[llvm] 6ac6312 - [LLVM] Only enable `-fno-lifetime-dse` in LTO mode (#131381)

[via llvm-commits]

Author: Joseph Huber
Date: 2025-03-14T15:21:39-05:00
New Revision: 6ac63129b7ef3413c9f86b81e9d33a619f94f911

URL: https://github.com/llvm/llvm-project/commit/6ac63129b7ef3413c9f86b81e9d33a619f94f911
DIFF: https://github.com/llvm/llvm-project/commit/6ac63129b7ef3413c9f86b81e9d33a619f94f911.diff

LOG: [LLVM] Only enable `-fno-lifetime-dse` in LTO mode (#131381)

Summary:
Always passing this option is problematic since it is not supported by
`clang.` this leads to conflicts when using extra CMake tools like
`compile-commands` or `include-what-you-use`. This mainly works around a
bug that showed up during the LTO build. Theoretically this can show up
without LTO, but it's likely to work.

This can be removed once
https://github.com/llvm/llvm-project/issues/24952 is resolved.

Added: 
    

Modified: 
    llvm/cmake/modules/HandleLLVMOptions.cmake

Removed: 
    


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diff  --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 5db06ccdadbeb..7319bb6b6a5e5 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -688,7 +688,7 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   append("-Werror=unguarded-availability-new" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 
-if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND LLVM_ENABLE_LTO)
   # LLVM data structures like llvm::User and llvm::MDNode rely on
   # the value of object storage persisting beyond the lifetime of the
   # object (#24952).  This is not standard compliant and causes a runtime