Re: [PATCH] mm/pg-r4k.c: Dump the generated code

[Nigel Stephens <nigel@mips.com>]

Thiemo Seufer wrote:
> Franck Bui-Huu wrote:
>   
> > Nigel Stephens wrote:
> >     
> > > Could you run that gcc command manually, adding the options "-v
> > > --save-temps", and post the resulting output messages, and the user.s file.
> > >
> > >       
> > Ok, I did it except I used init/do_mounts.c file since it has at least
> > one nop load delay slot (cf label $L50 in do_mount.s)
> >     
> I only see a nop after the final LW, this is alignment for the next label.
>
>   
Aha, that probably explains it. Franck is using the "SDE for Linux 
v6.05" toolchain, and in that version of GCC -march=mips32r2 implies a 
default of -mtune=24k. Tuning for 24K implies -falign-loops=8 
-falign-jumps=8 and -falign-functions=8. This is undoubtedly why code 
compiled with "-march=mips32r2 -msmartmips" contains more nops than 
"-march=4ksd".nIn theory the extra nops should also disappear if you 
compile with -Os instead of -O2.
Nigel