On Tue, 11 Jun 2019, Jason Merrill wrote:
> On Tue, Jun 11, 2019, 6:45 AM Richard Biener <rguent...@suse.de> wrote:
>
> >
> > The following fixes the documented(!) quadraticness in
> > split_nonconstant_init_1 by simply marking to be removed
> > constructor elements and doing that in a second run over
> > the constructor.
> >
> > More micro-optimizing would be possible by recording the
> > first removed element index and special-casing removing
> > of a single element. If you think that's worth the extra
> > complexity I can work on that (hopefully the case we
> > increase num_split_elts but not actually split is a bug...).
> >
> > Bootstrap / regtest running on x86_64-unknown-linux-gnu.
> >
> > OK if that passes?
> >
>
> Ok, thanks.
Installed.
Below is the simplest variant re-adding optimized handling
of single-element removal. Note the second hunk which
moves the num_split_elts increment so it doesn't happen
when split_nonconstant_init_1 returns false.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
OK?
Richard.
2019-06-12 Richard Biener <rguent...@suse.de>
PR c++/90801
* typeck2.c (split_nonconstant_init_1): Properly count
num_split_elts, optimize single constructor elt removal.
Index: gcc/cp/typeck2.c
===================================================================
--- gcc/cp/typeck2.c (revision 272177)
+++ gcc/cp/typeck2.c (working copy)
@@ -603,7 +603,7 @@ cxx_incomplete_type_error (location_t lo
static bool
split_nonconstant_init_1 (tree dest, tree init)
{
- unsigned HOST_WIDE_INT idx, tidx;
+ unsigned HOST_WIDE_INT idx, tidx = HOST_WIDE_INT_M1U;
tree field_index, value;
tree type = TREE_TYPE (dest);
tree inner_type = NULL;
@@ -657,9 +657,13 @@ split_nonconstant_init_1 (tree dest, tre
if (!split_nonconstant_init_1 (sub, value))
complete_p = false;
else
- /* Mark element for removal. */
- CONSTRUCTOR_ELT (init, idx)->index = NULL_TREE;
- num_split_elts++;
+ {
+ /* Mark element for removal. */
+ CONSTRUCTOR_ELT (init, idx)->index = NULL_TREE;
+ if (idx < tidx)
+ tidx = idx;
+ num_split_elts++;
+ }
}
else if (!initializer_constant_valid_p (value, inner_type))
{
@@ -668,6 +672,8 @@ split_nonconstant_init_1 (tree dest, tre
/* Mark element for removal. */
CONSTRUCTOR_ELT (init, idx)->index = NULL_TREE;
+ if (idx < tidx)
+ tidx = idx;
if (TREE_CODE (field_index) == RANGE_EXPR)
{
@@ -705,17 +711,18 @@ split_nonconstant_init_1 (tree dest, tre
num_split_elts++;
}
}
- if (num_split_elts != 0)
+ if (num_split_elts == 1)
+ CONSTRUCTOR_ELTS (init)->ordered_remove (tidx);
+ else if (num_split_elts > 1)
{
/* Perform the delayed ordered removal of non-constant elements
we split out. */
- for (tidx = 0, idx = 0; idx < CONSTRUCTOR_NELTS (init); ++idx)
+ for (idx = tidx; idx < CONSTRUCTOR_NELTS (init); ++idx)
if (CONSTRUCTOR_ELT (init, idx)->index == NULL_TREE)
;
else
{
- if (tidx != idx)
- *CONSTRUCTOR_ELT (init, tidx) = *CONSTRUCTOR_ELT (init, idx);
+ *CONSTRUCTOR_ELT (init, tidx) = *CONSTRUCTOR_ELT (init, idx);
++tidx;
}
vec_safe_truncate (CONSTRUCTOR_ELTS (init), tidx);
