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Optimize: Make Bool_Array take less memory.

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Less memory means: less cache misses.
This reduces the execution time of gperf on large inputs by ca. 2.5%.

* src/bool-array.h (Bool_Array): For the _storage_array and
_iteration_number fields, use 'unsigned char' instead of 'unsigned int'.
* src/bool-array.icc (Bool_Array::Bool_Array, Bool_Array::clear: Update.
* src/bool-array.cc (Bool_Array::~Bool_Array): Update.
This commit is contained in:
Bruno Haible
2025-04-19 15:00:14 +02:00
parent b52ad8ef32
commit 43fa5ebcb7
4 changed files with 18 additions and 8 deletions
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10
ChangeLog
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@@ -1,3 +1,13 @@
2025-04-19 Bruno Haible <bruno@clisp.org>
Optimize: Make Bool_Array take less memory.
Less memory means: less cache misses.
This reduces the execution time of gperf on large inputs by ca. 2.5%.
* src/bool-array.h (Bool_Array): For the _storage_array and
_iteration_number fields, use 'unsigned char' instead of 'unsigned int'.
* src/bool-array.icc (Bool_Array::Bool_Array, Bool_Array::clear: Update.
* src/bool-array.cc (Bool_Array::~Bool_Array): Update.
2025-04-19 Bruno Haible <bruno@clisp.org> 2025-04-19 Bruno Haible <bruno@clisp.org>
tests: Add unit test with many keywords. tests: Add unit test with many keywords.

2
src/bool-array.cc
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@@ -35,7 +35,7 @@ Bool_Array::~Bool_Array ()
fprintf (stderr, "\ndumping boolean array information\n" fprintf (stderr, "\ndumping boolean array information\n"
"size = %d\niteration number = %d\nend of array dump\n", "size = %d\niteration number = %d\nend of array dump\n",
_size, _iteration_number); _size, _iteration_number);
delete[] const_cast<unsigned int *>(_storage_array); delete[] const_cast<unsigned char *>(_storage_array);
} }
#ifndef __OPTIMIZE__ #ifndef __OPTIMIZE__

6
src/bool-array.h
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@@ -2,7 +2,7 @@
/* Simple lookup table abstraction implemented as an Iteration Number Array. /* Simple lookup table abstraction implemented as an Iteration Number Array.
Copyright (C) 1989-1998, 2002 Free Software Foundation, Inc. Copyright (C) 1989-1998, 2002, 2025 Free Software Foundation, Inc.
Written by Douglas C. Schmidt <schmidt@ics.uci.edu> Written by Douglas C. Schmidt <schmidt@ics.uci.edu>
and Bruno Haible <bruno@clisp.org>. and Bruno Haible <bruno@clisp.org>.
@@ -56,11 +56,11 @@ private:
/* Current iteration number. Always nonzero. Starts out as 1, and is /* Current iteration number. Always nonzero. Starts out as 1, and is
incremented each time clear() is called. */ incremented each time clear() is called. */
unsigned int _iteration_number; unsigned char _iteration_number;
/* For each index, we store in storage_array[index] the iteration_number at /* For each index, we store in storage_array[index] the iteration_number at
the time set_bit(index) was last called. */ the time set_bit(index) was last called. */
unsigned int * const _storage_array; unsigned char * const _storage_array;
}; };
#ifdef __OPTIMIZE__ /* efficiency hack! */ #ifdef __OPTIMIZE__ /* efficiency hack! */

8
src/bool-array.icc
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@@ -1,6 +1,6 @@
/* Inline Functions for bool-array.{h,cc}. /* Inline Functions for bool-array.{h,cc}.
Copyright (C) 1989-1998, 2002 Free Software Foundation, Inc. Copyright (C) 1989-1998, 2002, 2025 Free Software Foundation, Inc.
Written by Douglas C. Schmidt <schmidt@ics.uci.edu> Written by Douglas C. Schmidt <schmidt@ics.uci.edu>
and Bruno Haible <bruno@clisp.org>. and Bruno Haible <bruno@clisp.org>.
@@ -30,7 +30,7 @@ INLINE
Bool_Array::Bool_Array (unsigned int size) Bool_Array::Bool_Array (unsigned int size)
: _size (size), : _size (size),
_iteration_number (1), _iteration_number (1),
_storage_array (new unsigned int [size]) _storage_array (new unsigned char [size])
{ {
memset (_storage_array, 0, size * sizeof (_storage_array[0])); memset (_storage_array, 0, size * sizeof (_storage_array[0]));
if (option[DEBUG]) if (option[DEBUG])
@@ -60,8 +60,8 @@ INLINE void
Bool_Array::clear () Bool_Array::clear ()
{ {
/* If we wrap around it's time to zero things out again! However, this only /* If we wrap around it's time to zero things out again! However, this only
occurs once about every 2^32 iterations, so it will not happen more occurs once about every 2^8 iterations, so it does not take much time on
frequently than once per second. */ average. */
if (++_iteration_number == 0) if (++_iteration_number == 0)
{ {