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Re: Question about insn lengths
On Tue, Nov 02, 2004 at 02:28:49PM -0800, Eric Christopher wrote:
>
> > Well, it doesn't seem to be difficult to fix the situation in the
> > assembler. In fact, the binutils I have (patched for r5900, naturally)
> > currently emits a warning if the loop is too short.
> >
> > However, I've seen other places where CPU errata is handled by gcc,
> > which made me think there is a policy that gcc should always generate
> > correct assembly for the target processor. You wouldn't know if it is
> > so? Inserting the nops in the assembler might be easier, even.
>
> For this case you'll definitely want to deal with it in the assembler
> for a couple of reasons:
>
> user defined macro instructions
> it's just easier
>
> The sony development toolchain should have a patch already to do this.
Note that if you want to do this (with the FSF tools, at least!) you'll
need to give GCC's branch limits a big kick in the pants first. The
MIPS assembler and linker do not know how to lengthen short branches.
That's why I've dealt with MIPS errata in GCC in the past.
--
Daniel Jacobowitz