[llvm] Reland "[APFloat] Add exp functions for single and double using exp/expf implementations from LLVM libc." (#197440) (PR #199570)

[via llvm-commits]

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@@ -399,7 +399,12 @@ endif()
 target_include_directories(LLVMSupport
   PRIVATE
   ${LLVM_THIRD_PARTY_DIR}/siphash/include
+  ${LLVM_SOURCE_DIR}/../libc
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lntue wrote:

It's set from here I guess: https://github.com/llvm/llvm-project/blob/main/llvm/cmake/modules/AddLLVM.cmake#L2058

https://github.com/llvm/llvm-project/pull/199570