[clang][bytecode] Implement __builtin_arithmetic_fence (llvm#113937)

Author: tbaederr

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -1670,6 +1670,15 @@ static bool interp__builtin_operator_delete(InterpState &S, CodePtr OpPC,
       S, OpPC, *AllocForm, DynamicAllocator::Form::Operator, BlockDesc, Source);
 }
 
+static bool interp__builtin_arithmetic_fence(InterpState &S, CodePtr OpPC,
+                                             const InterpFrame *Frame,
+                                             const Function *Func,
+                                             const CallExpr *Call) {
+  const Floating &Arg0 = S.Stk.peek<Floating>();
+  S.Stk.push<Floating>(Arg0);
+  return true;
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
                       const CallExpr *Call, uint32_t BuiltinID) {
   const InterpFrame *Frame = S.Current;
@@ -2111,6 +2120,11 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
       return false;
     break;
 
+  case Builtin::BI__arithmetic_fence:
+    if (!interp__builtin_arithmetic_fence(S, OpPC, Frame, F, Call))
+      return false;
+    break;
+
   default:
     S.FFDiag(S.Current->getLocation(OpPC),
              diag::note_invalid_subexpr_in_const_expr)

clang/test/Sema/arithmetic-fence-builtin.c

@@ -1,8 +1,13 @@
 // RUN: %clang_cc1 -triple i386-pc-linux-gnu -emit-llvm -o - -verify -x c++ %s
+// RUN: %clang_cc1 -triple i386-pc-linux-gnu -emit-llvm -o - -verify -x c++ %s -fexperimental-new-constant-interpreter
 // RUN: %clang_cc1 -triple ppc64le -DPPC     -emit-llvm -o - -verify -x c++ %s
+// RUN: %clang_cc1 -triple ppc64le -DPPC     -emit-llvm -o - -verify -x c++ %s -fexperimental-new-constant-interpreter
 // RUN: not %clang_cc1 -triple ppc64le -DPPC     -emit-llvm -o - -x c++ %s \
 // RUN:            -fprotect-parens 2>&1 | FileCheck -check-prefix=PPC %s
+// RUN: not %clang_cc1 -triple ppc64le -DPPC     -emit-llvm -o - -x c++ %s -fexperimental-new-constant-interpreter \
+// RUN:            -fprotect-parens 2>&1 | FileCheck -check-prefix=PPC %s
 // RUN: %clang_cc1 -triple spir64 -emit-llvm -o - -verify -x c++ %s
+// RUN: %clang_cc1 -triple spir64 -emit-llvm -o - -verify -x c++ %s -fexperimental-new-constant-interpreter
 #ifndef PPC
 int v;
 template <typename T> T addT(T a, T b) {