On 7/20/20 3:19 PM, Kwok Cheung Yeung wrote:
> On 01/07/2020 3:28 pm, Tom de Vries wrote:
>> So, I think gcc needs a copy of (some of) the
>> gcc/testsuite/gcc.dg/ia64-sync-*.c tests for effective target
>> sync_char_short.
>>
>> However, since this patch only adds partial support, we cannot enable
>> sync_char_short for nvptx yet. So, if you stick to partial support, you
>> should add a char/short copy of ia64-sync-3.c to gcc.target/nvptx (which
>> ideally could be an include of a generic test-case that is active for
>> sync_char_short only, with mention that it can be removed once
>> sync_char_short is enabled for nvptx).
>>
>
> I have added gcc.target/nvptx/sync.c, which is a version of
> ia64-sync-3.c extended to test chars and shorts too.
I've:
- added the short/char part of that as gcc.dg/ia64-async-5.c
- included the sync_int_long ones of gcc.dg/ia64-async-* in
gcc.target/nvptx
- did the same for gcc.dg/ia64-async-5.c as part of this patch
> I kept the original
> int and long tests because sync_int_long isn't indicated as being
> supported on nvptx either.
>
Yep, I proposed a patch to enable that:
https://gcc.gnu.org/pipermail/gcc-patches/2020-August/551842.html .
>> I looked at the implementation, and it looks ok to me, though I think we
>> need to make explicit in a comment what the assumptions are:
>> - that we have read and write access to the entire word, and
>> - that the word is not volatile.
>>
>
> I've added some extra comments in the implementation. Like I said
> previously, the loop accounts for the larger word being volatile.
>
Right, I known what that loop is intending to do. The loop though may
manifest worst-case as a hang, so I've mentioned that in the comment.
>> As for the oacc test-case, you could add the __int128 bit, perhaps along
>> the lines of how things are done in
>> libgomp/testsuite/libgomp.c++/target-8.C ?
>>
>
> I've added a extra test for __int128 types in my libgomp testcase that
> runs if 128-bit types are supported.
>
> I've tested that there are no regressions with the patch on standalone
> nvptx, and that the new reduction-16.c testcase passes with both nvptx
> and AMD GCN offloading.
>
> Is this version okay for master and og10?
>
Pushed as attached to master.
Thanks,
- Tom
nvptx: Add support for subword compare-and-swap
This adds support for __sync_val_compare_and_swap and
__sync_bool_compare_and_swap for 1-byte and 2-byte long
values, which are not natively supported on nvptx.
Build and reg-tested on nvptx.
Build and reg-tested libgomp on x86_64 with nvptx accelerator.
2020-07-16 Kwok Cheung Yeung <k...@codesourcery.com>
libgcc/
* config/nvptx/atomic.c: New.
* config/nvptx/t-nvptx (LIB2ADD): Add atomic.c.
gcc/testsuite/
* gcc.target/nvptx/sync-5.c: New.
libgomp/
* testsuite/libgomp.c-c++-common/reduction-16.c: New.
---
gcc/testsuite/gcc.target/nvptx/ia64-sync-5.c | 2 +
libgcc/config/nvptx/atomic.c | 73 ++++++++++++++++++++++
libgcc/config/nvptx/t-nvptx | 3 +-
.../testsuite/libgomp.c-c++-common/reduction-16.c | 53 ++++++++++++++++
4 files changed, 130 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.target/nvptx/ia64-sync-5.c b/gcc/testsuite/gcc.target/nvptx/ia64-sync-5.c
new file mode 100644
index 00000000000..ec40f2ca7a9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/ia64-sync-5.c
@@ -0,0 +1,2 @@
+/* { dg-do run } */
+#include "../../gcc.dg/ia64-sync-5.c"
diff --git a/libgcc/config/nvptx/atomic.c b/libgcc/config/nvptx/atomic.c
new file mode 100644
index 00000000000..e1ea078692a
--- /dev/null
+++ b/libgcc/config/nvptx/atomic.c
@@ -0,0 +1,73 @@
+/* NVPTX atomic operations
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ Contributed by Mentor Graphics.
+
+ This file is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published by the
+ Free Software Foundation; either version 3, or (at your option) any
+ later version.
+
+ This file is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
+
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdbool.h>
+
+/* Implement __sync_val_compare_and_swap and __sync_bool_compare_and_swap
+ for 1 and 2-byte values (which are not natively supported) in terms of
+ __sync_val_compare_and_swap for 4-byte values (which is supported).
+ This assumes that the contents of the word surrounding the subword
+ value that we are interested in are accessible as well (which should
+ normally be the case). Note that if the contents of the word surrounding
+ the subword changes between the __sync_val_compare_and_swap_4 and the
+ preceeding load of oldword, while the subword does not, the implementation
+ loops, which may manifest worst-case as a hang. */
+
+#define __SYNC_SUBWORD_COMPARE_AND_SWAP(TYPE, SIZE) \
+ \
+TYPE \
+__sync_val_compare_and_swap_##SIZE (TYPE *ptr, TYPE oldval, TYPE newval) \
+{ \
+ unsigned int *wordptr = (unsigned int *)((__UINTPTR_TYPE__ ) ptr & ~3UL); \
+ int shift = ((__UINTPTR_TYPE__ ) ptr & 3UL) * 8; \
+ unsigned int valmask = (1 << (SIZE * 8)) - 1; \
+ unsigned int wordmask = ~(valmask << shift); \
+ unsigned int oldword = *wordptr; \
+ for (;;) \
+ { \
+ TYPE prevval = (oldword >> shift) & valmask; \
+ /* Exit if the subword value previously read from memory is not */ \
+ /* equal to the expected value OLDVAL. */ \
+ if (__builtin_expect (prevval != oldval, 0)) \
+ return prevval; \
+ unsigned int newword = oldword & wordmask; \
+ newword |= ((unsigned int) newval) << shift; \
+ unsigned int prevword \
+ = __sync_val_compare_and_swap_4 (wordptr, oldword, newword); \
+ /* Exit only if the compare-and-swap succeeds on the whole word */ \
+ /* (i.e. the contents of *WORDPTR have not changed since the last */ \
+ /* memory read). */ \
+ if (__builtin_expect (prevword == oldword, 1)) \
+ return oldval; \
+ oldword = prevword; \
+ } \
+} \
+ \
+bool \
+__sync_bool_compare_and_swap_##SIZE (TYPE *ptr, TYPE oldval, TYPE newval) \
+{ \
+ return __sync_val_compare_and_swap_##SIZE (ptr, oldval, newval) == oldval; \
+}
+
+__SYNC_SUBWORD_COMPARE_AND_SWAP (unsigned char, 1)
+__SYNC_SUBWORD_COMPARE_AND_SWAP (unsigned short, 2)
diff --git a/libgcc/config/nvptx/t-nvptx b/libgcc/config/nvptx/t-nvptx
index c4d20c94cbb..ede0bf0f87d 100644
--- a/libgcc/config/nvptx/t-nvptx
+++ b/libgcc/config/nvptx/t-nvptx
@@ -1,5 +1,6 @@
LIB2ADD=$(srcdir)/config/nvptx/reduction.c \
- $(srcdir)/config/nvptx/mgomp.c
+ $(srcdir)/config/nvptx/mgomp.c \
+ $(srcdir)/config/nvptx/atomic.c
LIB2ADDEH=
LIB2FUNCS_EXCLUDE=__main
diff --git a/libgomp/testsuite/libgomp.c-c++-common/reduction-16.c b/libgomp/testsuite/libgomp.c-c++-common/reduction-16.c
new file mode 100644
index 00000000000..d0e82b04790
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/reduction-16.c
@@ -0,0 +1,53 @@
+/* { dg-do run } */
+
+#include <stdlib.h>
+
+#define N 512
+
+#define GENERATE_TEST(T) \
+int test_##T (void) \
+{ \
+ T a[N], res = 0; \
+ \
+ for (int i = 0; i < N; ++i) \
+ a[i] = i & 1; \
+ \
+_Pragma("omp target teams distribute reduction(||:res) defaultmap(tofrom:scalar)") \
+ for (int i = 0; i < N; ++i) \
+ res = res || a[i]; \
+ \
+ /* res should be non-zero. */\
+ if (!res) \
+ return 1; \
+ \
+_Pragma("omp target teams distribute reduction(&&:res) defaultmap(tofrom:scalar)") \
+ for (int i = 0; i < N; ++i) \
+ res = res && a[i]; \
+ \
+ /* res should be zero. */ \
+ return res; \
+}
+
+GENERATE_TEST(char)
+GENERATE_TEST(short)
+GENERATE_TEST(int)
+GENERATE_TEST(long)
+#ifdef __SIZEOF_INT128__
+GENERATE_TEST(__int128)
+#endif
+
+int main(void)
+{
+ if (test_char ())
+ abort ();
+ if (test_short ())
+ abort ();
+ if (test_int ())
+ abort ();
+ if (test_long ())
+ abort ();
+#ifdef __SIZEOF_INT128__
+ if (test___int128 ())
+ abort ();
+#endif
+}
