Re: H8SX: Bit instructions for review

[Jeff Law <law at redhat dot com>]

Naveen H.S. wrote:
> Hi,
>
> H8SX target supports generation of bit instructions in memory addressing
>
> mode. However, these instructions are not getting generated and the bits
> in 
> memory are operated using other instructions which consume more memory.
> The 
> attached patch "h8sx.patch" generates these bit instructions and hence 
> generates optimized code. 
>
> We are aware that currently GCC is in stage-3. However, this patch is
> just 
> for review so that it can be modified according to the review comments.
> The 
> modified patch will then be posted to the gcc-patches mailing list once
> it 
> returns to stage-1. 
>
>   
Don't forget to include the ChangeLog.

Most of the patch looks OK for when we return to stage1 -- the only 
hunks I don't understand are the two peepholes.  I'm having trouble 
seeing how they can possibly be right.  It appears like the peepholes 
reverse the order of the branch and bit operation, thus causing the 
branch to be based on the output of the bit op rather than whatever was 
in cc0 from some previous operation.  Can you explain why those two 
peepholes are correct, as written?

Additionally, we'd prefer to use define_peephole2 rather than 
define_peephole whenever possible, if you could make that change as well 
it would be greatly appreciated.

Jeff