Changeset: fa96b6359cf5 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=fa96b6359cf5
Modified Files:
MonetDB5/src/mal/mal_interpreter.mx
Branch: default
Log Message:
Refine dataflow processing
Repeated assignments to the same variable should block subsequent use.
diffs (57 lines):
diff -r 1f76cdad9704 -r fa96b6359cf5 MonetDB5/src/mal/mal_interpreter.mx
--- a/MonetDB5/src/mal/mal_interpreter.mx Wed Sep 01 22:17:17 2010 +0200
+++ b/MonetDB5/src/mal/mal_interpreter.mx Thu Sep 02 21:37:25 2010 +0200
@@ -1212,11 +1212,27 @@
}
GDKfree(assign);
}
-
+...@-
+The liberal use of MAL to construct programs complicate proper dataflow
+dependency analysis. For example, consider the following fragment of
+a remote execution
+...@verbatim
+barrier go:=language.dataflow()
+con:= remote.connect(...)
+res:= remote.put(con, v:int)
+inp:= remote.put(con, i:int)
+res:= remote.exe(con,m,f,inp);
+ans:= remote.get(con,res)
+exit go
+...@end verbatim
+Naive interpretation could lead to execution of either 'res:=' operation in
non-determined order.
+Moreover, the result 'ans:' should be obtained after the corresponding 'res:='
has been executed.
+...@c
static int
DFLOWeligible(DataFlow flow, FlowStep fs, int i, InstrPtr p, int pc)
{
- int j, blocked = 0;
+ int j, k, l, blocked = 0;
+ InstrPtr q;
(void) pc;
for(j=0; j<p->argc && !blocked; j++) {
@@ -1228,12 +1244,22 @@
if ( getEndOfLife(flow->mb,getArg(p,j)) == fs[i].pc ) {
/* make sure all instructions interested have already
been executed */
/* and the eoscope variables are not used anymore */
- int k;
blocked += flow->inuse[getArg(p,j)] != 0;
for ( k=0; k < i && !blocked; k++)
if (fs[k].status != DFLOWwrapup && fs[k].pc >= 0 ) /*
pc = -1 could be the case before wrapup is set*/
blocked += !isNotUsedIn(getInstrPtr(flow->mb,
fs[k].pc), 0, getArg(p,j));
+ } else {
+ /* handle the dependencies sketched above */
+ /* search the statement that assigns a value to the
argument or target */
+ /* it should have been finished already */
+ for (l = i-1 ; l >= 0 && !blocked; l--)
+ if ( fs[l].status != DFLOWwrapup){
+ q= getInstrPtr(flow->mb, fs[l].pc);
+ for ( k=0; k < q->retc && !blocked; k++)
+ if ( getArg(q,k) == getArg(p,j) )
+ blocked = 1;
+ }
}
}
return blocked == 0;
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