Fix for bug #31207: Test "join_nested" shows different strategy on IA64

CPUs / Intel's ICC compile

The bug is a combination of two problems:

1. IA64/ICC MySQL binaries use glibc's qsort(), not the one in mysys.

2. The order relation implemented by join_tab_cmp() is not transitive,
i.e. it is possible to choose such a, b and c that (a < b) && (b < c)
but (c < a). This implies that result of a sort using the relation
implemented by join_tab_cmp() depends on the order in which
elements are compared, i.e. the result is implementation-specific. Since
choose_plan() uses qsort() to pre-sort the
join tables using join_tab_cmp() as a compare function, the results of
the sorting may vary depending on qsort() implementation.

It is neither possible nor important to implement a better ordering
algorithm in join_tab_cmp(). Therefore the only way to fix it is to
force our own qsort() to be used by renaming it to my_qsort(), so we don't depend
on linker to decide that.

This patch also "fixes" bug #20530: qsort redefinition violates the
standard.

5 files changed, 9 insertions, 9 deletions

diff --git a/mysys/mf_keycache.c b/mysys/mf_keycache.c
index 83363e6960d..baf3bffccb8 100644
--- a/mysys/mf_keycache.c
+++ b/mysys/mf_keycache.c
@@ -2268,7 +2268,7 @@ static int flush_cached_blocks(KEY_CACHE *keycache,
      As all blocks referred in 'cache' are marked by BLOCK_IN_FLUSH
      we are guarunteed no thread will change them
   */
-  qsort((byte*) cache, count, sizeof(*cache), (qsort_cmp) cmp_sec_link);
+  my_qsort((byte*) cache, count, sizeof(*cache), (qsort_cmp) cmp_sec_link);
 
   keycache_pthread_mutex_lock(&keycache->cache_lock);
   for ( ; cache != end ; cache++)
diff --git a/mysys/mf_qsort.c b/mysys/mf_qsort.c
index 3d52d56c952..4b3ecb603a6 100644
--- a/mysys/mf_qsort.c
+++ b/mysys/mf_qsort.c
@@ -91,10 +91,10 @@ typedef struct st_stack
 *****************************************************************************/
 
 #ifdef QSORT_EXTRA_CMP_ARGUMENT
-qsort_t qsort2(void *base_ptr, size_t count, size_t size, qsort2_cmp cmp,
+qsort_t my_qsort2(void *base_ptr, size_t count, size_t size, qsort2_cmp cmp,
 	       void *cmp_argument)
 #else
-qsort_t qsort(void *base_ptr, size_t count, size_t size, qsort_cmp cmp)
+qsort_t my_qsort(void *base_ptr, size_t count, size_t size, qsort_cmp cmp)
 #endif
 {
   char *low, *high, *pivot;
diff --git a/mysys/mf_sort.c b/mysys/mf_sort.c
index e7fd6873eee..a0c74642cb0 100644
--- a/mysys/mf_sort.c
+++ b/mysys/mf_sort.c
@@ -35,7 +35,7 @@ void my_string_ptr_sort(void *base, uint items, size_s size)
     if (size && items)
     {
       uint size_arg=size;
-      qsort2(base,items,sizeof(byte*),get_ptr_compare(size),(void*) &size_arg);
+      my_qsort2(base,items,sizeof(byte*),get_ptr_compare(size),(void*) &size_arg);
     }
   }
 }
diff --git a/mysys/my_lib.c b/mysys/my_lib.c
index 61de4ff9065..a076a0c971d 100644
--- a/mysys/my_lib.c
+++ b/mysys/my_lib.c
@@ -187,7 +187,7 @@ MY_DIR	*my_dir(const char *path, myf MyFlags)
   result->number_off_files= dir_entries_storage->elements;
   
   if (!(MyFlags & MY_DONT_SORT))
-    qsort((void *) result->dir_entry, result->number_off_files,
+    my_qsort((void *) result->dir_entry, result->number_off_files,
           sizeof(FILEINFO), (qsort_cmp) comp_names);
   DBUG_RETURN(result);
 
@@ -498,7 +498,7 @@ MY_DIR	*my_dir(const char *path, myf MyFlags)
   result->number_off_files= dir_entries_storage->elements;
 
   if (!(MyFlags & MY_DONT_SORT))
-    qsort((void *) result->dir_entry, result->number_off_files,
+    my_qsort((void *) result->dir_entry, result->number_off_files,
           sizeof(FILEINFO), (qsort_cmp) comp_names);
   DBUG_PRINT("exit", ("found %d files", result->number_off_files));
   DBUG_RETURN(result);
@@ -605,7 +605,7 @@ MY_DIR	*my_dir(const char* path, myf MyFlags)
   result->number_off_files= dir_entries_storage->elements;
   
   if (!(MyFlags & MY_DONT_SORT))
-    qsort((void *) result->dir_entry, result->number_off_files,
+    my_qsort((void *) result->dir_entry, result->number_off_files,
           sizeof(FILEINFO), (qsort_cmp) comp_names);
   DBUG_RETURN(result);
 
diff --git a/mysys/queues.c b/mysys/queues.c
index 7809c97131c..6b88420a1cd 100644
--- a/mysys/queues.c
+++ b/mysys/queues.c
@@ -250,6 +250,6 @@ static int queue_fix_cmp(QUEUE *queue, void **a, void **b)
 
 void queue_fix(QUEUE *queue)
 {
-  qsort2(queue->root+1,queue->elements, sizeof(void *),
-	 (qsort2_cmp)queue_fix_cmp, queue);
+  my_qsort2(queue->root+1,queue->elements, sizeof(void *),
+            (qsort2_cmp)queue_fix_cmp, queue);
 }