[compiler-rt] [llvm] [LLVM][compiler-rt] Fix build with LLVM_USE_SANITIZER=Undefined (PR #120006)

[Vitaly Buka via llvm-commits]

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@@ -707,8 +709,17 @@ endif( LLVM_USE_PERF )
 set(LLVM_USE_SANITIZER "" CACHE STRING
   "Define the sanitizer used to build binaries and tests.")
 option(LLVM_OPTIMIZE_SANITIZED_BUILDS "Pass -O1 on debug sanitizer builds" ON)
+
+check_c_compiler_flag(-fno-sanitize=function C_SUPPORTS_FNO_SANITIZE_FUNCTION_FLAG)
+check_cxx_compiler_flag(-fno-sanitize=function CXX_SUPPORTS_FNO_SANITIZE_FUNCTION_FLAG)
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vitalybuka wrote:

changes in llvm/ caused by unsupported flags
can you please extract them into a separate PR?

https://github.com/llvm/llvm-project/pull/120006