[gcc r12-2408] [gcn] Work-around libgomp 'error: array subscript 0 is outside array bounds of ‘__lds struct gomp_

[gcc r12-2408] [gcn] Work-around libgomp 'error: array subscript 0 is outside array bounds of ‘__lds struct gomp_

[Thomas Schwinge]

https://gcc.gnu.org/g:8168338684fc2bed576bb09202c63b3e9e678d92

commit r12-2408-g8168338684fc2bed576bb09202c63b3e9e678d92
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Mon Jul 19 23:11:38 2021 +0200

    [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]
    
    With yesterday's commit 9f2bc5077debef2b046b6c10d38591ac324ad8b5 "[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 a110855667782dac7b674d3e328b253b3b3c919b "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.

Diff:
---
 libgomp/config/gcn/team.c |  3 ---
 libgomp/configure.tgt     |  3 +++
 libgomp/libgomp.h         | 12 ------------
 3 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/libgomp/config/gcn/team.c b/libgomp/config/gcn/team.c
index 94ce2f2dfeb..627210ea407 100644
--- a/libgomp/config/gcn/team.c
+++ b/libgomp/config/gcn/team.c
@@ -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)
diff --git a/libgomp/configure.tgt b/libgomp/configure.tgt
index fe2bf1dac51..d4f1e741b5a 100644
--- a/libgomp/configure.tgt
+++ b/libgomp/configure.tgt
@@ -173,6 +173,9 @@ case "${target}" in
 
   amdgcn*-*-*)
 	config_path="gcn accel"
+
+	#TODO PR101484
+	XCFLAGS="$XCFLAGS -Wno-error=array-bounds"
 	;;
 
   *)
diff --git a/libgomp/libgomp.h b/libgomp/libgomp.h
index 4159cbe3334..8d25dc8e2a8 100644
--- a/libgomp/libgomp.h
+++ b/libgomp/libgomp.h
@@ -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)
 {