On 6/27/16, 11:40 AM, "Richardson, Bruce" <bruce.richardson at intel.com> wrote:
>On Mon, Jun 27, 2016 at 05:29:59PM +0100, Wiles, Keith wrote:
>> On 6/27/16, 7:58 AM, "dev on behalf of Wiles, Keith" <dev-bounces at
>> dpdk.org on behalf of keith.wiles at intel.com> wrote:
>>
>> >
>> >On 6/27/16, 3:46 AM, "Richardson, Bruce" <bruce.richardson at intel.com>
>> >wrote:
>> >
>> >>On Sun, Jun 26, 2016 at 10:54:12AM -0500, Keith Wiles wrote:
>> >>> Latest clang compiler 3.8.0 on latest update of Ubuntu
>> >>> creates a few more warnings on -Warray-bounds and extra
>> >>> () around 'if' expressions.
>> >>>
>> >>> Signed-off-by: Keith Wiles <keith.wiles at intel.com>
>> >>> ---
>> >>> app/test-pmd/Makefile | 3 +++
>> >>> app/test/Makefile | 3 +++
>> >>> drivers/net/bonding/Makefile | 4 ++++
>> >>> drivers/net/fm10k/Makefile | 2 ++
>> >>> drivers/net/i40e/Makefile | 2 ++
>> >>> lib/librte_cmdline/Makefile | 6 ++++++
>> >>> lib/librte_eal/linuxapp/eal/Makefile | 8 ++++++++
>> >>> 7 files changed, 28 insertions(+)
>> >>>
>> >>All the fixes in this patch seem to be just disabling the compiler
>> >>warnings, which
>> >>should really be the last resort in cases like this. Can some of the
>> >>issues be
>> >>fixed by actually fixing the issues in the code?
>> >
>> >I did look at the code to fix the problem, because I could not see one:
>> >
>> >/work/home/rkwiles/projects/intel/dpdk/app/test-pmd/cmdline.c:3357:2140:
>> >error: array index 3 is past the end of the array (which contains 3
>> >elements) [-Werror,-Warray-bounds]
>> > if (!__extension__ ({ size_t __s1_len, __s2_len; (__builtin_constant_p
>> > (res->proto) && __builtin_constant_p ("ip") && (__s1_len =
>> > __builtin_strlen (res->proto), __s2_len = __builtin_strlen ("ip"),
>> > (!((size_t)(const void *)((res->proto) + 1) - (size_t)(const void
>> > *)(res->proto) == 1) || __s1_len >= 4) && (!((size_t)(const void *)(("ip")
>> > + 1) - (size_t)(const void *)("ip") == 1) || __s2_len >= 4)) ?
>> > __builtin_strcmp (res->proto, "ip") : (__builtin_constant_p (res->proto)
>> > && ((size_t)(const void *)((res->proto) + 1) - (size_t)(const void
>> > *)(res->proto) == 1) && (__s1_len = __builtin_strlen (res->proto),
>> > __s1_len < 4) ? (__builtin_constant_p ("ip") && ((size_t)(const void
>> > *)(("ip") + 1) - (size_t)(const void *)("ip") == 1) ? __builtin_strcmp
>> > (res->proto, "ip") : (__extension__ ({ const unsigned char *__s2 = (const
>> > unsigned char *) (const char *) ("ip"); int __result = (((const unsigned
>> > char *) (const char *) (res->proto))[0] - __s2[0]); if (__s1_len > 0 &&
>> > __result == 0) { __result = (((const unsigned char *) (const char *)
>> > (res->proto))[1] - __s2[1]); if (__s1_len > 1 && __result == 0) { __result
>> > = (((const unsigned char *) (const char *) (res->proto))[2] - __s2[2]); if
>> > (__s1_len > 2 && __result == 0) __result = (((const unsigned char *)
>> > (const char *) (res->proto))[3] - __s2[3]); } } __result; }))) :
>> > (__builtin_constant_p ("ip") && ((size_t)(const void *)(("ip") + 1) -
>> > (size_t)(const void *)("ip") == 1) && (__s2_len = __builtin_strlen ("ip"),
>> > __s2_len < 4) ? (__builtin_constant_p (res->proto) && ((size_t)(const void
>> > *)((res->proto) + 1) - (size_t)(const void *)(res->proto) == 1) ?
>> > __builtin_strcmp (res->proto, "ip") : (- (__extension__ ({ const unsigned
>> > char *__s2 = (const unsigned char *) (const char *) (res->proto); int
>> > __result = (((const unsigned char *) (const char *) ("ip"))[0] - __s2[0]);
>> > if (__s2_len > 0 && __result == 0) { __result = (((const unsigned char *)
>> > (const char *) ("ip"))[1] - __s2[1]); if (__s2_len > 1 && __result == 0) {
>> > __result = (((const unsigned char *) (const char *) ("ip"))[2] - __s2[2]);
>> > if (__s2_len > 2 && __result == 0) __result = (((const unsigned char *)
>> > (const char *) ("ip"))[3] - __s2[3]); } } __result; })))) :
>> > __builtin_strcmp (res->proto, "ip")))); })) {
>> >
>> >Here is the line of code for that one:
>> > if (!strcmp(res->proto, "ip")) {
>> >
>> >The ?Wno-parenthese-equality problem gives the output here:
>> >
>> >/work/home/rkwiles/projects/intel/dpdk/lib/librte_cmdline/cmdline_cirbuf.c:288:19:
>> > error: equality comparison with extraneous parentheses
>> >[-Werror,-Wparentheses-equality]
>> > if (((cbuf)->len == 0)) {
>> >
>> >The line is:
>> >
>> > if (CIRBUF_IS_EMPTY(cbuf)) {
>> >
>> >This one is in cmdline_cirbuf.h, which can be changed, but I do not think
>> >we need to remove the parenthese.
>> >
>> >I will look at some of other solution, so I rejected the patch.
>>
>> I found the problem to the compile errors I am seeing with building with
>> clang and shared libraries.
>>
>> The x86_64-linux-gnu/bits/string2.h header file if getting included from
>> string.h, but this would be mean __GNUC__ is defined and this is the clang
>> compiler. After much investigation it turns out ?ccache? is the problem
>> here. If ccache is enabled with clang builds the __GNUC__ is defined some
>> how, I never did find the location.
>>
>> Just a warning it appears ?ccache? for caching object files is not
>> compatible with DPDK builds ? in all cases.
>>
>Actually, I believe it's a more general ccache and clang problem, not DPDK
>specific.
>
>See e.g.
>http://petereisentraut.blogspot.com/2011/09/ccache-and-clang-part-2.html
>
>where the recommendation is to set "export CCACHE_CPP2=yes" in your
>environment.
>This cleared quite a number of issues for me (and others) when compiling with
>clang.
Adding the CCACHE_CPP2=yes
Cleaned up all of the compiler errors I was seeing ?
Do we need to document this in DPDK and if so where in the docs would someone
suggest it be placed?
>
>[Credit too to Ferruh who first pointed this issue out to me]
>
>/Bruce
>
