From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15150 invoked by alias); 23 Jul 2014 22:17:44 -0000 Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org Received: (qmail 15025 invoked by uid 89); 23 Jul 2014 22:17:43 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.8 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 X-HELO: qmta13.emeryville.ca.mail.comcast.net Received: from qmta13.emeryville.ca.mail.comcast.net (HELO qmta13.emeryville.ca.mail.comcast.net) (76.96.27.243) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 23 Jul 2014 22:17:41 +0000 Received: from omta06.emeryville.ca.mail.comcast.net ([76.96.30.51]) by qmta13.emeryville.ca.mail.comcast.net with comcast id Vxif1o00716AWCUADyHgnP; Wed, 23 Jul 2014 22:17:40 +0000 Received: from redwood.eagercon.com ([24.7.16.38]) by omta06.emeryville.ca.mail.comcast.net with comcast id VyHf1o00W0pGQcg8SyHf9G; Wed, 23 Jul 2014 22:17:40 +0000 Message-ID: <53D03483.2060203@eagercon.com> Date: Wed, 23 Jul 2014 22:17:00 -0000 From: Michael Eager User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Chen Gang , Michael Eager CC: binutils@sourceware.org, gdb-patches@sourceware.org Subject: Re: [PATCH] gdb/microblaze-tdep.c: Check whether less than zero in conditional expression References: <53CBCC2F.7040702@gmail.com> <53D01542.9020107@eagerm.com> <53D031E7.40602@gmail.com> In-Reply-To: <53D031E7.40602@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2014-07/txt/msg00181.txt.bz2 On 07/23/14 15:06, Chen Gang wrote: > On 07/24/2014 04:04 AM, Michael Eager wrote: >> On 07/20/14 07:03, Chen Gang wrote: >>> Use typecast 'size_t' on 'reg', not only avoid the related warning, but >>> also check whether less than zero -- for 'reg' is type 'int', and sizeof >>> (dwarf2_to_reg_map) is less than 0x7fff. >>> >>> It is quoted in gdb_assert(), so need check 'reg' whether less than zero. >>> And the related warning (with '-W'): >>> >>> ../../binutils-gdb/gdb/microblaze-tdep.c:667:3: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare] >>> >>> ChangeLog: >>> >>> * microblaze-tdep.c (microblaze_dwarf2_reg_to_regnum): Check whether >>> less tha zero in conditional expression. >>> >>> >>> Signed-off-by: Chen Gang >>> --- >>> gdb/microblaze-tdep.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/gdb/microblaze-tdep.c b/gdb/microblaze-tdep.c >>> index 7e89241..9bec260 100644 >>> --- a/gdb/microblaze-tdep.c >>> +++ b/gdb/microblaze-tdep.c >>> @@ -664,7 +664,7 @@ static int dwarf2_to_reg_map[78] = >>> static int >>> microblaze_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int reg) >>> { >>> - gdb_assert (reg < sizeof (dwarf2_to_reg_map)); >>> + gdb_assert ((size_t) reg < sizeof (dwarf2_to_reg_map)); >>> return dwarf2_to_reg_map[reg]; >>> } >> >> I don't see anything in the patch which does what you describe, >> checking whether reg is less than zero. Converting a signed >> integer to an unsigned integer is not a way to check whether >> it is less than zero. This is better: >> >> + gdb_assert (reg >= 0 && (size_t) reg < sizeof (dwarf2_to_reg_map)); >> > > Yeah, it is common statement. It is also OK to me, although after type > cast, 'reg >=0' can be omited (it can let code simpler, but let code > not quit easy understanding). No, if you want to verify that the value is greater than zero, this cannot be omitted. A negative value would converted to a positive value by the cast. There no reason to believe that this would cause the other half of the test to fail. >> I do not see this error message in my build which uses -Wall. >> What is your build environment? Which version of GCC? >> > > Originally, I use "CFLAGS=-W -g -O2" pass to configure. And '-W' is > different from '-Wall'. '-W' reports real 'all' warnings which can be > found by compiler, but '-Wall' reports most valuable warnings. OK -- Michael Eager eager@eagercon.com 1960 Park Blvd., Palo Alto, CA 94306 650-325-8077