[clang] [clang][bytecode] Implement __noop (PR #106714)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/106714

This does nothing and returns 0.

>From 45d97a71f5e76091234d0d919db4cb605d2d1949 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Fri, 30 Aug 2024 13:45:37 +0200
Subject: [PATCH] [clang][bytecode] Implement __noop

This does nothing and returns 0.
---
 clang/lib/AST/ByteCode/InterpBuiltin.cpp | 4 ++++
 clang/test/AST/ByteCode/ms.cpp           | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 1a71bff25d2540..81e49f203524b7 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -1593,6 +1593,10 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
       return false;
     break;
 
+  case Builtin::BI__noop:
+    pushInteger(S, 0, Call->getType());
+    break;
+
   default:
     S.FFDiag(S.Current->getLocation(OpPC),
              diag::note_invalid_subexpr_in_const_expr)
diff --git a/clang/test/AST/ByteCode/ms.cpp b/clang/test/AST/ByteCode/ms.cpp
index fe5ed219946e76..816f61fec37747 100644
--- a/clang/test/AST/ByteCode/ms.cpp
+++ b/clang/test/AST/ByteCode/ms.cpp
@@ -8,3 +8,5 @@
 static_assert(_rotl(0x01, 5) == 32);
 
 static_assert(alignof(__unaligned int) == 1, "");
+
+static_assert(__noop() == 0, "");