[gomp4] loop abstraction fns

[gomp4] loop abstraction fns

[Nathan Sidwell]

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In implementing support for tile, the loop structure becomes a little more 
complex, such that oacc_loop_xform_loop's simple scanning approach fails.  I 
realized, that wasn't necessary, if rather than count the abstraction functions 
when discovering the loops, we record the gimple calls themselves. Then we can 
simply iterate over that vector to fill in the partitioning information.  That's 
a better solution on its own merits.

applied to gomp4

nathan

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2016-09-27  Nathan Sidwell  <nathan@codesourcery.com>

	* omp-low.c (struct oacc_loop): Change 'ifns' to vector of call
	stmts.
	(new_oacc_loop_raw, finish_oacc_loop): Adjust.
	(oacc_loop_discover_walk): Append loop abstraction sites to list.
	(oacc_loop_xform_loop): Delete.
	(oacc_loop_process): Iterate over call list directly.
	(execute_oacc_device_lower): Ignore unknown unspecs.

Index: omp-low.c
===================================================================
--- omp-low.c	(revision 240524)
+++ omp-low.c	(working copy)
@@ -253,7 +253,7 @@ struct oacc_loop
   unsigned mask;   /* Partitioning mask.  */
   unsigned inner;  /* Partitioning of inner loops.  */
   unsigned flags;  /* Partitioning flags.  */
-  unsigned ifns;   /* Contained loop abstraction functions.  */
+  vec<gcall *> ifns;  /* Contained loop abstraction functions.  */
   tree chunk_size; /* Chunk size.  */
   gcall *head_end; /* Final marker of head sequence.  */
 };
@@ -19341,7 +19341,6 @@ new_oacc_loop_raw (oacc_loop *parent, lo
   loop->routine = NULL_TREE;
 
   loop->mask = loop->flags = loop->inner = 0;
-  loop->ifns = 0;
   loop->chunk_size = 0;
   loop->head_end = NULL;
 
@@ -19404,7 +19403,7 @@ static oacc_loop *
 finish_oacc_loop (oacc_loop *loop)
 {
   /* If the loop has been collapsed, don't partition it.  */
-  if (!loop->ifns)
+  if (loop->ifns.is_empty ())
     loop->mask = loop->flags = 0;
   return loop->parent;
 }
@@ -19542,9 +19541,9 @@ oacc_loop_discover_walk (oacc_loop *loop
 	  break;
 
 	case IFN_GOACC_LOOP:
-	  /* Count the goacc loop abstraction fns, to determine if the
-	     loop was collapsed already.  */
-	  loop->ifns++;
+	  /* Record the abstraction function, so we can manipulate it
+	     later.  */
+	  loop->ifns.safe_push (call);
 	  break;
 
 	case IFN_UNIQUE:
@@ -19685,51 +19684,6 @@ oacc_loop_xform_head_tail (gcall *from,
     }
 }
 
-/* Transform the IFN_GOACC_LOOP internal functions by providing the
-   determined partitioning mask and chunking argument.  END_MARKER
-   points at the end IFN_HEAD_TAIL call intgroducing the loop.  IFNS
-   is the number of IFN_GOACC_LOOP calls for the loop.  MASK_ARG is
-   the replacement partitioning mask and CHUNK_ARG is the replacement
-   chunking arg.  */
-
-static void
-oacc_loop_xform_loop (gcall *end_marker, unsigned ifns,
-		      tree mask_arg, tree chunk_arg)
-{
-  gimple_stmt_iterator gsi = gsi_for_stmt (end_marker);
-  
-  gcc_checking_assert (ifns);
-  for (;;)
-    {
-      for (; !gsi_end_p (gsi); gsi_next (&gsi))
-	{
-	  gimple *stmt = gsi_stmt (gsi);
-
-	  if (!is_gimple_call (stmt))
-	    continue;
-
-	  gcall *call = as_a <gcall *> (stmt);
-      
-	  if (!gimple_call_internal_p (call))
-	    continue;
-
-	  if (gimple_call_internal_fn (call) != IFN_GOACC_LOOP)
-	    continue;
-
-	  *gimple_call_arg_ptr (call, 5) = mask_arg;
-	  *gimple_call_arg_ptr (call, 4) = chunk_arg;
-	  ifns--;
-	  if (!ifns)
-	    return;
-	}
-
-      /* The LOOP_BOUND ifn could be in the single successor
-	 block.  */
-      basic_block bb = single_succ (gsi_bb (gsi));
-      gsi = gsi_start_bb (bb);
-    }
-}
-
 /* Process the discovered OpenACC loops, setting the correct
    partitioning level etc.  */
 
@@ -19742,13 +19696,25 @@ oacc_loop_process (oacc_loop *loop)
   if (loop->mask && !loop->routine)
     {
       int ix;
-      unsigned mask = loop->mask;
-      unsigned dim = GOMP_DIM_GANG;
-      tree mask_arg = build_int_cst (unsigned_type_node, mask);
+      tree mask_arg = build_int_cst (unsigned_type_node, loop->mask);
       tree chunk_arg = loop->chunk_size;
+      gcall *call;
 
-      oacc_loop_xform_loop (loop->head_end, loop->ifns, mask_arg, chunk_arg);
+      for (ix = 0; loop->ifns.iterate (ix, &call); ix++)
+	switch (gimple_call_internal_fn (call))
+	  {
+	  case IFN_GOACC_LOOP:
+	    gcc_assert (gimple_call_arg (call, 5) == integer_zero_node);
+	    *gimple_call_arg_ptr (call, 5) = mask_arg;
+	    *gimple_call_arg_ptr (call, 4) = chunk_arg;
+	    break;
 
+	  default:
+	    gcc_unreachable ();
+	  }
+
+      unsigned dim = GOMP_DIM_GANG;
+      unsigned mask = loop->mask;
       for (ix = 0; ix != GOMP_DIM_MAX && mask; ix++)
 	{
 	  while (!(GOMP_DIM_MASK (dim) & mask))
@@ -20176,7 +20142,7 @@ execute_oacc_device_lower ()
 	      switch (kind)
 		{
 		default:
-		  gcc_unreachable ();
+		  break;
 
 		case IFN_UNIQUE_OACC_FORK:
 		case IFN_UNIQUE_OACC_JOIN: