RFC: Allow emergency EH pool size to be controlled (for stage 1)

[Richard Biener]

On Tue, Dec 13, 2016 at 2:50 PM, Jonathan Wakely <jwakely@redhat.com> wrote:
> This patch allows the size of the emergency buffer for exception
> handling to be controlled by a build-time macro (to avoid dynamic
> allocation) or by a run-time environment variable (to allocate a
> larger or smaller buffer).
>
> This will have to wait for the next stage 1 now, as it's too late for
> GCC 7, but this shows what I'm thinking about and so might avoid
> anybody else reinventing the wheel.
>
> The patch doesn't include documentation updates for the manual, which
> would be needed to explain the use of the macro and the env var. We
> could also add a --with-libstdcxx-static-eh-pool=N configure flag to
> make it easier to set the macro.

Looks reasonable.  But I wonder whether we'd want the default
arena size to be configurable as well, thus split static-eh-pool=N
into default-eh-pool-size=N and -static-eh-pool (without =N).

Also maybe N should be the number of exception objects rather
than bytes?  Otherwise a target independent N is hard to specify
for say, a distribution that wants either a different default or a
static buffer.

Richard.

>