From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeroen Hofstee Date: Thu, 11 Sep 2014 13:17:20 +0200 Subject: [U-Boot] [PATCH v3 0/8] add clang support for some ARM boards In-Reply-To: References: <1406750096-7281-1-git-send-email-jeroen@myspectrum.nl> <1410372532-8106-1-git-send-email-jeroen@myspectrum.nl> Message-ID: <1410434240.21166.21.camel@yellow> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello Albert, On do, 2014-09-11 at 10:32 +0200, Albert ARIBAUD wrote: > > On Wed, 10 Sep 2014 20:08:50 +0200, Jeroen Hofstee > wrote: > > > Changes since v2: > > - As Albert pointed out the clang instructions don't work with > > Debian based binary packages. While I was aware of that it is > > for a different reason then I thought, it is not that ARM is not > > enabled as a backend but older versions are a bit more picky on > > the target argument and don't tolerate a trailing dash to it as > > used for CROSS_COMPILE etc. The README is updated accordingly. > > > > As a side note clang3.5-svn as shipped in Ubuntu is not the 3.5 > > release but an snapshot of some svn commit and hence explain why > > the recompiled 3.5 can behave different then the ubuntu clang-3.5. > > Since it misses some patches, the clang3.5-svn can build less > > boards then 3.4 or an actual 3.5 release. > > > > - While add it, include Masahiro suggestion to also use c++ instead > > of g++. > > - Drop dependencies from the cover-letter as they are merged. > > - only patch 7/8 and 8/8 are reposted. 1..6 are the same as v2. > > Thanks, tested building rpi_b, it works now. > > The, tested on versatileqemu out of curiosity and got the following > results: > > 1. > > clang warns about Unused static functions in common/console.c, namely > console_printdevs and console_doenv (1). Why gcc does not flag this? > We have -Wall set which is supposed to imply -Wunused-functions. It is a gcc feature, see [1]: "Warn whenever a static function is declared but not defined or a _non-inline static function_ is unused. This warning is enabled by -Wall." > > There is also an unused variable warning in disk/part.c28 > (block_drvr). I haven't looked at why clang warns about it and not gcc, > but it could raise the same question as the functions above. > Also a gcc feature, see [2]. The constant is indeed not used. > 2. > > clang errors on arch/arm/lib/cache.c:28 for this: > asm("0: mrc p15, 0, r15, c7, c10, 3\n\t" "bne 0b\n" : : : "memory"); > and that is a clang mistake, as for ARM926EJS r15 is a valid (albeit > quite special semantically) Rd for Test and Clean DCache, see page 2-24. > This is the integrated-as complaining (the README tells you to disable it for the moment). The clang folks push UAL hard, up to a point we need to think about minimum gcc version etc. To avoid that, I just left out such changes and just use gas instead, at least for the time being. Below are some changes to compile versatileqemu with llvm integrated-as and gcc/gas. No idea if it actually boots though. > Jeroen, do you feel like raising point 2 to the clang/LLVM folks? It is removed on purpose as far as I understood. I don't think they regards it as a bug, see obfuscated patch below. > Other than that, the patch series seems to be good. I'll apply it > soonish. > Thanks, Jeroen [1] https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=13029 s/~/-/g ~~~