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Re: [PATCH] Fix PR middle-end/52894

On 10-Apr-12, at 7:06 AM, Richard Guenther wrote:

I can't immediately see how your description of "the list of pending externals
and the vector" is deleted. pa.c keeps its own vector which references the
decls and the only issue I see is that if you call assemble_external after
processing externals you ICE because the pointer-set is not initialized?

Why does the pa backend end up calling assemble_external at final time?

The backend calls assemble_integer to output function descriptors at final
time. This indirectly calls assemble_external from output_addr_const.
This can be seen in comment #4 in the PR. This occurs after the pending
externals are processed.

We have to ensure that we only output function descriptors that are referenced,
and we can only determine this at final.

As a result, assemble_external is called after the VEC has been deleted.
The compiler doesn't ICE. It goes into an infinite loop when a call to
pointer_set_insert tries to extend the deleted VEC. It does this even if the
pointer is already in the VEC hash.

Previously, the storage wasn't deleted. I suspect the ineffective calls on hpux
weren't noticed because assemble_external had already been called for the
function descriptors earlier, so the list in the backend was complete.

The problem was first seen with the Linux target.  There is no backend
list for this target because it doesn't use or need assemble_external.

I personally think it was wrong to add the deferral in assemble_external,
but that's another issue.


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