This properly tells the CFG manipulation of the case where we thread
through a loop exit - the duplicated header block will end up in the
outer loop and the original loop structure will be preserved.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2012-04-10 Richard Guenther <rguent...@suse.de>
PR tree-optimization/52912
* tree-ssa-threadupdate.c (thread_block): Tell the cfg
manipulation code we are threading through a loop header
to an exit destination.
* gcc.dg/torture/pr52912.c: New testcase.
Index: gcc/tree-ssa-threadupdate.c
===================================================================
*** gcc/tree-ssa-threadupdate.c (revision 186274)
--- gcc/tree-ssa-threadupdate.c (working copy)
*************** thread_block (basic_block bb, bool noloo
*** 661,666 ****
--- 661,673 ----
/* We do not update dominance info. */
free_dominance_info (CDI_DOMINATORS);
+ /* We know we only thread through the loop header to loop exits.
+ Let the basic block duplication hook know we are not creating
+ a multiple entry loop. */
+ if (noloop_only
+ && bb == bb->loop_father->header)
+ set_loop_copy (bb->loop_father, loop_outer (bb->loop_father));
+
/* Now create duplicates of BB.
Note that for a block with a high outgoing degree we can waste
*************** thread_block (basic_block bb, bool noloo
*** 692,697 ****
--- 699,708 ----
htab_delete (redirection_data);
redirection_data = NULL;
+ if (noloop_only
+ && bb == bb->loop_father->header)
+ set_loop_copy (bb->loop_father, NULL);
+
/* Indicate to our caller whether or not any jumps were threaded. */
return local_info.jumps_threaded;
}
Index: gcc/testsuite/gcc.dg/torture/pr52912.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr52912.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr52912.c (revision 0)
***************
*** 0 ****
--- 1,18 ----
+ /* { dg-do compile } */
+
+ int a, b, c;
+ static int
+ fn1 (p1)
+ {
+ lbl_549:
+ if (p1)
+ goto lbl_549;
+ return 0;
+ }
+
+ void
+ fn2 ()
+ {
+ b = (c && a) > fn1 (c) >= c;
+ }
+
