[MacPorts] #38218: default optflags should be -Os rather than -O2
#38218: default optflags should be -Os rather than -O2 ------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: defect | Status: new Priority: Normal | Milestone: Component: base | Version: 2.1.3 Keywords: | Port: ------------------------+-------------------------------- All the kids are doing it. -Os will result in smaller text allowing for more optimal use of spacial locality in the text cache. As an added benefit, ppc will benefit in areas where -O2 results in text segments that are too large for reloc (#37839) -- Ticket URL: <https://trac.macports.org/ticket/38218> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default optflags should be -Os rather than -O2 -------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: defect | Status: new Priority: Normal | Milestone: Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | -------------------------+-------------------------------- Comment (by egall@…): I've had times where altering the optimization level would make my code fail to compile. We should test to make sure this won't break anything before we go changing anything. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:1> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 -------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: defect | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | -------------------------+-------------------------------- Changes (by ryandesign@…): * cc: ryandesign@… (added) * milestone: => MacPorts Future Comment: There's no practical way to test that this won't break "anything". We can change it in trunk now and see if we notice any problems on our development machines. And we'll probably let the buildbots rebuild all ports after this (since hopefully it'll go into 2.2 for which we already have to rebuild all ports because of the libtool archive changes) but looking through a log of building thousands of ports to analyze the ones that failed is impractical, especially given how many of our ports already don't build for other reasons. We can handle this like we always do: if people find ports that are broken, because of this or any other reason, they can file tickets and we'll fix them on a case-by-case basis. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:2> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Changes (by ryandesign@…): * type: defect => enhancement -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:3> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Comment (by jeremyhu@…): And FWIW, the difference from -O2 to -Os is really a small set of safe optimizations. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:4> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Comment (by fmw@…): Replying to [comment:2 ryandesign@…]:
There's no practical way to test that this won't break "anything". We can change it in trunk now and see if we notice any problems on our development machines. And we'll probably let the buildbots rebuild all ports after this (since hopefully it'll go into 2.2 for which we already have to rebuild all ports because of the libtool archive changes) but looking through a log of building thousands of ports to analyze the ones that failed is impractical, especially given how many of our ports already don't build for other reasons. We can handle this like we always do: if people find ports that are broken, because of this or any other reason, they can file tickets and we'll fix them on a case-by-case basis.
Sorry in advance for not having much undrestanding of macports.... In the webkit-gtk portfile (which provoked this), I note the line "platform powerpc {". If this is only invoking options based on the compile time CPU, would a line like "target powerpc {" for the runtime CPU, be a base solution by providing a way of implementing patches and flags required when there is sometimes a difference between compile & execute CPUs? Moreover, such a facility might permit easy testing (or back tracking) before (after), a change like -Os goes live? This sort of facility is what I first went looking for when I found https://trac.macports.org/ticket/37839 -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:5> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Comment (by ryandesign@…): `platform powerpc` is syntactic sugar exactly equivalent to `if {${os.platform} == "powerpc"}`. There is no syntax `target powerpc` in MacPorts. We already have the ${configure.build_arch} and ${configure.universal_archs} variables which can be used to inspect the architecture(s) being built for. This ticket is only about the one- character change needed to change the default configure.optflags from `-O2` to `-Os`. Anything else should be discussed elsewhere. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:7> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Changes (by ryandesign@…): * cc: fmw@… (added) -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:8> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Comment (by jmr@…): Sounds fine to me. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:9> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: new Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: | Keywords: Port: | --------------------------+-------------------------------- Comment (by ryandesign@…): Replying to [comment:7 ryandesign@…]:
`platform powerpc` is syntactic sugar exactly equivalent to `if {${os.platform} == "powerpc"}`.
Correction: `platform powerpc` is syntactic sugar exactly equivalent to `if {${os.arch} == "powerpc"}`. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:10> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: closed Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: fixed | Keywords: Port: | --------------------------+-------------------------------- Changes (by ryandesign@…): * status: new => closed * resolution: => fixed Comment: Replying to [ticket:38218 jeremyhu@…]:
All the kids are doing it.
Don't I recall that Apple switched to using -Os for the programs shipped in OS X some versions ago? Snow Leopard maybe? (Absolutely impossible to find "-Os" on Google of course.) Changed in r103497. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:11> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: closed Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: fixed | Keywords: Port: | --------------------------+-------------------------------- Comment (by raimue@…): Replying to [ticket:38218 jeremyhu@…]:
All the kids are doing it. -Os will result in smaller text allowing for more optimal use of spacial locality in the text cache.
I am not opposed to the change, but I just can't leave that statement uncommented :-) I don't think `-Os` is always the better choice under all circumstances. There was a recent discussion on enabling [http://lwn.net/Articles/534735/ -Os for the Linux kernel] and it was turned down, although that is about gcc whereas we are mostly using clang now. For clang the man page states: {{{ -Os is like -O2 with extra optimizations to reduce code size. }}} I would say this is misleading. `-Os` is like `-O2`, but excludes optimizations that would cause the code size to grow. For example, it might disable inlining for larger functions and therefore, code locality can actually be decreased by `-Os`. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:12> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: closed Priority: Normal | Milestone: MacPorts Future Component: base | Version: 2.1.3 Resolution: fixed | Keywords: Port: | --------------------------+-------------------------------- Comment (by jmr@…): Is that actually true for clang? The gcc man page has a more detailed explanation of what the optimisation levels do, and also mentions -Oz, which "enables other optimizations intended solely to reduce code size" and is "very similar to -Os in FSF distributions of GCC". Clang could be doing any combination of the things selected by either of these levels in GCC, or more. -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:13> MacPorts <http://www.macports.org/> Ports system for Mac OS
#38218: default configure.optflags should be -Os rather than -O2 --------------------------+-------------------------------- Reporter: jeremyhu@… | Owner: macports-tickets@… Type: enhancement | Status: closed Priority: Normal | Milestone: MacPorts 2.2.0 Component: base | Version: 2.1.3 Resolution: fixed | Keywords: Port: | --------------------------+-------------------------------- Changes (by jmr@…): * milestone: MacPorts Future => MacPorts 2.2.0 -- Ticket URL: <https://trac.macports.org/ticket/38218#comment:14> MacPorts <http://www.macports.org/> Ports system for OS X
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