[PATCH 3/3] [og9] Use a single worker for OpenACC on AMD GCN

[Julian Brown <julian at codesourcery dot com>]

This patch sets the number of workers (per-gang) to 1 for AMD GCN,
as a stop-gap measure until the middle-end transformations to enable
multiple workers have been applied.

Julian

ChangeLog

	gcc/
	* config/gcn/gcn.c (gcn_goacc_validate_dims): Ensure
	flag_worker_partitioning is not set.
	(TARGET_GOACC_WORKER_PARTITIONING): Remove target hook definition.
	* config/gcn/gcn.opt (macc-experimental-workers): Default to off.

	libgomp/
	* plugin/plugin-gcn.c (gcn_exec): Use 1 for the default number of
	workers.
---
 gcc/ChangeLog.openacc       | 7 +++++++
 gcc/config/gcn/gcn.c        | 4 ++--
 gcc/config/gcn/gcn.opt      | 2 +-
 libgomp/ChangeLog.openacc   | 5 +++++
 libgomp/plugin/plugin-gcn.c | 4 +++-
 5 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/gcc/ChangeLog.openacc b/gcc/ChangeLog.openacc
index 0caa1cd1401..84d80511603 100644
--- a/gcc/ChangeLog.openacc
+++ b/gcc/ChangeLog.openacc
@@ -1,3 +1,10 @@
+2019-08-08  Julian Brown  <julian@codesourcery.com>
+
+	* config/gcn/gcn.c (gcn_goacc_validate_dims): Ensure
+	flag_worker_partitioning is not set.
+	(TARGET_GOACC_WORKER_PARTITIONING): Remove target hook definition.
+	* config/gcn/gcn.opt (macc-experimental-workers): Default to off.
+
 2019-07-31  Julian Brown  <julian@codesourcery.com>
 
 	* builtin-types.def (BT_FN_VOID_INT_INT_OMPFN_SIZE_PTR_PTR_PTR_VAR):
diff --git a/gcc/config/gcn/gcn.c b/gcc/config/gcn/gcn.c
index 9f73fc8161a..f3f112d95a9 100644
--- a/gcc/config/gcn/gcn.c
+++ b/gcc/config/gcn/gcn.c
@@ -4662,6 +4662,8 @@ gcn_goacc_validate_dims (tree decl, int dims[], int fn_level,
   /* FIXME: remove -facc-experimental-workers when they're ready.  */
   int max_workers = flag_worker_partitioning ? 16 : 1;
 
+  gcc_assert (!flag_worker_partitioning);
+
   /* The vector size must appear to be 64, to the user, unless this is a
      SEQ routine.  The real, internal value is always 1, which means use
      autovectorization, but the user should not see that.  */
@@ -6038,8 +6040,6 @@ print_operand (FILE *file, rtx x, int code)
 #define TARGET_GOACC_REDUCTION gcn_goacc_reduction
 #undef  TARGET_GOACC_VALIDATE_DIMS
 #define TARGET_GOACC_VALIDATE_DIMS gcn_goacc_validate_dims
-#undef  TARGET_GOACC_WORKER_PARTITIONING
-#define TARGET_GOACC_WORKER_PARTITIONING true
 #undef  TARGET_HARD_REGNO_MODE_OK
 #define TARGET_HARD_REGNO_MODE_OK gcn_hard_regno_mode_ok
 #undef  TARGET_HARD_REGNO_NREGS
diff --git a/gcc/config/gcn/gcn.opt b/gcc/config/gcn/gcn.opt
index 2fd3996edba..90d35f42e57 100644
--- a/gcc/config/gcn/gcn.opt
+++ b/gcc/config/gcn/gcn.opt
@@ -62,7 +62,7 @@ Target Report RejectNegative Var(flag_bypass_init_error)
 bool flag_worker_partitioning = false
 
 macc-experimental-workers
-Target Report Var(flag_worker_partitioning) Init(1)
+Target Report Var(flag_worker_partitioning) Init(0)
 
 int stack_size_opt = -1
 
diff --git a/libgomp/ChangeLog.openacc b/libgomp/ChangeLog.openacc
index 62c56e3bf92..2279545f361 100644
--- a/libgomp/ChangeLog.openacc
+++ b/libgomp/ChangeLog.openacc
@@ -1,3 +1,8 @@
+2019-08-08  Julian Brown  <julian@codesourcery.com>
+
+	* plugin/plugin-gcn.c (gcn_exec): Use 1 for the default number of
+	workers.
+
 2019-08-08  Julian Brown  <julian@codesourcery.com>
 
 	* plugin/configfrag.ac (amdgcn): Set tgt_plugin.
diff --git a/libgomp/plugin/plugin-gcn.c b/libgomp/plugin/plugin-gcn.c
index 6eaae66c1a9..a41568b3306 100644
--- a/libgomp/plugin/plugin-gcn.c
+++ b/libgomp/plugin/plugin-gcn.c
@@ -3233,8 +3233,10 @@ gcn_exec (struct kernel_info *kernel, size_t mapnum, void **hostaddrs,
      problem size, so let's do a reasonable number of single-worker gangs.
      64 gangs matches a typical Fiji device.  */
 
+  /* NOTE: Until support for middle-end worker partitioning is merged, use 1
+     for the default number of workers.  */
   if (dims[0] == 0) dims[0] = 64; /* Gangs.  */
-  if (dims[1] == 0) dims[1] = 16; /* Workers.  */
+  if (dims[1] == 0) dims[1] = 1;  /* Workers.  */
 
   /* The incoming dimensions are expressed in terms of gangs, workers, and
      vectors.  The HSA dimensions are expressed in terms of "work-items",