Add GRState::getSimplifiedSVal(), which provides an API hook for doing symbol -> constant folding. This isn't used yet, but
is prep for some pending optimizations in GRExprEngine.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112929 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Checker/PathSensitive/GRState.h b/include/clang/Checker/PathSensitive/GRState.h
index 984118e..7d99890 100644
--- a/include/clang/Checker/PathSensitive/GRState.h
+++ b/include/clang/Checker/PathSensitive/GRState.h
@@ -257,11 +257,18 @@
const llvm::APSInt *getSymVal(SymbolRef sym) const;
- SVal getSVal(const Stmt* Ex) const;
-
+ /// Returns the SVal bound to the statement 'S' in the state's environment.
+ SVal getSVal(const Stmt* S) const;
+
SVal getSValAsScalarOrLoc(const Stmt *Ex) const;
SVal getSVal(Loc LV, QualType T = QualType()) const;
+
+ /// Returns a "simplified" SVal bound to the location 'LV' in the state's
+ /// store. A simplified SVal will include optimizations such as
+ /// if the SVal is a symbol whose value is perfectly constrained then that
+ /// constant value is returned instead.
+ SVal getSimplifiedSVal(Loc LV, QualType T= QualType()) const;
SVal getSVal(const MemRegion* R) const;
diff --git a/lib/Checker/GRState.cpp b/lib/Checker/GRState.cpp
index 024237c..2a7c6dc 100644
--- a/lib/Checker/GRState.cpp
+++ b/lib/Checker/GRState.cpp
@@ -169,6 +169,42 @@
return UnknownVal();
}
+SVal GRState::getSimplifiedSVal(Loc location, QualType T) const {
+ SVal V = getSVal(cast<Loc>(location), T);
+
+ // If 'V' is a symbolic value that is *perfectly* constrained to
+ // be a constant value, use that value instead to lessen the burden
+ // on later analysis stages (so we have less symbolic values to reason
+ // about).
+ if (!T.isNull()) {
+ if (SymbolRef sym = V.getAsSymbol()) {
+ if (const llvm::APSInt *Int = getSymVal(sym)) {
+ // FIXME: Because we don't correctly model (yet) sign-extension
+ // and truncation of symbolic values, we need to convert
+ // the integer value to the correct signedness and bitwidth.
+ //
+ // This shows up in the following:
+ //
+ // char foo();
+ // unsigned x = foo();
+ // if (x == 54)
+ // ...
+ //
+ // The symbolic value stored to 'x' is actually the conjured
+ // symbol for the call to foo(); the type of that symbol is 'char',
+ // not unsigned.
+ const llvm::APSInt &NewV = getBasicVals().Convert(T, *Int);
+
+ if (isa<Loc>(V))
+ return loc::ConcreteInt(NewV);
+ else
+ return nonloc::ConcreteInt(NewV);
+ }
+ }
+ }
+
+ return V;
+}
const GRState *GRState::BindExpr(const Stmt* Ex, SVal V, bool Invalidate) const{
Environment NewEnv = getStateManager().EnvMgr.BindExpr(Env, Ex, V,