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| author | Jakub Jelinek <jakub@redhat.com> | 2020-03-12 08:28:05 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2020-03-12 08:28:05 +0100 |
| commit | 4069adf4bbc90d16b603e0308b48499c36b2b637 (patch) | |
| tree | eb80f36b3b6fac6badfaf0f01619bbc06ae8ae05 /gcc | |
| parent | aedb4c8fc77034a3a009bee887691d5727658627 (diff) | |
| download | gcc-4069adf4bbc90d16b603e0308b48499c36b2b637.zip gcc-4069adf4bbc90d16b603e0308b48499c36b2b637.tar.gz gcc-4069adf4bbc90d16b603e0308b48499c36b2b637.tar.bz2 | |
c++: Tweak reshape_init_array_1 [PR94124]
Isn't it wasteful to first copy perhaps a large constructor (recursively)
and then truncate it to very few elts (zero in this case)?
> We should certainly avoid copying if they're the same. The code above for
> only copying the bits that aren't going to be thrown away seems pretty
> straightforward, might as well use it even if the savings aren't likely to
> be large.
Calling vec_safe_truncate with the same number of elts the vector already
has is a nop, so IMHO we just should make sure we only unshare if it
changed.
2020-03-12 Jakub Jelinek <jakub@redhat.com>
PR c++/94124
* decl.c (reshape_init_array_1): Don't unshare constructor if there
aren't any trailing zero elts, otherwise only unshare the first
nelts.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/ChangeLog | 9 | ||||
| -rw-r--r-- | gcc/cp/decl.c | 19 |
2 files changed, 23 insertions, 5 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 8cde300..b94e3bb 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,10 @@ +2020-03-12 Jakub Jelinek <jakub@redhat.com> + + PR c++/94124 + * decl.c (reshape_init_array_1): Don't unshare constructor if there + aren't any trailing zero elts, otherwise only unshare the first + nelts. + 2020-03-11 Jason Merrill <jason@redhat.com> PR c++/93907 @@ -27,7 +34,7 @@ 2020-03-10 Jason Merrill <jason@redhat.com> - PR c++/93956 + PR c++/93596 * pt.c (maybe_aggr_guide): Check BRACE_ENCLOSED_INITIALIZER_P. 2020-03-10 Jason Merrill <jason@redhat.com> diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index aa58e5f..d240436 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -6066,10 +6066,21 @@ reshape_init_array_1 (tree elt_type, tree max_index, reshape_iter *d, overload resolution. E.g., initializing a class from {{0}} might be invalid while initializing the same class from {{}} might be valid. */ - if (reuse) - new_init = unshare_constructor (new_init); - - vec_safe_truncate (CONSTRUCTOR_ELTS (new_init), nelts); + if (reuse && nelts < CONSTRUCTOR_NELTS (new_init)) + { + vec<constructor_elt, va_gc> *v; + vec_alloc (v, nelts); + for (unsigned int i = 0; i < nelts; i++) + { + constructor_elt elt = *CONSTRUCTOR_ELT (new_init, i); + if (TREE_CODE (elt.value) == CONSTRUCTOR) + elt.value = unshare_constructor (elt.value); + v->quick_push (elt); + } + new_init = build_constructor (TREE_TYPE (new_init), v); + } + else + vec_safe_truncate (CONSTRUCTOR_ELTS (new_init), nelts); } return new_init; |