yaxunl added a comment. In D99683#2672554 <https://reviews.llvm.org/D99683#2672554>, @tejohnson wrote:
> This raises some higher level questions for me: > > First, how will you deal with other corner cases that won't or cannot be > imported right now? While enabling importing of noinline functions and > cranking up the threshold will get the majority of functions imported, there > are cases that we still won't import (functions/vars that are interposable, > certain funcs/vars that cannot be renamed, most non-const variables with > non-trivial initializers). We will document the limitation of thinLTO support of HIP toolchain and recommend users not to use thinLTO in those corner cases. > Second, force importing of everything transitively referenced defeats the > purpose of ThinLTO and would probably make it worse than regular LTO. The > main entry module will need to import everything transitively referenced from > there, so everything not dead in the binary, which should make that module > post importing equivalent to a regular LTO module. In addition, every other > module needs to transitively import everything referenced from those modules, > making them very large depending on how many leaf vs non-leaf functions and > variables they contain. What is the goal of doing ThinLTO in this case? The objective is to improve optimization/codegen time by using multi-threads of thinLTO. For example, I have 10 modules each containing a kernel. In full LTO linking, I get one big module containing 10 kernels with all functions inlined, and I have one thread for optimization/codegen. With thinLTO, I get one kernel in each module, with all functions inlined. AMDGPU internalization and global DCE will remove functions not used by that kernel in each module. I will get 10 threads, each doing optimization/codegen for one kernel. Theoretically, there could be 10 times speed up. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D99683/new/ https://reviews.llvm.org/D99683 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
