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From: Ian Lance Taylor <iant@google.com>
To: "Paulo J. Matos" <paulo@matos-sorge.com>
Cc: gcc@gcc.gnu.org
Subject: Re: Volatile qualification on pointer and data
References: <j5adnq$bb4$1@dough.gmane.org>
Date: Tue, 20 Sep 2011 16:36:00 -0000
In-Reply-To: <j5adnq$bb4$1@dough.gmane.org> (Paulo J. Matos's message of "Tue,	20 Sep 2011 17:07:21 +0100")
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"Paulo J. Matos" <paulo@matos-sorge.com> writes:

> The following code:
> static const unsigned int foo = 1;
> unsigned int test( void )
> {
>   const volatile unsigned int *bar = &foo;
>   return ( *bar );
> }
>
> in GCC45 works as expected:
> $test:
>   ld AL,#foo  ;; AL is return register
>   bra 0,X     ;; end function
>
> in GCC46:
> $test:
>   ld AL,0
>   bra 0,X
>
> This is worrying because qualifying the data as volatile should be
> enough to prevent these sort of optimizations. It did until GCC46.

I agree that this looks like a bug.  Please file a bug report marked as
a regression.

Ian