Add tunables for input buffer

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.

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.

4 files changed, 30 insertions, 2 deletions

diff --git a/gcc/input.cc b/gcc/input.cc
index 9f3cc66..8605202 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
@@ -192,6 +196,18 @@ 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 18ccf44..a60afe8 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 b5e7800..5d234a6 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 d45a12c..e03af8b 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 ();