[cmake] Use -pipe by default for compiling C++ files with g++

[Konstantin Tokarev]

[cmake] Use -pipe by default for compiling C++ files with g++

[Konstantin Tokarev]

Created attachment 314562 [details]
Patch

[Michael Catanzaro]

Comment on attachment 314562 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=314562&action=review

So the best description I've found for this is:

https://wiki.gentoo.org/wiki/GCC_optimization#-pipe

Basically it means the build should be a bit faster, at the expense of requiring a bit more memory.

Have you done a comparison? I'm reluctant to push anything that will increase memory requirements for builds, especially if it's not going to be a significant speed increase.

> Source/cmake/OptionsCommon.cmake:82
> +        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pipe")

It should be the opposite:

set(CMAKE_CXX_FLAGS "-pipe ${CMAKE_CXX_FLAGS}")

(So that it can be overridden.)

[Alex Christensen]

Comment on attachment 314562 [details]
Patch

Michael's comment needs to be addressed, and we need measurements of peak memory use with and without -pipe and build time with and without -pipe.  Please measure more than once.

[Konstantin Tokarev]

Turns out that -pipe has no positive effect. On Linux I got neutrals result, while in Windows VM with MinGW it's even negative