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[gcn] Work-around libgomp 'error: array subscript 0 is outside array bounds of ‘__lds struct gomp_thread * __lds[0]’ [-Werror=array-bounds]' some more [PR101484]

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With yesterday's commit 9f2bc5077d "[gcn]
Work-around libgomp 'error: array subscript 0 is outside array bounds of
‘__lds struct gomp_thread * __lds[0]’ [-Werror=array-bounds]' [PR101484]",
I did defuse the "unexpected" '-Werror=array-bounds' diagnostics that we see
as of commit a110855667 "Correct handling of
variable offset minus constant in -Warray-bounds [PR100137]".  However, these
'#pragma GCC diagnostic [...]' directives cause some code generation changes
(that seems unexpected, problematic!), which results in a lot (ten thousands)
of 'GCN team arena exhausted' run-time diagnostics, also leading to a few
FAILs:

    PASS: libgomp.c/../libgomp.c-c++-common/for-11.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-11.c execution test

    PASS: libgomp.c/../libgomp.c-c++-common/for-12.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-12.c execution test

    PASS: libgomp.c/../libgomp.c-c++-common/for-3.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-3.c execution test

    PASS: libgomp.c/../libgomp.c-c++-common/for-5.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-5.c execution test

    PASS: libgomp.c/../libgomp.c-c++-common/for-6.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-6.c execution test

    PASS: libgomp.c/../libgomp.c-c++-common/for-9.c (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-9.c execution test

Same for 'libgomp.c++'.

It remains to be analyzed how '#pragma GCC diagnostic [...]' directives can
cause code generation changes; for now I'm working around the "unexpected"
'-Werror=array-bounds' diagnostics differently.

Overall, still awaiting a different solution, of course.

	libgomp/
	PR target/101484
	* configure.tgt [amdgcn*-*-*] (XCFLAGS): Add
	'-Wno-error=array-bounds'.
	* config/gcn/team.c: Remove '-Werror=array-bounds' work-around.
	* libgomp.h [__AMDGCN__]: Likewise.
This commit is contained in:
Thomas Schwinge 2021-07-19 23:11:38 +02:00
parent 6d4da4aeef
commit 8168338684
3 changed files with 3 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
libgomp/config/gcn/team.c
View File

@ -65,12 +65,9 @@ gomp_gcn_enter_kernel (void)
void * __lds *arena_start = (void * __lds *)TEAM_ARENA_START;
void * __lds *arena_free = (void * __lds *)TEAM_ARENA_FREE;
void * __lds *arena_end = (void * __lds *)TEAM_ARENA_END;
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Warray-bounds" /*TODO PR101484 */
*arena_start = team_arena;
*arena_free = team_arena;
*arena_end = team_arena + TEAM_ARENA_SIZE;
# pragma GCC diagnostic pop
/* Allocate and initialize the team-local-storage data. */
struct gomp_thread *thrs = team_malloc_cleared (sizeof (*thrs)

3
libgomp/configure.tgt
View File

@ -173,6 +173,9 @@ case "${target}" in
amdgcn*-*-*)
config_path="gcn accel"
#TODO PR101484
XCFLAGS="$XCFLAGS -Wno-error=array-bounds"
;;
*)

12
libgomp/libgomp.h
View File

@ -128,10 +128,7 @@ team_malloc (size_t size)
: "=v"(result) : "v"(TEAM_ARENA_FREE), "v"(size), "e"(1L) : "memory");
/* Handle OOM. */
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Warray-bounds" /*TODO PR101484 */
if (result + size > *(void * __lds *)TEAM_ARENA_END)
# pragma GCC diagnostic pop
{
/* While this is experimental, let's make sure we know when OOM
happens. */
@ -162,11 +159,8 @@ team_free (void *ptr)
However, if we fell back to using heap then we should free it.
It would be better if this function could be a no-op, but at least
LDS loads are cheap. */
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Warray-bounds" /*TODO PR101484 */
if (ptr < *(void * __lds *)TEAM_ARENA_START
|| ptr >= *(void * __lds *)TEAM_ARENA_END)
# pragma GCC diagnostic pop
free (ptr);
}
#else
@ -795,19 +789,13 @@ static inline struct gomp_thread *gcn_thrs (void)
{
/* The value is at the bottom of LDS. */
struct gomp_thread * __lds *thrs = (struct gomp_thread * __lds *)4;
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Warray-bounds" /*TODO PR101484 */
return *thrs;
# pragma GCC diagnostic pop
}
static inline void set_gcn_thrs (struct gomp_thread *val)
{
/* The value is at the bottom of LDS. */
struct gomp_thread * __lds *thrs = (struct gomp_thread * __lds *)4;
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Warray-bounds" /*TODO PR101484 */
*thrs = val;
# pragma GCC diagnostic pop
}
static inline struct gomp_thread *gomp_thread (void)
{