[patch] Fix GIMPLE verification failure on CONSTRUCTOR

[Richard Guenther]

On Wed, Jul 18, 2012 at 4:25 PM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> This is a regression present on mainline and 4.7 branch.  The error message is:
>
> p.adb: In function 'P.Proc':
> p.adb:3:4: error: non-trivial conversion at assignment
> system__address
> void (*<T590>) (void)
> r.callback.callback.address = q__proc;
>
> +===========================GNAT BUG DETECTED==============================+
> | 4.8.0 20120716 (experimental) [trunk revision 189525] (x86_64-suse-linux) GCC
> error:|
> | verify_gimple failed                                                     |
> | Error detected around p.adb:3:4
>
> We lose a cast in an initializer before gimplification, hence type mismatch.
> This happens as follows: a CONSTRUCTOR used as the initializer of a global
> constant and whose only value contains the cast is embedded (shared) in a
> CONSTRUCTOR used as the initializer of a second global constant, which is in
> turn embedded (shared) in a CONSTRUCTOR used as the initializer of a local
> variable.
>
> The sharing is fine, since we have an unsharing pass running right before
> gimplification.  The problem is that, since:
>
> r171903 | matz | 2011-04-03 13:13:09 +0200 (Sun, 03 Apr 2011) | 7 lines
>
>         * cgraphbuild.c (record_reference): Canonicalize constructor
>         values.
>         * gimple-fold.c (canonicalize_constructor_val): Accept being called
>         without function context.
>         * cgraphunit.c (cgraph_finalize_compilation_unit): Clear
>         current_function_decl and cfun.
>
> record_reference can modify the contents of CONSTRUCTORs _before_ the unsharing
> pass is run and yield invalid GENERIC and later invalid GIMPLE.
>
> Tested on x86_64-suse-linux, OK for the mainline and 4.7 branch?

Ok.

Thanks,
Richard.

>
> 2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>
>
>         * gimple-fold.c (canonicalize_constructor_val): Strip only useless type
>         conversions.
>
>
> 2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>
>
>         * gnat.dg/aggr20.ad[sb]: New test.
>         * gnat.dg/aggr20_pkg.ads: New helper.
>
>
> --
> Eric Botcazou