On Mon, Jun 6, 2016 at 11:27 AM, Prasad Ghangal
<prasad.ghan...@gmail.com> wrote:
> Hi,
>
> This patch parses simple assignment statement
>
> int a;
> void __GIMPLE foo()
> {
> a = 1;
> }
>
> but it does not produce gimple dump. In debugging I found that
> cfun->gimple_body is not NULL and it contains GIMPLE_ASSIGN statement.
> Am I missing something ?
This is because the cgraph code does not call gimplify_function_tree
() on functions
with a gimple body (undertstandably) but that function produces said dump file.
Now, we don't even get that far as as you call finish_function () the C FE sees
no DECL_INITIAL on the fndecl (that contains the BLOCK tree), it doesn't even
finalize the function via the cgraph (cgraph_node::finalize_function ()).
While I believe that in the end we want a custom finish_function for
the GIMPLE FE
the immediate issue is the lack of a BLOCK tree which you can try initializing
to NULL_TREE or an empty scope by simply doing
DECL_INITIAL (fndecl) = make_node (BLOCK);
BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl)) = fndecl;
that then runs into
#1 0x0000000001798f21 in lower_function_body ()
at /space/rguenther/src/svn/GSoC/gcc/gimple-low.c:93
93 gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
(gdb) l
88 gimple *bind;
89 gimple *x;
90
91 /* The gimplifier should've left a body of exactly one statement,
92 namely a GIMPLE_BIND. */
93 gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
94 && gimple_code (gimple_seq_first_stmt (body)) ==
GIMPLE_BIND);
as GIMPLE lowering expects "high GIMPLE" and thus an outer GIMPLE_BIND.
It might be the time to investigate how to "skip" some early passes, for example
by first of all declaring what kind of GIMPLE you emit via setting
cfun->curr_properties - in this case to PROP_gimple_any | PROP_gimple_lcf
Ideally the pass manager would then skip parts of the pipeline that
are not necessary.
You will notice that a lot of time GCC development is chasing asserts
/ assumptions
of some part of the compiler and in this process understand GCC some more ;)
Richard.
>
>
> Thanks,
> Prasad Ghangal
>
> On 31 May 2016 at 15:57, Richard Biener <richard.guent...@gmail.com> wrote:
>> On Mon, May 30, 2016 at 5:15 PM, Prasad Ghangal
>> <prasad.ghan...@gmail.com> wrote:
>>> Hi,
>>>
>>> As David suggested in his rtlfe patch,
>>> this patch recognizes __GIMPLE keyword and switches to
>>> c_parser_parse_gimple_body by providing -fgimple option.
>>>
>>>
>>> diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
>>> index 4568cf6..41a8f05 100644
>>> --- a/gcc/c-family/c-common.c
>>> +++ b/gcc/c-family/c-common.c
>>> @@ -511,6 +511,7 @@ const struct c_common_resword c_common_reswords[] =
>>> { "__underlying_type", RID_UNDERLYING_TYPE, D_CXXONLY },
>>> { "__volatile", RID_VOLATILE, 0 },
>>> { "__volatile__", RID_VOLATILE, 0 },
>>> + { "__GIMPLE", RID_GIMPLE, 0 },
>>
>> I think we need a D_GIMPLE_ONLY flag which disables this reserved word
>> when -fgimple is not
>> in effect. That's something to put on a list of TODOs once everything
>> else works fine (it's not
>> high priority but a requirement to merge to trunk). For now you can
>> at least put D_CONLY there
>> (as -fgimple is a C only flag).
>>
>>> { "alignas", RID_ALIGNAS, D_CXXONLY | D_CXX11 | D_CXXWARN },
>>> { "alignof", RID_ALIGNOF, D_CXXONLY | D_CXX11 | D_CXXWARN },
>>> { "asm", RID_ASM, D_ASM },
>>> diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
>>> index 0295532..23a401d 100644
>>> --- a/gcc/c-family/c-common.h
>>> +++ b/gcc/c-family/c-common.h
>>> @@ -104,6 +104,9 @@ enum rid
>>> RID_DFLOAT32, RID_DFLOAT64, RID_DFLOAT128,
>>> RID_FRACT, RID_ACCUM, RID_AUTO_TYPE, RID_BUILTIN_CALL_WITH_STATIC_CHAIN,
>>>
>>> + /* "__GIMPLE", for the GIMPLE-parsing extension to the C frontend. */
>>> + RID_GIMPLE,
>>> +
>>> /* C11 */
>>> RID_ALIGNAS, RID_GENERIC,
>>>
>>> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>>> index 918df16..8ab56af 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
>>> +
>>> H
>>> C ObjC C++ ObjC++
>>> Print the name of header files as they are used.
>>> diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
>>> index 1cf4fb4..c5a4d3f 100644
>>> --- a/gcc/c/c-parser.c
>>> +++ b/gcc/c/c-parser.c
>>> @@ -1396,6 +1396,7 @@ static bool c_parser_cilk_verify_simd (c_parser
>>> *, enum pragma_context);
>>> static tree c_parser_array_notation (location_t, c_parser *, tree, tree);
>>> static tree c_parser_cilk_clause_vectorlength (c_parser *, tree, bool);
>>> static void c_parser_cilk_grainsize (c_parser *, bool *);
>>> +static void c_parser_parse_gimple_body (c_parser *parser);
>>>
>>> /* Parse a translation unit (C90 6.7, C99 6.9).
>>>
>>> @@ -1638,6 +1639,7 @@ 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;
>>>
>>> if (static_assert_ok
>>> && c_parser_next_token_is_keyword (parser, RID_STATIC_ASSERT))
>>> @@ -1687,6 +1689,17 @@ c_parser_declaration_or_fndef (c_parser
>>> *parser, bool fndef_ok,
>>> c_parser_skip_to_end_of_block_or_statement (parser);
>>> return;
>>> }
>>> +
>>> + if (c_parser_next_token_is (parser, CPP_KEYWORD))
>>> + {
>>> + c_token *kw_token = c_parser_peek_token (parser);
>>> + if (kw_token->keyword == RID_GIMPLE)
>>> + {
>>> + gimple_body_p = true;
>>> + c_parser_consume_token (parser);
>>> + }
>>> + }
>>> +
>>> finish_declspecs (specs);
>>> bool auto_type_p = specs->typespec_word == cts_auto_type;
>>> if (c_parser_next_token_is (parser, CPP_SEMICOLON))
>>> @@ -2102,6 +2115,14 @@ c_parser_declaration_or_fndef (c_parser
>>> *parser, bool fndef_ok,
>>> oacc_routine_clauses, false, first, true);
>>> DECL_STRUCT_FUNCTION (current_function_decl)->function_start_locus
>>> = c_parser_peek_token (parser)->location;
>>> +
>>> + if (gimple_body_p && flag_gimple)
>>> + {
>>> + c_parser_parse_gimple_body (parser);
>>> + finish_function ();
>>> + return;
>>> + }
>>> +
>>> fnbody = c_parser_compound_statement (parser);
>>> if (flag_cilkplus && contains_array_notation_expr (fnbody))
>>> fnbody = expand_array_notation_exprs (fnbody);
>>> @@ -2123,7 +2144,7 @@ c_parser_declaration_or_fndef (c_parser *parser,
>>> bool fndef_ok,
>>> add_stmt (fnbody);
>>> finish_function ();
>>> }
>>> -
>>> +
>>> timevar_pop (tv);
>>> break;
>>> }
>>
>> Always avoid stay changes like this.
>>
>>> @@ -18055,4 +18076,23 @@ c_parser_array_notation (location_t loc,
>>> c_parser *parser, tree initial_index,
>>> return value_tree;
>>> }
>>>
>>> +/* Parse the body of a function declaration marked with "__GIMPLE". */
>>> +
>>> +void
>>> +c_parser_parse_gimple_body (c_parser *parser)
>>> +{
>>> + if (!c_parser_require (parser, CPP_OPEN_BRACE, "expected %<{%>"))
>>> + return;
>>> +
>>> + location_t loc1 = c_parser_peek_token (parser)->location;
>>> + inform (loc1, "start of GIMPLE");
>>> +
>>> + while (c_parser_next_token_is_not (parser, CPP_CLOSE_BRACE))
>>> + {
>>> + c_parser_consume_token (parser);
>>> + }
>>> +
>>> + c_parser_consume_token (parser);
>>> +}
>>> +
>>> #include "gt-c-c-parser.h"
>>>
>>>
>>>
>>>
>>> GIMPLE function body consists of GIMPLE statements. For parsing GIMPLE
>>> function body, we need to populate gimple body with gimple statements
>>> which will emit GIMPLE as it is.
>>>
>>> I would like to hear suggestions about how can I emit GIMPLE directly from
>>> FE.
>>
>> You should be able to use gimple_build_* functions declared in gimple.h, for
>> example
>>
>> stmt = gimple_build_assign (res, PLUS_EXPR, op0, op1);
>>
>> will build an assignment to res computing op0 + op1. res, op0 and op1 can be
>> most easily parsed using the appropriate C parsing functions for identifiers.
>>
>> You'll need to queue stmts you built in a gimple_seq and attach that to the
>> function via gimple_set_body (fndecl, sequence).
>>
>> I suggest you try with a "simple" example like
>>
>> int a;
>>
>> __GIMPLE void foo (void)
>> {
>> a = 1;
>> }
>>
>> going forward with handling a = 1 + 2; and then, sth you'll need very
>> quickly,
>> handle local declarations like
>>
>> int a;
>> __GIMPLE int foo (void)
>> {
>> int b;
>> b = a;
>> b = b + 1;
>> a = b;
>> }
>>
>> this is sth C code like int foo (void) { a = a + 1; } is gimplified to.
>>
>> Richard.
>>
>>>
>>>
>>> Thanks,
>>> Prasad Ghangal
