> On May 16, 2016, at 6:52 AM, Rafael Espíndola <rafael.espind...@gmail.com> > wrote: > > + auto Used = collectUsedGlobalVariables(*M, UsedGlobals, true); > > Please use an explicit type instead of auto.
Sure. > > You deleted the assert Are you referring to the assertion that llvm.embedded.module has no uses. I added it back to check it has exactly one use. Attach the final patch with testcase. Steven
0001-Change-embed-bitcode-linkage-type.patch
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> > I think this is fine otherwise. > > Cheers, > Rafael > > > > > > On 13 May 2016 at 20:00, Steven Wu <steve...@apple.com> wrote: >> >>> On May 13, 2016, at 3:56 PM, Duncan P. N. Exon Smith <dexonsm...@apple.com> >>> wrote: >>> >>> Is this something that you need the linker to treat as "used", or just >>> something you don't want the compiler to drop? If the latter, >>> @llvm.compiler.used seems more appropriate. >> >> Bitcode is actually not really used by the compiler during compilation and >> shouldn't really used by any part of the code. llvm.compiler.used then. >> >> New patch. >> >> >> >> >> Steven >> >>> >>>> On 2016-May-13, at 14:01, Steven Wu <steve...@apple.com> wrote: >>>> >>>> Attach a patch using private linkage type and adding to llvm.used. I have >>>> to recreate llvm.used when embedding bitcode. I don't really like it but I >>>> don't have better solutions. >>>> Few other options: >>>> 1. Not allowing re-embedded bitcode will simplify the code a bit but not a >>>> lot. >>>> 2. Create a new "llvm.*.used" variable in llvm.metadata section. >>>> 3. Teach optimizer do not optimize away llvm.* variables. >>>> >>>> <0001-Fix-embed-bitcode-linkage-type.patch> >>>> >>>> Steven >>>> >>>>> On May 13, 2016, at 10:10 AM, Rafael Espíndola >>>>> <rafael.espind...@gmail.com> wrote: >>>>> >>>>> On 13 May 2016 at 13:02, Steven Wu <steve...@apple.com> wrote: >>>>>> Hi Rafael >>>>>> >>>>>> Thanks for notice this! That would definitely cause duplicated symbol >>>>>> error and I should definitely change that. >>>>>> Here is some background: >>>>>> ld64 in Xcode 7+ knows how to handle the embedded bitcode correctly but >>>>>> not the ones in earlier Xcode. The old ld64 will simply concatenate the >>>>>> bitcode files which is not the right thing to do. So there is a symbol >>>>>> generated at the place to prevent user to link the bitcode object file >>>>>> with old ld64 because older ld64 will fail and report duplicated symbols. >>>>>> I have a radar tracking to change the linkage type when upstream but I >>>>>> dropped the ball on that one. The correct thing to do is to make it >>>>>> internal and add to llvm.used. I will come up with a patch. >>>>> >>>>> Thank you so much! >>>>> >>>>> Cheers, >>>>> Rafael >>>> >>> >> >>
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