On Wed, Jan 18, 2023 at 4:17 PM Tim Düsterhus <t...@bastelstu.be> wrote:
> Hi > > On 1/18/23 18:51, Kamil Tekiela wrote: > > As you said yourself, this refactoring has no practical effect on > > It has no practical effect *yet*. The headers need to be untangled first > before actual optimization can happen. > > Or maybe have all > > ZEND headers included with a single header? > > That would go against the goal of reducing compile times. Much of the > time spent when compiling C is parsing megabytes of source code, because > deeply nested and/or unnecessary includes will bloat the amount of code > the toolchain will need to go through. > > Let me give a simple example: > > We have the following headers: > > a.h: 1 MB. > b.h: Includes a.h and is itself 100 kB in size. > c.h: Includes a.h and is itself 100 kB in size. > > foo.c: Includes b.h and c.h, but c.h is not actually used. Is itself 300 > kB in size. > > Now when compiling foo.c, a total of 2.5 MB of source code need to be > parsed, because a.h is included twice. If the unused include for c.h is > removed, then it will only be 1.4 MB in total. This multiplies quickly > for more complex include chains. I'd like to point to this commit once > more: > > > https://github.com/haproxy/haproxy/commit/340ef2502eae2a37781e460d3590982c0e437fbd > > Removing two headers in a single file reduced the total compile by > roughly 10%! > > Here's two more similar commits: > > > https://github.com/haproxy/haproxy/commit/e5983ffb3adbf71a8f286094b1c1afce6061d1f3 > > https://github.com/haproxy/haproxy/commit/1db546eecd3982ffc1ea92c2f542a3b01ce43137 > > Best regards > Tim Düsterhus > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > > Tim, This may be a silly question, but in that case, wouldn't #ifdef guards keep the compiler from including/parsing a.h twice? When a.h is *not* required by any of b.h, c.h nor foo.c, I agree that it should *not* be included at all, but when any of them, or even if all of them requires it, the guards should be enough to avoid redundant work afaik. Or am I missing anything here?
