Re: [OpenACC] internal fn folding

[Nathan Sidwell <nathan@acm.org>]

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On 11/04/15 05:02, Bernd Schmidt wrote:
> On 11/02/2015 02:56 PM, Nathan Sidwell wrote:
>> On 10/28/15 14:40, Nathan Sidwell wrote:
>>> Richard,
>>> this patch adds folding for the new GOACC_DIM_POS and GOACC_DIM_SIZE
>>> internal
>>> functions.  IIUC gimple_fold_call is the right place to add this.
>>>
>>> The size of a compute dimension is very often a compile-time
>>> constant.  On the
>>> host, in particular it's 1, which means we can deduce the POS must be
>>> zero.
>>>
>>> ok?

This is what I committed, using the helpers I recently added. (I realized we can 
only get here for functions with the oacc attribute already set)

nathan

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2015-11-05  Nathan Sidwell  <nathan@codesourcery.com>

	* gimple-fold.c: Include omp-low.h.
	(fold_internal_goacc_dim): New.
	(gimple_fold_call): Call it.

Index: gimple-fold.c
===================================================================
--- gimple-fold.c	(revision 229809)
+++ gimple-fold.c	(working copy)
@@ -52,6 +52,7 @@ along with GCC; see the file COPYING3.
 #include "gimple-match.h"
 #include "gomp-constants.h"
 #include "optabs-query.h"
+#include "omp-low.h"
 
 
 /* Return true when DECL can be referenced from current unit.
@@ -2906,6 +2907,28 @@ gimple_fold_builtin (gimple_stmt_iterato
   return false;
 }
 
+/* Transform IFN_GOACC_DIM_SIZE and IFN_GOACC_DIM_POS internal
+   function calls to constants, where possible.  */
+
+static tree
+fold_internal_goacc_dim (const gimple *call)
+{
+  int axis = get_oacc_ifn_dim_arg (call);
+  int size = get_oacc_fn_dim_size (current_function_decl, axis);
+  bool is_pos = gimple_call_internal_fn (call) == IFN_GOACC_DIM_POS;
+  tree result = NULL_TREE;
+
+  /* If the size is 1, or we only want the size and it is not dynamic,
+     we know the answer.  */
+  if (size == 1 || (!is_pos && size))
+    {
+      tree type = TREE_TYPE (gimple_call_lhs (call));
+      result = build_int_cst (type, size - is_pos);
+    }
+
+  return result;
+}
+
 /* Return true if ARG0 CODE ARG1 in infinite signed precision operation
    doesn't fit into TYPE.  The test for overflow should be regardless of
    -fwrapv, and even for unsigned types.  */
@@ -3106,6 +3129,10 @@ gimple_fold_call (gimple_stmt_iterator *
 	      return true;
 	    }
 	  break;
+	case IFN_GOACC_DIM_SIZE:
+	case IFN_GOACC_DIM_POS:
+	  result = fold_internal_goacc_dim (stmt);
+	  break;
 	case IFN_UBSAN_CHECK_ADD:
 	  subcode = PLUS_EXPR;
 	  break;