[PATCH] Fix PR85615
Richard Biener
rguenther@suse.de
Thu May 3 13:18:00 GMT 2018
We're threading into a loop across an inner exit.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2018-05-03 Richard Biener <rguenther@suse.de>
PR tree-optimization/85615
* tree-ssa-threadupdate.c (thread_block_1): Only allow exits
to loops not nested in BBs loop father to avoid creating multi-entry
loops.
* gcc.dg/torture/pr85615.c: New testcase.
Index: gcc/tree-ssa-threadupdate.c
===================================================================
--- gcc/tree-ssa-threadupdate.c (revision 259879)
+++ gcc/tree-ssa-threadupdate.c (working copy)
@@ -1309,7 +1309,9 @@ thread_block_1 (basic_block bb, bool nol
and thread this elsewhere, so just cancel the jump threading
request by clearing the AUX field now. */
if (bb->loop_father != e2->src->loop_father
- && !loop_exit_edge_p (e2->src->loop_father, e2))
+ && (!loop_exit_edge_p (e2->src->loop_father, e2)
+ || flow_loop_nested_p (bb->loop_father,
+ e2->dest->loop_father)))
{
/* Since this case is not handled by our special code
to thread through a loop header, we must explicitly
Index: gcc/testsuite/gcc.dg/torture/pr85615.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr85615.c (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr85615.c (working copy)
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+
+long a, d;
+int b, c;
+void fn1()
+{
+ int e = -1L, f = 2, g = 8;
+ for (;;)
+ {
+ for (; b; g++)
+ ;
+ int i;
+ for (; c;)
+ {
+ i = 5;
+ for (; e >= 1; i--)
+ ;
+ }
+ d = f ?: a;
+ if (d)
+ {
+ e = 0;
+ for (; i;)
+ for (; g < 3; f++)
+ ;
+ }
+ }
+}
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