[analyzer][Solver] Early return if sym is concrete on assuming (#115579)

This could deduce some complex syms derived from simple ones whose
values could be constrainted to be concrete during execution, thus
reducing some overconstrainted states.

This commit also fix `unix.StdCLibraryFunctions` crash due to these
overconstrainted states being added to the graph, which is marked as
sink node (PosteriorlyOverconstrained). The 'assume' API is used in
non-dual style so the checker should protectively test whether these
newly added nodes are actually impossible.

1. The crash: https://godbolt.org/z/8KKWeKb86
2. The solver needs to solve equivalent: https://godbolt.org/z/ed8WqsbTh

3 files changed, 11 insertions, 2 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 4f30b2a..5faaf9c 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -1354,6 +1354,8 @@ void StdLibraryFunctionsChecker::checkPreCall(const CallEvent &Call,
             if (BR.isInteresting(ArgSVal))
               OS << Msg;
           }));
+      if (NewNode->isSink())
+        break;
     }
   }
 }
diff --git a/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp
index c0b3f34..2b77167 100644
--- a/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp
@@ -74,7 +74,7 @@ ConstraintManager::assumeDualImpl(ProgramStateRef &State,
       // it might happen that a Checker uncoditionally uses one of them if the
       // other is a nullptr. This may also happen with the non-dual and
       // adjacent `assume(true)` and `assume(false)` calls. By implementing
-      // assume in therms of assumeDual, we can keep our API contract there as
+      // assume in terms of assumeDual, we can keep our API contract there as
       // well.
       return ProgramStatePair(StInfeasible, StInfeasible);
     }
diff --git a/clang/lib/StaticAnalyzer/Core/RangedConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangedConstraintManager.cpp
index 4bbe933..171b4c6 100644
--- a/clang/lib/StaticAnalyzer/Core/RangedConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangedConstraintManager.cpp
@@ -23,7 +23,14 @@ RangedConstraintManager::~RangedConstraintManager() {}
 ProgramStateRef RangedConstraintManager::assumeSym(ProgramStateRef State,
                                                    SymbolRef Sym,
                                                    bool Assumption) {
-  Sym = simplify(State, Sym);
+  SVal SimplifiedVal = simplifyToSVal(State, Sym);
+  if (SimplifiedVal.isConstant()) {
+    bool Feasible = SimplifiedVal.isZeroConstant() != Assumption;
+    return Feasible ? State : nullptr;
+  }
+
+  if (SymbolRef SimplifiedSym = SimplifiedVal.getAsSymbol())
+    Sym = SimplifiedSym;
 
   // Handle SymbolData.
   if (isa<SymbolData>(Sym))