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 Robotics / NXT / NXT Firmware Hacking / 37
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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: 
Thu, 5 Apr 2007 02:03:36 GMT
Viewed: 
20275 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.

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 toolchain.  The code size was

firmware  :
section             size      addr
.text             158492   1048576
.data               6216   2097152
.bss               46240   2103368
.comment            2052         0
.debug_aranges      7312         0
.debug_pubnames    16026         0
.debug_info       213843         0
.debug_abbrev      42027         0
.debug_line        53237         0
.debug_frame       19336         0
.debug_str         30069         0
.debug_loc        126303         0
.debug_ranges       3744         0
Total             724897

I then built the firmware without linking to libc, and supplied the missing
functions from source ripped out of linux's klibc. I got this for code size

firmware  :
section             size      addr
.text             127080   1048576
.data               5116   2097152
.bss               45752   2102268
.comment            1188         0
.debug_aranges      5912         0
.debug_pubnames    12976         0
.debug_info        92527         0
.debug_abbrev      20705         0
.debug_line        30860         0
.debug_frame       14212         0
.debug_str         22560         0
.debug_loc         75593         0
.debug_ranges       2616         0
Total             457097

I haven't tried the klibc firmware so this could be complete garbage, but it may
be a place to start.

Andrew



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 (...) (18 years ago, 14-Mar-07, to lugnet.robotics.nxt.nxthacking)

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