isl_scheduler.c: graph_find_compressed_node: look up node in correct …

…graph

The function graph_find_compressed_node has a fail-safe that checks
that the pointer recorded in the isl_id actually corresponds
to a node in the graph.  However, it failed to take into account
that the pointer refers to the original dependence graph,
while the graph in which the node is looked up may be subgraph
(with different node pointers).
Check that the node is valid for the original graph rather than
the current graph and if the current graph is not the same as
the original graph, then look up the corresponding node in
the current graph.

The new test case is different from the one that was
reported by Michael Kruse because the latter does not
appear to have a valid solution.
The test case is checked using the isl_schedule (and isl_schedule_cmp)
application(s) because it is easier to introduce test cases this way
(both the current test case and any future scheduling test cases).

Reported-by: Michael Kruse <[email protected]>
Signed-off-by: Sven Verdoolaege <[email protected]>

Makefile.am

@@ -14,7 +14,7 @@ noinst_PROGRAMS = isl_test isl_polyhedron_sample isl_pip \
 	isl_closure isl_bound isl_schedule isl_codegen isl_test_int \
 	isl_flow isl_flow_cmp isl_schedule_cmp
 TESTS = isl_test codegen_test.sh pip_test.sh bound_test.sh isl_test_int \
-	flow_test.sh
+	flow_test.sh schedule_test.sh
 
 if IMATH_FOR_MP
 

configure.ac

@@ -36,7 +36,9 @@ CXX11FLAGS=${CXX#$ac_save_CXX}
 CXX="$ac_save_CXX"
 CXXCPP="$ac_save_CXXCPP"
 
+AC_PROG_GREP
 AC_PROG_LIBTOOL
+AC_PROG_SED
 
 AC_CHECK_PROG(PERL, perl, perl, [])
 AC_CHECK_PROG(PDFLATEX, pdflatex, pdflatex, [])
@@ -138,6 +140,7 @@ AC_CONFIG_FILES([bound_test.sh], [chmod +x bound_test.sh])
 AC_CONFIG_FILES([codegen_test.sh], [chmod +x codegen_test.sh])
 AC_CONFIG_FILES([pip_test.sh], [chmod +x pip_test.sh])
 AC_CONFIG_FILES([flow_test.sh], [chmod +x flow_test.sh])
+AC_CONFIG_FILES([schedule_test.sh], [chmod +x schedule_test.sh])
 AC_CONFIG_COMMANDS_POST([
 	dnl pass on arguments to subdir configures, but don't
 	dnl add them to config.status

isl_scheduler.c

@@ -3874,6 +3874,10 @@ static void isl_carry_clear(struct isl_carry *carry)
  * If so, return that node.
  * Otherwise, "space" was constructed by construct_compressed_id and
  * contains a user pointer pointing to the node in the tuple id.
+ * However, this node belongs to the original dependence graph.
+ * If "graph" is a subgraph of this original dependence graph,
+ * then the node with the same space still needs to be looked up
+ * in the current graph.
  */
 static struct isl_sched_node *graph_find_compressed_node(isl_ctx *ctx,
 	struct isl_sched_graph *graph, __isl_keep isl_space *space)
@@ -3895,9 +3899,11 @@ static struct isl_sched_node *graph_find_compressed_node(isl_ctx *ctx,
 	if (!node)
 		return NULL;
 
-	if (!is_node(graph, node))
+	if (!is_node(graph->root, node))
 		isl_die(ctx, isl_error_internal,
 			"space points to invalid node", return NULL);
+	if (graph != graph->root)
+		node = graph_find_node(ctx, graph, node->space);
 
 	return node;
 }

schedule_test.sh.in

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+EXEEXT=@EXEEXT@
+GREP=@GREP@
+SED=@SED@
+srcdir=@srcdir@
+
+failed=0
+
+for i in $srcdir/test_inputs/schedule/*.sc; do
+	echo $i;
+	base=`basename $i .sc`
+	test=test-$base.st
+	dir=`dirname $i`
+	ref=$dir/$base.st
+	options=`$GREP 'OPTIONS:' $i | $SED 's/.*://'`
+	(./isl_schedule$EXEEXT $options < $i > $test &&
+	./isl_schedule_cmp$EXEEXT $ref $test && rm $test) || failed=1
+done
+
+test $failed -eq 0 || exit

test_inputs/schedule/feautrier_compressed.sc

@@ -0,0 +1,5 @@
+# Check that the Feautrier schedule is not confused by
+# compressed nodes in a subgraph of the original dependence graph.
+# OPTIONS: --schedule-algorithm=feautrier
+domain: { A[]; B[0]; C[] }
+validity: { A[] -> B[0] }

test_inputs/schedule/feautrier_compressed.st

@@ -0,0 +1,11 @@
+domain: "{ B[0]; C[]; A[] }"
+child:
+  set:
+  - filter: "{ B[i0]; A[] }"
+    child:
+      schedule: "[{ B[i0] -> [(1)]; A[] -> [(0)] }]"
+      child:
+        set:
+        - filter: "{ A[] }"
+        - filter: "{ B[i0] }"
+  - filter: "{ C[] }"