[llvm-dev] why do undefined globals end up in .data instead of .bss?

Friedman, Eli via llvm-dev llvm-dev at lists.llvm.org
Mon Apr 24 11:53:06 PDT 2017

On 4/23/2017 10:10 AM, Andrew Kelley via llvm-dev wrote:
> Here is a module:
> @vals = internal unnamed_addr global [20000000 x i32] undef, align 4
> LLVM puts the global in the .data section, and results in a 77MB .o 
> file of mostly zeroes. Why does this variable not go in the .bss section?

I think it's just an oversight; it doesn't matter for clang because it 
never emits globals like that.  See 
TargetLoweringObjectFile::getKindForGlobal for the relevant logic.


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