Split libAnalysis into two libraries: libAnalysis and libChecker.

(1) libAnalysis is a generic analysis library that can be used by
    Sema.  It defines the CFG, basic dataflow analysis primitives, and
    inexpensive flow-sensitive analyses (e.g. LiveVariables).

(2) libChecker contains the guts of the static analyzer, incuding the
    path-sensitive analysis engine and domain-specific checks.

Now any clients that want to use the frontend to build their own tools
don't need to link in the entire static analyzer.

This change exposes various obvious cleanups that can be made to the
layout of files and headers in libChecker.  More changes pending.  :)

This change also exposed a layering violation between AnalysisContext
and MemRegion.  BlockInvocationContext shouldn't explicitly know about
BlockDataRegions.  For now I've removed the BlockDataRegion* from
BlockInvocationContext (removing context-sensitivity; although this
wasn't used yet).  We need to have a better way to extend
BlockInvocationContext (and any LocationContext) to add
context-sensitivty.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94406 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 164 insertions, 0 deletions

diff --git a/lib/Checker/Environment.cpp b/lib/Checker/Environment.cpp
new file mode 100644
index 0000000000..c2c9190fc9
--- /dev/null
+++ b/lib/Checker/Environment.cpp
@@ -0,0 +1,164 @@
+//== Environment.cpp - Map from Stmt* to Locations/Values -------*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defined the Environment and EnvironmentManager classes.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Checker/PathSensitive/GRState.h"
+#include "clang/Analysis/Analyses/LiveVariables.h"
+#include "llvm/ADT/ImmutableMap.h"
+
+using namespace clang;
+
+SVal Environment::GetSVal(const Stmt *E, ValueManager& ValMgr) const {
+
+  for (;;) {
+
+    switch (E->getStmtClass()) {
+
+      case Stmt::AddrLabelExprClass:
+        return ValMgr.makeLoc(cast<AddrLabelExpr>(E));
+
+        // ParenExprs are no-ops.
+
+      case Stmt::ParenExprClass:
+        E = cast<ParenExpr>(E)->getSubExpr();
+        continue;
+
+      case Stmt::CharacterLiteralClass: {
+        const CharacterLiteral* C = cast<CharacterLiteral>(E);
+        return ValMgr.makeIntVal(C->getValue(), C->getType());
+      }
+
+      case Stmt::IntegerLiteralClass: {
+        // In C++, this expression may have been bound to a temporary object.
+        SVal const *X = ExprBindings.lookup(E);
+        if (X)
+          return *X;
+        else
+          return ValMgr.makeIntVal(cast<IntegerLiteral>(E));
+      }
+
+      // Casts where the source and target type are the same
+      // are no-ops.  We blast through these to get the descendant
+      // subexpression that has a value.
+
+      case Stmt::ImplicitCastExprClass:
+      case Stmt::CStyleCastExprClass: {
+        const CastExpr* C = cast<CastExpr>(E);
+        QualType CT = C->getType();
+
+        if (CT->isVoidType())
+          return UnknownVal();
+
+        break;
+      }
+
+        // Handle all other Stmt* using a lookup.
+
+      default:
+        break;
+    };
+
+    break;
+  }
+
+  return LookupExpr(E);
+}
+
+Environment EnvironmentManager::BindExpr(Environment Env, const Stmt *S,
+                                         SVal V, bool Invalidate) {
+  assert(S);
+
+  if (V.isUnknown()) {
+    if (Invalidate)
+      return Environment(F.Remove(Env.ExprBindings, S), Env.ACtx);
+    else
+      return Env;
+  }
+
+  return Environment(F.Add(Env.ExprBindings, S, V), Env.ACtx);
+}
+
+namespace {
+class MarkLiveCallback : public SymbolVisitor {
+  SymbolReaper &SymReaper;
+public:
+  MarkLiveCallback(SymbolReaper &symreaper) : SymReaper(symreaper) {}
+  bool VisitSymbol(SymbolRef sym) { SymReaper.markLive(sym); return true; }
+};
+} // end anonymous namespace
+
+// RemoveDeadBindings:
+//  - Remove subexpression bindings.
+//  - Remove dead block expression bindings.
+//  - Keep live block expression bindings:
+//   - Mark their reachable symbols live in SymbolReaper,
+//     see ScanReachableSymbols.
+//   - Mark the region in DRoots if the binding is a loc::MemRegionVal.
+
+Environment
+EnvironmentManager::RemoveDeadBindings(Environment Env, const Stmt *S,
+                                       SymbolReaper &SymReaper,
+                                       const GRState *ST,
+                              llvm::SmallVectorImpl<const MemRegion*> &DRoots) {
+
+  CFG &C = *Env.getAnalysisContext().getCFG();
+
+  // We construct a new Environment object entirely, as this is cheaper than
+  // individually removing all the subexpression bindings (which will greatly
+  // outnumber block-level expression bindings).
+  Environment NewEnv = getInitialEnvironment(&Env.getAnalysisContext());
+
+  // Iterate over the block-expr bindings.
+  for (Environment::iterator I = Env.begin(), E = Env.end();
+       I != E; ++I) {
+
+    const Stmt *BlkExpr = I.getKey();
+
+    // Not a block-level expression?
+    if (!C.isBlkExpr(BlkExpr))
+      continue;
+
+    const SVal &X = I.getData();
+
+    if (SymReaper.isLive(S, BlkExpr)) {
+      // Copy the binding to the new map.
+      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);
+
+      // If the block expr's value is a memory region, then mark that region.
+      if (isa<loc::MemRegionVal>(X)) {
+        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
+        DRoots.push_back(R);
+        // Mark the super region of the RX as live.
+        // e.g.: int x; char *y = (char*) &x; if (*y) ...
+        // 'y' => element region. 'x' is its super region.
+        // We only add one level super region for now.
+
+        // FIXME: maybe multiple level of super regions should be added.
+        if (const SubRegion *SR = dyn_cast<SubRegion>(R))
+          DRoots.push_back(SR->getSuperRegion());
+      }
+
+      // Mark all symbols in the block expr's value live.
+      MarkLiveCallback cb(SymReaper);
+      ST->scanReachableSymbols(X, cb);
+      continue;
+    }
+
+    // Otherwise the expression is dead with a couple exceptions.
+    // Do not misclean LogicalExpr or ConditionalOperator.  It is dead at the
+    // beginning of itself, but we need its UndefinedVal to determine its
+    // SVal.
+    if (X.isUndef() && cast<UndefinedVal>(X).getData())
+      NewEnv.ExprBindings = F.Add(NewEnv.ExprBindings, BlkExpr, X);
+  }
+
+  return NewEnv;
+}