Re: Building perf with clang

[Milian Wolff <milian.wolff@kdab.com>]

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On Freitag, 1. April 2016 19:16:02 CEST Arnaldo Carvalho de Melo wrote:
> Em Fri, Apr 01, 2016 at 11:19:05PM +0200, Milian Wolff escreveu:
> > Hey all,
> > 
> > I usually use clang to build my code, and have configured CC and CXX
> > globally for that purpose. When I forget to unset that before I run
> > "make" in the perf folder, I get into serious trouble as that is not
> > supported at all.
> > 
> > So, can that be fixed, either by making perf buildable with clang, or by
> > enforcing GCC within the Makefile if clang is not supported? Or at least
> > error out early if clang would be used?
> 
> I never tried, but I have it installed to test perf + BPF, so I'll try
> it, fixing things as I go, patches welcome, as I'll start this tomorrow,
> at the earliest.

Just FYI, this is the error I'm seeing:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CC=clang make
makeobj[0]: Entering directory `/home/milian/projects/src/linux/tools/perf'
  BUILD:   Doing 'make -j4' parallel build
warning: unknown warning option '-Wstrict-aliasing=3'; did you mean '-Wstring-
plus-int'? [-Wunknown-warning-option]
1 warning generated.

Auto-detecting system features:
...                         dwarf: [ on  ]
...                         glibc: [ on  ]
...                          gtk2: [ on  ]
...                      libaudit: [ on  ]
...                        libbfd: [ on  ]
...                        libelf: [ on  ]
...                       libnuma: [ on  ]
...        numa_num_possible_cpus: [ on  ]
...                       libperl: [ on  ]
...                     libpython: [ on  ]
...                      libslang: [ on  ]
...                     libcrypto: [ on  ]
...                     libunwind: [ on  ]
...            libdw-dwarf-unwind: [ on  ]
...                          zlib: [ on  ]
...                          lzma: [ on  ]
...                     get_cpuid: [ on  ]
...                           bpf: [ on  ]

  GEN      common-cmds.h
  CC       fixdep.o
cat: ./.fixdep.o.d: No such file or directory
/home/milian/projects/src/linux/tools/build/Makefile.build:77: recipe for 
target 'fixdep.o' failed
make[3]: *** [fixdep.o] Error 1
Makefile:36: recipe for target 'fixdep-in.o' failed
make[2]: *** [fixdep-in.o] Error 2
/home/milian/projects/src/linux/tools/build/Makefile.include:7: recipe for 
target 'fixdep' failed
make[1]: *** [fixdep] Error 2
make[1]: *** Waiting for unfinished jobs....
  PERF_VERSION = 4.2.rc6.g7a9420
make[1]: *** wait: No child processes.  Stop.
Makefile:68: recipe for target 'all' failed
make: *** [all] Error 2
makeobj[0]: Leaving directory `/home/milian/projects/src/linux/tools/perf'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I have no clue what's going on here, I never edit Makefiles by hand...

Speaking of Makefiles, how can I change the CFLAGS when building perf (with 
GCC)? I.e. how can I build it in -O0, or how can I enable sanitizers?

Thanks

-- 
Milian Wolff | milian.wolff@kdab.com | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts

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