[v3] string::_S_create tweaks + array_allocator fixes

[Paolo Carlini <pcarlini at suse dot de>]

Hi,

tested x86/x86_64/ia64-linux, committed to mainline.

Paolo.

////////////////
2004-10-13  Paolo Carlini  <pcarlini@suse.de>

	* include/bits/basic_string.tcc (_S_create): Use consistently
	the exponential policy, simplify.
	* testsuite/performance/21_strings/string_append_2.cc: New.

	* include/ext/array_allocator.h (allocate): Fix bad_alloc check.
	* testsuite/ext/array_allocator/2.cc: Fix wrt 64-bit archs (in
	that case sizeof(_Rep) == 24).

diff -urN libstdc++-v3-orig/include/bits/basic_string.tcc libstdc++-v3/include/bits/basic_string.tcc
--- libstdc++-v3-orig/include/bits/basic_string.tcc	2004-09-28 10:58:31.000000000 +0200
+++ libstdc++-v3/include/bits/basic_string.tcc	2004-10-13 02:42:11.000000000 +0200
@@ -503,9 +503,8 @@
       // low-balling it (especially when this algorithm is used with
       // malloc implementations that allocate memory blocks rounded up
       // to a size which is a power of 2).
-      const size_type __pagesize = 4096; // must be 2^i * __subpagesize
-      const size_type __subpagesize = 128; // should be >> __malloc_header_size
-      const size_type __malloc_header_size = 4 * sizeof (void*);
+      const size_type __pagesize = 4096;
+      const size_type __malloc_header_size = 4 * sizeof(void*);
 
       // The below implements an exponential growth policy, necessary to
       // meet amortized linear time requirements of the library: see
@@ -513,14 +512,7 @@
       // It's active for allocations requiring an amount of memory above
       // system pagesize. This is consistent with the requirements of the
       // standard: http://gcc.gnu.org/ml/libstdc++/2001-07/msg00130.html
-
-      // The biggest string which fits in a memory page
-      const size_type __page_capacity = ((__pagesize - __malloc_header_size
-					  - sizeof(_Rep) - sizeof(_CharT))
-					 / sizeof(_CharT));
-
-      if (__capacity > __old_capacity && __capacity < 2 * __old_capacity
-	  && __capacity > __page_capacity)
+      if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 	__capacity = 2 * __old_capacity;
 
       // NB: Need an array of char_type[__capacity], plus a terminating
@@ -538,12 +530,6 @@
 	    __capacity = _S_max_size;
 	  __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
 	}
-      else if (__size > __subpagesize)
-	{
-	  const size_type __extra = __subpagesize - __adj_size % __subpagesize;
-	  __capacity += __extra / sizeof(_CharT);
-	  __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
-	}
 
       // NB: Might throw, but no worries about a leak, mate: _Rep()
       // does not throw.
diff -urN libstdc++-v3-orig/include/ext/array_allocator.h libstdc++-v3/include/ext/array_allocator.h
--- libstdc++-v3-orig/include/ext/array_allocator.h	2004-10-08 00:06:22.000000000 +0200
+++ libstdc++-v3/include/ext/array_allocator.h	2004-10-13 02:12:31.000000000 +0200
@@ -116,11 +116,11 @@
       pointer
       allocate(size_type __n, const void* = 0)
       {
-	static size_type used;
-	if (__builtin_expect(used > array_type::_S_index, false))
+	static size_type __used;
+	if (__builtin_expect(__used + __n > array_type::_S_index, false))
 	  throw std::bad_alloc();
-	pointer __ret = _M_array->begin() + used;
-	used += __n;
+	pointer __ret = _M_array->begin() + __used;
+	__used += __n;
 	return __ret;
       }
     };
diff -urN libstdc++-v3-orig/testsuite/ext/array_allocator/2.cc libstdc++-v3/testsuite/ext/array_allocator/2.cc
--- libstdc++-v3-orig/testsuite/ext/array_allocator/2.cc	2004-10-08 00:06:23.000000000 +0200
+++ libstdc++-v3/testsuite/ext/array_allocator/2.cc	2004-10-13 02:12:31.000000000 +0200
@@ -32,7 +32,7 @@
 
 typedef char char_type;
 typedef std::char_traits<char_type> traits_type;
-typedef std::tr1::array<char_type, 17> array_type;
+typedef std::tr1::array<char_type, 32> array_type;
 
 array_type extern_array;
 
diff -urN libstdc++-v3-orig/testsuite/performance/21_strings/string_append_2.cc libstdc++-v3/testsuite/performance/21_strings/string_append_2.cc
--- libstdc++-v3-orig/testsuite/performance/21_strings/string_append_2.cc	1970-01-01 01:00:00.000000000 +0100
+++ libstdc++-v3/testsuite/performance/21_strings/string_append_2.cc	2004-10-13 02:44:10.000000000 +0200
@@ -0,0 +1,55 @@
+// Copyright (C) 2004 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// As a special exception, you may use this file as part of a free software
+// library without restriction.  Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License.  This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+
+#include <string>
+#include <testsuite_performance.h>
+
+// Short strings didn't grow quickly...
+void test01()
+{
+  using namespace __gnu_test;
+  time_counter time;
+  resource_counter resource;
+
+  start_counters(time, resource);
+  for (unsigned i = 0; i < 200000; ++i)
+    {
+      std::string a;
+      for (unsigned j = 0; j < 400; ++j)
+	a.append(1, 'x');
+    }
+  stop_counters(time, resource);
+
+  report_performance(__FILE__, "", time, resource);
+  clear_counters(time, resource);
+}
+
+int main()
+{
+  test01();
+  return 0;
+}