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Subject:	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 15:32:31 GMT
Viewed:	17171 times

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. Best, Rasmus

Message has 4 Replies:

		Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
Regarrding overwriting the flash system. I encountered the problem of flash file system overwriting user code as well. It's because it is hard coded in the code the starting address of the file system. There's a constant named "STARTOFUSERFLASH" (...) (18 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

		Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
(...) Are you adjusting these values in d_loader.h? #define STARTOFFILETABLE (0x13FF00L) #define STARTOFUSERFLASH (0x11F000L) #define SIZEOFUSERFLASH (STARTOFFILETABLE - STARTOFUSERFLASH) I've been told by folks at LEGO that if I grow the size of (...) (18 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

		Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
(...) 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: (URL) removing (...) (18 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

		Re: GCC vs. IAR compiler: Could GCC be tweaked to generate code as tight as IAR?
(...) I read a paper that attributed most of the code size increases in gcc generated code to the printf library - search for AN52-ARM-C-Benchmark.pdf to read the paper. Out of curiosity I built the firmware using the newlib libc and the gcc 4.1.1 (...) (18 years ago, 5-Apr-07, to lugnet.robotics.nxt.nxthacking)

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