New subject: [Monetdb-developers] [Monetdb-pf-checkins] pathfinder/compiler/mil milprint_summer.c, 1.367, 1.368

2 May 2007

I have great compilation troubles with the last lesson from the master:-) The 
compiler doesn not know the realloc() and the malloc() function() in the 
current setting. When I change them into PFrealloc() and PFmalloc() it 
compiles. But then I still have problems with the "free(buf);" line. There is 
no PFfree(); and I think GDKfree() will not always work,

JanF.

On Tuesday 01 May 2007 17:58, Sjoerd Mullender wrote:
...
Update of /cvsroot/monetdb/pathfinder/compiler/mil
In directory sc8-pr-cvs16:/tmp/cvs-serv17830
Modified Files:
  milprint_summer.c
Log Message:
When you want to use a library function, make sure the appropriate
include file is included.  For alloca there is an extra twist: for the
way to include alloca.h see e.g. monet_utils.mx.  Do not hide the lack
of a declaration with a cast.  The compiler then thinks the function
returns an int which may well be smaller in space than the actual
value, and hence some bytes of the value may get lost.
Having said this, alloca should *not* be used in a loop.  It allocates
memory in each iteration which is only freed at the end of the
function.  If the loop loops many times, that can be a lot of memory
which is allocated on the stack (which is a very finite resource!).
Here ends today's lesson.
Index: milprint_summer.c
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/compiler/mil/milprint_summer.c,v
retrieving revision 1.367
retrieving revision 1.368
diff -u -d -r1.367 -r1.368

--- milprint_summer.c	27 Apr 2007 18:22:40 -0000	1.367
+++ milprint_summer.c	1 May 2007 15:57:59 -0000	1.368
@@ -11140,12 +11140,18 @@
         /* ============================= */
         /* initialize function variables */
         /* ============================= */
+        size_t maxbufsize = 0;
+        char *buf = NULL;
         while (args->kind != c_nil)
         {
             /* get the type name, and assure there *is* a namespace */
             char *tpe = PFty_str(TY(LR(args)));
-            char *buf = (char*) alloca(4+strlen(tpe));
-            char *nme = buf;
+            char *nme;
+            if (maxbufsize < strlen(tpe) + 4) {
+                maxbufsize = strlen(tpe) + 4;
+                buf = buf ? realloc(buf, maxbufsize) : malloc(maxbufsize);
+            }
+            nme = buf;
             if (strchr(tpe, ':') == NULL)  {
                 *buf++ = 'x';
                 *buf++ = 's';
@@ -11171,6 +11177,8 @@
args = R(args);
         }
+        if (buf)
+            free(buf);
         /* create the full signature that also is a valid MIL identifier
*/ c->sem.fun->sig = PFmalloc(12+3*(strlen(sig)+strlen(p)));
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Re: [Monetdb-developers] [Monetdb-pf-checkins] pathfinder/compiler/mil milprint_summer.c, 1.367, 1.368

Jan Flokstra

Fabian Groffen

Sjoerd Mullender

Sjoerd Mullender

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participants (3)