> -----Original Message-----
> From: Andrew Pinski [mailto:[EMAIL PROTECTED]
> Sent: 19 March 2007 00:47
> To: Alexander Lamaison
> Cc: [email protected]
> Subject: Re: Pointer addition/subtraction tree node
>
> On 3/18/07, Alexander Lamaison <[EMAIL PROTECTED]> wrote:
> > As part of adding a new pass to GCC I am intercepting addition to and
> > subtraction from pointers. These are represented by PLUS_EXPR and
> > MINUS_EXPR tree nodes. I need to be able to find out which of the
> node's
> > two operands is the actual pointer and which is the integer that has
> been
> > added to it.
> >
> > Is there another way to find out which is which?
>
> Not right now, I have been working on a new representation of pointer
> arithmetic for the tree level. The basic implementation is already
> done, see the pointer_plus branch.
>
> Thanks,
> Andrew Pinski
Apologies for top-posting before:
Code of the form
int[10] a;
int* p = a; int* q = a;
int i = 3;
p = q + i;
is transformed into
int * D.900;
unsigned int D.899;
unsigned int i.0;
<bb 0>:
i = 3;
p = &a;
q = &a;
i.0 = (unsigned int) i;
D.899 = i.0 * 4;
D.900 = (int *) D.899;
p = D.900 + q;
by the time it reaches the fixupcfg pass.
It has been suggested to me that a solution might be to trace back through the
tree to find which of the operands is derived from a non-pointer variable. I
am new to GCC development. How might I go about doing this?
Another approach I tried was to detect which of the operands was a compiler
intermediate (my theory being that this would always be the non-pointer
operand) by using DECL_ARTIFICIAL (TREE_OPERAND (t, 0)) but this breaks if
tried on an operand that is not a VAR_DECL. I don't think my theory is sounds
but if it is, is there a way to get this to work?
Thanks.
Alex.
