From mboxrd@z Thu Jan 1 00:00:00 1970 From: Detlev Zundel Date: Wed, 01 Jul 2009 15:53:24 +0200 Subject: [U-Boot] warnings from gcc-4.4 build In-Reply-To: <9B5E5AE1-2907-49C2-870F-2D7B2F2DE598@kernel.crashing.org> (Kumar Gala's message of "Tue, 30 Jun 2009 10:28:25 -0500") References: <9B5E5AE1-2907-49C2-870F-2D7B2F2DE598@kernel.crashing.org> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Kumar, > When building the MPC8572DS_config w/gcc-4.4 I get: > > sys_eeprom.c: In function ?do_mac?: > sys_eeprom.c:323: warning: dereferencing type-punned pointer will > break strict-aliasing rules > sys_eeprom.c: In function ?mac_read_from_eeprom?: > sys_eeprom.c:395: warning: dereferencing type-punned pointer will > break strict-aliasing rules > ahci.c: In function ?ata_scsiop_read_capacity10?: > ahci.c:616: warning: dereferencing type-punned pointer will break > strict-aliasing rules > biosemu.c: In function ?BE_setVGA?: > biosemu.c:147: warning: dereferencing type-punned pointer will break > strict-aliasing rules > tsec.c: In function ?tsec_init?: > tsec.c:200: warning: dereferencing type-punned pointer will break > strict-aliasing rules > dlmalloc.c: In function ?malloc_bin_reloc?: > dlmalloc.c:1502: warning: dereferencing pointer ?p? does break strict- > aliasing rules > dlmalloc.c:1502: warning: dereferencing pointer ?p? does break strict- > aliasing rules > dlmalloc.c:1499: note: initialized from here > dlmalloc.c:1502: note: initialized from here > dlmalloc.c: In function ?free?: > dlmalloc.c:2474: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2474: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2474: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2474: note: initialized from here > dlmalloc.c: In function ?malloc?: > dlmalloc.c:2219: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2219: note: initialized from here > dlmalloc.c:2228: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2228: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2228: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2228: note: initialized from here > dlmalloc.c:2235: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2235: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2235: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2235: note: initialized from here > dlmalloc.c:2292: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2292: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2292: warning: dereferencing pointer ?({anonymous})? does > break strict-aliasing rules > dlmalloc.c:2292: note: initialized from here You already fixed quite a few problems in dlmalloc: commit 57c219ad5d34dd9d49991777a62e3899595f2ec7 Author: Kumar Gala Date: Wed Jul 30 08:01:15 2008 -0500 Fix compile warnings in dlmalloc The origional code was using on odd reference to get to the first real element in av_[]. The first two elements of the array are not used for actual bins, but for house keeping. If we are more explicit about how use the first few elements we can get rid of the warnings: dlmalloc.c: In function 'malloc_extend_top': dlmalloc.c:1971: warning: dereferencing type-punned pointer will break strict-aliasing rules dlmalloc.c:1999: warning: dereferencing type-punned pointer will break strict-aliasing rules dlmalloc.c:2029: warning: dereferencing type-punned pointer will break strict-aliasing rules ... The logic of how this code came to be is: bin_at(0) = (char*)&(av_[2]) - 2*SIZE_SZ SIZE_SZ is the size of pointer, and av_ is arry of pointers so: bin_at(0) = &(av_[0]) Going from there to bin_at(0)->fd or bin_at(0)->size should be straight forward. Signed-off-by: Kumar Gala > xyzModem.c: In function ?xyzModem_stream_open?: > xyzModem.c:564: warning: ?dummy? is used uninitialized in this function > xyzModem.c:547: note: ?dummy? was declared here > > Should would be turning on -fno-strict-aliasing. The linux kernel has > been doing this for some time. Last time around, i.e. moving to gcc 4.x (as proven by the commit above), we were able to fix the problems. Did anything significantly change in the arguments? Cheers Detlev -- The mathematician's patterns, like the painter's or the poet's, must be beautiful; the ideas, like the colours or the words, must fit together in a harmonious way. Beauty is the first test: there is no permanent place in the world for ugly mathematics. -- G. H. Hardy -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de