emit_conditional_move w/o compare insn (was: Full comparison in 'cbranchsi4' leads to error in gcc 4.0)

[Richard Earnshaw]

On Tue, 2005-05-10 at 17:32, Sami Khawam wrote:
> Hi Gary,
> 
> Thanks a lot for the tip.
> 
> After debugging, the problem seem to be coming from 'emit_conditional_move'
> which is called by 'expand_sdiv_pow2' when converting division-by-constants into 
> shifting.
> The problem is that the architecture I have does not support compare operations: 
> It either has a conditional move or a conditional branch instructions (the 
> compare operation is part of these instructions).
> 
> To make a conditional move, 'emit_conditional_move' generates a seperate compare 
> and then a move insns, maybe hoping that these will be later combined into a 
> single instruction during the optimization steps.
> 
> Would it be possible to tell this to emit_conditional_move so that it generates 
> the cmove insn directely?

The Thumb instruction set on ARM uses cbranchsi4 with very similar
constraints to those you have.  It would really help if you could post a
testcase so that we can analyse this in a scientific manner rather than
guessing what the problem might be.

R.