On Tue, Feb 03, 2015 at 02:27:52PM +0900, ISHIKAWA,chiaki wrote: > I did a non-unified build and saw the expected failure. > This is a summary of what I saw. > > Background: > > I may need to modify and debug basic I/O routines on local PC, and so > want to avoid unnecessary compilation. I use ccache locally to make > sure I can avoid re-compilation of touched but not modified C++ source > files (files get touched and remain unmodified when I execute > "hg qpop" and "hg qpush" in successions to work on different patches. > Without ccache, I have to compile many files. ccache helps a lot.) > > There is a different perspective on unified compilation. > > Compiler farm users: > One time fast compilation　is very important. > So unified compilation is a win. > (I suspect precompiled headers, -pch, would be a good win, too.) > > Developers who repeats "edit a small set of files, compile and link" > many times on local PC: > > He/she may modify only a few files and want quick > turn around of the compile of a few files and link time. > > Unified compilation actually compiles more lines than he/she wants > (because of the extra source lines included in unified source files > in which his/her modified files are also included. > (Correct? Am I missing something here?) > So he/she may not like unified compilation in such scenario.
Here's my take on this: yes, we should optimize for build times when code is modified. But here's the thing: in most directories, unified compilation shouldn't be making a huge difference. That is, compiling one unified source vs. compiling one source shouldn't make a big difference. If it does (and it does in some directories like js/src), then the number of unified sources in the directory where it's a problem should be adjusted. Mike _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
