Remove assertion on analysis of rvalue vector

[FlameTop]

Summary

ExprEngine::VisitLvalArraySubscriptExpr contains an assert to ensure it is passed either a GLvalue or a small number of C exemptions. This change adds vector types to the assert as these also can be rvalues.

A provided test ensures the assertion no longer fires for vector rvalues.

[zaks.anna]

Thank you! The assert definitely needs to be relaxed.

Would be great to add test cases that check if the analyzer models the vector types correctly, not just that we do not crash. (Not a blocker, but would be very useful.)

llvm/tools/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp

void ExprEngine::VisitLvalArraySubscriptExpr(const ArraySubscriptExpr *A,
   const Expr *Base = A->getBase()->IgnoreParens();
   const Expr *Idx  = A->getIdx()->IgnoreParens();
 
   ExplodedNodeSet checkerPreStmt;
   getCheckerManager().runCheckersForPreStmt(checkerPreStmt, Pred, A, *this);
 
   StmtNodeBuilder Bldr(checkerPreStmt, Dst, *currBldrCtx);
   assert(A->isGLValue() ||
-          (!AMgr.getLangOpts().CPlusPlus &&
+         A->getBase()->getType()->isVectorType() ||
            A->getType().isCForbiddenLValueType()));
 
   for (ExplodedNodeSet::iterator it = checkerPreStmt.begin(),
                                  ei = checkerPreStmt.end(); it != ei; ++it) {
     const LocationContext *LCtx = (*it)->getLocationContext();
     ProgramStateRef state = (*it)->getState();
     SVal V = state->getLValue(A->getType(),
                               state->getSVal(Idx, LCtx),

llvm/tools/clang/test/Analysis/crash-vector-rvalue.c

+// RUN: %clang_cc1 -analyze -analyzer-checker=core -verify %s
+typedef int vec __attribute__((__vector_size__(4)));;
+vec bar();
+int foo() {
+  int op = bar()[2];
+  return op;
+}