From 4afc10ef28d9df8b212dbeb28d0ea4dab6519699 Mon Sep 17 00:00:00 2001
From: Matevz Kovacic <117923752+matevz-kovacic@users.noreply.github.com>
Date: Thu, 6 Aug 2026 08:49:52 +0200
Subject: [PATCH] compiler: honour LIKELY/UNLIKELY under clang-cl

Same __GNUC__ gate as TARGET_ATTRIBUTE. clang-cl supports
__builtin_expect, so test for it with __has_builtin and keep __GNUC__
as a fallback. Without this, every branch hint in the library is
discarded under clang-cl.
---
 lib/common/compiler.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/common/compiler.h b/lib/common/compiler.h
index 135149599..2cb8b1615 100644
--- a/lib/common/compiler.h
+++ b/lib/common/compiler.h
@@ -201,7 +201,16 @@
  * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
  * and clang, please do.
  */
-#if defined(__GNUC__)
+#if defined(__has_builtin)
+#  if __has_builtin(__builtin_expect)
+#    define ZSTD_HAS_BUILTIN_EXPECT 1
+#  endif
+#endif
+#if !defined(ZSTD_HAS_BUILTIN_EXPECT) && defined(__GNUC__)
+#  define ZSTD_HAS_BUILTIN_EXPECT 1
+#endif
+
+#if defined(ZSTD_HAS_BUILTIN_EXPECT)
 #define LIKELY(x) (__builtin_expect((x), 1))
 #define UNLIKELY(x) (__builtin_expect((x), 0))
 #else