104 lines
3.5 KiB
C++
104 lines
3.5 KiB
C++
//=== BuiltinFunctionChecker.cpp --------------------------------*- 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 checker evaluates clang builtin functions.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/Basic/Builtins.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class BuiltinFunctionChecker : public Checker<eval::Call> {
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public:
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bool evalCall(const CallExpr *CE, CheckerContext &C) const;
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};
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}
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bool BuiltinFunctionChecker::evalCall(const CallExpr *CE,
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CheckerContext &C) const {
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ProgramStateRef state = C.getState();
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const FunctionDecl *FD = C.getCalleeDecl(CE);
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const LocationContext *LCtx = C.getLocationContext();
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if (!FD)
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return false;
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switch (FD->getBuiltinID()) {
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default:
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return false;
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case Builtin::BI__builtin_unpredictable:
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case Builtin::BI__builtin_expect:
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case Builtin::BI__builtin_assume_aligned:
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case Builtin::BI__builtin_addressof: {
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// For __builtin_unpredictable, __builtin_expect, and
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// __builtin_assume_aligned, just return the value of the subexpression.
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// __builtin_addressof is going from a reference to a pointer, but those
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// are represented the same way in the analyzer.
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assert (CE->arg_begin() != CE->arg_end());
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SVal X = state->getSVal(*(CE->arg_begin()), LCtx);
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C.addTransition(state->BindExpr(CE, LCtx, X));
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return true;
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}
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case Builtin::BI__builtin_alloca_with_align:
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case Builtin::BI__builtin_alloca: {
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// FIXME: Refactor into StoreManager itself?
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MemRegionManager& RM = C.getStoreManager().getRegionManager();
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const AllocaRegion* R =
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RM.getAllocaRegion(CE, C.blockCount(), C.getLocationContext());
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// Set the extent of the region in bytes. This enables us to use the
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// SVal of the argument directly. If we save the extent in bits, we
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// cannot represent values like symbol*8.
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DefinedOrUnknownSVal Size =
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state->getSVal(*(CE->arg_begin()), LCtx).castAs<DefinedOrUnknownSVal>();
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SValBuilder& svalBuilder = C.getSValBuilder();
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DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
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DefinedOrUnknownSVal extentMatchesSizeArg =
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svalBuilder.evalEQ(state, Extent, Size);
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state = state->assume(extentMatchesSizeArg, true);
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assert(state && "The region should not have any previous constraints");
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C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R)));
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return true;
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}
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case Builtin::BI__builtin_object_size: {
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// This must be resolvable at compile time, so we defer to the constant
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// evaluator for a value.
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SVal V = UnknownVal();
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llvm::APSInt Result;
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if (CE->EvaluateAsInt(Result, C.getASTContext(), Expr::SE_NoSideEffects)) {
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// Make sure the result has the correct type.
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SValBuilder &SVB = C.getSValBuilder();
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BasicValueFactory &BVF = SVB.getBasicValueFactory();
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BVF.getAPSIntType(CE->getType()).apply(Result);
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V = SVB.makeIntVal(Result);
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}
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C.addTransition(state->BindExpr(CE, LCtx, V));
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return true;
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}
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}
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}
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void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) {
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mgr.registerChecker<BuiltinFunctionChecker>();
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}
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