From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2948 invoked by alias); 24 Oct 2014 22:55:52 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 2937 invoked by uid 89); 24 Oct 2014 22:55:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pd0-f172.google.com Received: from mail-pd0-f172.google.com (HELO mail-pd0-f172.google.com) (209.85.192.172) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Fri, 24 Oct 2014 22:55:50 +0000 Received: by mail-pd0-f172.google.com with SMTP id r10so2224588pdi.31 for ; Fri, 24 Oct 2014 15:55:48 -0700 (PDT) X-Received: by 10.69.15.225 with SMTP id fr1mr7610850pbd.43.1414191348534; Fri, 24 Oct 2014 15:55:48 -0700 (PDT) Received: from ShengShiZhuChengdeMacBook-Pro.local ([223.72.65.25]) by mx.google.com with ESMTPSA id oe10sm4725730pdb.66.2014.10.24.15.55.44 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Oct 2014 15:55:47 -0700 (PDT) Message-ID: <544ADA5D.4010507@gmail.com> Date: Fri, 24 Oct 2014 22:55:00 -0000 From: Chen Gang User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: palves@redhat.com, mark.kettenis@xs4all.nl, Iain Buclaw , Joel Brobecker , gdb-patches@sourceware.org Subject: Re: [PATCH v3] gdb/i387-tdep.c: Avoid warning for "-Werror=strict-overflow" References: <543FB512.60607@gmail.com> In-Reply-To: <543FB512.60607@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2014-10/txt/msg00682.txt.bz2 Hell Maintainers: Is this patch OK, if need additional improvements, please let me know. By the way: for "I387_MXCSR_REGNUM", I guess, gcc 'think' it is for 2 variables, which does not match "(X + c) >= X" ('c' means constant, I guess), so gcc does not report warning for it (then I did not touch it). Thanks. On 10/16/14 20:07, Chen Gang wrote: > gdb requires "-Werror", and I387_ST0_REGNUM (tdep) is 'variable', then > compiler can think that I387_ST0_REGNUM (tdep) may be a large number to > add a constant value, which may cause issue, so report warning. > > Need fix this warning, and still keep the code clear enough for readers > (I387_NUM_REGS is much clearer than I387_XMM0_REGNUM). The related > warning under Darwin with gnu built gcc: > > gcc -g -O2 -I. -I../../binutils-gdb/gdb -I../../binutils-gdb/gdb/common -I../../binutils-gdb/gdb/config -DLOCALEDIR="\"/usr/local/share/locale\"" -DHAVE_CONFIG_H -I../../binutils-gdb/gdb/../include/opcode -I../../binutils-gdb/gdb/../opcodes/.. -I../../binutils-gdb/gdb/../readline/.. -I../bfd -I../../binutils-gdb/gdb/../bfd -I../../binutils-gdb/gdb/../include -I../libdecnumber -I../../binutils-gdb/gdb/../libdecnumber -I../../binutils-gdb/gdb/gnulib/import -Ibuild-gnulib/import -DTUI=1 -D_THREAD_SAFE -I/usr/local/Cellar/guile/2.0.11/include/guile/2.0 -I/usr/local/Cellar/gmp/6.0.0a/include -I/usr/local/Cellar/readline/6.3.5/include -I/usr/local/Cellar/bdw-gc/7.2e/include -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -Wall -Wdeclaration-after-statement -Wpointer-arith -Wpointer-sign -Wno-unused -Wunused-value -Wunused-function -Wno-switch -Wno-char-subscripts -Wmissing-prot ot > ypes -Wdeclaration-after-statement -Wempty-body -Wmissing-parameter-type -Wold-style-declaration -Wold-style-definition -Wformat-nonliteral -Werror -c -o i387-tdep.o -MT i387-tdep.o -MMD -MP -MF .deps/i387-tdep.Tpo ../../binutils-gdb/gdb/i387-tdep.c > ../../binutils-gdb/gdb/i387-tdep.c: In function 'i387_supply_fsave': > ../../binutils-gdb/gdb/i387-tdep.c:447:1: error: assuming signed overflow does not occur when assuming that (X + c) >= X is always true [-Werror=strict-overflow] > i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave) > ^ > ../../binutils-gdb/gdb/i387-tdep.c: In function 'i387_collect_fsave': > ../../binutils-gdb/gdb/i387-tdep.c:502:1: error: assuming signed overflow does not occur when assuming that (X + c) >= X is always true [-Werror=strict-overflow] > i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave) > ^ > cc1: all warnings being treated as errors > > Also give related comment for it, or other code readers may doubt why > need 'end'. > > > 2014-10-13 Chen Gang > > * i387-tdep.c (i387_supply_fsave): Avoid warning for > "-Werror=strict-overflow" > --- > gdb/i387-tdep.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/gdb/i387-tdep.c b/gdb/i387-tdep.c > index d66ac6a..f39c090 100644 > --- a/gdb/i387-tdep.c > +++ b/gdb/i387-tdep.c > @@ -450,11 +450,13 @@ i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave) > struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); > enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); > const gdb_byte *regs = fsave; > - int i; > + int i, end; > > gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM); > > - for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++) > + /* Avoid -Werror=strict-overflow for (X + c) >= X, so use 'end' */ > + end = I387_ST0_REGNUM (tdep) + I387_NUM_REGS; > + for (i = I387_ST0_REGNUM (tdep); i < end; i++) > if (regnum == -1 || regnum == i) > { > if (fsave == NULL) > @@ -503,11 +505,13 @@ i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave) > { > struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache)); > gdb_byte *regs = fsave; > - int i; > + int i, end; > > gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM); > > - for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++) > + /* Avoid -Werror=strict-overflow for (X + c) >= X, so use 'end' */ > + end = I387_ST0_REGNUM (tdep) + I387_NUM_REGS; > + for (i = I387_ST0_REGNUM (tdep); i < end; i++) > if (regnum == -1 || regnum == i) > { > /* Most of the FPU control registers occupy only 16 bits in > -- Chen Gang Open, share, and attitude like air, water, and life which God blessed