FrozenGene edited a comment on issue #4657: [CodeGen] Generate blob use LLVM 
directly
URL: https://github.com/apache/incubator-tvm/pull/4657#issuecomment-572199993
 
 
   @tqchen @zhiics About the LLVM target part, I also think current way maybe 
is not good. I also think of it and cost my some time. So I want to discuss it 
too. 
   
   Firstly Let me describe why we need llvm target host. 
   
   When we use PackImportToLLVM, we will need to use LLVM to create LLVM 
module. 
   
   However, we must need one target machine, this is answered to @tqchen 's 
question. We can not create one generic target. Because we have platform's 
specific feature to handle. 
See:https://github.com/apache/incubator-tvm/blob/4f1772c0598ae708477f457a993f5be52fa71eb9/src/codegen/llvm/codegen_blob.cc#L107
 and 
https://github.com/apache/incubator-tvm/blob/4f1772c0598ae708477f457a993f5be52fa71eb9/src/codegen/llvm/codegen_blob.cc#L167.
 Another thing is if we leave the target is empty, i.e. no 
module->setTargetTriple(target_triple.str()); On llvm 6.0 of Mac will report 
problem : assert error Target-incompatible DataLayout.
   
   More import thing is we need to consider the target host is not x86 cpu. For 
example, target host is llvm -target aarch64, if we leave it empty and build it 
on x86 server, we will generate devc.o into x86 format, but in fact we want 
aarch64 of devc.o. So in the codegen_blob part, we should know the correct llvm 
target host to generate correct file.
   
   Current way is a little ugly I think too. Current way will create target 
host based on LLVM when we have detected target host finally (because tvm.build 
/ relay.build's api could leave `target_host` be None, we have some logic to 
handle this situation). One simple way of course is let users specific the 
target host of llvm representation, but I use this ugly way is just to detect 
it automatically and don't want to let users do. I also want to listen to your 
advices. Thanks in advance.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org


With regards,
Apache Git Services

Reply via email to