[clang] 76cf895 - Revert "[HLSL] error on out of bounds vector accesses (#128952)"

[Hans Wennborg via cfe-commits]

Author: Hans Wennborg
Date: 2025-03-12T12:31:37+01:00
New Revision: 76cf895717e9eba4d2a158d5bc3e48f2f7794181

URL: https://github.com/llvm/llvm-project/commit/76cf895717e9eba4d2a158d5bc3e48f2f7794181
DIFF: https://github.com/llvm/llvm-project/commit/76cf895717e9eba4d2a158d5bc3e48f2f7794181.diff

LOG: 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 f1e36759d2e6c26d2d5825f955c51fd595909b52.

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/include/clang/Basic/DiagnosticSemaKinds.td
    clang/include/clang/Sema/Sema.h
    clang/lib/Sema/SemaChecking.cpp
    clang/test/CodeGenCXX/x86_64-arguments.cpp

Removed: 
    clang/test/SemaHLSL/Language/VectorOutOfRange-errors.hlsl


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c89ea878905c0..f6e4d6a34e5dc 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/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.

diff  --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 4bdbb797c2b86..8e6e6e892cdd7 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/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<

diff  --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index c034de0e633da..9ac26d8728446 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/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);

diff  --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 3a24bcf1c7094..9bcb014ab9bfc 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/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());
 

diff  --git a/clang/test/CodeGenCXX/x86_64-arguments.cpp b/clang/test/CodeGenCXX/x86_64-arguments.cpp
index 6915e5d6761dd..ebeba7fd65495 100644
--- a/clang/test/CodeGenCXX/x86_64-arguments.cpp
+++ b/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
 }

diff  --git a/clang/test/SemaHLSL/Language/VectorOutOfRange-errors.hlsl b/clang/test/SemaHLSL/Language/VectorOutOfRange-errors.hlsl
deleted file mode 100644
index b4d423fb24bd2..0000000000000
--- a/clang/test/SemaHLSL/Language/VectorOutOfRange-errors.hlsl
+++ /dev/null
@@ -1,19 +0,0 @@
-// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -verify
-
-export void fn1() {
-  int2 A = {1,2};
-  int X = A[-1];
-  // expected-error at -1 {{vector element index -1 is out of bounds}}
-}
-
-export void fn2() {
-  int4 A = {1,2,3,4};
-  int X = A[4];
-  // expected-error at -1 {{vector element index 4 is out of bounds}}
-}
-
-export void fn3() {
-  bool2 A = {true,true};
-  bool X = A[-1];
-  // expected-error at -1 {{vector element index -1 is out of bounds}}
-}