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Subject:	Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
Newsgroups:	lugnet.robotics.nxt.nxthacking
Date:	Wed, 14 Mar 2007 20:45:40 GMT
Viewed:	24280 times

In lugnet.robotics.nxt.nxthacking, Rasmus Pedersen wrote: > Hi, > > If I compile the LEGO firmware sources with gcc, the code size increases much > beyond the 128 KB (which I think) the IAR compiled sources fits into. That means > that one have to relocate part of the compiled code into the memory areas > between 128KB-256KB. That is ok, but not totally optimal as the files, > filehandles, and file verion info is also in that region making it a puzzle. > Also I think it is hard to download new files if the flash is partly taken for > code purposes. > > With the http://nxtgcc.sf.net project (which you need to look into this) I get > these numbers from the make process: > > Size after: > m_sched.elf : > section size addr > .text 126176 1048576 > .text2 23572 1279744 > .data 6180 2097152 > .bss 45828 2103332 > .comment 2133 0 > .debug_aranges 496 0 > .debug_pubnames 31 0 > .debug_info 2139 0 > .debug_abbrev 512 0 > .debug_line 2732 0 > .debug_frame 216 0 > .debug_str 276 0 > .debug_loc 353 0 > .debug_ranges 48 0 > Total 210692 > > text2 and data is relocated. (See AT91SAM7S256_memory.ldh linker details in the > "common") folder for details. I have tried with a "home-made" toolchain (see > "toolchain" folder and now with the precompiled WinArm toolchain, which produces > tighter code. The GNUARM toolchain did worse than WinARM. Have you experimented at all with the compiler optimisation flags? I don't know if all of them are supported for the ARM architecture, and some options cause problems on other architectures, but there's a bit of a list here: http://developer.apple.com/documentation/DeveloperTools/gcc-3.3/gcc/Optimize-Options.html Also, removing debug information (-s) will reduce the size, but you may not want to do that while hacking. ROSCO

Message has 1 Reply:

		Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
... (...) I have not done that. Well, just a little bit:-). The best one (not surprisingly) is the "-Os" optimization, which does this "Optimize for size. -Os enables all -O2 optimizations that do not typically increase code size." (...) I tried (...) (20 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

Message is in Reply To:

		GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
Hi, If I compile the LEGO firmware sources with gcc, the code size increases much beyond the 128 KB (which I think) the IAR compiled sources fits into. That means that one have to relocate part of the compiled code into the memory areas between (...) (20 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

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