[llvm-dev] Strange function time

mayuyu.io via llvm-dev llvm-dev at lists.llvm.org
Tue Jul 17 02:51:26 PDT 2018


Since they are just llvm debug intrinsics, would running StripDebugInfo prior to yours help?
Zhang

> 在 2018年7月17日,17:42,Muhui Jiang via llvm-dev <llvm-dev at lists.llvm.org> 写道:
> 
> Hi
> 
> I write a LLVM function pass to try to analysis all the functions inside one binary. 
> 
> However, this pass has been run for 80 CPU hours.
> 
> You can refer to https://groups.google.com/forum/#!searchin/llvm-dev/slow$20pass%7Csort:date/llvm-dev/BNbqiSbrh70/mQFZkAj-BgAJ
> 
> I look at the functions it analyzed. Then I found some very strange function name. There are more than one hundred functions whose name is output_xxx. I randomly select some of them and found that the IR are all the same like below:
> 
> Source Line:115|Column:11|File:insn-output.c|IR:  call void @llvm.dbg.value(metadata %struct.rtx_def** %operands, metadata !441244, metadata !DIExpression()), !dbg !441246
> Source Line:116|Column:10|File:insn-output.c|IR:  call void @llvm.dbg.value(metadata %struct.rtx_def* %insn, metadata !441245, metadata !DIExpression()), !dbg !441247
> Source Line:118|Column:9|File:insn-output.c|IR:  %call = tail call fastcc i8* @output_fp_compare(%struct.rtx_def* %insn, %struct.rtx_def** %operands, i32 0, i32 0) #5, !dbg !43814
> Source Line:118|Column:2|File:insn-output.c|IR:  ret i8* %call, !dbg !43815
> 
> I am not sure this is the reason that make my pass running such a long time. The target bitcode is just less than 50Mb. I don't think it will cost me so much time. Do anyone has any ideas? I
> 
> Regards
> Muhui
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