[tree-ssa-branch]: Patch to make sure simplified pieces of for_expr is unshared.

[tree-ssa-branch]: Patch to make sure simplified pieces of for_expr is unshared.

[Daniel Berlin]

This fixes the problem i've been seeing where we'd end up with for loops 
like:

for (T.4530 = la - lb; j <= T.4530; T.4530 = la - lb)
where the "T.4530 = la - lb" nodes were shared.

The cause is that tail_expression returns the same init_expr in both 
cases, which is the shared.
Since we throw that directly in the EXPR_STMT_EXPR, we end up with a 
shared node situation like above.

Now, the PRE result looks like:

for (T.4530 = pretmp.4753 = la - lb; j <= T.4530; T.4530 = pretmp.4753)

which is correct.

2002-07-22  Daniel Berlin  <dberlin@dberlin.org>

        * c-simplify.c (simplify_for_stmt): Deep copy the result of the
        tail_expression, so it's unshared.

Index: c-simplify.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/c-simplify.c,v
retrieving revision 1.1.4.7
diff -c -3 -p -w -B -b -r1.1.4.7 c-simplify.c
*** c-simplify.c        22 Jul 2002 07:44:09 -0000      1.1.4.7
--- c-simplify.c        22 Jul 2002 19:56:50 -0000
*************** simplify_for_stmt (stmt, pre_p)
*** 599,605 ****
    add_tree (post_init_s, pre_p);
    add_tree (deep_copy_list (pre_cond_s), pre_p);

!   EXPR_STMT_EXPR (FOR_INIT_STMT (stmt)) = tail_expression (pre_p, 0);

    /* Build the new FOR_COND.  */
    FOR_COND (stmt) = cond_s;
--- 599,605 ----
    add_tree (post_init_s, pre_p);
    add_tree (deep_copy_list (pre_cond_s), pre_p);

!   EXPR_STMT_EXPR (FOR_INIT_STMT (stmt)) = deep_copy_list (tail_expression (pre_p, 0));

    /* Build the new FOR_COND.  */
    FOR_COND (stmt) = cond_s;
*************** simplify_for_stmt (stmt, pre_p)
*** 615,621 ****
      add_tree (post_expr_s, &expr_chain);
      add_tree (pre_cond_s, &expr_chain);

!     FOR_EXPR (stmt) = tail_expression (&expr_chain, 1);

      if (expr_chain)
        insert_before_continue_end (expr_chain, FOR_BODY (stmt));
--- 615,621 ----
      add_tree (post_expr_s, &expr_chain);
      add_tree (pre_cond_s, &expr_chain);

!     FOR_EXPR (stmt) = deep_copy_list (tail_expression (&expr_chain, 1));

      if (expr_chain)
        insert_before_continue_end (expr_chain, FOR_BODY (stmt));

Re: [tree-ssa-branch]: Patch to make sure simplified pieces of for_expr is unshared.

[Diego Novillo]

On Mon, 22 Jul 2002, Daniel Berlin wrote:

> 2002-07-22  Daniel Berlin  <dberlin@dberlin.org>
> 
>         * c-simplify.c (simplify_for_stmt): Deep copy the result of the
>         tail_expression, so it's unshared.
> 
Looks fine.  Please install after bootstrapping and regression
testing.


Thanks.  Diego.

Re: [tree-ssa-branch]: Patch to make sure simplified pieces of for_expr is unshared.

[Jason Merrill]

You should only need to copy it the first time.

Jason

Re: [tree-ssa-branch]: Patch to make sure simplified pieces of for_expr is unshared.

[Daniel Berlin]

On Sat, 27 Jul 2002, Jason Merrill wrote:

> You should only need to copy it the first time.

Then it would just be shared elsewhere (I tested this, and it was).
Remember, we are asking for a tree that is on the list of trees to add to 
pre-conditions/etc.
Thus, it'll be added somewhere else *besides* EXPR_STMT_EXPR 
(FOR_INIT_STMT) and FOR_EXPR (stmt).

If you don't copy it in both cases, one of them will still be shared.

> 
> Jason
> 
>