Re: [PATCH] Do not use invalid log links

[Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>]

> There are a couple of things it should do:
>
> (1) Use REG_BASIC_BLOCK as a smoke test.  If it equals BLOCK_FOR_INSN,
>     then you know the value is confined to the current block, and can
>     return false without knowing whether it's a constant.
>
> (2) The scan from "first" is doltish.  It may scan the current block
>     twice.  It doesn't scan all blocks.  The second loop should be 
>     rewritten to use FOR_EACH_BB.

I had noticed (2) myself.  But then, I'm also tempted to change it to 
respectively "return 0;" and "return 1;", and compare the resulting 
assembly outputs.

Paolo