Hi,

in attachment the new patch. I also checked the behavior with
move_alloc: it synchronizes right after the deregistration of the
destination.
I also noticed that __asm__ __volatile__ ("":::"memory") is called
before sync all and not after. It shouldn't be a problem, right?


2015-12-08 11:01 GMT+01:00 Tobias Burnus <tobias.bur...@physik.fu-berlin.de>:
> Dear Alessandro, dear all,
>
> On Mon, Dec 07, 2015 at 03:48:17PM +0100, Alessandro Fanfarillo wrote:
>> Your patch fixes the issues. In attachment patch, test case and changelog.
>
> Regarding the ChangeLog: Please include the added lines, only, and not the
> change as patch. gcc/testsuite/ChangeLog changes too often such that a patch
> won't apply.
>
>
> Regarding the patch, I wonder where the memory synchronization makes sense
> and where it is not required. (cf. also my email to Matthew in this thread,
> https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00828.html)
>
>
> I think it should be after all image control statements (8.5.1 in
> http://j3-fortran.org/doc/year/15/15-007r2.pdf):
> SYNC ALL, SYNC IMAGES, SYNC MEMORY, ALLOCATE, DEALLOCATE,
> CRITICAL ... END CRITICAL, EVENT POST, EVENT WAIT, LOCK, UNLOCK,
> MOVE_ALLOC.
>
> Thus:
> - SYNC ..., ALLOCATE/DEALLOCATE: I think those are all handled by the
>   current patch
> - MOVE_ALLOC: This one should be handled via the internal (de)allocate
>   handling (please check!)
> - EVENT WAIT, CRITICAL and LOCK: Obtaining a lock or receiving an event
>   implies that quite likely some other process has changed something
>   before. For those, the assembler statement really has to be added.
> - EVENT POST, UNLOCK and END CRITICAL: While those are image control
>   statements, I do not see how a remote image could modify a value in
>   a well defined way, which is guaranteed to be available after that
>   statement - but might not yet be available already at the previous
>   segment (i.e. the previous image control statement).
>
> Hence: I think you should update the patch to also handle
> EVENT WAIT, CRITICAL and LOCK - and to check MOVE_ALLOC.
>
>
>
> Additionally, we need to handle the alias issue of:
>   var = 5
>   var[this_image()] = 42
>   tmp = var
>
> Both _gfortran_caf_send and _gfortran_caf_sendget can modify the
> value of a variable; thus, calling the assembler after the function
> makes sense.
>
>
> However, _gfortran_caf_get does not modify the associated variable;
> adding the assembler statement *after* _gfortran_caf_get. The
> question is, however, whether one needs to take care of 'flushing'
> the variable before the _gfortran_caf_get:
>    var = 7
>    ...
>    var = 5
>    tmp = var[this_image()]
>    result = var + tmp
> Here, one needs to prevent the compiler of keeping "5" only in a
> register or moving "var = 5" after the _gfortran_caf_get call.
>
>
> Thus, you have to move the assembler statement before the library
> call in _gfortran_caf_get - and add another one at the beginning
> of _gfortran_caf_sendget.
>
> (For send/get, might might come up with something better than
> ""::"memory", but for now, it should do.)
>
> Cheers,
>
> Tobias
2015-12-08  Tobias Burnus  <bur...@net-b.de>
            Alessandro Fanfarillo <fanfarillo....@gmail.com>

        * trans.c (gfc_allocate_using_lib,gfc_deallocate_with_status):
        Introducing __asm__ __volatile__ ("":::"memory")
        after image control statements.
        * trans-stmt.c  (gfc_trans_sync, gfc_trans_event_post_wait,
        gfc_trans_lock_unlock, gfc_trans_critical): Ditto.
        * trans-intrinsic.c (gfc_conv_intrinsic_caf_get,
        conv_caf_send): Introducing __asm__ __volatile__ ("":::"memory")
        after send, before get and around sendget.

2015-12-08  Tobias Burnus  <bur...@net-b.de>
            Alessandro Fanfarillo <fanfarillo....@gmail.com>

        * gfortran.dg/coarray_40.f90: New.

commit 6cdffc285931eb604d4c900d77fe60b96d604556
Author: Alessandro Fanfarillo <fanfari...@ing.uniroma2.it>
Date:   Tue Dec 8 14:58:20 2015 +0100

    Introducing __asm__ __volatile__ (:::memory) after image control 
statements, send, get and sendget

diff --git a/gcc/fortran/trans-intrinsic.c b/gcc/fortran/trans-intrinsic.c
index 21efe44..0e4fcc5 100644
--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -1211,6 +1211,14 @@ gfc_conv_intrinsic_caf_get (gfc_se *se, gfc_expr *expr, 
tree lhs, tree lhs_kind,
   if (lhs == NULL_TREE)
     may_require_tmp = boolean_false_node;
 
+  /* It guarantees memory consistency within the same segment */
+  tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+  tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                   gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                   tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+  ASM_VOLATILE_P (tmp) = 1;
+  gfc_add_expr_to_block (&se->pre, tmp);
+
   tmp = build_call_expr_loc (input_location, gfor_fndecl_caf_get, 9,
                             token, offset, image_index, argse.expr, vec,
                             dst_var, kind, lhs_kind, may_require_tmp);
@@ -1222,6 +1230,15 @@ gfc_conv_intrinsic_caf_get (gfc_se *se, gfc_expr *expr, 
tree lhs, tree lhs_kind,
   se->expr = res_var;
   if (array_expr->ts.type == BT_CHARACTER)
     se->string_length = argse.string_length;
+
+  /* It guarantees memory consistency within the same segment */
+  /* tmp = gfc_build_string_const (strlen ("memory")+1, "memory"), */
+  /* tmp = build5_loc (input_location, ASM_EXPR, void_type_node, */
+  /*               gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE, */
+  /*               tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE); */
+  /* ASM_VOLATILE_P (tmp) = 1; */
+  /* gfc_add_expr_to_block (&se->pre, tmp); */
+
 }
 
 
@@ -1375,6 +1392,14 @@ conv_caf_send (gfc_code *code) {
     {
       tree rhs_token, rhs_offset, rhs_image_index;
 
+      /* It guarantees memory consistency within the same segment */
+      tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+       tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                         gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                         tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+      ASM_VOLATILE_P (tmp) = 1;
+      gfc_add_expr_to_block (&block, tmp);
+
       caf_decl = gfc_get_tree_for_caf_expr (rhs_expr);
       if (TREE_CODE (TREE_TYPE (caf_decl)) == REFERENCE_TYPE)
        caf_decl = build_fold_indirect_ref_loc (input_location, caf_decl);
@@ -1390,6 +1415,15 @@ conv_caf_send (gfc_code *code) {
   gfc_add_expr_to_block (&block, tmp);
   gfc_add_block_to_block (&block, &lhs_se.post);
   gfc_add_block_to_block (&block, &rhs_se.post);
+
+  /* It guarantees memory consistency within the same segment */
+  tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+  tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                   gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                   tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+  ASM_VOLATILE_P (tmp) = 1;
+  gfc_add_expr_to_block (&block, tmp);
+
   return gfc_finish_block (&block);
 }
 
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 3df483a..0075ae4 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -818,6 +818,15 @@ gfc_trans_lock_unlock (gfc_code *code, gfc_exec_op op)
                                   errmsg, errmsg_len);
       gfc_add_expr_to_block (&se.pre, tmp);
 
+      /* It guarantees memory consistency within the same segment */
+      tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+      tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                       gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                       tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+      ASM_VOLATILE_P (tmp) = 1;
+
+      gfc_add_expr_to_block (&se.pre, tmp);
+
       if (stat2 != NULL_TREE)
        gfc_add_modify (&se.pre, stat2,
                        fold_convert (TREE_TYPE (stat2), stat));
@@ -995,6 +1004,14 @@ gfc_trans_event_post_wait (gfc_code *code, gfc_exec_op op)
                               errmsg, errmsg_len);
   gfc_add_expr_to_block (&se.pre, tmp);
 
+  /* It guarantees memory consistency within the same segment */
+  tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+  tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                   gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                   tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+  ASM_VOLATILE_P (tmp) = 1;
+  gfc_add_expr_to_block (&se.pre, tmp);
+
   if (stat2 != NULL_TREE)
     gfc_add_modify (&se.pre, stat2, fold_convert (TREE_TYPE (stat2), stat));
 
@@ -1080,6 +1097,18 @@ gfc_trans_sync (gfc_code *code, gfc_exec_op type)
                               fold_convert (integer_type_node, images));
     }
 
+  /* Per F2008, 8.5.1, a SYNC MEMORY is implied by calling the
+     image control statements SYNC IMAGES and SYNC ALL.  */
+  if (flag_coarray == GFC_FCOARRAY_LIB)
+    {
+      tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+      tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                       gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                       tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+      ASM_VOLATILE_P (tmp) = 1;
+      gfc_add_expr_to_block (&se.pre, tmp);
+    }
+
   if (flag_coarray != GFC_FCOARRAY_LIB)
     {
       /* Set STAT to zero.  */
@@ -1401,6 +1430,15 @@ gfc_trans_critical (gfc_code *code)
       gfc_add_expr_to_block (&block, tmp);
     }
 
+  /* It guarantees memory consistency within the same segment */
+  tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+    tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                     gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                     tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+  ASM_VOLATILE_P (tmp) = 1;
+
+  gfc_add_expr_to_block (&block, tmp);
+
   tmp = gfc_trans_code (code->block->next);
   gfc_add_expr_to_block (&block, tmp);
 
@@ -1413,6 +1451,14 @@ gfc_trans_critical (gfc_code *code)
       gfc_add_expr_to_block (&block, tmp);
     }
 
+      /* It guarantees memory consistency within the same segment */
+      tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+      tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                       gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                       tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+      ASM_VOLATILE_P (tmp) = 1;
+
+      gfc_add_expr_to_block (&block, tmp);
 
   return gfc_finish_block (&block);
 }
diff --git a/gcc/fortran/trans.c b/gcc/fortran/trans.c
index 001db41..1993743 100644
--- a/gcc/fortran/trans.c
+++ b/gcc/fortran/trans.c
@@ -746,6 +746,14 @@ gfc_allocate_using_lib (stmtblock_t * block, tree pointer, 
tree size,
                         TREE_TYPE (pointer), pointer,
                         fold_convert ( TREE_TYPE (pointer), tmp));
   gfc_add_expr_to_block (block, tmp);
+
+  /* It guarantees memory consistency within the same segment */
+  tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+  tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                   gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                   tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+  ASM_VOLATILE_P (tmp) = 1;
+  gfc_add_expr_to_block (block, tmp);
 }
 
 
@@ -1356,6 +1364,14 @@ gfc_deallocate_with_status (tree pointer, tree status, 
tree errmsg,
             token, pstat, errmsg, errlen);
       gfc_add_expr_to_block (&non_null, tmp);
 
+      /* It guarantees memory consistency within the same segment */
+      tmp = gfc_build_string_const (strlen ("memory")+1, "memory"),
+      tmp = build5_loc (input_location, ASM_EXPR, void_type_node,
+                       gfc_build_string_const (1, ""), NULL_TREE, NULL_TREE,
+                       tree_cons (NULL_TREE, tmp, NULL_TREE), NULL_TREE);
+      ASM_VOLATILE_P (tmp) = 1;
+      gfc_add_expr_to_block (&non_null, tmp);
+
       if (status != NULL_TREE)
        {
          tree stat = build_fold_indirect_ref_loc (input_location, status);
diff --git a/gcc/testsuite/gfortran.dg/coarray_40.f90 
b/gcc/testsuite/gfortran.dg/coarray_40.f90
new file mode 100644
index 0000000..84af50e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/coarray_40.f90
@@ -0,0 +1,25 @@
+! { dg-do run }
+! { dg-options "-fcoarray=lib -lcaf_single" }
+!
+! Run-time test for memory consistency
+!
+! Contributed by Deepak Eachempati
+
+program cp_bug
+    implicit none
+    integer :: v1, v2, u[*]
+    integer :: me
+
+    me = this_image()
+
+    u = 0
+    v1 = 10
+
+    v1 = u[me]
+
+    ! v2 should get value in u (0)
+    v2 = v1
+
+    if(v2 /= u) call abort()
+
+end program

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