On 19/02/15 11:21, Arvind Padmanabhan wrote: > Thanks to both Eric and David for their inputs. Indeed, although "-Os > -g" worked for me, it was difficult to set breakpoints at the right > places. At times I had to resort single-stepping in assembly to get > what I wanted. > > It is nice David pointed out that CCS default optimization is like > 0.8 on mspgcc scale. I attempted "-O1 -g" and the code fits nicely in > Flash. I also figured out that -g option affects only the ELF file > size and has no effect on the program size downloaded to Flash. > Option "-O3" explodes the code size. I assume it is sophisticated > performance optimization probably involved lookup tables. Finally, I > tried "-O1 -g3" (maximum debugging) and this is probably what I will > use for debugging. See below for full comparison. >
-O3 does things like extra inlining (inlining can save space or cost space, depending on the size of the functions and the degree of additional optimisations it allows - but -O3 inlines even when there is significant cost in space), loop unrolling (which will be faster on an msp430, but takes more space), and other such expensive optimisations. It is seldom a useful choice. Some compilers generate different code when debugging is enabled, because they (and their matching debuggers) cannot track program state for some types of optimisation. gcc + gdb can do a pretty good job of tracking the state even in heavily optimised code - so "-g" makes almost no difference to the code generation. mvh., David ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=190641631&iu=/4140/ostg.clktrk _______________________________________________ Mspgcc-users mailing list Mspgcc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mspgcc-users
