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</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>Hi David, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>Thank you for replying! I have checked the symbol of libclang_rt.profile-<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>aarch64-android.a file. This archive library contains InstrProfilingValue.o <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>as well as the symbol of '__llvm_profile_instrument_target' that i need(see <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>https://pastebin.com/7LqpFtkP ). So I have tried to add this archive <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>library as a link-time library when building the Android kernel. But the <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>error still remains. I think the Android kernel may not be able to call <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>libraries outside the kernel source tree when linking and running. So I'm <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>porting pgo-related files (compiler-rt/lib/profile/) from compiler-rt to <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>Android kernel source tree. Is this the right and feasible way? <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:等线'>Yi Ma</span><span lang=EN-US style='font-size:10.5pt;font-family:"Calibri",sans-serif'><o:p></o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'> Xinliang David Li <xinliangli@gmail.com> <br><b>Sent:</b> Wednesday, April 29, 2020 1:09 AM<br><b>To:</b> Yi Ma <mayi.rjpt@vivo.com><br><b>Cc:</b> llvm-dev <llvm-dev@lists.llvm.org><br><b>Subject:</b> Re: [llvm-dev] Android kernel PGO with LLVM<o:p></o:p></span></p></div></div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-US>The entry point is for value profiling and should be defined in InstrProfilingValue.o in the archive library. Can you check the symbol table of the .a file?<o:p></o:p></span></p><div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p class=MsoNormal><span lang=EN-US>David<o:p></o:p></span></p></div></div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><div><div><p class=MsoNormal><span lang=EN-US>On Tue, Apr 28, 2020 at 4:25 AM Yi Ma via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<o:p></o:p></span></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt'><p class=MsoNormal><span lang=EN-US>Hello, <br><br>I'm working on Android kernel profile-guided optimization to figure out <br>whether pgo can improve the performance of Android kernel. I have tried <br>to added '-fprofile-generate' option to build Android kernel(msm-4.19). <br>But error occurs during building: "undefined reference to <br>'__llvm_profile_instrument_target'". <br>I have tried to add libclang_rt.profile-aarch64-android.a as a library <br>when building Android kernel, but the error still shows up. I think the <br>kernel may not be able to call libraries outside the kernel source tree, <br>so I was porting pgo-related files(compiler-rt/lib/profile/) from <br>compiler-rt to Android kernel source tree. <br><br>Do you know why did this error occurs? And am I doing the right thing? <br>Is it possible to improve the performance of Android kernel with llvm <br>pgo mechanism?<br><br>Thanks,<br>Yi Ma<br><br>_______________________________________________<br>LLVM Developers mailing list<br><a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" target="_blank">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></span></p></blockquote></div></div></div></body></html>