[Clang][Interp] Diagnose use sizeless vector type as the argument of __builtin_vectorelements

[yronglin]

This PR implement an opcode to diagnose use sizeless vector type as the argument of __builtin_vectorelements.

[llvmbot]

@llvm/pr-subscribers-clang

Author: None (yronglin)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/99794.diff

4 Files Affected:

• (modified) clang/lib/AST/Interp/Compiler.cpp (+2-4)
• (modified) clang/lib/AST/Interp/Interp.h (+8)
• (modified) clang/lib/AST/Interp/Opcodes.td (+2)
• (modified) clang/test/SemaCXX/builtin_vectorelements.cpp (+1)

diff --git a/clang/lib/AST/Interp/Compiler.cpp b/clang/lib/AST/Interp/Compiler.cpp
index ef579bc5d8972..aeefaf89cfc4b 100644
--- a/clang/lib/AST/Interp/Compiler.cpp
+++ b/clang/lib/AST/Interp/Compiler.cpp
@@ -1698,10 +1698,8 @@ bool Compiler<Emitter>::VisitUnaryExprOrTypeTraitExpr(
   if (Kind == UETT_VectorElements) {
     if (const auto *VT = E->getTypeOfArgument()->getAs<VectorType>())
       return this->emitConst(VT->getNumElements(), E);
-
-    // FIXME: Apparently we need to catch the fact that a sizeless vector type
-    // has been passed and diagnose that (at run time).
-    assert(E->getTypeOfArgument()->isSizelessVectorType());
+    if (E->getTypeOfArgument()->isSizelessVectorType())
+      return this->emitSizelessVectorElementSize(E);
   }
 
   if (Kind == UETT_VecStep) {
diff --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
index f86b787fb034e..be224a7b0dfd0 100644
--- a/clang/lib/AST/Interp/Interp.h
+++ b/clang/lib/AST/Interp/Interp.h
@@ -29,6 +29,7 @@
 #include "State.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Expr.h"
+#include "clang/Basic/DiagnosticSema.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APSInt.h"
 #include <type_traits>
@@ -870,6 +871,13 @@ bool Comp(InterpState &S, CodePtr OpPC) {
   return false;
 }
 
+inline bool SizelessVectorElementSize(InterpState &S, CodePtr OpPC) {
+  const SourceRange &ArgRange = S.Current->getRange(OpPC);
+  const Expr *E = S.Current->getExpr(OpPC);
+  S.FFDiag(E, diag::note_constexpr_non_const_vectorelements) << ArgRange;
+  return false;
+}
+
 //===----------------------------------------------------------------------===//
 // EQ, NE, GT, GE, LT, LE
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/Interp/Opcodes.td b/clang/lib/AST/Interp/Opcodes.td
index 49ebb156ab2fb..9f29fa9272711 100644
--- a/clang/lib/AST/Interp/Opcodes.td
+++ b/clang/lib/AST/Interp/Opcodes.td
@@ -733,6 +733,8 @@ def InvalidDeclRef : Opcode {
   let Args = [ArgDeclRef];
 }
 
+def SizelessVectorElementSize : Opcode;
+
 def Assume : Opcode;
 
 def ArrayDecay : Opcode;
diff --git a/clang/test/SemaCXX/builtin_vectorelements.cpp b/clang/test/SemaCXX/builtin_vectorelements.cpp
index 59ff09ac72e42..197ab2fd9625e 100644
--- a/clang/test/SemaCXX/builtin_vectorelements.cpp
+++ b/clang/test/SemaCXX/builtin_vectorelements.cpp
@@ -2,6 +2,7 @@
 
 // REQUIRES: aarch64-registered-target
 // RUN: %clang_cc1 -triple aarch64 -target-feature +sve -std=c++20 -fsyntax-only -verify -disable-llvm-passes %s
+// RUN: %clang_cc1 -triple aarch64 -target-feature +sve -std=c++20 -fsyntax-only -verify -disable-llvm-passes -fexperimental-new-constant-interpreter %s
 
 template <typename T>
 using VecT __attribute__((vector_size(16))) = T;

[tbaederr]

LGTM, thanks!