Hi,
When running the test-case included in this patch using an
nvptx accelerator, it fails in execution.
The problem is that the expansion of GOMP_SIMT_XCHG_BFLY is optimized away
during pass_jump as "trivially dead insns".
This is caused by this code in expand_GOMP_SIMT_XCHG_BFLY:
...
class expand_operand ops[3];
create_output_operand (&ops[0], target, mode);
...
expand_insn (targetm.code_for_omp_simt_xchg_bfly, 3, ops);
...
which doesn't guarantee that target is assigned to by the expanded insn.
F.i., if target is:
...
(gdb) call debug_rtx ( target )
(subreg/s/u:QI (reg:SI 40 [ _61 ]) 0)
...
then after expand_insn, we have:
...
(gdb) call debug_rtx ( ops[0].value )
(reg:QI 57)
...
See commit 3af3bec2e4d "internal-fn: Avoid dropping the lhs of some
calls [PR94941]" for a similar problem.
Fix this in the same way, by adding:
...
if (!rtx_equal_p (target, ops[0].value))
emit_move_insn (target, ops[0].value);
...
where applicable in the expand_GOMP_SIMT_* functions.
Tested libgomp on x86_64 with nvptx accelerator.
Any comments?
Thanks,
- Tom
[omp, simt] Fix expand_GOMP_SIMT_*
gcc/ChangeLog:
2021-04-28 Tom de Vries <tdevr...@suse.de>
PR target/100232
* internal-fn.c (expand_GOMP_SIMT_ENTER_ALLOC)
(expand_GOMP_SIMT_LAST_LANE, expand_GOMP_SIMT_ORDERED_PRED)
(expand_GOMP_SIMT_VOTE_ANY, expand_GOMP_SIMT_XCHG_BFLY)
(expand_GOMP_SIMT_XCHG_IDX): Ensure target is assigned to.
---
gcc/internal-fn.c | 12 ++++++++++++
libgomp/testsuite/libgomp.c/target-43.c | 24 ++++++++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index dd7173126fb..d209a52f823 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -243,6 +243,8 @@ expand_GOMP_SIMT_ENTER_ALLOC (internal_fn, gcall *stmt)
create_input_operand (&ops[2], align, Pmode);
gcc_assert (targetm.have_omp_simt_enter ());
expand_insn (targetm.code_for_omp_simt_enter, 3, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* Deallocate per-lane storage and leave non-uniform execution region. */
@@ -300,6 +302,8 @@ expand_GOMP_SIMT_LAST_LANE (internal_fn, gcall *stmt)
create_input_operand (&ops[1], cond, mode);
gcc_assert (targetm.have_omp_simt_last_lane ());
expand_insn (targetm.code_for_omp_simt_last_lane, 2, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* Non-transparent predicate used in SIMT lowering of OpenMP "ordered". */
@@ -319,6 +323,8 @@ expand_GOMP_SIMT_ORDERED_PRED (internal_fn, gcall *stmt)
create_input_operand (&ops[1], ctr, mode);
gcc_assert (targetm.have_omp_simt_ordered ());
expand_insn (targetm.code_for_omp_simt_ordered, 2, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* "Or" boolean reduction across SIMT lanes: return non-zero in all lanes if
@@ -339,6 +345,8 @@ expand_GOMP_SIMT_VOTE_ANY (internal_fn, gcall *stmt)
create_input_operand (&ops[1], cond, mode);
gcc_assert (targetm.have_omp_simt_vote_any ());
expand_insn (targetm.code_for_omp_simt_vote_any, 2, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* Exchange between SIMT lanes with a "butterfly" pattern: source lane index
@@ -361,6 +369,8 @@ expand_GOMP_SIMT_XCHG_BFLY (internal_fn, gcall *stmt)
create_input_operand (&ops[2], idx, SImode);
gcc_assert (targetm.have_omp_simt_xchg_bfly ());
expand_insn (targetm.code_for_omp_simt_xchg_bfly, 3, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* Exchange between SIMT lanes according to given source lane index. */
@@ -382,6 +392,8 @@ expand_GOMP_SIMT_XCHG_IDX (internal_fn, gcall *stmt)
create_input_operand (&ops[2], idx, SImode);
gcc_assert (targetm.have_omp_simt_xchg_idx ());
expand_insn (targetm.code_for_omp_simt_xchg_idx, 3, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
}
/* This should get expanded in adjust_simduid_builtins. */
diff --git a/libgomp/testsuite/libgomp.c/target-43.c
b/libgomp/testsuite/libgomp.c/target-43.c
new file mode 100644
index 00000000000..46b1cfc5b20
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/target-43.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+#include <stdlib.h>
+
+#define N 32
+#define TYPE char
+
+int
+main (void)
+{
+ TYPE result = 1;
+ TYPE a[N];
+ for (int x = 0; x < N; ++x)
+ a[x] = 1;
+
+#pragma omp target map(tofrom: result) map(to:a)
+#pragma omp for simd reduction(&&:result)
+ for (int x = 0; x < N; ++x)
+ result = result && a[x];
+
+ if (result != 1)
+ abort ();
+
+ return 0;
+}
