llvm dev - Mar 2005 - [LLVMdev] Branch simplification

Hi,

I have a CFG built by LLVM with blocks that look like this:

myBlock:           ; preds = %predA, %predB
   %cond = phi bool [ false, %predA ], [ %otherCond, %predB ]
   br bool %cond, %succA, %succB

Is there a pass or sequence of passes that will see the constant
'false' in the PHI instruction and change the target of %predA to
point directly to %succB?  I tried -simplifycfg but it didn't seem to
help.

Thanks,
Eric

On Wed, 30 Mar 2005, Eric Zimmerman wrote:
> I have a CFG built by LLVM with blocks that look like this:
>
> myBlock:           ; preds = %predA, %predB
>   %cond = phi bool [ false, %predA ], [ %otherCond, %predB ]
>   br bool %cond, %succA, %succB
>
> Is there a pass or sequence of passes that will see the constant
> 'false' in the PHI instruction and change the target of %predA to
> point directly to %succB?  I tried -simplifycfg but it didn't seem to
> help.
Currently there isn't.  -simplifycfg does some of this sort of thing, but 
isn't smart enough to see through PHI nodes yet.

-Chris

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