Date: Mon, 27 Mar 2017 23:40:45 +0200 From: Dimitry Andric <dim@FreeBSD.org> To: Mark Millard <markmi@dsl-only.net> Cc: FreeBSD Ports <freebsd-ports@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>, FreeBSD Toolchain <freebsd-toolchain@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: FYI: what it takes for RAM+swap to build devel/llvm40 with 4 processors or cores and WITH__DEBUG= (powerpc64 example) Message-ID: <7FFF80B9-CE74-49C8-B295-DCB630368152@FreeBSD.org> In-Reply-To: <D0E5EBD5-F050-407C-B57B-B0630090BB4F@dsl-only.net> References: <3EDEF0B7-59C5-4648-9737-6682E18645BC@dsl-only.net> <39C60316-F905-490D-B0AB-BC24D7F351A2@dsl-only.net> <7F94CE59-D2CC-4D6F-B1CD-FF3D1F8EDCE7@FreeBSD.org> <45E32F4F-A238-47AA-8E1E-7AD4D9E857D9@dsl-only.net> <F73D89C4-4E7F-469E-8613-17427231E5C0@FreeBSD.org> <D0E5EBD5-F050-407C-B57B-B0630090BB4F@dsl-only.net>
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On 27 Mar 2017, at 23:11, Mark Millard <markmi@dsl-only.net> wrote:
>
> On 2017-Mar-27, at 5:53 AM, Dimitry Andric <dim at FreeBSD.org> wrote:
>> On 27 Mar 2017, at 12:25, Mark Millard <markmi at dsl-only.net> wrote:
>>>
>>> On 2017-Mar-27, at 2:41 AM, Dimitry Andric <dim@FreeBSD.org> wrote:
>>>> On 26 Mar 2017, at 23:36, Mark Millard <markmi@dsl-only.net> wrote:
>> ...
>>>>> Installed packages to be REMOVED:
>>>>> llvm40-4.0.0.r4
>>>>>
>>>>> Number of packages to be removed: 1
>>>>>
>>>>> The operation will free 49 GiB.
>>>>
>>>> Yes, this is big. But there is no real need to build the llvm ports
>>>> with debug information, unless you want to hack on llvm itself. And
>>>> in that case, you are better served by a Subversion checkout or Git
>>>> clone from upstream instead.
>> ...
>>> Historically unless something extreme like this ends up
>>> involved I build everything using WITH_DEBUG= or explicit
>>> -g's in order to have better information on any failure.
>>
>> The problem with the ports implementation of WITH_DEBUG is that it
>> always disables all optimizations, without a possibility to override.
>> Which bloats the resulting object files, libraries and executables, and
>> especially so for large C++ projects such as LLVM.
>>
>> I can recommend the following workaround. If you want to build a port
>> with optimizations disabled, you can always pass -O0 in CFLAGS.
>>
>> -Dimitry
>>
>> Index: Mk/bsd.port.mk
>> ===================================================================
>> --- Mk/bsd.port.mk (revision 436685)
>> +++ Mk/bsd.port.mk (working copy)
>> @@ -1646,7 +1646,7 @@ MAKE_ENV+= DONTSTRIP=yes
>> STRIP_CMD= ${TRUE}
>> .endif
>> DEBUG_FLAGS?= -g
>> -CFLAGS:= ${CFLAGS:N-O*:N-fno-strict*} ${DEBUG_FLAGS}
>> +CFLAGS:= ${CFLAGS} ${DEBUG_FLAGS}
>> .if defined(INSTALL_TARGET)
>> INSTALL_TARGET:= ${INSTALL_TARGET:S/^install-strip$/install/g}
>> .endif
>
> Interesting. WITH_DEBUG's description in the file does not
> mention that stripping of optimization flags:
>
> # WITH_DEBUG - If set, debugging flags are added to CFLAGS and the
> # binaries don't get stripped by INSTALL_PROGRAM or
> # INSTALL_LIB. Besides, individual ports might
> # add their specific to produce binaries for debugging
> # purposes. You can override the debug flags that are
> # passed to the compiler by setting DEBUG_FLAGS. It is
> # set to "-g" at default.
>
> I'll probably give myself an override that I can specify in
> /etc/make.conf , such as:
>
> # svnlite diff /usr/ports/Mk/bsd.port.mk
> Index: /usr/ports/Mk/bsd.port.mk
> ===================================================================
> --- /usr/ports/Mk/bsd.port.mk (revision 436747)
> +++ /usr/ports/Mk/bsd.port.mk (working copy)
> @@ -1646,7 +1646,11 @@
> STRIP_CMD= ${TRUE}
> .endif
> DEBUG_FLAGS?= -g
> +.if defined(ALLOW_OPTIMIZATIONS_FOR_WITH_DEBUG)
> +CFLAGS:= ${CFLAGS} ${DEBUG_FLAGS}
> +.else
> CFLAGS:= ${CFLAGS:N-O*:N-fno-strict*} ${DEBUG_FLAGS}
> +.endif
> .if defined(INSTALL_TARGET)
> INSTALL_TARGET:= ${INSTALL_TARGET:S/^install-strip$/install/g}
> .endif
Effectively, this gives some sort of support for three of CMake's build
types, e.g:
* Debug, which disables optimization, and obviously adds debuginfo
* Release, which optimizes for speed, and does not add debuginfo
* RelWithDebInfo, similar to Release but does add debuginfo
It would be nice if there was some way of directly utilizing these. The
RelWithDebInfo target is very useful with the LLVM projects.
-Dimitry
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