On Sat, Jul 25, 2020 at 2:23 PM Martin Liška <mli...@suse.cz> wrote:
>
> Hello.
>
> When inserting into fast_call_summary (or fast_function_summary), we grow
> a vector to a _exact_ size based on cgraph_max_summary_id or
> edges_max_summary_id.
> Problem is that it causes very many reallocation and we should rather use
> ::reserve
> function that selects a reasonable size of a new vector.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> Fixes chromium WPA build time:
> https://gist.githubusercontent.com/marxin/223890df4d8d8e490b6b2918b77dacad/raw/f766f6546739e739a273639dde90ac6179aa3077/chromium-gcc10-fixed-summary-crash.svg
>
> Ready to be installed?
OK. I guess the previous code tried to use less memory.
Thanks,
Richard.
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> * symbol-summary.h: Call vec_safe_reserve before grow is called
> in order to grow to a reasonable size.
> * vec.h (vec_safe_reserve): Add missing function for vl_ptr
> type.
> ---
> gcc/symbol-summary.h | 13 ++++++++++---
> gcc/vec.h | 11 +++++++++++
> 2 files changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/symbol-summary.h b/gcc/symbol-summary.h
> index a38eb1db778..fa1df5c8015 100644
> --- a/gcc/symbol-summary.h
> +++ b/gcc/symbol-summary.h
> @@ -354,8 +354,11 @@ public:
> id = this->m_symtab->assign_summary_id (node);
>
> if ((unsigned int)id >= m_vector->length ())
> - vec_safe_grow_cleared (m_vector,
> - this->m_symtab->cgraph_max_summary_id);
> + {
> + int newlen = this->m_symtab->cgraph_max_summary_id;
> + vec_safe_reserve (m_vector, newlen - m_vector->length ());
> + m_vector->quick_grow_cleared (newlen);
> + }
>
> if ((*m_vector)[id] == NULL)
> (*m_vector)[id] = this->allocate_new ();
> @@ -812,7 +815,11 @@ public:
> id = this->m_symtab->assign_summary_id (edge);
>
> if ((unsigned)id >= m_vector->length ())
> - vec_safe_grow_cleared (m_vector, this->m_symtab->edges_max_summary_id);
> + {
> + int newlen = this->m_symtab->edges_max_summary_id;
> + m_vector->reserve (newlen - m_vector->length ());
> + m_vector->quick_grow_cleared (newlen);
> + }
>
> if ((*m_vector)[id] == NULL)
> (*m_vector)[id] = this->allocate_new ();
> diff --git a/gcc/vec.h b/gcc/vec.h
> index bd7c7351dcd..3ad99b83690 100644
> --- a/gcc/vec.h
> +++ b/gcc/vec.h
> @@ -753,6 +753,17 @@ vec_safe_grow_cleared (vec<T, va_heap, vl_ptr> *&v,
> v->safe_grow_cleared (len PASS_MEM_STAT);
> }
>
> +/* If V does not have space for NELEMS elements, call
> + V->reserve(NELEMS, EXACT). */
> +
> +template<typename T>
> +inline bool
> +vec_safe_reserve (vec<T, va_heap, vl_ptr> *&v, unsigned nelems, bool exact =
> false
> + CXX_MEM_STAT_INFO)
> +{
> + return v->reserve (nelems, exact);
> +}
> +
>
> /* If V is NULL return false, otherwise return V->iterate(IX, PTR). */
> template<typename T, typename A>
> --
> 2.27.0
>
