Hello,
This ICE comes from the ix86_dependencies_evaluation_hook code assumption
that any scheduling region will be connected. This assumption is not
correct in case of the outer loops pipelining of the selective scheduler as
explained in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60901#c3.
Trying to add dependencies between insns from the different scheduling
regions results in a segfault within the dependency analyzer code.
The fix is to adjust the code to account for the situation when basic
block's predecessors do not belong to the same scheduling region.
Bootstrapped and tested on x86-64, OK for trunk? Branches? The fix is low
risk as the additional test should always be true for the regular scheduler.
Yours,
Andrey
gcc/
2014-05-14 Andrey Belevantsev <a...@ispras.ru>
PR rtl-optimization/60901
* config/i386/i386.c (ix86_dependencies_evaluation_hook): Check that bb
predecessor belongs to the same scheduling region. Adjust comment.
testsuite/
2014-05-14 Andrey Belevantsev <a...@ispras.ru>
PR rtl-optimization/60901
* gcc.dg/pr60901.c: New test.
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 99f0657..0274288 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -26254,13 +26254,17 @@ ix86_dependencies_evaluation_hook (rtx head, rtx tail)
{
edge e;
edge_iterator ei;
- /* Assume that region is SCC, i.e. all immediate predecessors
- of non-head block are in the same region. */
+
+ /* Regions are SCCs with the exception of selective
+ scheduling with pipelining of outer blocks enabled.
+ So also check that immediate predecessors of a non-head
+ block are in the same region. */
FOR_EACH_EDGE (e, ei, bb->preds)
{
/* Avoid creating of loop-carried dependencies through
- using topological odering in region. */
- if (BLOCK_TO_BB (bb->index) > BLOCK_TO_BB (e->src->index))
+ using topological ordering in the region. */
+ if (rgn == CONTAINING_RGN (e->src->index)
+ && BLOCK_TO_BB (bb->index) > BLOCK_TO_BB (e->src->index))
add_dependee_for_func_arg (first_arg, e->src);
}
}
diff --git a/gcc/testsuite/gcc.dg/pr60901.c b/gcc/testsuite/gcc.dg/pr60901.c
new file mode 100644
index 0000000..1350f16
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr60901.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target powerpc*-*-* ia64-*-* x86_64-*-* } } */
+/* { dg-options "-O -fselective-scheduling -fschedule-insns -fsel-sched-pipelining -fsel-sched-pipelining-outer-loops -fno-tree-dominator-opts" } */
+
+extern int n;
+extern void bar (void);
+extern int baz (int);
+
+void
+foo (void)
+{
+ int i, j;
+ for (j = 0; j < n; j++)
+ {
+ for (i = 1; i < j; i++)
+ bar ();
+ baz (0);
+ }
+}
