[llvm-dev] Multi-Threading Compilers

David Greene via llvm-dev llvm-dev at lists.llvm.org
Fri Mar 6 08:52:20 PST 2020

Neil Nelson via llvm-dev <llvm-dev at lists.llvm.org> writes:

> For example, you remarked there are use cases, and having a realistic 
> appreciation for what use cases there may be is important, where a 
> multi-threading compile would be useful.

LTO could significantly benefit.

> There is also a gain in compile time for small source files as against 
> larger source files and some argument with regard to design could be 
> made for some maximum source file size to reduce complexity that would 
> also address keeping compile time down. Is there a reason to expect an 
> increase in source file size that would increase compile time?

One data point: we see many customer codes with generated sources.
Those sources just keep growing and growing.

> Noting the LLVM compile test from my prior post gave an average compile 
> time of 14*0.1532 = 2.1448 seconds, is compile time a significant or 
> marginal issue? What would be the target for an average compile time?

It is significant for us.  Over the years we have even added special
options just to speed up compile time for customers' develop-test-debug


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