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Date: Mon, 26 Oct 2009 17:31:00 -0000
Message-ID: <84fc9c000910260941v67686891u6d228dd918905130@mail.gmail.com>
Subject: Re: RFC: allowing fold to change location of args (PR/41451)
From: Richard Guenther <richard.guenther@gmail.com>
To: Aldy Hernandez <aldyh@redhat.com>
Cc: gcc@gcc.gnu.org
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On Mon, Oct 26, 2009 at 5:37 PM, Aldy Hernandez <aldyh@redhat.com> wrote:
>> > ? ? ?tem =3D fold_build2_loc (loc, code, type,
>> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? fold_convert_loc (loc, TREE_TYPE (op0),
>> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TREE_OPERAND (arg0, 1)),=
 op1);
>> > ? ? ?protected_set_expr_location (tem, loc);
>> >
>> > When --enable-checking=3Dfold, fold verifies that none of the arguments
>> > changed, which in this case it obviously does.
>> >
>> > Would be ok to allow a TREE_EXP's location to change within fold? ?Tha=
t is,
>> > add locus (for TREE_EXP's) to the list of allowed changeable fields in
>> > fold_checksum_tree()?
>>
>> Why? =A0It looks like the above should already take care of the
>> correct location via passing loc to fold_build2_loc.
>
> The correct location is being passed. =A0The problem is that in the
> testcase in question, we modify the original statement (with the new
> locus). =A0Modifying the original statement is a no no in
> fold_checksum_tree.

That wasn't my question.

     tem =3D fold_build2_loc (loc, code, type,
                            fold_convert_loc (loc, TREE_TYPE (op0),
                                              TREE_OPERAND (arg0, 1)), op1);
     protected_set_expr_location (tem, loc);

here tem is built by calling fold_build2_loc.  So why is the location
of tem not loc after that.  This sounds like the actual bug
(and the protected_set_expr_location should be redundant).

Richard.