[llvm] [llvm] Disable HandleLLVMOptions in runtimes mode (PR #73031)

[Petr Hosek via llvm-commits]

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@@ -151,6 +151,9 @@ endif()
 # Avoid checking whether the compiler is working.
 set(LLVM_COMPILER_CHECKED ON)
 
+# This can be used to detect whether we're in the runtimes build.
+set(LLVM_RUNTIMES_BUILD ON)
+
 # Handle common options used by all runtimes.
 include(AddLLVM)
 include(HandleLLVMOptions)
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petrhosek wrote:

That depends whether we just want to do the minimal thing now and clean up later or whether we want to try and do both at the same time. For example, I'd like to leverage native CMake option where possible, so instead of manually adding `-fPIC` to compiler flags, we should set `POSITION_INDEPENDENT_CODE` property on targets that actually need it. Feel free to make only the necessary minimum of changes you need and leave a `TODO`; we can follow up with more clean up changes later.

https://github.com/llvm/llvm-project/pull/73031