Fix relwithdebuginfo in 3.0-branch #5176
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…S_RELWITHDEBINFO for swift and llvm. Turns out -DLLVM_ENABLE_ASSERTIONS does not actually enable assertions in LLVM! What it actually does is rewrite the -DNDEBUG flag to be -UNDEBUG. This means that we always want to pass in -DNDEBUG to swift. There are some complications though. This means that we can not compile the C++ part of the runtime with a different assertions setting than the swift compiler/llvm. This is a trade off that for now we are ok with to get the no-asserts build working. As part of a separate change, we are going to make -DLLVM_ENABLE_ASSERTIONS more robust by doing what swift does now, putting -DNDEBUG or -UNDEBUG after CMake's -DNDEBUG so we get the correct behavior of disabling or enabling assertions. rdar://28485525
This patch resolves some post-commit feedback from @llvmbeanz. Specifically, the only time that we need to hard code these flags are when compiling with RelWithDebInfo since we need extra control in that case to ensure that CMake does not sneak in a -g flag on the command line. This is important to ensure that we are compiling with -gline-tables-only instead of -g. Given that it is a performance fix specific to compiling with LTO with debug info, we should no perform such a change when compiling with: 1. MINRELSIZE since we do not ever perform that build. 2. RELEASE since it does not have debug info. 3. DEBUG since why would one perform an LTO build in DEBUG mode. In terms of 3, I can potentially imagine someone trying to compile Swift in Debug with LTO to try to debug an LTO bug, but I imagine such a test case to be such a rare need that there is no point in trying to make it faster.
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@swift-ci please test |
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LGTM |
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This fixes relwithdebuginfo in the swift-3.0-branch