Re: Fix regression on PR46590 (slow compile with -O0)

[Eric Botcazou <ebotcazou at adacore dot com>]

> It was supposed to not change the set of conflicts, no.  But I made a
> thinko, and sometimes too many conflicts are generated.  On the testcases
> I tried that wasn't the case, so thanks for finding one :)

You're welcome.  In fact, I should have installed it in the gnat.dg testsuite 
long ago but it had been created before -fstack-usage was contributed and then 
I forgot.  So it would be nice to install it once the regression is fixed, the 
incantation being modelled on that of gcc.dg/stack-usage-1.c:

-- { dg-do compile }
-- { dg-options "-fstack-usage" }

[...]

-- { dg-final { scan-stack-usage "xxxx" } }
-- { dg-final { cleanup-stack-usage } }

The expected stack usage is <= 100 bytes for x86 and x86-64.

> Trivially fixing the thinko (iterating over (work bit-and old_conflict) in
> the first inner loop) would fix the testcase but in general create too few
> conflicts, i.e. generate wrong code.  I need some time to think about this
> again.

OK, thanks in advance.

-- 
Eric Botcazou