From: Julian Brown <julian@codesourcery.com>
Date: Fri, 9 Aug 2019 20:01:33 +0000 (-0700)
Subject: [og9] Wait at end of OpenACC asynchronous kernels regions
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f2d70bb7ed647e662f049d445b9fac1ae03044c;p=thirdparty%2Fgcc.git

[og9] Wait at end of OpenACC asynchronous kernels regions

	gcc/
	* omp-oacc-kernels.c (add_wait): New function, split out of...
	(add_async_clauses_and_wait): ...here. Call new outlined function.
	(decompose_kernels_region_body): Add wait at the end of
	explicitly-asynchronous kernels regions.

(cherry picked from openacc-gcc-9-branch commit
79cc9084f24fec88df02daa5b099c8288ee06626)
---

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 84d805116030..a22f07c817c0 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,10 @@
+2019-08-13  Julian Brown  <julian@codesourcery.com>
+
+	* omp-oacc-kernels.c (add_wait): New function, split out of...
+	(add_async_clauses_and_wait): ...here. Call new outlined function.
+	(decompose_kernels_region_body): Add wait at the end of
+	explicitly-asynchronous kernels regions.
+
 2019-08-08  Julian Brown  <julian@codesourcery.com>
 
 	* config/gcn/gcn.c (gcn_goacc_validate_dims): Ensure
diff --git a/gcc/omp-oacc-kernels.c b/gcc/omp-oacc-kernels.c
index 20913859c124..a6c4220f472c 100644
--- a/gcc/omp-oacc-kernels.c
+++ b/gcc/omp-oacc-kernels.c
@@ -900,6 +900,18 @@ maybe_build_inner_data_region (location_t loc, gimple *body,
   return body;
 }
 
+static void
+add_wait (location_t loc, gimple_seq *region_body)
+{
+  /* A "#pragma acc wait" is just a call GOACC_wait (acc_async_sync, 0).  */
+  tree wait_fn = builtin_decl_explicit (BUILT_IN_GOACC_WAIT);
+  tree sync_arg = build_int_cst (integer_type_node, GOMP_ASYNC_SYNC);
+  gimple *wait_call = gimple_build_call (wait_fn, 2,
+                                         sync_arg, integer_zero_node);
+  gimple_set_location (wait_call, loc);
+  gimple_seq_add_stmt (region_body, wait_call);
+}
+
 /* Helper function of decompose_kernels_region_body.  The statements in
    REGION_BODY are expected to be decomposed parallel regions; add an
    "async" clause to each.  Also add a "wait" pragma at the end of the
@@ -923,13 +935,7 @@ add_async_clauses_and_wait (location_t loc, gimple_seq *region_body)
       gimple_omp_target_set_clauses (as_a <gomp_target *> (stmt),
                                      target_clauses);
     }
-  /* A "#pragma acc wait" is just a call GOACC_wait (acc_async_sync, 0).  */
-  tree wait_fn = builtin_decl_explicit (BUILT_IN_GOACC_WAIT);
-  tree sync_arg = build_int_cst (integer_type_node, GOMP_ASYNC_SYNC);
-  gimple *wait_call = gimple_build_call (wait_fn, 2,
-                                         sync_arg, integer_zero_node);
-  gimple_set_location (wait_call, loc);
-  gimple_seq_add_stmt (region_body, wait_call);
+  add_wait (loc, region_body);
 }
 
 /* Auxiliary analysis of the body of a kernels region, to determine for each
@@ -1378,6 +1384,14 @@ decompose_kernels_region_body (gimple *kernels_region, tree kernels_clauses)
      a wait directive at the end.  */
   if (async_clause == NULL)
     add_async_clauses_and_wait (loc, &region_body);
+  else
+    /* !!! If we have asynchronous parallel blocks inside a (synchronous) data
+       region, then target memory will get unmapped at the point the data
+       region ends, even if the inner asynchronous parallels have not yet
+       completed.  For kernels marked "async", we might want to use "enter data
+       async(...)" and "exit data async(...)" instead.
+       For now, insert a (synchronous) wait at the end of the block.  */
+    add_wait (loc, &region_body);
 
   tree kernels_locals = gimple_bind_vars (as_a <gbind *> (kernels_body));
   gimple *body = gimple_build_bind (kernels_locals, region_body,