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Re: [GSoC] How to get started with the isl code generation

On 01/06/2014 01:21, Roman Gareev wrote:
Hi Tobias,

Allright. It seems you understood the tree traversel. For the actual
patch that we want to commit, let's leave it out for now.  Instead,
let's try to get a minimal patch that only adds the flag and the new
file for the isl_ast stuff. In case the isl is choosen as code
generation option, the cloog pass is disabled (they would otherwise get
into their way later) and we dump the ast. We also need a simple test case
that checks that the dump is generated.

What do you mean by simple test case that checks that the dump is
generated? Is it checking of the dump_flags?

I mean that we verify that the dump that is created contains a printed
AST that matches the one we expect.

for (int c1 = 0; c1 < n - 1; c1 += 1)
  for (int c3 = 0; c3 < n; c3 += 1)
    S_5(c1, c3);

Instead of adding this functionality to gloog() I would create a
semilar function that provides the functionality gloog has for the isl
codegen counterpart. -fgraphite-code-generator switches then between
these two functions. To start with the isl counterpart is almost empty.
It just contains the parts of this patch needed for printing. When we
add more functionality and we encounter reuse opportunities, we can move
parts of graphite-clast-to-gimple.c into a generic codegen file.

What do you think?

I think that it's good. It would help to begin removing of CLooG
dependency and make the file with generation of ISL AST easier to
maintain. I implemented it in the patch, which can be found below. You
can also find my post about my second task of the proposal at the
following link

Nice post.

diff --git a/gcc/ b/gcc/
index e74bb67..39cb7bd 100644
--- a/gcc/
+++ b/gcc/
@@ -1250,6 +1250,7 @@ OBJS = \
 	graphite.o \
 	graphite-blocking.o \
 	graphite-clast-to-gimple.o \
+	graphite-isl-ast-to-gimple.o \
 	graphite-dependences.o \
 	graphite-interchange.o \
 	graphite-optimize-isl.o \
diff --git a/gcc/common.opt b/gcc/common.opt
index 5c3f834..731aaf5 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1250,6 +1250,19 @@ fgraphite-identity
 Common Report Var(flag_graphite_identity) Optimization
 Enable Graphite Identity transformation

+Common Report RejectNegative Joined Optimization Enum(fgraphite_generator) Var(flag_graphite_code_gen) Init(FGRAPHITE_CODE_GEN_CLOOG)
+Choose code generator of Graphite
+Name(fgraphite_generator) Type(enum fgraphite_generator) UnknownError(unknown code generator of graphite %qs)
+Enum(fgraphite_generator) String(isl) Value(FGRAPHITE_CODE_GEN_ISL)
+Enum(fgraphite_generator) String(cloog) Value(FGRAPHITE_CODE_GEN_CLOOG)


+#include "config.h"
+#include <isl/set.h>
+#include <isl/map.h>
+#include <isl/union_map.h>
+#include <isl/list.h>
+#include <isl/constraint.h>
+#include <isl/ilp.h>
+#include <isl/aff.h>
+#include <isl/ast_build.h>
+#include "system.h"
+#include "coretypes.h"
+#include "diagnostic-core.h"
+#include "tree.h"
+#include "basic-block.h"
+#include "tree-ssa-alias.h"
+#include "internal-fn.h"
+#include "gimple-expr.h"
+#include "is-a.h"
+#include "gimple.h"
+#include "gimple-iterator.h"
+#include "gimplify-me.h"
+#include "gimple-ssa.h"
+#include "tree-ssa-loop-manip.h"
+#include "tree-ssa-loop.h"
+#include "tree-into-ssa.h"
+#include "tree-pass.h"
+#include "cfgloop.h"
+#include "tree-chrec.h"
+#include "tree-data-ref.h"
+#include "tree-scalar-evolution.h"
+#include "sese.h"
+#include "graphite-poly.h"
+#include "graphite-isl-ast-to-gimple.h"
+#include "graphite-htab.h"

Are these the minimal includes necessary?

+/* This flag is set when an error occurred during the translation of
+   ISL AST to Gimple.  */
+static bool isl_gloog_error;
+/* Prints NODE to FILE.  */
+print_isl_ast_node (FILE *file, __isl_keep isl_ast_node *node,
+		    __isl_keep isl_ctx *ctx)
+  isl_printer *prn = isl_printer_to_file (ctx, file);
+  prn = isl_printer_set_output_format (prn, ISL_FORMAT_C);
+  prn = isl_printer_print_ast_node (prn, node);
+  prn = isl_printer_print_str (prn, "\n");
+  isl_printer_free (prn);
+/* Generates a build, which specifies the constraints on the parameters. */
+static isl_ast_build *
+generate_isl_context (scop_p scop)
+  isl_set * context_isl = isl_set_params (isl_set_copy (scop->context));
+  return isl_ast_build_from_context (context_isl);
+/* Generates a schedule, which specifies an order used to
+   visit elements in a domain. */
+static isl_union_map *
+generate_isl_schedule (scop_p scop)
+  int i;
+  poly_bb_p pbb;
+  isl_union_map *schedule_isl =
+    isl_union_map_empty (isl_set_get_space (scop->context));
+  FOR_EACH_VEC_ELT (SCOP_BBS (scop), i, pbb)
+    {
+      /* Dead code elimination: when the domain of a PBB is empty,
+	 don't generate code for the PBB.  */
+      if (isl_set_is_empty (pbb->domain))
+	continue;
+      isl_map *bb_schedule = isl_map_copy (pbb->transformed);
+      bb_schedule = isl_map_intersect_domain (bb_schedule,
+					      isl_set_copy (pbb->domain));
+      schedule_isl =
+        isl_union_map_union (schedule_isl,
+			     isl_union_map_from_map (bb_schedule));
+    }
+  return schedule_isl;
+static isl_ast_node *
+scop_to_isl_ast (scop_p scop)
+  isl_union_map *schedule_isl = generate_isl_schedule (scop);
+  isl_ast_build *context_isl = generate_isl_context (scop);
+  isl_ast_node *ast_isl = isl_ast_build_ast_from_schedule (context_isl,
+							   schedule_isl);
+  isl_ast_build_free (context_isl);
+  return ast_isl;
+/* GIMPLE Loop Generator: generates loops from STMT in GIMPLE form for
+   the given SCOP.  Return true if code generation succeeded.
+   BB_PBB_MAPPING is a basic_block and it's related poly_bb_p mapping.

You do not yet pass a BB_PBB_MAPPING. Please remove it from the comment.

+gloog_isl (scop_p scop)
+  timevar_push (TV_GRAPHITE_CODE_GEN);
+  isl_gloog_error = false;
+  isl_ast_node *root_node = scop_to_isl_ast (scop);
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "\nISL AST generated by ISL: \n");
+      print_isl_ast_node (dump_file, root_node, scop->ctx);
+    }
+  isl_ast_node_free (root_node);
+  timevar_pop (TV_GRAPHITE_CODE_GEN);
+  return !isl_gloog_error;
diff --git a/gcc/graphite-isl-ast-to-gimple.h b/gcc/graphite-isl-ast-to-gimple.h
new file mode 100644
index 0000000..c7d924e
--- /dev/null
+++ b/gcc/graphite-isl-ast-to-gimple.h
@@ -0,0 +1,24 @@
+/* Translation of ISL AST to Gimple.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+   Contributed by Roman Gareev <>.
+This file is part of GCC.
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<>.  */

This file is empty. It seems to be the perfect place for gloog_isl,
maybe give it a more descriptive name. E.g.,


We could then rename gloog, to graphite_regenerate_ast_cloog().

gloog comes from graphite + cloog and does not make sense in the context
of isl.

diff --git a/gcc/graphite.c b/gcc/graphite.c
index 2e1f439..c384ca7 100644
--- a/gcc/graphite.c
+++ b/gcc/graphite.c
@@ -73,6 +73,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "graphite-poly.h"
 #include "graphite-scop-detection.h"
 #include "graphite-clast-to-gimple.h"
+#include "graphite-isl-ast-to-gimple.h"
 #include "graphite-sese-to-poly.h"
 #include "graphite-htab.h"

@@ -301,7 +302,10 @@ graphite_transform_loops (void)

 	if (POLY_SCOP_P (scop)
 	    && apply_poly_transforms (scop)
-	    && gloog (scop, bb_pbb_mapping))
+	    && (((flag_graphite_code_gen == FGRAPHITE_CODE_GEN_ISL)
+	    && gloog_isl (scop))
+	    || ((flag_graphite_code_gen == FGRAPHITE_CODE_GEN_CLOOG)
+	    && gloog (scop, bb_pbb_mapping))))
 	  need_cfg_cleanup_p = true;


Overall, this patch is wonderful. Small, self-contained, clean,
easy-to-review. A perfect patch.

Please address the comments mentioned above, add the test case and
repost for review. We should get this committed soon.


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