3d101dd46
Denis Vlasenko
2007-03-19
Subject
expand documentation
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docs/keep_data_small.txt+29 -0
| @@ -125,3 +125,32 @@ less readable, use #defines: | |
| If applet doesn't use much of global data, converting it to use | |
| one of above methods is not worth the resulting code obfuscation. | |
| If you have less than ~300 bytes of global data - don't bother. | |
| + | |
| + | |
| + | gcc's data alignment problem |
| + | |
| + | The following attribute added in vi.c: |
| + | |
| + | static int tabstop; |
| + | static struct termios term_orig __attribute__ ((aligned (4))); |
| + | static struct termios term_vi __attribute__ ((aligned (4))); |
| + | |
| + | reduced bss size by 32 bytes, because gcc sometimes aligns structures to |
| + | ridiculously large values. asm output diff for above example: |
| + | |
| + | tabstop: |
| + | .zero 4 |
| + | .section .bss.term_orig,"aw",@nobits |
| + | - .align 32 |
| + | + .align 4 |
| + | .type term_orig, @object |
| + | .size term_orig, 60 |
| + | term_orig: |
| + | .zero 60 |
| + | .section .bss.term_vi,"aw",@nobits |
| + | - .align 32 |
| + | + .align 4 |
| + | .type term_vi, @object |
| + | .size term_vi, 60 |
| + | |
| + | gcc doesn't seem to have options for altering this behaviour. |