Re: [Gomp-discuss] [Fwd: [Open64-devel] Announcement of an OpenMP package for ORC1.1/2.0]

[Pop Sébastian]

On Mon, Jun 09, 2003 at 12:05:21PM +0200, Steven Bosscher wrote:
> I assume you've asked for c-parse.y on their mailing list or something?
> 
I think that the c-parse.y won't be of much help in our case, since our 
c++ parser is no longer written using yacc, and the c will be rewritten as 
well.  

Now that I have analyzed a little the patch, here is a short sketch:
they slightly modified the lexer to recognise the openMP specific tokens, 
then they modified the parser adding constructs like:

+case 355:
+#line 1787 "c-parse.y"
+{ yyval.pclause_type = build_parallel_clause_if(yyvsp[-1].ttype); ;
+    break;}

Each clause is added to a list of clauses with functions like:

struct parallel_clause_list *
chain_parallel_list_on (struct parallel_clause_list * pclause_list, struct 
parallel_clause_list * pclause)

Then, once all the clauses have been collected, they build the omp pragma WHIRL 
nodes 
based on the lists of clauses:

+case 349:
+#line 1763 "c-parse.y"
+{      
+           expand_start_parallel(yyvsp[0].pclause_type);
+           free(yyvsp[0].pclause_type);
+       ;
+    break;}


void expand_start_parallel (struct parallel_clause_list * clause_list)

that calls the WHIRL emitter:

void WFE_expand_start_parallel (struct Parallel_clause_wn_type 
*parallel_clause_wn)
{
...
       wn = WN_CreatePragma(WN_PRAGMA_PARALLEL_BEGIN, 
                             (ST_IDX) NULL, 
                             0, 
                             0);   
...
}

Other notes: 

The parser and lexer are based on gcc-2.95.3, and thus they are quite different 
from 
what we have to play with...  For example, the lexer has been modified when the 
new 
preprocessor has been included in gcc-3.0

I like the source code comments :-)  /*ÏÂÃæÑéÖ¤ÊÇ·ñopenmp¹Ø¼ü×Ö*/

I don't know how good is their diagnostic system (ie. warnings emitted when a 
pragma
is ill formed, ...) since this is encoded in the grammar file c-parse.y

It is possible to catch the main idea that we could follow in our 
implementation:
- add new token types to the lexer,
- add new rules to the parser that will emit new tree types,
- lower the GOMP_TREE_NODEs at an appropriate level.