[gcc r14-4328] use *_grow_cleared rather than *_grow on vect_unpromoted_value

[gcc r14-4328] use *_grow_cleared rather than *_grow on vect_unpromoted_value

[Jakub Jelinek]

https://gcc.gnu.org/g:59cda1f9525702d5d6560002c874f12c0103f7df

commit r14-4328-g59cda1f9525702d5d6560002c874f12c0103f7df
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Sep 29 11:23:16 2023 +0200

    use *_grow_cleared rather than *_grow on vect_unpromoted_value
    
    vect_recog_over_widening_pattern is another spot which triggers the
    right now commented out static assertion in vec.h which asserts
    {quick,safe}_grow vec operations are only used with trivially default
    constructible types.
    
    I had a look at this and I think using quick_grow_cleared is best choice
    here.  The nops is 2 or 1 most of the time, worst case 3, so the price of
    extra initialization of 4 pointer-sized-or-less members times 1, 2 or 3
    doesn't seem worth bothering, it is similar to the bitmap_head case where
    we already pay the price for just one structure anytime we do
      vect_unpromoted_value unprom_diff;
    (and later set_op on it) or even
      vect_unpromoted_value unprom0[2];
    
    With this patch and Richard S's poly_int_pod removal the static_assert can
    be enabled as well and gcc builds.
    
    2023-09-29  Jakub Jelinek  <jakub@redhat.com>
    
            * tree-vect-patterns.cc (vect_recog_over_widening_pattern): Use
            quick_grow_cleared method on unprom rather than quick_grow.

Diff:
---
 gcc/tree-vect-patterns.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
index a2ed0365b18..6964c998698 100644
--- a/gcc/tree-vect-patterns.cc
+++ b/gcc/tree-vect-patterns.cc
@@ -2944,7 +2944,7 @@ vect_recog_over_widening_pattern (vec_info *vinfo,
   /* Check the operands.  */
   unsigned int nops = gimple_num_ops (last_stmt) - first_op;
   auto_vec <vect_unpromoted_value, 3> unprom (nops);
-  unprom.quick_grow (nops);
+  unprom.quick_grow_cleared (nops);
   unsigned int min_precision = 0;
   bool single_use_p = false;
   for (unsigned int i = 0; i < nops; ++i)