[compiler-rt] [compiler-rt][builtins] Add missing flag for builtins standalone build (PR #133046)

[Wu Yingcong via llvm-commits]

https://github.com/yingcong-wu created https://github.com/llvm/llvm-project/pull/133046

When builtins are built with runtimes, it is built before compiler-rt, and this makes some of the HAS_XXX_FLAGs missing. In this case, the COMPILER_RT_HAS_FCF_PROTECTION_FLAG is missing which makes it impossible to enable CET in this case. This patch addresses this issue by also check for such flag in standalone build instead of relying on the compiler-rt's detection.

>From 16d4e047c61de10e50c8a70f6cc43d79c012373c Mon Sep 17 00:00:00 2001
From: "Wu, Yingcong" <yingcong.wu at intel.com>
Date: Wed, 26 Mar 2025 14:51:56 +0800
Subject: [PATCH] add missing flag

---
 compiler-rt/cmake/builtin-config-ix.cmake | 1 +
 1 file changed, 1 insertion(+)

diff --git a/compiler-rt/cmake/builtin-config-ix.cmake b/compiler-rt/cmake/builtin-config-ix.cmake
index b1bde47ec8555..7bd3269bd999d 100644
--- a/compiler-rt/cmake/builtin-config-ix.cmake
+++ b/compiler-rt/cmake/builtin-config-ix.cmake
@@ -25,6 +25,7 @@ builtin_check_c_compiler_flag(-fconvergent-functions COMPILER_RT_HAS_FCONVERGENT
 builtin_check_c_compiler_flag("-Xclang -mcode-object-version=none" COMPILER_RT_HAS_CODE_OBJECT_VERSION_FLAG)
 builtin_check_c_compiler_flag(-Wbuiltin-declaration-mismatch COMPILER_RT_HAS_WBUILTIN_DECLARATION_MISMATCH_FLAG)
 builtin_check_c_compiler_flag(/Zl COMPILER_RT_HAS_ZL_FLAG)
+builtin_check_c_compiler_flag(-fcf-protection=full COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
 
 builtin_check_c_compiler_source(COMPILER_RT_HAS_ATOMIC_KEYWORD
 "