[gomp4] Initialize some extra variables at the entry to an OpenACC offloaded region

[Bernd Schmidt <bernds at codesourcery dot com>]

This initializes worker count and worker id variables; these will be 
used in a followup patch to allocate arrays in gang-local memory to be 
used for synchronizing threads. Committed to gomp-4_0-branch.


Bernd

Index: gcc/ChangeLog.gomp
===================================================================
--- gcc/ChangeLog.gomp	(revision 223870)
+++ gcc/ChangeLog.gomp	(working copy)
@@ -1,5 +1,10 @@
 2015-05-29  Bernd Schmidt  <bernds@codesourcery.com>
 
+	* omp-low.c (struct omp_context): Add worker_var and worker_count
+	fields.
+	(oacc_init_count_vars): New function.
+	(lower_omp_target): Call it.
+
 	* config/nvptx/nvptx.md (UNSPECV_BARSYNC): New constant.
 	(oacc_threadbarrier): New expander.
 	(threadbarrier_insn): New pattern.
Index: gcc/omp-low.c
===================================================================
--- gcc/omp-low.c	(revision 223869)
+++ gcc/omp-low.c	(working copy)
@@ -243,6 +243,11 @@ typedef struct omp_context
   tree ganglocal_ptr;
   tree ganglocal_size;
   tree ganglocal_size_host;
+
+  /* For OpenACC offloaded regions, variables holding the worker id and count
+     of workers.  */
+  tree worker_var;
+  tree worker_count;
 } omp_context;
 
 /* A structure holding the elements of:
@@ -12300,6 +12305,35 @@ lower_omp_taskreg (gimple_stmt_iterator
     }
 }
 
+/* A subroutine of lower_omp_target.  Build variables holding the
+   worker count and index for use inside in ganglocal memory allocations.  */
+
+static void
+oacc_init_count_vars (omp_context *ctx, tree clauses ATTRIBUTE_UNUSED)
+{
+  tree gettid = builtin_decl_explicit (BUILT_IN_GOACC_TID);
+  tree getntid = builtin_decl_explicit (BUILT_IN_GOACC_NTID);
+  tree worker_var, worker_count;
+  tree u1 = fold_convert (unsigned_type_node, integer_one_node);
+  tree u0 = fold_convert (unsigned_type_node, integer_zero_node);
+  if (ctx->gwv_this & MASK_WORKER)
+    {
+      worker_var = create_tmp_var (unsigned_type_node, ".worker");
+      worker_count = create_tmp_var (unsigned_type_node, ".workercount");
+      gimple call1 = gimple_build_call (gettid, 1, u1);
+      gimple_call_set_lhs (call1, worker_var);
+      gimple_seq_add_stmt (&ctx->ganglocal_init, call1);
+      gimple call2 = gimple_build_call (getntid, 1, u1);
+      gimple_call_set_lhs (call2, worker_count);
+      gimple_seq_add_stmt (&ctx->ganglocal_init, call2);
+    }
+  else
+    worker_var = u0, worker_count = u1;
+
+  ctx->worker_var = worker_var;
+  ctx->worker_count = worker_count;
+}
+
 /* Lower the GIMPLE_OMP_TARGET in the current statement
    in GSI_P.  CTX holds context information for the directive.  */
 
@@ -12465,6 +12499,9 @@ lower_omp_target (gimple_stmt_iterator *
   irlist = NULL;
   orlist = NULL;
 
+  if (is_gimple_omp_oacc (stmt))
+    oacc_init_count_vars (ctx, clauses);
+
   if (has_reduction)
     {
       lower_rec_input_clauses (clauses, &irlist, &orlist, ctx, NULL);