Add the SQLITE_HAVE_ISNAN compile-time option which, if present, causes

SQLite to use the math library isnan() function rather than its own homebrew
implementation of isnan(). (CVS 6517)

FossilOrigin-Name: 54d23521c37938b9d98f41f5547975c469c0c8f0

manifest

@@ -1,5 +1,5 @@
-C Check-in\s(6514)\sdid\snot\scompletely\sremove\sthe\sobsolete\stest,\sresulting\sin\sa\nsegfault.\s\sThis\scheck-in\sfinishes\sthe\sjob.\s\sTicket\s#3802.\s(CVS\s6516)
-D 2009-04-17T11:56:28
+C Add\sthe\sSQLITE_HAVE_ISNAN\scompile-time\soption\swhich,\sif\spresent,\scauses\nSQLite\sto\suse\sthe\smath\slibrary\sisnan()\sfunction\srather\sthan\sits\sown\shomebrew\nimplementation\sof\sisnan().\s(CVS\s6517)
+D 2009-04-17T11:57:22
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 583e87706abc3026960ed759aff6371faf84c211
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -198,7 +198,7 @@ F src/tokenize.c 7bd3b6dd56566604ad24ed4aa017e6618166b500
 F src/trigger.c 21f39db410cdc32166a94900ac1b3df98ea560e6
 F src/update.c 8ededddcde6f7b6da981dd0429a5d34518a475b7
 F src/utf.c 9541d28f40441812c0b40f00334372a0542c00ff
-F src/util.c 469d74f5bf09ed6398702c7da2ef8a34e979a1c1
+F src/util.c 3990f949a4a0fbdd62552ee34b4d22aec7910305
 F src/vacuum.c 07121a727beeee88f27d704a00313ad6a7c9bef0
 F src/vdbe.c 88bc70921ccdcff8bfdf574f3e2285d17ab97103
 F src/vdbe.h 35a648bc3279a120da24f34d9a25213ec15daf8a
@@ -717,7 +717,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P fbbc80eaf3bb3726b053d1050104b4ec602eb0c1
-R c8bde6c6b0390f10634d507d904faa5d
+P c29b37ea36fe6a360807e66dffc467c66be00d38
+R 247ae40bc2309c99608c794edcff5bc4
 U drh
-Z 8e3db78cb71447734b970da6417db69a
+Z da2ba0741571881997e395a38a2e00f8

manifest.uuid

@@ -1 +1 @@
-c29b37ea36fe6a360807e66dffc467c66be00d38
+54d23521c37938b9d98f41f5547975c469c0c8f0

src/util.c

@@ -14,10 +14,11 @@
 ** This file contains functions for allocating memory, comparing
 ** strings, and stuff like that.
 **
-** $Id: util.c,v 1.249 2009/03/01 22:29:20 drh Exp $
+** $Id: util.c,v 1.250 2009/04/17 11:57:22 drh Exp $
 */
 #include "sqliteInt.h"
 #include <stdarg.h>
+#include <math.h>
 
 /*
 ** Routine needed to support the testcase() macro.
@@ -52,9 +53,19 @@ int sqlite3Assert(void){
 
 /*
 ** Return true if the floating point value is Not a Number (NaN).
+**
+** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
+** Otherwise, we have our own implementation that works on most systems.
 */
 int sqlite3IsNaN(double x){
-  /* This NaN test sometimes fails if compiled on GCC with -ffast-math.
+#if defined(SQLITE_HAVE_ISNAN)
+  /*
+  ** Systems that support the isnan() library function should probably
+  ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
+  ** found that many systems do not have a working isnan() function so
+  ** this implementation is provided as an alternative.
+  **
+  ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
   ** On the other hand, the use of -ffast-math comes with the following
   ** warning:
   **
@@ -77,6 +88,9 @@ int sqlite3IsNaN(double x){
   volatile double y = x;
   volatile double z = y;
   return y!=z;
+#else  /* if defined(SQLITE_HAVE_ISNAN) */
+  return isnan(x);
+#endif /* SQLITE_HAVE_ISNAN */
 }
 
 /*