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Von: Thomas Zimmermann

Betreff: [SDL] [PATCH] Make static variables const
Datum: Tue, 19 May 2009 19:45:37 +0200

Hi,

this is a set of simple changes which make some of SDL's internal static
arrays constant. The purpose is to shrink the number of write-able
static bytes and thus increase the number of memory pages shared between
SDL applications.

The patch set is against trunk@4513. Each of the attached patch files is
specific to a sub-system. The set is completed by a second mail, because
of the list's 40 KiB limit.

The files readelf-r4513.txt and readelf-const-patch.txt where made by
calling 'readelf -S libSDL.so'. They show the difference in ELF sections
without and with the patch. Some numbers measured on my x86-64:

Before

 [13] .rodata           PROGBITS         00000000000eaaa0  000eaaa0
      0000000000008170  0000000000000000   A       0     0     32
 [19] .data.rel.ro      PROGBITS         00000000003045e0  001045e0
      00000000000023d0  0000000000000000  WA       0     0     32
 [23] .data             PROGBITS         00000000003076e0  001076e0
      0000000000004988  0000000000000000  WA       0     0     32

After

 [13] .rodata           PROGBITS         00000000000eaaa0  000eaaa0
      0000000000009a50  0000000000000000   A       0     0     32
 [19] .data.rel.ro      PROGBITS         0000000000306040  00106040
      0000000000002608  0000000000000000  WA       0     0     32
 [23] .data             PROGBITS         0000000000309360  00109360
      0000000000002e88  0000000000000000  WA       0     0     32

The size of the write-able data section decreased considerably. Some
entries became const-after-relocation, while most of its content went
straight into the read-only data section.

Best regards, Thomas
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slouken committed Jun 3, 2009
1 parent 6b7fccd commit 8ec0e16b15c7875384594f1156e99d158b3b93fd

File 7 of 31 in 8ec0e16

@@ -27,7 +27,7 @@
- experimentation on various ADB and USB ISO keyboards and one ADB ANSI keyboard
*/
/* *INDENT-OFF* */
static SDL_scancode darwin_scancode_table[] = {
static const SDL_scancode darwin_scancode_table[] = {
/* 0 */ SDL_SCANCODE_A,
/* 1 */ SDL_SCANCODE_S,
/* 2 */ SDL_SCANCODE_D,

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