[llvm-commits] patch: preserve branch to unreachable until codegenprep time

[Dan Gohman]

On Oct 18, 2009, at 12:16 AM, Nick Lewycky <nicholas at mxc.ca> wrote:

> This patch moves the code that optimizes "branch to unreachable"  
> from SimplifyCFG to CodeGenPrep. Most of this patch is just updating  
> the unit tests that use unreachable everywhere. I've done my best to  
> preserve the intent of the tests.

I haven't read the patch, but I'm concerned about this interfering  
with other optimizations.  Deleting the condition can expose further  
dce and related optimizations.  Also if the branch is a loop exit,  
deleting it makes it easier to compute a trip count.

Dan