Serious code size regression from 3.0.2 to now part two

[tm]

On Fri, 26 Jul 2002, Joern Rennecke wrote:

> tm wrote:
> > 
> > Okay, I've started using -fno-reorder-blocks on my testcase map_fog.i, and
> > the code size is still about 10% worse than 3.0.x.
> > 
> > I think I've tracked this down to really bad branches being generated by
> > gcc. Take a look at this code sequence:
> > 

Here's a comparison of code sizes for VideoDraw32OnlyFog32Alpha from
map_fog.i:


  gcc3.0.4      gcc-CVS w/-fno-reorder-blocks
0x2702 (8306)        0x2658 (9816)


I counted 78 alignment directives (.align 5) generated by funky branch
logic. If you assume an average of 16 bytes of padding generated per
.align 5 statement, then you wind up with 1248 bytes of padding.

The empirically observed code size difference is 1510 bytes, so
approximately 262 bytes of code size bloat are still unexplained.

Toshi