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The pass used to be enabled by default with CodeGenOpt::Less (-O1). This is too aggressive, considering the pass indiscriminately merges all globals together. Currently, performance doesn't always improve, and, on code that uses few globals (e.g., the odd file- or function- static), more often than not is degraded by the optimization. Lengthy discussion can be found on llvmdev (AArch64-focused; ARM has similar problems): http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-February/082800.html Also, it makes tooling and debuggers less useful when dealing with globals and data sections. GlobalMerge needs to better identify those cases that benefit, and this will be done separately. In the meantime, move the pass to run with -O3 rather than -O1, on both ARM and AArch64. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233024 91177308-0d34-0410-b5e6-96231b3b80d8
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