[clang] [test] Add bit < 8 testcase for x86 __builtin_bswapg (PR #180124)

[via cfe-commits]

https://github.com/woruyu created https://github.com/llvm/llvm-project/pull/180124

### Summary
the related PR: https://github.com/llvm/llvm-project/pull/179177, add bits < 8 testcase for __builtin_bswapg

>From 71048d3190c11fbcd18cbde5770fe3674723cf6a Mon Sep 17 00:00:00 2001
From: woruyu <1214539920 at qq.com>
Date: Fri, 6 Feb 2026 13:52:12 +0800
Subject: [PATCH] [test] Add bit < 8 testcase for x86 __builtin_bswapg

---
 clang/test/AST/ByteCode/builtin-functions.cpp | 3 +++
 clang/test/Sema/constant-builtins-2.c         | 2 ++
 clang/test/SemaCXX/builtin-bswapg.cpp         | 2 ++
 3 files changed, 7 insertions(+)

diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp
index 10f7ff294ae00..779bb450084b3 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -851,6 +851,9 @@ namespace bswap {
   int h15 = __builtin_bswapg((_BitInt(24))0x1234) == (_BitInt(24))0x3412 ? 1 : f();
   // expected-error at -1 {{_BitInt type '_BitInt(24)' (24 bits) must be a multiple of 16 bits for byte swapping}}
   // ref-error at -2 {{_BitInt type '_BitInt(24)' (24 bits) must be a multiple of 16 bits for byte swapping}}
+  int h16 = __builtin_bswapg((_BitInt(5))0x1) == (_BitInt(5))0x1 ? 1 : f();
+  // expected-error at -1 {{_BitInt type '_BitInt(5)' (5 bits) must be a multiple of 16 bits for byte swapping}}
+  // ref-error at -2 {{_BitInt type '_BitInt(5)' (5 bits) must be a multiple of 16 bits for byte swapping}}
 #endif
 
   constexpr const int const_expr = 0x1234;
diff --git a/clang/test/Sema/constant-builtins-2.c b/clang/test/Sema/constant-builtins-2.c
index e875863e7fa91..3c437fcbe5e0d 100644
--- a/clang/test/Sema/constant-builtins-2.c
+++ b/clang/test/Sema/constant-builtins-2.c
@@ -502,6 +502,8 @@ int h21 = __builtin_bswapg((_BitInt(64))0x0000000000001234) == (_BitInt(64))0x34
 int h22 = __builtin_bswapg(~(_BitInt(128))0) == (~(_BitInt(128))0) ? 1 : f();
 int h23 = __builtin_bswapg((_BitInt(24))0x1234) == (_BitInt(24))0x3412 ? 1 : f();
 // expected-error at -1 {{_BitInt type '_BitInt(24)' (24 bits) must be a multiple of 16 bits for byte swapping}}
+int h24 = __builtin_bswapg((_BitInt(3))0x3) == (_BitInt(3))0x3 ? 1 : f();
+// expected-error at -1 {{_BitInt type '_BitInt(3)' (3 bits) must be a multiple of 16 bits for byte swapping}}
 extern long int bi0;
 extern __typeof__(__builtin_expect(0, 0)) bi0;
 
diff --git a/clang/test/SemaCXX/builtin-bswapg.cpp b/clang/test/SemaCXX/builtin-bswapg.cpp
index 815cc0085f89e..88c387d5c4004 100644
--- a/clang/test/SemaCXX/builtin-bswapg.cpp
+++ b/clang/test/SemaCXX/builtin-bswapg.cpp
@@ -228,4 +228,6 @@ void test_bitint() {
   static_assert(__builtin_bswapg(~(_BitInt(128))0) == (~(_BitInt(128))0), "");
   static_assert(__builtin_bswapg((_BitInt(24))0x1234) == (_BitInt(24))0x3412, "");
   // expected-error at -1 {{_BitInt type '_BitInt(24)' (24 bits) must be a multiple of 16 bits for byte swapping}}
+  static_assert(__builtin_bswapg((_BitInt(4))0x7) == (_BitInt(4))0x7, "");
+  // expected-error at -1 {{_BitInt type '_BitInt(4)' (4 bits) must be a multiple of 16 bits for byte swapping}}
 }