Once again the vectorizer isn't prepared to vectorize dead code.
Fortunately in this case it's easy to fix - just remove the assert
that triggers and continue doing nothing for the non-existing
use of the reduction result.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2013-08-30 Richard Biener <rguent...@suse.de>
PR tree-optimization/58010
* tree-vect-loop.c (vect_create_epilog_for_reduction): Remove
assert that we have a loop-closed PHI.
* gcc.dg/pr58010.c: New testcase.
Index: gcc/tree-vect-loop.c
===================================================================
*** gcc/tree-vect-loop.c (revision 202068)
--- gcc/tree-vect-loop.c (working copy)
*************** vect_finalize_reduction:
*** 4373,4381 ****
if (!flow_bb_inside_loop_p (loop, gimple_bb (USE_STMT (use_p))))
phis.safe_push (USE_STMT (use_p));
! /* We expect to have found an exit_phi because of loop-closed-ssa
! form. */
! gcc_assert (!phis.is_empty ());
FOR_EACH_VEC_ELT (phis, i, exit_phi)
{
--- 4373,4380 ----
if (!flow_bb_inside_loop_p (loop, gimple_bb (USE_STMT (use_p))))
phis.safe_push (USE_STMT (use_p));
! /* While we expect to have found an exit_phi because of loop-closed-ssa
! form we can end up without one if the scalar cycle is dead. */
FOR_EACH_VEC_ELT (phis, i, exit_phi)
{
Index: gcc/testsuite/gcc.dg/pr58010.c
===================================================================
*** gcc/testsuite/gcc.dg/pr58010.c (revision 0)
--- gcc/testsuite/gcc.dg/pr58010.c (working copy)
***************
*** 0 ****
--- 1,15 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -funswitch-loops -ftree-vectorize" } */
+
+ short a, b, c, d;
+
+ void f(void)
+ {
+ short e;
+
+ for(; e; e++)
+ for(; b; b++);
+
+ for(d = 0; d < 4; d++)
+ a ^= (e ^= 1) || c ? : e;
+ }
