[analyzer] [PointerArithChecker] do not warn on indexes into vector types

rdar://35041502

Differential Revision: https://reviews.llvm.org/D44172

llvm-svn: 326952

clang/lib/StaticAnalyzer/Checkers/PointerArithChecker.cpp

@@ -308,6 +308,10 @@ void PointerArithChecker::checkPreStmt(const ArraySubscriptExpr *SubsExpr,
   // Indexing with 0 is OK.
   if (Idx.isZeroConstant())
     return;
+
+  // Indexing vector-type expressions is also OK.
+  if (SubsExpr->getBase()->getType()->isVectorType())
+    return;
   reportPointerArithMisuse(SubsExpr->getBase(), C);
 }
 

clang/test/Analysis/ptr-arith.c

@@ -347,3 +347,9 @@ void test_no_crash_on_pointer_to_label() {
   a[0] = 0;
 label:;
 }
+
+typedef __attribute__((__ext_vector_type__(2))) float simd_float2;
+float test_nowarning_on_vector_deref() {
+  simd_float2 x = {0, 1};
+  return x[1]; // no-warning
+}