Date: Sun, 16 Jan 2011 01:55:37 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Garrett Cooper <gcooper@freebsd.org> Cc: svn-src-head@freebsd.org, mdf@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: svn commit: r217369 - in head/sys: cam/scsi sys Message-ID: <20110116013102.E21684@besplex.bde.org> In-Reply-To: <AANLkTimoT9c6q2=K=C7dSnxJXkT=qZx=wPbAf6k68hWZ@mail.gmail.com> References: <201101131820.p0DIKXip059402@svn.freebsd.org> <AANLkTinh619WaGgq=5fFxTvEX0JPir34k8xb%2Bs6oSH8Y@mail.gmail.com> <20110114174719.D28159@besplex.bde.org> <AANLkTikVwuSO3h8tKeYXCvC6zqYVHVxdY5Abrzo-Ks2R@mail.gmail.com> <20110115133929.D16210@besplex.bde.org> <AANLkTi=B5mZCJ_bhe=Gf1pLUmWsTswi3O3U2ZLnHMODV@mail.gmail.com> <20110115170529.T16715@besplex.bde.org> <AANLkTimoT9c6q2=K=C7dSnxJXkT=qZx=wPbAf6k68hWZ@mail.gmail.com>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --0-1463948836-1295103337=:21684 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE On Sat, 15 Jan 2011, Garrett Cooper wrote: > On Fri, Jan 14, 2011 at 10:27 PM, Bruce Evans <brde@optusnet.com.au> wrot= e: >> On Fri, 14 Jan 2011, Garrett Cooper wrote: >> >>> On Fri, Jan 14, 2011 at 6:42 PM, Bruce Evans <brde@optusnet.com.au> wro= te: >>>> ... >>>> Oops. =A0I think sizeof() and issigned() can be used to determine the = type >>>> well enough in functions and initialized data (do a fuller type check = if >>>> the compiler supports it), but I don't know how to do this in static >>>> sysctl declarations (since sizeof() can't be used in cpp expressions). >>> >>> =A0 Why not just create some dumb testcases that can be run at build >>> time to determine that for you? >> >> Well, how? =A0You are given SYSCTL_I(&var, ...) and have to convert this >> to what is now in SYSCTL_INT(), using only the type of var, in hundreds >> or thousands of files. =A0I don't even know how to do this with a test >> ... >> >> =A0 =A0 =A0 =A0/* Only works for arithmetic types: */ >> =A0 =A0 =A0 =A0#define isinteger(var) =A0((typeof(var))0.1 =3D=3D 0) >> =A0 =A0 =A0 =A0#define issigned(var) =A0 ((typeof(var))-1 < 0) >> =A0 =A0 =A0 =A0... > > This is what I meant: > > $ cat test_warnings.c > #include <sys/types.h> > > size_t x =3D (int) -1; > int y =3D 20000000000L; > $ gcc -Wconversion -Wstrict-overflow -Wsign-compare -c test_warnings.c > test_size_t.c:3: warning: negative integer implicitly converted to unsign= ed type > test_size_t.c:4: warning: overflow in implicit constant conversion > $ > > With the right CFLAGS and a few properly written tests, and a few > make rules, you can figure out what's what pretty easily *shrugs*. That's a lot more parsing than seems reasonable. Anyway, we already depend on gnu __typeof() being avaible for the much more central API of pcpu. All pcpu accesses on amd64 and i386 use it, except curthread (curthread has been hacked to use a more direct asm for compile-time efficiency). SYSCTL_I() works even better that I first thought. It automatically gives support for all typedefed integral types. No SYSCTL_FOO_T()s with messy MD ifdefs for matching up foo_t with an integral type are needed. Instead there are even messier MI ifdefs in SYSCTL_I() :-). But not so many. There are hundreds of typedefed types of interest, but only 8 different integer types to map to (8/16/32/64 bits signed and unsigned). The complication that int64_t is plain long on 64 bit arches but long long on 32-bit arches still arises. CTLTYPE_QUAD can be associated with int64_t on all arches, but the format for printing these is arch-dependent. (Note that quad_t's cannot be printed using %qd, and %qd is unusable, since %qd is just an alias for %lld, while quad_t is an alias for int64_t and int64_t is plain long on 64-bit arches so its format is %ld on these arches and %lld on others.) Bruce --0-1463948836-1295103337=:21684--
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