Update Makefile so LTO works on OSX #37356
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The gold linker can only produce ELF binaries, not Mach, so it doesn't work on OSX. This lets link-time optimization work when linking Mach binaries from clang.
ZhilkinSerg
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This was referenced Jan 26, 2020
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Summary
SUMMARY: Build "Update Makefile so LTO works on OSX"Purpose of change
Using the LTO flag on OSX would previously break the build (linking) process. The gold linker can only produce ELF binaries, not Mach, so it doesn't work on OSX. This minor tweak lets link-time optimization work when linking Mach binaries from clang.
I also added a commented-out line to let people easily build custom binaries for their hardware by uncommenting it:
# OTHERS += -march=native # Uncomment this to build an optimized binary for your machine onlyDescribe the solution
This uses
-flto=fullto use clang LTO instead of trying to use the gold linker via-fuse-ld=gold, thus enabling LTO on OSX.Describe alternatives you've considered
I considering consolidating the
ifdef LTOconditionals but I can see why someone would in principlewant to separate out the OPTLEVEL and LTOFLAGS stages.
Testing
I built it on OSX and it works.
Additional context
Current OSX binaries are basically unoptimized, because optimizations apparently break compatibility with OSX 10.11 and older versions. If we dropped compatibility for those old versions of OSX then user-facing performance would significantly increase.