Automerge.

configure.in

@@ -825,7 +825,7 @@ AC_TYPE_SIZE_T
 AC_HEADER_DIRENT
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS(fcntl.h float.h floatingpoint.h ieeefp.h limits.h \
+AC_CHECK_HEADERS(fcntl.h fenv.h float.h floatingpoint.h ieeefp.h limits.h \
  memory.h pwd.h select.h \
  stdlib.h stddef.h \
  strings.h string.h synch.h sys/mman.h sys/socket.h netinet/in.h arpa/inet.h \
@@ -2060,7 +2060,7 @@ AC_FUNC_UTIME_NULL
 AC_FUNC_VPRINTF
 
 AC_CHECK_FUNCS(alarm bcmp bfill bmove bzero chsize cuserid fchmod fcntl \
-  fconvert fdatasync finite fpresetsticky fpsetmask fsync ftruncate \
+  fconvert fdatasync fesetround finite fpresetsticky fpsetmask fsync ftruncate \
   getcwd gethostbyaddr_r gethostbyname_r getpass getpassphrase getpwnam \
   getpwuid getrlimit getrusage getwd gmtime_r index initgroups isnan \
   localtime_r locking longjmp lrand48 madvise mallinfo memcpy memmove \

include/config-win.h

@@ -31,7 +31,6 @@ functions */
 
 #include <sys/locking.h>
 #include <windows.h>
-#include <math.h>			/* Because of rint() */
 #include <fcntl.h>
 #include <io.h>
 #include <malloc.h>
@@ -223,13 +222,6 @@ typedef uint rf_SetTimer;
 #define inline __inline
 #endif /* __cplusplus */
 
-inline double rint(double nr)
-{
-  double f = floor(nr);
-  double c = ceil(nr);
-  return (((c-nr) >= (nr-f)) ? f :c);
-}
-
 #ifdef _WIN64
 #define ulonglong2double(A) ((double) (ulonglong) (A))
 #define my_off_t2double(A)  ((double) (my_off_t) (A))
@@ -281,7 +273,6 @@ inline ulonglong double2ulonglong(double d)
 #define HAVE_FLOAT_H
 #define HAVE_LIMITS_H
 #define HAVE_STDDEF_H
-#define HAVE_RINT		/* defined in this file */
 #define NO_FCNTL_NONBLOCK	/* No FCNTL */
 #define HAVE_ALLOCA
 #define HAVE_STRPBRK

include/my_global.h

@@ -484,8 +484,39 @@ typedef unsigned short ushort;
 #define set_bits(type, bit_count) (sizeof(type)*8 <= (bit_count) ? ~(type) 0 : ((((type) 1) << (bit_count)) - (type) 1))
 #define array_elements(A) ((uint) (sizeof(A)/sizeof(A[0])))
 #ifndef HAVE_RINT
-#define rint(A) floor((A)+(((A) < 0)? -0.5 : 0.5))
-#endif
+/**
+   All integers up to this number can be represented exactly as double precision
+   values (DBL_MANT_DIG == 53 for IEEE 754 hardware).
+*/
+#define MAX_EXACT_INTEGER ((1LL << DBL_MANT_DIG) - 1)
+
+/**
+   rint(3) implementation for platforms that do not have it.
+   Always rounds to the nearest integer with ties being rounded to the nearest
+   even integer to mimic glibc's rint() behavior in the "round-to-nearest"
+   FPU mode. Hardware-specific optimizations are possible (frndint on x86).
+   Unlike this implementation, hardware will also honor the FPU rounding mode.
+*/
+
+static inline double rint(double x)
+{
+  double f, i;
+  f = modf(x, &i);
+  /*
+    All doubles with absolute values > MAX_EXACT_INTEGER are even anyway,
+    no need to check it.
+  */
+  if (x > 0.0)
+    i += (double) ((f > 0.5) || (f == 0.5 &&
+                                 i <= (double) MAX_EXACT_INTEGER &&
+                                 (longlong) i % 2));
+  else
+    i -= (double) ((f < -0.5) || (f == -0.5 &&
+                                  i >= (double) -MAX_EXACT_INTEGER &&
+                                  (longlong) i % 2));
+  return i;
+}
+#endif /* HAVE_RINT */
 
 /* Define some general constants */
 #ifndef TRUE

mysql-test/r/func_math.result

@@ -360,4 +360,34 @@ SELECT a DIV 2 FROM t1 UNION SELECT a DIV 2 FROM t1;
 a DIV 2
 0
 DROP TABLE t1;
+CREATE TABLE t1 (a DOUBLE);
+INSERT INTO t1 VALUES (-1.1), (1.1),
+(-1.5), (1.5),
+(-1.9), (1.9),
+(-2.1), (2.1),
+(-2.5), (2.5),
+(-2.9), (2.9),
+# Check numbers with absolute values > 2^53 - 1 
+# (see comments for MAX_EXACT_INTEGER)
+(-1e16 - 0.5), (1e16 + 0.5),
+(-1e16 - 1.5), (1e16 + 1.5);
+SELECT a, ROUND(a) FROM t1;
+a	ROUND(a)
+-1.1	-1
+1.1	1
+-1.5	-2
+1.5	2
+-1.9	-2
+1.9	2
+-2.1	-2
+2.1	2
+-2.5	-2
+2.5	2
+-2.9	-3
+2.9	3
+-1e+16	-10000000000000000
+1e+16	10000000000000000
+-1e+16	-10000000000000002
+1e+16	10000000000000002
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/func_math.test

@@ -229,5 +229,25 @@ INSERT INTO t1 VALUES ('a');
 SELECT a DIV 2 FROM t1 UNION SELECT a DIV 2 FROM t1;
 DROP TABLE t1;
 
+#
+# Bug #15936: "round" differs on Windows to Unix
+#
+
+CREATE TABLE t1 (a DOUBLE);
+
+INSERT INTO t1 VALUES (-1.1), (1.1),
+                      (-1.5), (1.5),
+                      (-1.9), (1.9),
+                      (-2.1), (2.1),
+                      (-2.5), (2.5),
+                      (-2.9), (2.9),
+# Check numbers with absolute values > 2^53 - 1 
+# (see comments for MAX_EXACT_INTEGER)
+                      (-1e16 - 0.5), (1e16 + 0.5),
+                      (-1e16 - 1.5), (1e16 + 1.5);
+
+SELECT a, ROUND(a) FROM t1;
+
+DROP TABLE t1;
 
 --echo End of 5.0 tests

sql/mysqld.cc

@@ -186,39 +186,44 @@ int initgroups(const char *,unsigned int);
 #ifdef HAVE_FP_EXCEPT				// Fix type conflict
 typedef fp_except fp_except_t;
 #endif
+#endif /* __FreeBSD__ && HAVE_IEEEFP_H */
+#ifdef HAVE_FENV_H
+#include <fenv.h>
+#endif
+#ifdef HAVE_SYS_FPU_H
+/* for IRIX to use set_fpc_csr() */
+#include <sys/fpu.h>
+#endif
 
+inline void setup_fpu()
+{
+#if defined(__FreeBSD__) && defined(HAVE_IEEEFP_H)
   /* We can't handle floating point exceptions with threads, so disable
      this on freebsd
+     Don't fall for overflow, underflow,divide-by-zero or loss of precision
   */
-
-inline void set_proper_floating_point_mode()
-{
-  /* Don't fall for overflow, underflow,divide-by-zero or loss of precision */
 #if defined(__i386__)
   fpsetmask(~(FP_X_INV | FP_X_DNML | FP_X_OFL | FP_X_UFL | FP_X_DZ |
 	      FP_X_IMP));
 #else
   fpsetmask(~(FP_X_INV |             FP_X_OFL | FP_X_UFL | FP_X_DZ |
               FP_X_IMP));
-#endif
-}
-#elif defined(__sgi)
-/* for IRIX to use set_fpc_csr() */
-#include <sys/fpu.h>
+#endif /* __i386__ */
+#endif /* __FreeBSD__ && HAVE_IEEEFP_H */
 
-inline void set_proper_floating_point_mode()
-{
+#ifdef HAVE_FESETROUND
+    /* Set FPU rounding mode to "round-to-nearest" */
+  fesetround(FE_TONEAREST);
+#endif /* HAVE_FESETROUND */
+    
+#if defined(__sgi) && defined(HAVE_SYS_FPU_H)
   /* Enable denormalized DOUBLE values support for IRIX */
-  {
   union fpc_csr n;
   n.fc_word = get_fpc_csr();
   n.fc_struct.flush = 0;
   set_fpc_csr(n.fc_word);
-  }
+#endif
 }
-#else
-#define set_proper_floating_point_mode()
-#endif /* __FreeBSD__ && HAVE_IEEEFP_H */
 
 } /* cplusplus */
 
@@ -3279,7 +3284,7 @@ static int init_server_components()
   query_cache_init();
   query_cache_resize(query_cache_size);
   randominit(&sql_rand,(ulong) server_start_time,(ulong) server_start_time/2);
-  set_proper_floating_point_mode();
+  setup_fpu();
   init_thr_lock();
 #ifdef HAVE_REPLICATION
   init_slave_list();