On Fri, 2024-12-06 at 06:32 -0700, Jeff Law wrote: > > On 12/6/24 5:23 AM, Sam James wrote: > > Georg-Johann Lay <a...@gjlay.de> writes: > > > > > This patch disables CRC lookup tables which consume quite some RAM. > > > > Given that -foptimize-crc is new, it may be useful to CC the pass > > authors in case they have input. > I think this is trivially OK for the AVR. The bigger question is should > we do something more general for -Os. > > CRC generation through table lookups is going to take more data space. > You need a 256 byte table for each unique CRC (sizes & polynomial), and > the code to compute the index into the table can be (from a code size > standpoint) relatively expensive as well, particularly on the > micro-controllers if the crc is to be computed in a mode wider than a > word on the target. > > So I would actually even support a more general "don't optimize CRCs by > default for -Os". >
I've been putting CRC tables for many years into .text / .rodata on various MCU projects. Never considered putting them into .data, since flash is usually a lot larger than RAM. What's the reasoning behind putting the tables in .data? Best regards, Oleg Endo
