[PATCH] Fix(?) PR66002

[Richard Biener <rguenther@suse.de>]

This fixes a missed vectorization of a function in paq8p.  Without
merged PHI nodes phiopt doesn't recognize adjacent MIN/MAX_EXPRs.
Certainly no other pass I schedule mergephi over cares for merged
PHIs (DCE might even be confused here).

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2015-05-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66002
	* passes.def: Schedule pass_merge_phi after VRP, right before
	ifcombine and phiopt.

	* gcc.dg/vect/vect-125.c: New testcase.

Index: gcc/passes.def
===================================================================
*** gcc/passes.def	(revision 222760)
--- gcc/passes.def	(working copy)
*************** along with GCC; see the file COPYING3.
*** 168,174 ****
        NEXT_PASS (pass_build_alias);
        NEXT_PASS (pass_return_slot);
        NEXT_PASS (pass_fre);
-       NEXT_PASS (pass_merge_phi);
        NEXT_PASS (pass_vrp);
        NEXT_PASS (pass_chkp_opt);
        NEXT_PASS (pass_dce);
--- 168,173 ----
*************** along with GCC; see the file COPYING3.
*** 176,181 ****
--- 175,181 ----
        NEXT_PASS (pass_call_cdce);
        NEXT_PASS (pass_cselim);
        NEXT_PASS (pass_copy_prop);
+       NEXT_PASS (pass_merge_phi);
        NEXT_PASS (pass_tree_ifcombine);
        NEXT_PASS (pass_phiopt);
        NEXT_PASS (pass_tail_recursion);
Index: gcc/testsuite/gcc.dg/vect/vect-125.c
===================================================================
*** gcc/testsuite/gcc.dg/vect/vect-125.c	(revision 0)
--- gcc/testsuite/gcc.dg/vect/vect-125.c	(working copy)
***************
*** 0 ****
--- 1,19 ----
+ /* { dg-do compile } */
+ /* { dg-require-effective-target vect_int } */
+ /* { dg-require-effective-target vect_pack_trunc } */
+ /* { dg-require-effective-target vect_unpack } */
+ 
+ void train(short *t, short *w, int n, int err)
+ {
+   n=(n+7)&-8;
+   for (int i=0; i<n; ++i)
+     {
+       int wt=w[i]+((t[i]*err*2>>16)+1>>1);
+       if (wt<-32768) wt=-32768;
+       if (wt>32767) wt=32767;
+       w[i]=wt;
+     }
+ }
+ 
+ /* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { xfail vect_no_int_max } } } */
+ /* { dg-final { cleanup-tree-dump "vect" } } */