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

This caused false-positive errors, see comment on the PR.

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

This reverts commit f1e3675.

Author: zmodem

clang/docs/ReleaseNotes.rst

@@ -236,8 +236,6 @@ Improvements to Clang's diagnostics
   under the subgroup ``-Wunsafe-buffer-usage-in-libc-call``.
 - Diagnostics on chained comparisons (``a < b < c``) are now an error by default. This can be disabled with
   ``-Wno-error=parentheses``.
-- Adds an error diagnostic for out of bounds vector accesses; produces an error
-  for compile time statically provable out of bounds vector accesses.
 - The ``-Wshift-bool`` warning has been added to warn about shifting a boolean. (#GH28334)
 - Fixed diagnostics adding a trailing ``::`` when printing some source code
   constructs, like base classes.

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10688,9 +10688,6 @@ def err_block_on_vm : Error<
 def err_sizeless_nonlocal : Error<
   "non-local variable with sizeless type %0">;
 
-def err_vector_index_out_of_range : Error<
-  "vector element index %0 is out of bounds">;
-
 def err_vec_builtin_non_vector : Error<
  "%select{first two|all}1 arguments to %0 must be vectors">;
 def err_vec_builtin_incompatible_vector : Error<

clang/include/clang/Sema/Sema.h

@@ -2468,7 +2468,6 @@ class Sema final : public SemaBase {
                         const ArraySubscriptExpr *ASE = nullptr,
                         bool AllowOnePastEnd = true, bool IndexNegated = false);
   void CheckArrayAccess(const Expr *E);
-  void CheckVectorAccess(const Expr *BaseExpr, const Expr *IndexExpr);
 
   bool CheckPointerCall(NamedDecl *NDecl, CallExpr *TheCall,
                         const FunctionProtoType *Proto);

clang/lib/Sema/SemaChecking.cpp

@@ -14055,23 +14055,6 @@ 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) {
@@ -14086,12 +14069,6 @@ 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());
 

clang/test/CodeGenCXX/x86_64-arguments.cpp

@@ -215,6 +215,6 @@ union U {
   float f1;
   char __attribute__((__vector_size__(1))) f2;
 };
-int f(union U u) { return u.f2[0]; }
+int f(union U u) { return u.f2[1]; }
 // CHECK-LABEL: define{{.*}} i32 @_ZN6test111fENS_1UE(i32
 }