implicit declaration of function and undefined reference to - c

Question

About compile suricata.
In Makefile,when CFLAGS wrap "-Werror-implicit-function-declaration"
I got the error:
detect-engine-siggroup.c: In function ‘SigGroupHeadFree’:
detect-engine-siggroup.c:187:9: error: implicit declaration of function ‘_mm_free’ [-Werror=implicit-function-declaration]
SCFreeAligned(sgh->mask_array);
^
detect-engine-siggroup.c: In function ‘SigGroupHeadBuildHeadArray’:
detect-engine-siggroup.c:1715:5: error: implicit declaration of function ‘_mm_malloc’ [-Werror=implicit-function-declaration]
sgh->mask_array = (SignatureMask *)SCMallocAligned((cnt * sizeof(SignatureMask)), 16);
When I delete "-Werror-implicit-function-declaration" in Makefile,I will got the error:
detect-engine-siggroup.o: In function `SigGroupHeadFree':
/root/suricata/suricata-2.0.9/src/detect-engine-siggroup.c:187: undefined reference to `_mm_free'
detect-engine-siggroup.o: In function `SigGroupHeadBuildHeadArray':
/root/suricata/suricata-2.0.9/src/detect-engine-siggroup.c:1715: undefined reference to `_mm_malloc'
Note:_mm_free and _mm_malloc is define in util-mem.h
Yet,I add some code in the other source file,but not in detect-engine-siggroup.c and util-mem.h.
What's wrong?
in detect-engine-siggroup.c(note I have deleted some redundant code here):
void SigGroupHeadFree(SigGroupHead *sgh)
{
if (sgh == NULL)
return;
SCLogDebug("sgh %p", sgh);
PatternMatchDestroyGroup(sgh);
#if defined(__SSE3__) || defined(__tile__)
if (sgh->mask_array != NULL) {
/* mask is aligned */
SCFreeAligned(sgh->mask_array);
sgh->mask_array = NULL;
}
#endif
if (sgh->head_array != NULL) {
SCFree(sgh->head_array);
sgh->head_array = NULL;
}
if (sgh->match_array != NULL) {
detect_siggroup_matcharray_free_cnt++;
detect_siggroup_matcharray_memory -= (sgh->sig_cnt * sizeof(Signature *));
SCFree(sgh->match_array);
sgh->match_array = NULL;
}
sgh->sig_cnt = 0;
if (sgh->init != NULL) {
SigGroupHeadInitDataFree(sgh->init);
sgh->init = NULL;
}
SCFree(sgh);
detect_siggroup_head_free_cnt++;
detect_siggroup_head_memory -= sizeof(SigGroupHead);
return;
}
in util-mem.h(note I have deleted some redundant code here):
#ifndef __UTIL_MEM_H__
#define __UTIL_MEM_H__
#include "util-atomic.h"
#if CPPCHECK==1
#define SCMalloc malloc
#define SCCalloc calloc
#define SCRealloc realloc
#define SCFree free
#define SCStrdup strdup
#define SCMallocAligned _mm_malloc
#define SCFreeAligned _mm_free
#else /* CPPCHECK */
#if defined(_WIN32) || defined(__WIN32)
#include "mm_malloc.h"
#endif
#if defined(__tile__)
/* Need to define __mm_ function alternatives, since these are SSE only.
*/
#include <malloc.h>
#define _mm_malloc(a,b) memalign((b),(a))
#define _mm_free(a) free((a))
#endif /* defined(__tile__) */
SC_ATOMIC_EXTERN(unsigned int, engine_stage);
/* Use this only if you want to debug memory allocation and free()
* It will log a lot of lines more, so think that is a performance killer */
/* Uncomment this if you want to print memory allocations and free's() */
//#define DBG_MEM_ALLOC
#ifdef DBG_MEM_ALLOC
#define SCFree(a) ({ \
extern uint8_t print_mem_flag; \
if (print_mem_flag == 1) { \
SCLogInfo("SCFree at %p", (a)); \
} \
free((a)); \
})
#else /* !DBG_MEM_ALLOC */
#define SCFree(a) ({ \
free(a); \
})
#if defined(__WIN32) || defined(_WIN32)
#define SCFreeAligned(a) ({ \
_mm_free(a); \
})
#else /* !win */
#define SCFreeAligned(a) ({ \
_mm_free((a)); \
})
#endif /* __WIN32 */
#endif /* DBG_MEM_ALLOC */
#endif /* CPPCHECK */
#endif /* __UTIL_MEM_H__ */
#endif /* DBG_MEM_ALLOC */
#endif /* CPPCHECK */
#endif /* __UTIL_MEM_H__ */
/*********************************************************************/
Now solved the problem,reason is forgetting to #include <pmmintrin.h> /* for SSE3 */
/*********************************************************************/

Answer 1

It looks like you have not included util-mem.h properly. SCFreeAligned seem to expand to _mm_free, but _mm_free doesn't seem to expand. Looking at the header file the definition of _mm_free seem to be dependent on __title__ being defined.
Then the compiler just sees a call to _mm_free which is given an implicit prototype as _mm_free doesn't exist. Then of course _mm_free will not be found during linking.