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Re: [PATCH] Handle empty infinite loops in OpenACC for PR84955
On 04/09/2018 04:31 AM, Richard Biener wrote:
> On Fri, 6 Apr 2018, Jakub Jelinek wrote:
>
>> On Fri, Apr 06, 2018 at 06:48:52AM -0700, Cesar Philippidis wrote:
>>> 2018-04-06 Cesar Philippidis <cesar@codesourcery.com>
>>>
>>> PR middle-end/84955
>>>
>>> gcc/
>>> * cfgloop.c (flow_loops_find): Add assert.
>>> * omp-expand.c (expand_oacc_for): Add dummy false branch for
>>> tiled basic blocks without omp continue statements.
>>> * tree-cfg.c (execute_fixup_cfg): Handle calls to internal
>>> functions like regular functions.
>>>
>>> libgomp/
>>> * testsuite/libgomp.oacc-c-c++-common/pr84955.c: New test.
>>> * testsuite/libgomp.oacc-fortran/pr84955.f90: New test.
>>
>> I'd like to defer the cfgloop.c and tree-cfg.c changes to Richard, just want to
>> mention that:
>>
>>> --- a/gcc/tree-cfg.c
>>> +++ b/gcc/tree-cfg.c
>>> @@ -9586,10 +9586,7 @@ execute_fixup_cfg (void)
>>> for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
>>> {
>>> gimple *stmt = gsi_stmt (gsi);
>>> - tree decl = is_gimple_call (stmt)
>>> - ? gimple_call_fndecl (stmt)
>>> - : NULL;
>>> - if (decl)
>>> + if (is_gimple_call (stmt))
>>
>> This change doesn't affect just internal functions, but also all indirect
>> calls through function pointers with const, pure or noreturn attributes.
>
> I think the change is desirable nevertheless. The question is if we
> want to do it at this point in time.
>
> The description of the problem sounds more like LTO writing writing out
> loops without previously fixing up state. So sth like the following
> which I'd prefer at this stage (the above hunk is ok for stage1 then).
OK, I'll save that hunk for stage 1.
> Index: gcc/lto-streamer-out.c
> ===================================================================
> --- gcc/lto-streamer-out.c (revision 259227)
> +++ gcc/lto-streamer-out.c (working copy)
> @@ -2084,6 +2151,9 @@ output_function (struct cgraph_node *nod
> /* Set current_function_decl and cfun. */
> push_cfun (fn);
>
> + /* Fixup loops if required to match discovery done in the reader. */
> + loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
> +
> /* Make string 0 be a NULL string. */
> streamer_write_char_stream (ob->string_stream, 0);
>
> @@ -2176,12 +2246,13 @@ output_function (struct cgraph_node *nod
> streamer_write_record_start (ob, LTO_null);
>
> output_cfg (ob, fn);
> -
> - pop_cfun ();
> }
> else
> streamer_write_uhwi (ob, 0);
>
> + loop_optimizer_finalize ();
> + pop_cfun ();
> +
> /* Create a section to hold the pickled output of this function. */
> produce_asm (ob, function);
That worked. Is this patch OK for trunk, GCC 6 and GCC 7?
Thanks,
Cesar
2018-04-11 Cesar Philippidis <cesar@codesourcery.com>
Richard Biener <rguenther@suse.de>
PR middle-end/84955
gcc/
* cfgloop.c (flow_loops_find): Add assert.
* lto-streamer-out.c (output_function): Fix CFG loop state before
streaming out.
* omp-expand.c (expand_oacc_for): Handle calls to internal
functions like regular functions.
libgomp/
* testsuite/libgomp.oacc-c-c++-common/pr84955.c: New test.
* testsuite/libgomp.oacc-fortran/pr84955.f90: New test.
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index 8af793c6015..6e68639452c 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -462,6 +462,9 @@ flow_loops_find (struct loops *loops)
{
struct loop *loop;
+ if (!from_scratch)
+ gcc_assert (header->loop_father != NULL);
+
/* The current active loop tree has valid loop-fathers for
header blocks. */
if (!from_scratch
diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index 1d2ab9757f1..fd6788a69b0 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -2084,6 +2084,9 @@ output_function (struct cgraph_node *node)
/* Set current_function_decl and cfun. */
push_cfun (fn);
+ /* Fixup loops if required to match discovery done in the reader. */
+ loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
+
/* Make string 0 be a NULL string. */
streamer_write_char_stream (ob->string_stream, 0);
@@ -2176,12 +2179,13 @@ output_function (struct cgraph_node *node)
streamer_write_record_start (ob, LTO_null);
output_cfg (ob, fn);
-
- pop_cfun ();
}
else
streamer_write_uhwi (ob, 0);
+ loop_optimizer_finalize ();
+ pop_cfun ();
+
/* Create a section to hold the pickled output of this function. */
produce_asm (ob, function);
diff --git a/gcc/omp-expand.c b/gcc/omp-expand.c
index bb204906ea6..c7d30ea3964 100644
--- a/gcc/omp-expand.c
+++ b/gcc/omp-expand.c
@@ -5439,6 +5439,14 @@ expand_oacc_for (struct omp_region *region, struct omp_for_data *fd)
split->flags ^= EDGE_FALLTHRU | EDGE_TRUE_VALUE;
+ /* Add a dummy exit for the tiled block when cont_bb is missing. */
+ if (cont_bb == NULL)
+ {
+ edge e = make_edge (body_bb, exit_bb, EDGE_FALSE_VALUE);
+ e->probability = profile_probability::even ();
+ split->probability = profile_probability::even ();
+ }
+
/* Initialize the user's loop vars. */
gsi = gsi_start_bb (elem_body_bb);
expand_oacc_collapse_vars (fd, true, &gsi, counts, e_offset);
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955.c
new file mode 100644
index 00000000000..5910b57b68d
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+
+int
+main ()
+{
+ int i, j;
+
+#pragma acc parallel loop tile(2,3)
+ for (i = 1; i < 10; i++)
+ for (j = 1; j < 10; j++)
+ for (;;)
+ ;
+
+#pragma acc parallel loop
+ for (i = 1; i < 10; i++)
+ for (;;)
+ ;
+
+ return i + j;
+}
diff --git a/libgomp/testsuite/libgomp.oacc-fortran/pr84955.f90 b/libgomp/testsuite/libgomp.oacc-fortran/pr84955.f90
new file mode 100644
index 00000000000..878d8a89f41
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-fortran/pr84955.f90
@@ -0,0 +1,20 @@
+! { dg-do compile }
+
+subroutine s
+ integer :: i, j
+ !$acc parallel loop tile(2,3)
+ do i = 1, 10
+ do j = 1, 10
+ do
+ end do
+ end do
+ end do
+ !$acc end parallel loop
+
+ !$acc parallel loop
+ do i = 1, 10
+ do
+ end do
+ end do
+ !$acc end parallel loop
+end subroutine s