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@dpdk.org on behalf of keith.wiles@intel.com> wrote:

quoted

On 6/27/16, 3:46 AM, "Richardson, Bruce" [off-list ref] wrote:

quoted

On Sun, Jun 26, 2016 at 10:54:12AM -0500, Keith Wiles wrote:

quoted

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 <redacted>
---
 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.

[Credit too to Ferruh who first pointed this issue out to me]

/Bruce