On Sat, 2025-01-25 at 23:30 -0800, Andi Kleen wrote:
> From: Andi Kleen <[email protected]>
>
> The input machinery to read the source code independent of the lexer
> has a range of hard coded maximum array sizes that can impact
> performance.
> Make them tunable.
>
> input.cc is part of libcommon so it cannot direct access params
> without a level of indirection.
Thanks; this patch is OK for trunk
Dave
>
> gcc/ChangeLog:
>
> PR preprocessor/118168
> * input.cc (file_cache::tune): New function.
> * input.h (class file_cache): Make tunables non const.
> * params.opt: Add new tunables.
> * toplev.cc (toplev::main): Initialize input buffer context
> tunables.
> ---
> gcc/input.cc | 18 +++++++++++++++++-
> gcc/input.h | 4 +++-
> gcc/params.opt | 8 ++++++++
> gcc/toplev.cc | 2 ++
> 4 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/input.cc b/gcc/input.cc
> index 7ed80cad13f..f824c34e0cc 100644
> --- a/gcc/input.cc
> +++ b/gcc/input.cc
> @@ -79,6 +79,10 @@ public:
> void evict ();
> void set_content (const char *buf, size_t sz);
>
> + static void tune(size_t line_record_size_) {
> + line_record_size = line_record_size_;
> + }
> +
> private:
> /* These are information used to store a line boundary. */
> class line_info
> @@ -116,7 +120,7 @@ public:
> bool goto_next_line ();
>
> static const size_t buffer_size = 4 * 1024;
> - static const size_t line_record_size = 100;
> + static size_t line_record_size;
>
> /* The number of time this file has been accessed. This is used
> to designate which file cache to evict from the cache
> @@ -189,6 +193,18 @@ public:
>
> };
>
> +size_t file_cache_slot::line_record_size = 100;
> +
> +/* Tune file_cache. */
> +void
> +file_cache::tune (size_t num_file_slots_, size_t lines)
> +{
> + num_file_slots = num_file_slots_;
> + file_cache_slot::tune (lines);
> +}
> +
> +size_t file_cache::num_file_slots = 16;
> +
> static const char *
> find_end_of_line (const char *s, size_t len);
>
> diff --git a/gcc/input.h b/gcc/input.h
> index 18ccf4429fc..a60afe80681 100644
> --- a/gcc/input.h
> +++ b/gcc/input.h
> @@ -161,13 +161,15 @@ class file_cache
> const char *buffer,
> size_t sz);
>
> + static void tune(size_t num_file_slots_, size_t lines);
> +
> private:
> file_cache_slot *evicted_cache_tab_entry (unsigned
> *highest_use_count);
> file_cache_slot *add_file (const char *file_path);
> file_cache_slot *lookup_file (const char *file_path);
>
> private:
> - static const size_t num_file_slots = 16;
> + static size_t num_file_slots;
> file_cache_slot *m_file_slots;
> input_context m_input_context;
> };
> diff --git a/gcc/params.opt b/gcc/params.opt
> index b5e7800d7e4..5d234a607c0 100644
> --- a/gcc/params.opt
> +++ b/gcc/params.opt
> @@ -134,6 +134,14 @@ Maximum size (in bytes) of objects tracked
> bytewise by dead store elimination.
> Common Joined UInteger Var(param_early_inlining_insns) Init(6)
> Optimization Param
> Maximal estimated growth of function body caused by early inlining
> of single call.
>
> +-param=file-cache-files=
> +Common Joined UInteger Var(param_file_cache_files) Init(16) Param
> +Max number of files in the file cache.
> +
> +-param=file-cache-lines=
> +Common Joined UInteger Var(param_file_cache_lines) Init(100) Param
> +Max number of lines to index into file cache.
> +
> -param=fsm-scale-path-stmts=
> Common Joined UInteger Var(param_fsm_scale_path_stmts) Init(2)
> IntegerRange(1, 10) Param Optimization
> Scale factor to apply to the number of statements in a threading
> path crossing a loop backedge when comparing to max-jump-thread-
> duplication-stmts.
> diff --git a/gcc/toplev.cc b/gcc/toplev.cc
> index d45a12cab45..e03af8b1805 100644
> --- a/gcc/toplev.cc
> +++ b/gcc/toplev.cc
> @@ -2333,6 +2333,8 @@ toplev::main (int argc, char **argv)
> UNKNOWN_LOCATION, global_dc,
> targetm.target_option.override);
>
> + file_cache::tune (param_file_cache_files, param_file_cache_lines);
> +
> handle_common_deferred_options ();
>
> init_local_tick ();
