[GSoC] replacing op in c_expr

[Prathamesh Kulkarni]

On Mon, Aug 11, 2014 at 4:58 PM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Sun, Aug 10, 2014 at 11:17 PM, Prathamesh Kulkarni
> <bilbotheelffriend@gmail.com> wrote:
>> On Mon, Aug 4, 2014 at 2:13 PM, Richard Biener
>> <richard.guenther@gmail.com> wrote:
>>> On Sun, Aug 3, 2014 at 6:58 PM, Prathamesh Kulkarni
>>> <bilbotheelffriend@gmail.com> wrote:
>>>> On Tue, Jul 29, 2014 at 4:29 PM, Richard Biener
>>>> <richard.guenther@gmail.com> wrote:
>>>>> On Mon, Jul 28, 2014 at 10:02 PM, Prathamesh Kulkarni
>>>>> <bilbotheelffriend@gmail.com> wrote:
>>>>>> I am having few issues replacing op in c_expr.
>>>>>> I thought of following possibilities:
>>>>>>
>>>>>> a) create a new vec<cpp_token> vector new_code.
>>>>>> for each token in code
>>>>>>   {
>>>>>>     if token.type is not CPP_NAME
>>>>>>       new_code.safe_push (token);
>>>>>>     else
>>>>>>      {
>>>>>>         cpp_token new_token =
>>>>>>             ??? create new token of type CPP_NAME
>>>>>>                   with contents as name of operator ???
>>>>>>      }
>>>>>>   }
>>>>>>
>>>>>> I tried to go this way, but am stuck with creating a new token type.
>>>>>> i started by:
>>>>>> cpp_token new_token = token;  // get same attrs as token.
>>>>>> CPP_HASHNODE (new_token.val.node.node)->ident.str = name of operator.
>>>>>> CPP_HASHNODE (new_token.val.node.node)->ident.len = len of operator name.
>>>>>> name of operator is obtained from opers[i] in parse_for.
>>>>>>
>>>>>> however this does not work because I guess
>>>>>>  new_token = token, shallow copies
>>>>>> the token (default assignment operator, i didn't find an overloaded version).
>>>>>>
>>>>>> b) create new struct c_expr_elem and use
>>>>>> vec<c_expr_elem> code, instead of vec<cpp_token> code;
>>>>>>
>>>>>> sth like:
>>>>>> struct c_expr_elem
>>>>>> {
>>>>>>    enum c_expr_elem_type { ID, TOKEN };
>>>>>>    enum c_expr_elem_type type;
>>>>>>
>>>>>>    union {
>>>>>>      cpp_token token;
>>>>>>      const char *id;
>>>>>>    };
>>>>>> };
>>>>>>
>>>>>> while replacing op, compare token with op, and if it matches,
>>>>>> create a new c_expr_elem with type = ID, and id = name of operator.
>>>>>> This shall probably work, but shall require many changes to other parts
>>>>>> since we change c_expr::code.
>>>>>>
>>>>>> I would like to hear any other suggestions.
>>>>>
>>>>> Together with the vector of tokens recorded at parse_c_expr time
>>>>> record a vector of token mappings (op -> plus, op2 -> ...) and do
>>>>> the replacement at code-generation time where we also special-case
>>>>> captures.
>>>>>
>>>>> Yeah, it's a but unfortunate that c_expr parsing is done the way it
>>>>> is done....
>>>> Thanks. I guess we would require a multi-map for this since there can
>>>> be many operators
>>>> (op -> [plus, minus], op2 -> [negate]) ?
>>>
>>> Well, it would be enough to attach the mapping to c_expr()s after the
>>> AST lowering when there is at most one?  Because obviously
>>> code-generation cannot know which to replace.
>>>
>>>> Unfortunately, I somehow seem to have missed your response and ended up with a
>>>> hackish way of doing it, although it works. I will soon change that to
>>>> use token mappings.
>>>>
>>>> I mostly followed b), except i made it sub-class of cpp_token, so the
>>>> other code using c_expr::code
>>>> (outline_c_expr, c_expr::gen_transform) did not require changes except
>>>> for special-casing op.
>>>
>>> Indeed not too ugly.  Still at the point where you replace in the for()
>>> processing
>>>
>>> -             operand *result_op = replace_id (s->result, user_id, opers[i]);
>>> +
>>> +             operand *result_op;
>>> +             if (is_a<c_expr *> (s->result))
>>> +               result_op = replace_op_in_c_expr (s->result, user_id, opers[i]);
>>> +             else
>>> +               result_op = replace_id (s->result, user_id, opers[i]);
>>> +
>>> +
>>>
>>> it should be "easy" to attach a replacemet vector/map to the c_expr
>>> and use that duing code-generation.
>>>
>>> Note that sub-expressions can also be c_exprs, thus
>>>
>>> (match-and-simplify
>>>    (....)
>>>    (plus { ... } @2))
>>>
>>> I don't think your patch covers that.  That is, you should add
>>> c_expr handing to replace_id instead.
>> Thanks, this patch covers that case.
>> For now, I have still kept the old way, since the change was one-liner.
>> I will change it after I am done with conditional convert
>
> I'll wait for that - the patch introduces extra warnings which will break
> bootstrap.
>
Hi,
    This patch replaces op in c_expr, by using vector in c_expr to record
<user_id, operator> mapping.
Sorry for late response.

I needed to clone c_expr, so added clone member function to operand hierarchy.
Ideally it should be a pure member function (= 0) in operand, however
for simplicity I have
put gcc_unreachable (), since I only want it used for c_expr (not
required so far for other classes).
Is that okay for now ? Eventually I will implement clone for other classes...

* genmatch.c (operand): New member function clone.
     (c_expr): Override clone.
     (c_expr): New struct id_tab.
     (c_expr): New member ids.
     (simplify::simplify): Adjust to clone c_expr.
     (replace_id): New default parameter replace_c_expr.
     (c_expr::gen_transform): Adjust to replace user-defined
identifier in c_expr.
     (outline_c_expr): Likewise.
     (parse_for): Likewise.

Thanks,
Prathamesh

> Thanks,
> Richard.
>
>> * genmatch.c (c_expr::elem): New struct.
>>      (c_expr::code): Change type to vec<c_expr::elem>.
>>      (replace_op_in_c_expr): New function.
>>      (replace_id): Call replace_op_in_c_expr.
>>      (c_expr::gen_transform): Adjust to changes in c_expr.
>>      (outline_c_expr): Likewise.
>>      (parse_c_expr): Likewise.
>>      (parse_for): Call replace_op_in_c_expr.
>> Thanks,
>> Prathamesh
>>>
>>> Richard.
>>>
>>>> * genmatch.c (c_expr::elem): New struct.
>>>>      (c_expr::code): Change type to vec<c_expr::elem>.
>>>>      (replace_op_in_c_expr): New function.
>>>>      (c_expr::gen_transform): Adjust to changes in c_expr.
>>>>      (outline_c_expr): Likewise.
>>>>      (parse_c_expr): Likewise.
>>>>      (parse_for): Call replace_op_in_c_expr.
>>>>
>>>> Thanks,
>>>> Prathamesh
>>>>
>>>>>
>>>>> Richard.
>>>>>
>>>>>> Thanks,
>>>>>> Prathamesh.
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