On Tue, Nov 21, 2017 at 11:01:52AM +1000, Nicholas Piggin wrote: > I just wonder are you doing this because there is some worthwhile > performance gain? Or to enable more testing and development of LTO? > Any clues for why a user would want to enable it.
I'm primarily interested in CFI, which with clang requires LTO; not for the optimizations, but for source visibility. We do expect to see performance improvements with LTO though, especially if combined with PGO. > Thanks, if you could. Possibly file a request with LLVMgold too, it > seems to be that toolchain support for archives is quite strong, so it > will be good to keep pushing for that. It turns out LLVMgold is fine with mixed IR/object archives, but we need to use llvm-ar to generate symbol tables for them, and there are some compatibility issues with objdump that I had to work around. I'll send v3 for review once I receive some feedback for the clang/gold patches we need first. Sami