From: Andi Kleen <a...@gcc.gnu.org>
While the input line cache size now tunable it's better if the compiler
auto tunes it. Otherwise large files needing random file access will
still have to search many lines to find the right lines.
Add support for allocating one line anchor per hundred input lines.
This means an overhead of ~235k per 1M input lines on 64bit, which
seems reasonable.
gcc/ChangeLog:
PR preprocessor/118168
* input.cc (file_cache_slot::get_next_line): Implement
dynamic sizing of m_line_record based on input length.
* params.opt: (param_file_cache_lines): Set to 0 to size
dynamically.
---
gcc/input.cc | 11 ++++++++---
gcc/params.opt | 2 +-
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/gcc/input.cc b/gcc/input.cc
index b3fe38eb77c..d5d7dbb043e 100644
--- a/gcc/input.cc
+++ b/gcc/input.cc
@@ -194,7 +194,7 @@ public:
};
-size_t file_cache_slot::line_record_size = 100;
+size_t file_cache_slot::line_record_size = 0;
size_t file_cache_slot::recent_cached_lines_shift = 8;
/* Tune file_cache. */
@@ -865,8 +865,13 @@ file_cache_slot::get_next_line (char **line, ssize_t
*line_len)
size_t delta = rlen >= 1 ?
m_line_num - m_line_record[rlen - 1].line_num : 1;
+ size_t max_size = line_record_size;
+ /* One anchor per hundred input lines. */
+ if (max_size == 0)
+ max_size = m_line_num / 100;
+
/* If we're too far beyond drop half of the lines to rebalance. */
- if (rlen == line_record_size && delta >= spacing*2)
+ if (rlen == max_size && delta >= spacing*2)
{
size_t j = 0;
for (size_t i = 1; i < rlen; i += 2)
@@ -876,7 +881,7 @@ file_cache_slot::get_next_line (char **line, ssize_t
*line_len)
spacing *= 2;
}
- if (rlen < line_record_size && delta >= spacing)
+ if (rlen < max_size && delta >= spacing)
m_line_record.safe_push
(file_cache_slot::line_info (m_line_num,
m_line_start_idx,
diff --git a/gcc/params.opt b/gcc/params.opt
index 5d234a607c0..a56c20af2f8 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -139,7 +139,7 @@ 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
+Common Joined UInteger Var(param_file_cache_lines) Init(0) Param
Max number of lines to index into file cache.
-param=fsm-scale-path-stmts=
--
2.47.1
