[HLSL] error on out of bounds vector accesses (#128952)

Add Sema checking and diagnostics to error on out of bounds vector
accesses
Add tests
Closes #91640

---------

Co-authored-by: Chris B <beanz@abolishcrlf.org>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a6cdbbaf..89932b5 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -14054,6 +14054,23 @@ void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
     << TRange << Op->getSourceRange();
 }
 
+void Sema::CheckVectorAccess(const Expr *BaseExpr, const Expr *IndexExpr) {
+  const auto *VTy = BaseExpr->getType()->getAs<VectorType>();
+  if (!VTy)
+    return;
+
+  Expr::EvalResult Result;
+  if (!IndexExpr->EvaluateAsInt(Result, Context, Expr::SE_AllowSideEffects))
+    return;
+
+  unsigned DiagID = diag::err_vector_index_out_of_range;
+
+  llvm::APSInt index = Result.Val.getInt();
+  if (index.isNegative() || index >= VTy->getNumElements())
+    Diag(BaseExpr->getBeginLoc(), DiagID) << toString(index, 10, true);
+  return;
+}
+
 void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
                             const ArraySubscriptExpr *ASE,
                             bool AllowOnePastEnd, bool IndexNegated) {
@@ -14068,6 +14085,12 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
   const Type *EffectiveType =
       BaseExpr->getType()->getPointeeOrArrayElementType();
   BaseExpr = BaseExpr->IgnoreParenCasts();
+
+  if (BaseExpr->getType()->isVectorType()) {
+    CheckVectorAccess(BaseExpr, IndexExpr);
+    return;
+  }
+
   const ConstantArrayType *ArrayTy =
       Context.getAsConstantArrayType(BaseExpr->getType());