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tree-ssa-threadupdate.c (mark_threaded_blocks): Truncate jump threading paths first, then perform PHI node checks if applicable.

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* tree-ssa-threadupdate.c (mark_threaded_blocks): Truncate jump
        threading paths first, then perform PHI node checks if applicable.

From-SVN: r204659
This commit is contained in:
Jeff Law 2013-11-10 20:04:57 -07:00 • committed by Jeff Law
parent eef5b2855b
commit b11b9adbb1
2 changed files with 49 additions and 40 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2013-11-08 Jeff Law <law@redhat.com>
* tree-ssa-threadupdate.c (mark_threaded_blocks): Truncate jump
threading paths first, then perform PHI node checks if applicable.
2013-11-10 Karlson2k <k2k@narod.ru>
Kai Tietz <ktietz@redhat.com>

84
gcc/tree-ssa-threadupdate.c
View file

@ -1269,46 +1269,6 @@ mark_threaded_blocks (bitmap threaded_blocks)
bitmap_set_bit (tmp, e->dest->index);
}
/* If we have a joiner block (J) which has two successors S1 and S2 and
we are threading though S1 and the final destination of the thread
is S2, then we must verify that any PHI nodes in S2 have the same
PHI arguments for the edge J->S2 and J->S1->...->S2.
We used to detect this prior to registering the jump thread, but
that prohibits propagation of edge equivalences into non-dominated
PHI nodes as the equivalency test might occur before propagation.
This works for now, but will need improvement as part of the FSA
optimization.
Note since we've moved the thread request data to the edges,
we have to iterate on those rather than the threaded_edges vector. */
EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
{
bb = BASIC_BLOCK (i);
FOR_EACH_EDGE (e, ei, bb->preds)
{
if (e->aux)
{
vec<jump_thread_edge *> *path = THREAD_PATH (e);
bool have_joiner = ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK);
if (have_joiner)
{
basic_block joiner = e->dest;
edge final_edge = path->last ()->e;
basic_block final_dest = final_edge->dest;
edge e2 = find_edge (joiner, final_dest);
if (e2 && !phi_args_equal_on_edges (e2, final_edge))
{
delete_jump_thread_path (path);
e->aux = NULL;
}
}
}
}
}
/* If optimizing for size, only thread through block if we don't have
@ -1398,6 +1358,50 @@ mark_threaded_blocks (bitmap threaded_blocks)
}
}
/* If we have a joiner block (J) which has two successors S1 and S2 and
we are threading though S1 and the final destination of the thread
is S2, then we must verify that any PHI nodes in S2 have the same
PHI arguments for the edge J->S2 and J->S1->...->S2.
We used to detect this prior to registering the jump thread, but
that prohibits propagation of edge equivalences into non-dominated
PHI nodes as the equivalency test might occur before propagation.
This must also occur after we truncate any jump threading paths
as this scenario may only show up after truncation.
This works for now, but will need improvement as part of the FSA
optimization.
Note since we've moved the thread request data to the edges,
we have to iterate on those rather than the threaded_edges vector. */
EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
{
bb = BASIC_BLOCK (i);
FOR_EACH_EDGE (e, ei, bb->preds)
{
if (e->aux)
{
vec<jump_thread_edge *> *path = THREAD_PATH (e);
bool have_joiner = ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK);
if (have_joiner)
{
basic_block joiner = e->dest;
edge final_edge = path->last ()->e;
basic_block final_dest = final_edge->dest;
edge e2 = find_edge (joiner, final_dest);
if (e2 && !phi_args_equal_on_edges (e2, final_edge))
{
delete_jump_thread_path (path);
e->aux = NULL;
}
}
}
}
}
BITMAP_FREE (tmp);
}