Re: [patch] [gsoc] [gimplefe] GIMPLE FE Project

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, Oct 25, 2016 at 1:13 PM, Prasad Ghangal
<prasad.ghangal@gmail.com> wrote:
> On 25 October 2016 at 15:49, Richard Biener <richard.guenther@gmail.com> wrote:
>> On Thu, Oct 6, 2016 at 1:28 AM, Joseph Myers <joseph@codesourcery.com> wrote:
>>> On Fri, 26 Aug 2016, Prasad Ghangal wrote:
>>>
>>>> >> Thanks for your feedback. I had missed removing some unwanted code
>>>> >> while code cleanup. I have updated the patch.
>>>> >> I am not sure if we should move all gimple parsing related functions
>>>> >> to the new file (?)
>>>> >
>>>> > I think it might be good to make the parts of the C parser you use more
>>>> > obvious (you'd need to export functions like c_parser_next_token_is).
>>>> >
>>>> > The easiest way to "force" that is to put all of the gimple parsing into
>>>> > a separate file.
>>>> >
>>>> > Note I am not so much concerned about this at the moment, the parts to
>>>> > improve would be avoiding more of the C-isms like convert_lvalue_to_rvalue,
>>>> > handling of SIZEOF_EXPR and other stuff that looks redundant (you've
>>>> > probably copied this from the C parsing routines and refactored it).
>>>> > Also the GIMPLE parser shouldn't do any warnings (just spotted
>>>> > a call to warn_for_memset).
>>>> >
>>>> PFA updated patch (successfully bootstrapped and tested on
>>>> x86_64-pc-linux-gnu). I have removed unnecessary code. On side I am
>>>> also trying to move gimple parser related functions to new file. But
>>>> for it we also have to move structs like c_token, c_parser. Won't it
>>>> disturb the c-parser code structure ?
>>
>> Thanks Joseph for the review.  Prasad - do you have time in the next few weeks
>> to continue working on this?  I'm currently trying to move what is on the github
>> branch to a branch on git://gcc.gnu.org/git/gcc.git to make it mergeable
> Sorry I couldn't work on the project in last few weeks. Since I will
> be on vacation in the next week, I will definitely work on it. If we
> can't merge it before closure of stage1, can we merge it in the stage2
> or stage3?

I think we might be able to merge early during stage3 as well.  I'm working my
way through the changes that affect not just the GIMPLE FE itself.

>> (looks like the github repo isn't a clone of the gcc git mirror on github?).
> No. (Unfortunately) I had reinitialised git locally. That's why I am
> also struggling while rebasing and syncing to the trunk. Any solution?

I almost finished pushing the last state plus Josephs review comments
fixed (the style ones) to the official GCC git mirror as a branch off
current trunk.
I'll send a short announcement once I managed to "push" ...

> Since I am employed now, do I need to update the copyright assignment?

If your employer has a copyright assignment then things should be fine.
If you work on this during non-work time then your personal assignment is
also fine.

Thanks,
Richard.

>
> Thanks,
> Prasad
>>
>> Thanks,
>> Richard.
>>
>>> I think the GIMPLE parsing should go in a separate file (meaning exporting
>>> relevant types and function declarations in a new c-parser.h).
>>>
>>>> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>>>> index a5358ed..3c4d2cc 100644
>>>> --- a/gcc/c-family/c.opt
>>>> +++ b/gcc/c-family/c.opt
>>>> @@ -200,6 +200,10 @@ F
>>>>  Driver C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
>>>>  -F <dir>     Add <dir> to the end of the main framework include path.
>>>>
>>>> +fgimple
>>>> +C Var(flag_gimple) Init(0)
>>>> +Enable parsing GIMPLE
>>>
>>> You should get a test failure here from the missing "." at the end of the
>>> help text.
>>>
>>> Of course the option also needs documenting in invoke.texi.
>>>
>>>> @@ -1659,6 +1695,9 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
>>>>    tree all_prefix_attrs;
>>>>    bool diagnosed_no_specs = false;
>>>>    location_t here = c_parser_peek_token (parser)->location;
>>>> +  bool gimple_body_p = false;
>>>> +  opt_pass *pass = NULL;
>>>> +  bool startwith_p = false;
>>>
>>> The comment above the function needs updating to document the new syntax.
>>>
>>>> +static void
>>>> +c_parser_gimple_expression (c_parser *parser, gimple_seq *seq)
>>>> +{
>>>> +  struct c_expr lhs, rhs;
>>>> +  gimple *assign = NULL;
>>>> +  enum tree_code subcode = NOP_EXPR;
>>>> +  location_t loc;
>>>> +  tree arg = NULL_TREE;
>>>> +  auto_vec<tree> vargs;
>>>> +
>>>> +  lhs = c_parser_gimple_unary_expression (parser);
>>>> +  rhs.value = error_mark_node;
>>>> +
>>>> +  if (c_parser_next_token_is (parser, CPP_EQ))
>>>> +    {
>>>> +      c_parser_consume_token (parser);
>>>> +    }
>>>
>>> Redundant braces around a single statement.  Also, this looks wrong, in
>>> that it seems like you'd accept a random '=' token at this point
>>> regardless of what follows and whether '=' makes sense in this context.
>>> You need to have proper cases: if '=' parse what makes sense after '=',
>>> otherwise parse what makes sense without '=', so that invalid syntax is
>>> not accepted.
>>>
>>>> +  if (c_parser_next_token_is (parser, CPP_AND) ||
>>>> +      c_parser_next_token_is (parser, CPP_MULT) ||
>>>> +      c_parser_next_token_is (parser, CPP_PLUS) ||
>>>> +      c_parser_next_token_is (parser, CPP_MINUS) ||
>>>> +      c_parser_next_token_is (parser, CPP_COMPL) ||
>>>> +      c_parser_next_token_is (parser, CPP_NOT))
>>>
>>> Operators go at the start of a continuation line, not at the end of the
>>> line.
>>>
>>>> +      if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
>>>> +     {
>>>> +       return;
>>>> +     }
>>>
>>> Please generally review the patch for redundant braces and remove them.
>>>
>>>> +  /* ssa token string.  */
>>>> +  const char *ssa_token = IDENTIFIER_POINTER (c_parser_peek_token (parser)->value);
>>>> +  token = new char [strlen (ssa_token)];
>>>> +  strcpy (token, ssa_token);
>>>
>>> That looks like a buffer overrun.  To copy a string ssa_token, you need
>>> strlen (ssa_token) + 1 bytes of space.
>>>
>>>> +  /* seperate var name and version.  */
>>>
>>> Uppercase letters at start of comments, throughout the patch (and it
>>> should be "Separate", with 'a' not 'e').
>>>
>>> --
>>> Joseph S. Myers
>>> joseph@codesourcery.com