.release());
657
InstructionsToSkipBeforeDeleting = CurInstructionNum;
658
goto TryAgain; // I wish I had a multi-level break here!
663
if (InstructionsToSkipBeforeDeleting) {
664
InstructionsToSkipBeforeDeleting = 0;
668
} while (Simplification);
671
// Try to clean up the testcase by running funcresolve and globaldce...
672
if (!BugpointIsInterrupted) {
673
outs() << "\n*** Attempting to perform final cleanups: ";
674
Module *M = CloneModule(BD.getProgram());
675
M = BD.performFinalCleanups(M, true).release();
677
// Find out if the pass still crashes on the cleaned up program...
679
BD.setNewProgram(M); // Yup, it does, keep the reduced version...
685
BD.EmitProgressBitcode(BD.getProgram(), "reduced-simplified");
690
static bool TestForOptimizerCrash(const BugDriver &BD, Module *M) {
691
return BD.runPasses(M);
694
/// debugOptimizerCrash - This method is called when some pass crashes on input.
695
/// It attempts to prune down the testcase to something reasonable, and figure
696
/// out exactly which pass is crashing.
698
bool BugDriver::debugOptimizerCrash(const std::string &ID) {
699
outs() << "\n*** Debugging optimizer crash!\n";
702
// Reduce the list of passes which causes the optimizer to crash...
703
if (!BugpointIsInterrupted && !DontReducePassList)
704
ReducePassList(*this).reduceList(PassesToRun, Error);
705
assert(Error.empty());
707
outs() << "\n*** Found crashing pass"
708
<< (PassesToRun.size() == 1 ? ": " : "es: ")
709
<< getPassesString(PassesToRun) << '\n';
711
EmitProgressBitcode(Program, ID);
713
bool Success = DebugACrash(*this, TestForOptimizerCrash, Error);
714
assert(Error.empty());
718
static bool TestForCodeGenCrash(const BugDriver &BD, Module *M) {
720
BD.compileProgram(M, &Error);
721
if (!Error.empty()) {
722
errs() << "<crash>\n";
723
return true; // Tool is still crashing.
729
/// debugCodeGeneratorCrash - This method is called when the code generator
730
/// crashes on an input. It attempts to reduce the input as much as possible
731
/// while still causing the code generator to crash.
732
bool BugDriver::debugCodeGeneratorCrash(std::string &Error) {
733
errs() << "*** Debugging code generator crash!\n";
735
return DebugACrash(*this, TestForCodeGenCrash, Error);