On Sat, Oct 27, 2012 at 12:53 AM, Dehao Chen <de...@google.com> wrote:
> Hi,
>
> I've updated the patch:
>
> 1. abandon the changes in cfgexpand.c
> 2. set the block for trees when lowering gimple stmt.
> 3. add a unittest.
Index: gcc/gimple-low.c
===================================================================
--- gcc/gimple-low.c (revision 192809)
+++ gcc/gimple-low.c (working copy)
@@ -331,7 +331,18 @@ lower_omp_directive (gimple_stmt_iterator *gsi, st
gsi_next (gsi);
}
+/* Call back function to set the block for expr. */
+static tree
+tree_set_block_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
+ void *data)
+{
+ tree block = (tree) data;
+ if (CAN_HAVE_LOCATION_P (*tp))
+ TREE_SET_BLOCK (*tp, block);
+ return NULL_TREE;
+}
+
/* Lower statement GSI. DATA is passed through the recursion. We try to
track the fallthruness of statements and get rid of unreachable return
statements in order to prevent the EH lowering pass from adding useless
@@ -343,8 +354,11 @@ static void
lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
{
gimple stmt = gsi_stmt (*gsi);
+ unsigned i;
gimple_set_block (stmt, data->block);
+ for (i = 0; i < gimple_num_ops (stmt); i++)
+ walk_tree (gimple_op_ptr (stmt, i), tree_set_block_r, data->block, NULL);
switch (gimple_code (stmt))
{
why do you need this? The stmt location is taken from the operands and in fact
they may have more precise locations. So it seems completely pointless to me
(wasting location entries where a NULL block is just fine (take the block from
the stmt)).
So, what is the issue you try to fix? Yes, the stmt operands will
keep the BLOCK
live, but it is live if the frontend assigned it.
Richard.
> However, this patch will trigger two lto bug when asserting
> LTO_NO_PREVAIL for TREE_CHAIN. After debugging for a while, I found
> that the problem was also there even without the patch. This patch
> just reveal the problem by moving a decl into cache so that it will be
> checked. As I'm not familiar with LTO, not quite sure what the root
> problem is. Can anyone help take a look?
>
> Thanks,
> Dehao
>
> gcc/ChangeLog:
> 2012-10-25 Dehao Chen <de...@google.com>
>
> * tree-eh.c (do_return_redirection): Set location for jump statement.
> (do_goto_redirection): Likewise.
> (frob_into_branch_around): Likewise.
> (lower_try_finally_nofallthru): Likewise.
> (lower_try_finally_copy): Likewise.
> (lower_try_finally_switch): Likewise.
> * gimple-low.c (tree_set_block_r): New callback function.
> (lower_stmt): Set block for tested expr.
>
> gcc/testsuite/ChangeLog:
> 2012-10-25 Dehao Chen <de...@google.com>
>
> * g++.dg/debug/dwarf2/block.C: New testcase.
