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Place undefined globals in .bss instead of .data #109
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Following up on the discussion from http://lists.llvm.org/pipermail/llvm-dev/2017-April/112305.html, undef values are now placed in the .bss as well as null values. This prevents undef global values taking up potentially huge amounts of space in the .data section. The following two lines now both generate equivalent .bss data: @vals1 = internal unnamed_addr global [20000000 x i32] zeroinitializer, align 4 @Vals2 = internal unnamed_addr global [20000000 x i32] undef, align 4 ; previously unaccounted for This is primarily motivated by the corresponding issue in the Rust compiler (rust-lang/rust#41315). Differential Revision: https://reviews.llvm.org/D41705 Patch by varkor! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@324424 91177308-0d34-0410-b5e6-96231b3b80d8
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(I can't merge PRs in this repo :-) |
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Awesome, thanks! Would it be possible to upstream this to LLVM first though? |
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@alexcrichton This has already been merged upstream: commit: https://reviews.llvm.org/rL324424 review: https://reviews.llvm.org/D41705 |
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Oh! Sorry I forgot to expand the commit message here... In that case! |
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Thanks @alexcrichton! @varkor you can now prepare a rust-lang/rust PR that updates the LLVM submodule |
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Merge the fix for rust-lang/rust#41315, moving undefined global constants to the bss section instead of the data section.
cc @japaric