[LLVMdev] CMake does not propagate flags to build

Tue Jul 21 11:40:46 PDT 2015

Sorry for the late response.

Yes, we explicitly add -fomit-frame-pointer when we build sanitizer
runtimes, and it may override what you set in CMAKE_CXX_FLAGS. It is indeed
related to performance overhead, which is especially critical for slower
tools like ThreadSanitizer, which inserts a call into runtime for *every*
load/store in the original problem.

On Mon, Jul 20, 2015 at 3:25 PM, Chris Bieneman <cbieneman at apple.com> wrote:

> At the moment I don’t believe we support building ASAN with
> -fno-omit-frame-pointer because doing so would likely have significant
> adverse impact on performance. Samsonov would know better, but especially
> if you’re looking to run profiling tools you really don’t want frame
> pointers for the runtime libraries.
>

>
> -Chris
>
> > On Jul 20, 2015, at 3:00 PM, adek at adek.io wrote:
> >
> > This is just for compiler-rt. The reason for having
> > -fno-omit-frame-pointer is that tools like
> > https://perf.wiki.kernel.org/index.php/Main_Page would work on ASAN
> > binaries.
> >
> > Adrian
> >
> > On Mon, Jul 20, 2015, at 02:23 PM, adek at adek.io wrote:
> >> Hey,
> >>
> >> Thanks for ideas. I tried them on, but none of them succeeded.
> >>
> >> If I remove this line:
> >>
> https://github.com/llvm-mirror/compiler-rt/blob/c9d8d35a5c2bdd6a0dd41f1b6cf3afb822df6a6e/CMakeLists.txt#L207
> >>
> >> Everything is correctly built with -fno-omit-frame-pointer.
> >>
> >> Any suggestion why it would be the case?
> >>
> >> Thanks,
> >> Adrian
> >>
> >> On Mon, Jul 20, 2015, at 01:39 PM, Martin J. O'Riordan wrote:
> >>> I regularly use '-DCMAKE_CXX_FLAGS' when configuring CLang/LLVM to
> >>> distinguish my builds (Alpha/Beta/Final) or to build custom versions,
> >>> usually by adding additional '-D' flags, but I discovered I had to add
> >>> the ':STRING' qualifier to it when invoking 'cmake'.  With 'gmake' this
> >>> is equivalent to '--with-extra-options="whatever flags":
> >>>
> >>>     -DCMAKE_CXX_FLAGS:STRING="whatever flags"
> >>>
> >>> This works regardless of whether it is a Debug or Release build.
> >>>
> >>> All the best,
> >>>
> >>>     MartinO
> >>>
> >>> -----Original Message-----
> >>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> On
> >>> Behalf Of Chris Bieneman
> >>> Sent: 20 July 2015 19:23
> >>> To: adek at adek.io
> >>> Cc: llvmdev at cs.uiuc.edu
> >>> Subject: Re: [LLVMdev] CMake does not propagate flags to build
> >>>
> >>> Adrian,
> >>>
> >>> What makes you think CMAKE_CXX_FLAGS isn’t being respected?
> >>>
> >>> The tests will always occur regardless of whether or not you set the
> >>> CXX_FLAGS explicitly.
> >>>
> >>> -Chris
> >>>
> >>>> On Jul 20, 2015, at 9:36 AM, adek at adek.io wrote:
> >>>>
> >>>>
> >>>> Hey Pete,
> >>>>
> >>>> I also tried CMAKE_CXX_FLAGS_RELEASE
> >>>> with the same effect.
> >>>>
> >>>> On Mon, Jul 20, 2015, at 09:34 AM, Pete Cooper wrote:
> >>>>> Hi Adrian
> >>>>>
> >>>>> I’m not sure if the CMAKE_CXX_FLAGS is used in LLVM.  We have our own
> >>>>> flags for different configurations.  I don’t remember if our ones
> >>>>> inherit from CMAKE_CXX_FLAGS or override it completely.  Anyway,
> they are:
> >>>>> - CMAKE_CXX_FLAGS_DEBUG
> >>>>> - CMAKE_CXX_FLAGS_MINSIZEREL
> >>>>> - CMAKE_CXX_FLAGS_RELEASE
> >>>>> - CMAKE_CXX_FLAGS_RELWITHDEBINFO
> >>>>>
> >>>>> The one of those you get depends on what you set CMAKE_BUILD_TYPE to.
> >>>>> Options are ‘Debug, Release, RelWithDebInfo, MinSizeRel’
> >>>>>
> >>>>> Cheers,
> >>>>> Pete
> >>>>>> On Jul 17, 2015, at 8:41 PM, adek at adek.io wrote:
> >>>>>>
> >>>>>> '-DCMAKE_CXX_FLAGS=-fno-omit-frame-pointer -Wno-maybe-uninitialized
> >>>>>> -fPIC -fPIE'
> >>>>>> -- The C compiler identification is GNU 4.8.1
> >>>>>> -- The CXX compiler identification is GNU 4.8.1
> >>>>>> -- Check for working C compiler:
> >>>>>> /home/engshare/third-party2/gcc/4.8.1/centos6-native/cc6c9dc/bin/gcc
> >>>>>> -- Check for working C compiler:
> >>>>>> /home/engshare/third-party2/gcc/4.8.1/centos6-native/cc6c9dc/bin/gcc
> >>>>>> -- works
> >>>>>> -- Detecting C compiler ABI info
> >>>>>> -- Detecting C compiler ABI info - done
> >>>>>> -- Detecting C compile features
> >>>>>> -- Detecting C compile features - done
> >>>>>> -- Check for working CXX compiler:
> >>>>>> /home/engshare/third-party2/gcc/4.8.1/centos6-native/cc6c9dc/bin/g++
> >>>>>> -- Check for working CXX compiler:
> >>>>>> /home/engshare/third-party2/gcc/4.8.1/centos6-native/cc6c9dc/bin/g++
> >>>>>> -- works
> >>>>>> -- Detecting CXX compiler ABI info
> >>>>>> -- Detecting CXX compiler ABI info - done
> >>>>>> -- Detecting CXX compile features
> >>>>>> -- Detecting CXX compile features - done
> >>>>>> -- Found PythonInterp:
> >>>>>> /home/engshare/third-party2/python/2.7.5/centos6-native/da39a3e/bin/
> >>>>>> python2.7
> >>>>>> (found version "2.7.5")
> >>>>>> -- Looking for unwind.h
> >>>>>> -- Looking for unwind.h - found
> >>>>>> -- Performing Test COMPILER_RT_HAS_FPIC_FLAG
> >>>>>> -- Performing Test COMPILER_RT_HAS_FPIC_FLAG - Success
> >>>>>> -- Performing Test COMPILER_RT_HAS_FPIE_FLAG
> >>>>>> -- Performing Test COMPILER_RT_HAS_FPIE_FLAG - Success
> >>>>>> -- Performing Test COMPILER_RT_HAS_FNO_BUILTIN_FLAG
> >>>>>> -- Performing Test COMPILER_RT_HAS_FNO_BUILTIN_FLAG - Success
> >>>>>> -- Performing Test COMPILER_RT_HAS_FNO_EXCEPTIONS_FLAG
> >>>>>> -- Performing Test COMPILER_RT_HAS_FNO_EXCEPTIONS_FLAG - Success
> >>>>>> -- Performing Test COMPILER_RT_HAS_FOMIT_FRAME_POINTER_FLAG
> >>>>>> -- Performing Test COMPILER_RT_HAS_FOMIT_FRAME_POINTER_FLAG -
> >>>>>> Success
> >>>>>>
> >>>>>> Is it still related to this:
> >>>>>> http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-March/071394.html
> >>>>>>
> >>>>>>
> >>>>>> Adrian Zgorzałek
> >>>>>>
> >>>>>> _______________________________________________
> >>>>>> LLVM Developers mailing list
> >>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> >>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >>>>>
> >>>>
> >>>> _______________________________________________
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> >>>
> >>>
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> >>>
> >>
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-- 
Alexey Samsonov
vonosmas at gmail.com
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