Edges, predictions, and GC crashes ...

[Daniel Berlin]

On Thu, 2 Jun 2005, Ulrich Weigand wrote:

> Hello,
>
> I'm seeing compiler crashes during garbage collection when using mudflap.

> The problem appears to be that some basic_block_def structures point to
> edge_prediction structures which point to edge_def structures that have
> already been ggc_free()'d.

I keep hitting this problem on my darwin machine with my "rename exit and 
entry blocks to block 0 and 1" patch.
At first i thought it was something in the patch, but it's not.
It's the exact problem you describe.

>
> Now, looking at remove_edge (cfg.c) is does indeed appear that it is
> possible for edges to get deleted without the corresponding prediction
> structure being removed as well ...