Maarten Brock wrote: > Hello Karl, > > Yes, you ran out of 'data' memory. Especially when > accessing xdata (--model-large) the compiler uses many > temporaries which are stored in registers and then in > data memory. It tries to overlay them but is not very > good at that. The result: high usage of the limited data > memory resource. As you can see in the .mem file all is > used. It has no point putting temporaries in xdata as > xdata access (only indirect) was the issue in the first > place. > > Am I saying all hope is lost? No, not all. You can try > to use --stack-auto to put all temporaries on the stack. > The stack uses idata which can be about twice as big as > data memory, but it also might introduce extra > temporaries. Also on the stack overlaying happens by > definition in it's most efficient way. But I cannot > guarantee this will solve your problems, it might even > create more as stack pressure rises and stack overflows > can happen. > > Greets, > Maarten > >
Thanks for the info. I'm thinking though that --stack-auto will cause more problems with potential stack overflows. Any near term improvements coming the the compiler to help improve it's usage of these temporaries? Are there things i can do with my code, that will make the compiler work better to help improve things? What i have in mind: * remove reentrant function (i have 1 now) I would think that this only reduces stack usage though. * break functions into smaller pieces * reduce function depth (reduce stack usage) * I have 2 register banks for high priority interrupts allocated, I may try not "using x" register bank, trade off on performance, but will add a few bytes of "data" space. * This processor (analog devices ADUC842) supports a 11 bit stack pointer (SP and SPH) that would allow me to use --stack-auto and now worry about overflows. However I don't know how to make SDCC do this, or if it's supported. I'm trying these now... Thanks -- Karl Hiramoto http://karl.hiramoto.org/ >> Hi all, >> >> My code was compiling/linking/running fine, I added a few functions, >> and now when linking i get: >> >> ?ASlink-Error-Could not get 4 consecutive bytes in internal RAM for area >> OSEG. >> >> sdcc -v >> SDCC : mcs51/gbz80/z80/avr/ds390/pic16/pic14/TININative/xa51/ds400/hc08 >> 2.6.1 #4398 (Oct 2 2006) (UNIX) >> >> I also had the same with the 2.6.0 release. >> >> >> I compile/link with args like: >> >> sdcc -c --iram-size 256 --model-large --xram-size 2048 --code-size >> 63487 --opt-code-size --profile -I/usr/local/sdcc/share/sdcc/include >> -L/usr/local/sdcc/share/sdcc/lib/large SD_MMC.c >> /usr/local/sdcc/share/sdcc/include/malloc.h:46: warning 187: ISO C90 >> does not support flexible array members >> sdcc --iram-size 256 --model-large --xram-size 2048 --code-size 63487 >> --opt-code-size --profile -I/usr/local/sdcc/share/sdcc/include >> -L/usr/local/sdcc/share/sdcc/lib/large main.rel adc.rel alarms.rel >> bluetooth.rel dac.rel interrupt.rel timer.rel uart.rel eeprom.rel >> temperature.rel lookup_table.rel motor.rel lonworks-compat.rel >> velocity.rel vfd_lcd_led.rel vel_to_vol.rel pressure.rel humidity.rel >> FAT_format_disk.rel FAT_File_System.rel String_Util.rel >> flash_sect_serv.rel SD_MMC.rel >> ?ASlink-Error-Could not get 4 consecutive bytes in internal RAM for area >> OSEG. >> ?ASlink-Error-Could not get 4 consecutive bytes in internal RAM for area >> OSEG. >> >> >> $ cat main.mem >> Internal RAM layout: >> 0 1 2 3 4 5 6 7 8 9 A B C D E F >> 0x00:|0|0|0|0|0|0|0|0|1|1|1|1|1|1|1|1| >> 0x10:|2|2|2|2|2|2|2|2|a|a|a|a|b|b|b|b| >> 0x20:|B|B|B|B|c|c|c|c|d|d|e|e|e|e|f|f| >> 0x30:|f|f|g|g|g|g|g|g|g|g|h|h|h|h|h|h| >> 0x40:|h|h|h|h|h|h|i|i|i|i|i|i|i|i|j|j| >> 0x50:|j|j|k|k|k|k|l|l|l|l|l|l|l|l|l|l| >> 0x60:|l|l|m|m|n|n|n|n|o|o|o|o|o|p|p|q| >> 0x70:|q|q|q|q|q|q|q|r|s|s|s|s|s|t|Q|S| >> 0x80:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0x90:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xa0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xb0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xc0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xd0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xe0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0xf0:|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S|S| >> 0-3:Reg Banks, T:Bit regs, a-z:Data, B:Bits, Q:Overlay, I:iData, >> S:Stack, A:Absolute >> >> ERROR: Couldn't get 4 bytes allocated in internal RAM for area OSEG. >> Stack starts at: 0x7f (sp set to 0x7e) with 129 bytes available. >> >> Other memory: >> Name Start End Size Max >> ---------------- -------- -------- -------- -------- >> PAGED EXT. RAM 0 256 >> EXTERNAL RAM 0x0000 0x0593 1428 2048 >> ROM/EPROM/FLASH 0x0000 0xbdf8 48633 63487 >> >> >> >> If interested, i can post .map, .mem, .sym, .lnk. >> >> Am I reading the error message correctly?: There is no more overlay >> space? I have plenty of xram where I would think variables could be >> allocated. >> >> >> Should I be using different compile/link flags? My target processor is >> analog devices ADUC842. >> >> Thanks.. >> >> -- >> Karl Hiramoto http://karl.hiramoto.org/ ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
