forked from OSchip/llvm-project
Add a -lint pass which checks for common sources of undefined or likely
unintended behavior. llvm-svn: 100798
This commit is contained in:
Dan Gohman
parent
359b013129
commit
98bc4371c7
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@ -0,0 +1,52 @@
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//===-- llvm/Analysis/Lint.h - LLVM IR Lint ---------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This file defines lint interfaces that can be used for some sanity checking
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// of input to the system, and for checking that transformations
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// haven't done something bad. In contrast to the Verifier, the Lint checker
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// checks for undefined behavior or constructions with likely unintended
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// behavior.
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//
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// To see what specifically is checked, look at Lint.cpp
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LINT_H
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#define LLVM_ANALYSIS_LINT_H
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#include <string>
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namespace llvm {
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class FunctionPass;
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class Module;
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class Function;
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/// @brief Create a lint pass.
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///
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/// Check a module or function.
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FunctionPass *createLintPass();
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/// @brief Check a module.
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///
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/// This should only be used for debugging, because it plays games with
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/// PassManagers and stuff.
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void lintModule(
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const Module &M, ///< The module to be checked
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std::string *ErrorInfo = 0 ///< Information about failures.
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);
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// lintFunction - Check a function.
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void lintFunction(
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const Function &F ///< The function to be checked
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);
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} // End llvm namespace
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#endif
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@ -23,6 +23,7 @@
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#include "llvm/Analysis/PointerTracking.h"
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#include "llvm/Analysis/PostDominators.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/Lint.h"
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#include "llvm/Assembly/PrintModulePass.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/Function.h"
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@ -137,6 +138,7 @@ namespace {
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(void) llvm::createGEPSplitterPass();
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(void) llvm::createSCCVNPass();
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(void) llvm::createABCDPass();
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(void) llvm::createLintPass();
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(void)new llvm::IntervalPartition();
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(void)new llvm::FindUsedTypes();
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@ -0,0 +1,368 @@
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//===-- Lint.cpp - Check for common errors in LLVM IR ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This pass statically checks for common and easily-identified constructs
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// which produce undefined or likely unintended behavior in LLVM IR.
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//
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// It is not a guarantee of correctness, in two ways. First, it isn't
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// comprehensive. There are checks which could be done statically which are
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// not yet implemented. Some of these are indicated by TODO comments, but
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// those aren't comprehensive either. Second, many conditions cannot be
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// checked statically. This pass does no dynamic instrumentation, so it
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// can't check for all possible problems.
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//
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// Another limitation is that it assumes all code will be executed. A store
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// through a null pointer in a basic block which is never reached is harmless,
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// but this pass will warn about it anyway.
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// Optimization passes may make conditions that this pass checks for more or
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// less obvious. If an optimization pass appears to be introducing a warning,
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// it may be that the optimization pass is merely exposing an existing
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// condition in the code.
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//
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// This code may be run before instcombine. In many cases, instcombine checks
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// for the same kinds of things and turns instructions with undefined behavior
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// into unreachable (or equivalent). Because of this, this pass makes some
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// effort to look through bitcasts and so on.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/Lint.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Assembly/Writer.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Pass.h"
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#include "llvm/PassManager.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Function.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/InstVisitor.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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class Lint : public FunctionPass, public InstVisitor<Lint> {
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friend class InstVisitor<Lint>;
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void visitCallSite(CallSite CS);
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void visitMemoryReference(Instruction &I, Value *Ptr, unsigned Align,
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const Type *Ty);
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void visitInstruction(Instruction &I);
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void visitCallInst(CallInst &I);
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void visitInvokeInst(InvokeInst &I);
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void visitReturnInst(ReturnInst &I);
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void visitLoadInst(LoadInst &I);
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void visitStoreInst(StoreInst &I);
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void visitSDiv(BinaryOperator &I);
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void visitUDiv(BinaryOperator &I);
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void visitSRem(BinaryOperator &I);
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void visitURem(BinaryOperator &I);
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void visitAllocaInst(AllocaInst &I);
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void visitVAArgInst(VAArgInst &I);
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void visitIndirectBrInst(IndirectBrInst &I);
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public:
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Module *Mod;
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AliasAnalysis *AA;
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TargetData *TD;
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std::string Messages;
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raw_string_ostream MessagesStr;
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static char ID; // Pass identification, replacement for typeid
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Lint() : FunctionPass(&ID), MessagesStr(Messages) {}
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virtual bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequired<AliasAnalysis>();
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}
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virtual void print(raw_ostream &O, const Module *M) const {}
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void WriteValue(const Value *V) {
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if (!V) return;
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if (isa<Instruction>(V)) {
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MessagesStr << *V << '\n';
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} else {
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WriteAsOperand(MessagesStr, V, true, Mod);
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MessagesStr << '\n';
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}
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}
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void WriteType(const Type *T) {
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if (!T) return;
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MessagesStr << ' ';
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WriteTypeSymbolic(MessagesStr, T, Mod);
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}
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// CheckFailed - A check failed, so print out the condition and the message
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// that failed. This provides a nice place to put a breakpoint if you want
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// to see why something is not correct.
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void CheckFailed(const Twine &Message,
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const Value *V1 = 0, const Value *V2 = 0,
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const Value *V3 = 0, const Value *V4 = 0) {
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MessagesStr << Message.str() << "\n";
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WriteValue(V1);
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WriteValue(V2);
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WriteValue(V3);
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WriteValue(V4);
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}
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void CheckFailed(const Twine &Message, const Value *V1,
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const Type *T2, const Value *V3 = 0) {
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MessagesStr << Message.str() << "\n";
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WriteValue(V1);
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WriteType(T2);
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WriteValue(V3);
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}
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void CheckFailed(const Twine &Message, const Type *T1,
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const Type *T2 = 0, const Type *T3 = 0) {
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MessagesStr << Message.str() << "\n";
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WriteType(T1);
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WriteType(T2);
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WriteType(T3);
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}
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};
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}
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char Lint::ID = 0;
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static RegisterPass<Lint>
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X("lint", "Statically lint-checks LLVM IR", false, true);
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// Assert - We know that cond should be true, if not print an error message.
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#define Assert(C, M) \
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do { if (!(C)) { CheckFailed(M); return; } } while (0)
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#define Assert1(C, M, V1) \
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do { if (!(C)) { CheckFailed(M, V1); return; } } while (0)
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#define Assert2(C, M, V1, V2) \
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do { if (!(C)) { CheckFailed(M, V1, V2); return; } } while (0)
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#define Assert3(C, M, V1, V2, V3) \
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do { if (!(C)) { CheckFailed(M, V1, V2, V3); return; } } while (0)
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#define Assert4(C, M, V1, V2, V3, V4) \
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do { if (!(C)) { CheckFailed(M, V1, V2, V3, V4); return; } } while (0)
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// Lint::run - This is the main Analysis entry point for a
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// function.
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//
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bool Lint::runOnFunction(Function &F) {
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Mod = F.getParent();
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AA = &getAnalysis<AliasAnalysis>();
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TD = getAnalysisIfAvailable<TargetData>();
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visit(F);
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dbgs() << MessagesStr.str();
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return false;
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}
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void Lint::visitInstruction(Instruction &I) {
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}
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void Lint::visitCallSite(CallSite CS) {
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Instruction &I = *CS.getInstruction();
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Value *Callee = CS.getCalledValue();
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// TODO: Check function alignment?
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visitMemoryReference(I, Callee, 0, 0);
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if (Function *F = dyn_cast<Function>(Callee->stripPointerCasts())) {
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Assert1(CS.getCallingConv() == F->getCallingConv(),
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"Caller and callee calling convention differ", &I);
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const FunctionType *FT = F->getFunctionType();
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unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
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Assert1(FT->isVarArg() ?
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FT->getNumParams() <= NumActualArgs :
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FT->getNumParams() == NumActualArgs,
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"Call argument count mismatches callee argument count", &I);
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// TODO: Check argument types (in case the callee was casted)
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// TODO: Check ABI-significant attributes.
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// TODO: Check noalias attribute.
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// TODO: Check sret attribute.
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}
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// TODO: Check the "tail" keyword constraints.
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if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I))
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switch (II->getIntrinsicID()) {
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default: break;
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// TODO: Check more intrinsics
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case Intrinsic::memcpy: {
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MemCpyInst *MCI = cast<MemCpyInst>(&I);
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visitMemoryReference(I, MCI->getSource(), MCI->getAlignment(), 0);
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visitMemoryReference(I, MCI->getDest(), MCI->getAlignment(), 0);
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unsigned Size = 0;
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if (const ConstantInt *Len =
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dyn_cast<ConstantInt>(MCI->getLength()->stripPointerCasts()))
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if (Len->getValue().isIntN(32))
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Size = Len->getValue().getZExtValue();
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Assert1(AA->alias(MCI->getSource(), Size, MCI->getDest(), Size) !=
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AliasAnalysis::MustAlias,
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"memcpy source and destination overlap", &I);
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break;
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}
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case Intrinsic::memmove: {
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MemMoveInst *MMI = cast<MemMoveInst>(&I);
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visitMemoryReference(I, MMI->getSource(), MMI->getAlignment(), 0);
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visitMemoryReference(I, MMI->getDest(), MMI->getAlignment(), 0);
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break;
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}
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case Intrinsic::memset: {
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MemSetInst *MSI = cast<MemSetInst>(&I);
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visitMemoryReference(I, MSI->getDest(), MSI->getAlignment(), 0);
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break;
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}
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case Intrinsic::vastart:
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visitMemoryReference(I, CS.getArgument(0), 0, 0);
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break;
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case Intrinsic::vacopy:
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visitMemoryReference(I, CS.getArgument(0), 0, 0);
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visitMemoryReference(I, CS.getArgument(1), 0, 0);
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break;
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case Intrinsic::vaend:
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visitMemoryReference(I, CS.getArgument(0), 0, 0);
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break;
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case Intrinsic::stackrestore:
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visitMemoryReference(I, CS.getArgument(0), 0, 0);
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break;
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}
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}
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void Lint::visitCallInst(CallInst &I) {
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return visitCallSite(&I);
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}
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void Lint::visitInvokeInst(InvokeInst &I) {
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return visitCallSite(&I);
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}
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void Lint::visitReturnInst(ReturnInst &I) {
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Function *F = I.getParent()->getParent();
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Assert1(!F->doesNotReturn(),
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"Return statement in function with noreturn attribute", &I);
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}
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// TODO: Add a length argument and check that the reference is in bounds
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// TODO: Add read/write/execute flags and check for writing to read-only
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// memory or jumping to suspicious writeable memory
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void Lint::visitMemoryReference(Instruction &I,
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Value *Ptr, unsigned Align, const Type *Ty) {
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Assert1(!isa<ConstantPointerNull>(Ptr->getUnderlyingObject()),
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"Null pointer dereference", &I);
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Assert1(!isa<UndefValue>(Ptr->getUnderlyingObject()),
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"Undef pointer dereference", &I);
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if (TD) {
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if (Align == 0 && Ty) Align = TD->getABITypeAlignment(Ty);
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if (Align != 0) {
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unsigned BitWidth = TD->getTypeSizeInBits(Ptr->getType());
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APInt Mask = APInt::getAllOnesValue(BitWidth),
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KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
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ComputeMaskedBits(Ptr, Mask, KnownZero, KnownOne, TD);
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Assert1(!(KnownOne & APInt::getLowBitsSet(BitWidth, Log2_32(Align))),
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"Memory reference address is misaligned", &I);
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}
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}
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}
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void Lint::visitLoadInst(LoadInst &I) {
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visitMemoryReference(I, I.getPointerOperand(), I.getAlignment(), I.getType());
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}
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void Lint::visitStoreInst(StoreInst &I) {
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visitMemoryReference(I, I.getPointerOperand(), I.getAlignment(),
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I.getOperand(0)->getType());
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}
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static bool isZero(Value *V, TargetData *TD) {
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unsigned BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
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APInt Mask = APInt::getAllOnesValue(BitWidth),
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KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
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ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD);
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return KnownZero.isAllOnesValue();
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}
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void Lint::visitSDiv(BinaryOperator &I) {
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Assert1(!isZero(I.getOperand(1), TD), "Division by zero", &I);
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}
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void Lint::visitUDiv(BinaryOperator &I) {
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Assert1(!isZero(I.getOperand(1), TD), "Division by zero", &I);
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}
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void Lint::visitSRem(BinaryOperator &I) {
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Assert1(!isZero(I.getOperand(1), TD), "Division by zero", &I);
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}
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void Lint::visitURem(BinaryOperator &I) {
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Assert1(!isZero(I.getOperand(1), TD), "Division by zero", &I);
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}
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void Lint::visitAllocaInst(AllocaInst &I) {
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if (isa<ConstantInt>(I.getArraySize()))
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// This isn't undefined behavior, it's just an obvious pessimization.
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Assert1(&I.getParent()->getParent()->getEntryBlock() == I.getParent(),
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"Static alloca outside of entry block", &I);
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}
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void Lint::visitVAArgInst(VAArgInst &I) {
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visitMemoryReference(I, I.getOperand(0), 0, 0);
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}
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void Lint::visitIndirectBrInst(IndirectBrInst &I) {
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visitMemoryReference(I, I.getAddress(), 0, 0);
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}
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//===----------------------------------------------------------------------===//
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// Implement the public interfaces to this file...
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//===----------------------------------------------------------------------===//
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FunctionPass *llvm::createLintPass() {
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return new Lint();
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}
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/// lintFunction - Check a function for errors, printing messages on stderr.
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///
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void llvm::lintFunction(const Function &f) {
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Function &F = const_cast<Function&>(f);
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assert(!F.isDeclaration() && "Cannot lint external functions");
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FunctionPassManager FPM(F.getParent());
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Lint *V = new Lint();
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FPM.add(V);
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FPM.run(F);
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}
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/// lintModule - Check a module for errors, printing messages on stderr.
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/// Return true if the module is corrupt.
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///
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void llvm::lintModule(const Module &M, std::string *ErrorInfo) {
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PassManager PM;
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Lint *V = new Lint();
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PM.add(V);
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PM.run(const_cast<Module&>(M));
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if (ErrorInfo)
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*ErrorInfo = V->MessagesStr.str();
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}
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@ -0,0 +1,31 @@
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; RUN: opt -lint -disable-output < %s |& FileCheck %s
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target datalayout = "e-p:64:64:64"
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declare fastcc void @bar()
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define i32 @foo() noreturn {
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; CHECK: Caller and callee calling convention differ
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call void @bar()
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; CHECK: Null pointer dereference
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store i32 0, i32* null
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; CHECK: Null pointer dereference
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%t = load i32* null
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; CHECK: Memory reference address is misaligned
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%x = inttoptr i32 1 to i32*
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load i32* %x, align 4
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; CHECK: Division by zero
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%sd = sdiv i32 2, 0
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; CHECK: Division by zero
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%ud = udiv i32 2, 0
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; CHECK: Division by zero
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%sr = srem i32 2, 0
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; CHECK: Division by zero
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%ur = urem i32 2, 0
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br label %next
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next:
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; CHECK: Static alloca outside of entry block
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%a = alloca i32
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; CHECK: Return statement in function with noreturn attribute
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||||
ret i32 0
|
||||
}
|
||||
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Reference in New Issue