Hi!
On 2019-11-12T13:29:15+0000, Andrew Stubbs <a...@codesourcery.com> wrote:
> This patch prevents the compiler using multiple workers in a gang.
Almost. The GCN back end fails to enforce this for the case of run-time
variable 'num_workers': that's 'dims[GOMP_DIM_WORKER] == 0', and the
current 'gcc/config/gcn/gcn.c:gcn_goacc_validate_dims' logic doesn't
consider that case:
/* Check the num workers is not too large. */
if (dims[GOMP_DIM_WORKER] > max_workers)
{
warning_at (decl ? DECL_SOURCE_LOCATION (decl) : UNKNOWN_LOCATION,
OPT_Wopenacc_dims,
"using num_workers (%d), ignoring %d",
max_workers, dims[GOMP_DIM_WORKER]);
dims[GOMP_DIM_WORKER] = max_workers;
We could fix that either here, or simply in the GCN libgomp plugin. I've
pushed "[GCN] Fix run-time variable 'num_workers'" to master branch in
commit 30656822b3792712c7a69fe1a0a79739f8f29abc, see attached. As
detailed there, this actually affects/fixes a small number of testcases.
> This
> should be reverted when worker support is committed.
ACK; working on that.
Grüße
Thomas
> 2019-11-12 Andrew Stubbs <a...@codesourcery.com>
> Julian Brown <jul...@codesourcery.com>
>
> 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.
> ---
> gcc/config/gcn/gcn.c | 4 ++--
> gcc/config/gcn/gcn.opt | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/config/gcn/gcn.c b/gcc/config/gcn/gcn.c
> index cdd24277cf6..1a69737f693 100644
> --- a/gcc/config/gcn/gcn.c
> +++ b/gcc/config/gcn/gcn.c
> @@ -4695,6 +4695,8 @@ 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. */
> @@ -6073,8 +6075,6 @@ 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 bdc878f35ad..402deb625bd 100644
> --- a/gcc/config/gcn/gcn.opt
> +++ b/gcc/config/gcn/gcn.opt
> @@ -65,7 +65,7 @@ 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
>
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>From 30656822b3792712c7a69fe1a0a79739f8f29abc Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tho...@codesourcery.com>
Date: Sat, 5 Jun 2021 22:39:21 +0200
Subject: [PATCH] [GCN] Fix run-time variable 'num_workers'
... which currently has *not* been forced to 'num_workers (1)'.
In addition to the testcases modified here, this also fixes:
FAIL: libgomp.oacc-c/../libgomp.oacc-c-c++-common/mode-transitions.c -DACC_DEVICE_TYPE_radeon=1 -DACC_MEM_SHARED=0 -foffload=amdgcn-amdhsa -O0 execution test
[Etc.]
mode-transitions.exe: [...]/libgomp.oacc-c-c++-common/mode-transitions.c:702: t17: Assertion `arr_b[i] == (i ^ 31) * 8' failed.
libgomp/
* plugin/plugin-gcn.c (gcn_exec): Force 'num_workers (1)'
unconditionally.
* testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c:
Update.
* testsuite/libgomp.oacc-c-c++-common/parallel-dims.c: Likewise.
* testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c: Likewise.
---
libgomp/plugin/plugin-gcn.c | 5 ++---
.../testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c | 4 +---
libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims.c | 5 +++--
libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c | 3 ++-
4 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/libgomp/plugin/plugin-gcn.c b/libgomp/plugin/plugin-gcn.c
index 8aab708b0ef..cfed42a2d4d 100644
--- a/libgomp/plugin/plugin-gcn.c
+++ b/libgomp/plugin/plugin-gcn.c
@@ -3041,10 +3041,9 @@ 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] = get_cu_count (kernel->agent); /* Gangs. */
- if (dims[1] == 0) dims[1] = 1; /* Workers. */
+ /* NOTE: Until support for middle-end worker partitioning is merged, force 'num_workers (1)'. */
+ if (/*TODO dims[1] == 0*/ true) 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",
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c
index 7f74ee922b7..6c136c26c93 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c
@@ -94,9 +94,7 @@ static void cb_enqueue_launch_start (acc_prof_info *prof_info, acc_event_info *e
if (num_workers < 1)
assert (event_info->launch_event.num_workers >= 1);
/* GCN currently enforces 'num_workers (1)'. */
- else if (acc_device_type == acc_device_radeon
- /*TODO ... just not in the "Parallelism dimensions: variable" case. */
- && /*TODO*/ num_gangs != 22)
+ else if (acc_device_type == acc_device_radeon)
assert (event_info->launch_event.num_workers == 1);
else
{
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims.c
index 974e1504534..fe0dacd5aac 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/parallel-dims.c
@@ -313,8 +313,9 @@ int main ()
}
else if (acc_on_device (acc_device_radeon))
{
- /* The GCC GCN back end is limited to num_workers (16). */
- workers_actual = 16;
+ /* The GCC GCN back end is limited to num_workers (16).
+ Temporarily set this to 1 until multiple workers are permitted. */
+ workers_actual = 1; // 16;
}
else
__builtin_abort ();
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c
index a03a2c2b163..624ec24e437 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/routine-wv-2.c
@@ -6,7 +6,8 @@
#include <gomp-constants.h>
#ifdef ACC_DEVICE_TYPE_radeon
-#define NUM_WORKERS 16
+/* Temporarily set this to 1 until multiple workers are permitted. */
+#define NUM_WORKERS 1
#define NUM_VECTORS 1
#else
#define NUM_WORKERS 16
--
2.30.2
