tree-optimization/121638 - missed SLP discovery of live induction

The following fixes a missed SLP discovery of a live induction.
Our pattern matching of those fails because of the PR81529 fix
which I think was misguided and should now no longer be relevant.
So this essentially reverts that fix.  I have added a GIMPLE
testcase to increase the chance the particular IL is preserved
through the future.

This shows that how we make some IVs live because of early-break
isn't quite correct, so I had to preserve a hack here.  Hopefully
to be investigated at some point.

	PR tree-optimization/121638
	* tree-vect-stmts.cc (process_use): Do not make induction
	PHI backedge values relevant.

	* gcc.dg/vect/pr121638.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/vect/pr121638.c b/gcc/testsuite/gcc.dg/vect/pr121638.c
new file mode 100644 (file)
index 0000000..52d5d6d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr121638.c
@@ -0,0 +1,74 @@
+/* { dg-additional-options "-fgimple -fno-tree-scev-cprop" } */
+
+#include "tree-vect.h"
+
+int a, b, f, j, i, *m, n, o, p = 1, q;
+
+int __GIMPLE (ssa,guessed_local(1073741824),startwith("loop"))
+main ()
+{
+  int D_3005;
+  int D_3003;
+  int d;
+  int * e;
+  long unsigned int _9;
+  long unsigned int _10;
+  int * _11;
+  int _15;
+  int _32;
+
+  __BB(2,guessed_local(1073741824)):
+  check_vect ();
+  e_6 = __builtin_malloc (64ul);
+  goto __BB3(precise(134217728));
+
+  __BB(3,loop_header(2),guessed_local(8687547538)):
+  d_29 = __PHI (__BB3: d_8, __BB2: 0);
+  d_8 = d_29 + 1;
+  _9 = (long unsigned int) d_29;
+  _10 = _9 * 4ul;
+  _11 = e_6 + _10;
+  __MEM <int> (_11) = d_29;
+  if (d_8 <= 15)
+    goto __BB3(guessed(119453778));
+  else
+    goto __BB4(guessed(14763950));
+
+  __BB(4,guessed_local(955630224)):
+  if (d_8 != 16)
+    goto __BB9(guessed(58814510));
+  else
+    goto __BB5(guessed(75403218));
+
+  __BB(5,guessed_local(536870912)):
+  a = 0;
+  if (d_8 > 0)
+    goto __BB6(guessed(119453778));
+  else
+    goto __BB8(guessed(14763950));
+
+  __BB(6,loop_header(1),guessed_local(4343773769)):
+  _32 = __PHI (__BB6: _15, __BB5: 0);
+  _15 = _32 + 1;
+  if (d_29 > _32)
+    goto __BB6(guessed(119453778));
+  else
+    goto __BB7(guessed(14763950));
+
+  __BB(7,guessed_local(477815112)):
+  a = _15;
+  goto __BB8(precise(134217728));
+
+  __BB(8,guessed_local(1073741824)):
+  __builtin_free (e_6);
+  f = 0;
+  return 0;
+
+  __BB(9,precise(0)):
+  a = d_8;
+  f = 1;
+  __builtin_abort ();
+
+}
+
+

diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 47cd29fb1b89e9396a2ac7f883a71c11b9ae63dc..653c5e38e2746d2e4627d2e8dac01d4b0c4f1b84 100644 (file)
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -417,7 +417,9 @@ vect_stmt_relevant_p (stmt_vec_info stmt_info, loop_vec_info loop_vinfo,
 
   /* Check if it's a not live PHI and multiple exits.  In this case
      there will be a usage later on after peeling which is needed for the
-     alternate exit.  */
+     alternate exit.
+     ???  Unless the PHI was marked live because of early
+     break, which also needs the latch def live and vectorized.  */
   if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
       && is_a <gphi *> (stmt)
       && gimple_bb (stmt) == LOOP_VINFO_LOOP (loop_vinfo)->header
@@ -655,14 +657,15 @@ process_use (stmt_vec_info stmt_vinfo, tree use, loop_vec_info loop_vinfo,
     }
   /* We are also not interested in uses on loop PHI backedges that are
      inductions.  Otherwise we'll needlessly vectorize the IV increment
-     and cause hybrid SLP for SLP inductions.  Unless the PHI is live
-     of course.  */
+     and cause hybrid SLP for SLP inductions.  */
   else if (gimple_code (stmt_vinfo->stmt) == GIMPLE_PHI
           && STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_induction_def
-          && ! STMT_VINFO_LIVE_P (stmt_vinfo)
           && (PHI_ARG_DEF_FROM_EDGE (stmt_vinfo->stmt,
                                      loop_latch_edge (bb->loop_father))
-              == use))
+              == use)
+          && (!LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
+              || (gimple_bb (stmt_vinfo->stmt)
+                  != LOOP_VINFO_LOOP (loop_vinfo)->header)))
     {
       if (dump_enabled_p ())
        dump_printf_loc (MSG_NOTE, vect_location,
@@ -670,7 +673,6 @@ process_use (stmt_vec_info stmt_vinfo, tree use, loop_vec_info loop_vinfo,
       return opt_result::success ();
     }
 
-
   vect_mark_relevant (worklist, dstmt_vinfo, relevant, false);
   return opt_result::success ();
 }