Hi! On Thu, 5 Nov 2015 10:48:02 -0500, Nathan Sidwell <nat...@acm.org> wrote: > On 11/04/15 05:02, Bernd Schmidt wrote: > > On 11/02/2015 02:56 PM, Nathan Sidwell wrote: > >> On 10/28/15 14:40, Nathan Sidwell wrote: > >>> Richard, > >>> this patch adds folding for the new GOACC_DIM_POS and GOACC_DIM_SIZE > >>> internal > >>> functions. IIUC gimple_fold_call is the right place to add this. > >>> > >>> The size of a compute dimension is very often a compile-time > >>> constant. On the > >>> host, in particular it's 1, which means we can deduce the POS must be > >>> zero.
> This is what I committed, using the helpers I recently added. (I realized we
> can
> only get here for functions with the oacc attribute already set)
> --- gimple-fold.c (revision 229809)
> +++ gimple-fold.c (working copy)
> +/* Transform IFN_GOACC_DIM_SIZE and IFN_GOACC_DIM_POS internal
> + function calls to constants, where possible. */
> +
> +static tree
> +fold_internal_goacc_dim (const gimple *call)
> +{
> + int axis = get_oacc_ifn_dim_arg (call);
> + int size = get_oacc_fn_dim_size (current_function_decl, axis);
> + bool is_pos = gimple_call_internal_fn (call) == IFN_GOACC_DIM_POS;
> + tree result = NULL_TREE;
> +
> + /* If the size is 1, or we only want the size and it is not dynamic,
> + we know the answer. */
> + if (size == 1 || (!is_pos && size))
> + {
> + tree type = TREE_TYPE (gimple_call_lhs (call));
> + result = build_int_cst (type, size - is_pos);
> + }
> +
> + return result;
> +}
> @@ -3106,6 +3129,10 @@ gimple_fold_call (gimple_stmt_iterator *
> return true;
> }
> break;
> + case IFN_GOACC_DIM_SIZE:
> + case IFN_GOACC_DIM_POS:
> + result = fold_internal_goacc_dim (stmt);
> + break;
Merging this into gomp-4_0-branch, we'd run into a lot of regressions
(for OpenACC kernels construct), for example:
[...]/source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop-g.c: In
function 'main._omp_fn.0':
[...]/source-gcc/gcc/testsuite/c-c++-common/goacc/kernels-loop-g.c:8:0:
internal compiler error: Segmentation fault
0xac387f crash_signal
[...]/source-gcc/gcc/toplev.c:336
0x9b8399 tree_int_cst_elt_check
[...]/source-gcc/gcc/tree.h:3129
0x9b8399 get_oacc_fn_dim_size(tree_node*, int)
[...]/source-gcc/gcc/omp-low.c:12630
0x86c530 fold_internal_goacc_dim
[...]/source-gcc/gcc/gimple-fold.c:2917
0x86c530 gimple_fold_call
[...]/source-gcc/gcc/gimple-fold.c:3134
0x86dfe4 fold_stmt_1
[...]/source-gcc/gcc/gimple-fold.c:3702
0xbf9953 execute
[...]/source-gcc/gcc/tree-ssa-forwprop.c:2310
The dims in gcc/omp-low.c:get_oacc_fn_dim_size don't have values set, so
the "TREE_INT_CST_LOW (TREE_VALUE (dims))" fails. I have not analyzed
what exactly is going wrong; I just figured out that it's related to the
IFN_GOACC_DIM_POS without LHS usage that Tom introduced in
gomp-4_0-branch r228735 for OpenACC kernels to "neuter gang-single code
in gang-redundant mode",
<http://news.gmane.org/find-root.php?message_id=%3C561C1336.2050401%40mentor.com%3E>.
So, in r229948 I merged Nathan's trunk r229816 into gomp-4_0-branch with
an additional hack as indicated ("++" prefix) by the following three-way
diff:
commit b421a6415fc223866bc97f8248a1fbd0a524505e
Merge: 7a6eb6b b0ccb4e
Author: tschwinge <tschwinge@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Sun Nov 8 13:49:46 2015 +0000
svn merge -r 229814:229816 svn+ssh://gcc.gnu.org/svn/gcc/trunk
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gomp-4_0-branch@229948
138bc75d-0d04-0410-961f-82ee72b054a4
gcc/ChangeLog | 6 ++++++
gcc/gimple-fold.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)
diff --cc gcc/gimple-fold.c
index c9b9593,45840af..869c6c2
--- gcc/gimple-fold.c
+++ gcc/gimple-fold.c
@@@ -2906,6 -2907,28 +2907,34 @@@ gimple_fold_builtin (gimple_stmt_iterat
return false;
}
+ /* Transform IFN_GOACC_DIM_SIZE and IFN_GOACC_DIM_POS internal
+ function calls to constants, where possible. */
+
+ static tree
+ fold_internal_goacc_dim (const gimple *call)
+ {
++ /* TODO. There is something going wrong here, for the gang_single
++ IFN_GOACC_DIM_POS without LHS, generated in
gcc/omp-low.c:lower_omp_target
++ for is_oacc_kernels (see gomp-4_0-branch r228735). */
++ if (gimple_call_lhs (call) == NULL_TREE)
++ return NULL_TREE;
++
+ int axis = get_oacc_ifn_dim_arg (call);
+ int size = get_oacc_fn_dim_size (current_function_decl, axis);
+ bool is_pos = gimple_call_internal_fn (call) == IFN_GOACC_DIM_POS;
+ tree result = NULL_TREE;
+
+ /* If the size is 1, or we only want the size and it is not dynamic,
+ we know the answer. */
+ if (size == 1 || (!is_pos && size))
+ {
+ tree type = TREE_TYPE (gimple_call_lhs (call));
+ result = build_int_cst (type, size - is_pos);
+ }
+
+ return result;
+ }
+
/* Return true if ARG0 CODE ARG1 in infinite signed precision operation
doesn't fit into TYPE. The test for overflow should be regardless of
-fwrapv, and even for unsigned types. */
Grüße
Thomas
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