[llvm-commits] Debug-check in SSAUpdater detecting PHI/CFG missmatches

[Bob Wilson]

On Jul 16, 2011, at 2:56 AM, Ludwig Meier wrote:

> This patch adds a debug-check to SSAUpdater, that verifies that the
> predecessor list (as derived from the CFG) matches the predecessor list
> in the PHI-nodes.
> 
> For performance reasons the SSAUpdater uses the incoming-edges of a
> PHI-Node (if one exists) to determine the predecessors of a basic-block.
> When the PHI-nodes incoming edges differ from the CFG, subsequent calls
> to SSAUpdater::GetValue...() may crash.
> This occurs only when the IR is currently invalid, of course.

I think this should go in as a verifier check.  We don't want to have to debugging checks for well-formed IR scattered throughout LLVM.