llvm-project/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp

69 lines
2.7 KiB
C++

//===--- LoopWidening.cpp - Widen loops -------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// This file contains functions which are used to widen loops. A loop may be
/// widened to approximate the exit state(s), without analyzing every
/// iteration. The widening is done by invalidating anything which might be
/// modified by the body of the loop.
///
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/LoopWidening.h"
using namespace clang;
using namespace ento;
/// Return the loops condition Stmt or NULL if LoopStmt is not a loop
static const Expr *getLoopCondition(const Stmt *LoopStmt) {
switch (LoopStmt->getStmtClass()) {
default:
return nullptr;
case Stmt::ForStmtClass:
return cast<ForStmt>(LoopStmt)->getCond();
case Stmt::WhileStmtClass:
return cast<WhileStmt>(LoopStmt)->getCond();
case Stmt::DoStmtClass:
return cast<DoStmt>(LoopStmt)->getCond();
}
}
namespace clang {
namespace ento {
ProgramStateRef getWidenedLoopState(ProgramStateRef PrevState,
const LocationContext *LCtx,
unsigned BlockCount, const Stmt *LoopStmt) {
assert(isa<ForStmt>(LoopStmt) || isa<WhileStmt>(LoopStmt) ||
isa<DoStmt>(LoopStmt));
// Invalidate values in the current state.
// TODO Make this more conservative by only invalidating values that might
// be modified by the body of the loop.
// TODO Nested loops are currently widened as a result of the invalidation
// being so inprecise. When the invalidation is improved, the handling
// of nested loops will also need to be improved.
const StackFrameContext *STC = LCtx->getCurrentStackFrame();
MemRegionManager &MRMgr = PrevState->getStateManager().getRegionManager();
const MemRegion *Regions[] = {MRMgr.getStackLocalsRegion(STC),
MRMgr.getStackArgumentsRegion(STC),
MRMgr.getGlobalsRegion()};
RegionAndSymbolInvalidationTraits ITraits;
for (auto *Region : Regions) {
ITraits.setTrait(Region,
RegionAndSymbolInvalidationTraits::TK_EntireMemSpace);
}
return PrevState->invalidateRegions(Regions, getLoopCondition(LoopStmt),
BlockCount, LCtx, true, nullptr, nullptr,
&ITraits);
}
} // end namespace ento
} // end namespace clang