static bool
tree_ssa_ifcombine_bb (basic_block inner_cond_bb)
{
basic_block then_bb = NULL, else_bb = NULL;
if (!recognize_if_then_else (inner_cond_bb, &then_bb, &else_bb))
return false;
/* Recognize && and || of two conditions with a common
then/else block which entry edges we can merge. That is:
if (a || b)
;
and
if (a && b)
;
This requires a single predecessor of the inner cond_bb. */
if (single_pred_p (inner_cond_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
basic_block outer_cond_bb = single_pred (inner_cond_bb);
if (tree_ssa_ifcombine_bb_1 (inner_cond_bb, outer_cond_bb,
then_bb, else_bb, inner_cond_bb))
return true;
if (forwarder_block_to (else_bb, then_bb))
{
/* Other possibilities for the && form, if else_bb is
empty forwarder block to then_bb. Compared to the above simpler
forms this can be treated as if then_bb and else_bb were swapped,
and the corresponding inner_cond_bb not inverted because of that.
For same_phi_args_p we look at equality of arguments between
edge from outer_cond_bb and the forwarder block. */
if (tree_ssa_ifcombine_bb_1 (inner_cond_bb, outer_cond_bb, else_bb,
then_bb, else_bb))
return true;
}
else if (forwarder_block_to (then_bb, else_bb))
{
/* Other possibilities for the || form, if then_bb is
empty forwarder block to else_bb. Compared to the above simpler
forms this can be treated as if then_bb and else_bb were swapped,
and the corresponding inner_cond_bb not inverted because of that.
For same_phi_args_p we look at equality of arguments between
edge from outer_cond_bb and the forwarder block. */
if (tree_ssa_ifcombine_bb_1 (inner_cond_bb, outer_cond_bb, else_bb,
then_bb, then_bb))
return true;
}
}
return false;
}
static bool
tree_ssa_ifcombine_bb (basic_block inner_cond_bb)
{
basic_block then_bb = NULL, else_bb = NULL;
if (!recognize_if_then_else (inner_cond_bb, &then_bb, &else_bb))
return false;
/* Recognize && and || of two conditions with a common
then/else block which entry edges we can merge. That is:
if (a || b)
;
and
if (a && b)
;
This requires a single predecessor of the inner cond_bb. */
if (single_pred_p (inner_cond_bb))
{
basic_block outer_cond_bb = single_pred (inner_cond_bb);
/* The && form is characterized by a common else_bb with
the two edges leading to it mergable. The latter is
guaranteed by matching PHI arguments in the else_bb and
the inner cond_bb having no side-effects. */
if (recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &else_bb)
&& same_phi_args_p (outer_cond_bb, inner_cond_bb, else_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto inner_cond_bb; else goto else_bb;
<inner_cond_bb>
if (p) goto ...; else goto else_bb;
...
<else_bb>
...
*/
return ifcombine_ifandif (inner_cond_bb, outer_cond_bb);
}
/* The || form is characterized by a common then_bb with the
two edges leading to it mergable. The latter is guaranteed
by matching PHI arguments in the then_bb and the inner cond_bb
having no side-effects. */
if (recognize_if_then_else (outer_cond_bb, &then_bb, &inner_cond_bb)
&& same_phi_args_p (outer_cond_bb, inner_cond_bb, then_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto then_bb; else goto inner_cond_bb;
<inner_cond_bb>
if (q) goto then_bb; else goto ...;
<then_bb>
...
*/
return ifcombine_iforif (inner_cond_bb, outer_cond_bb);
}
}
return false;
}
static bool
tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
basic_block then_bb, basic_block else_bb,
basic_block phi_pred_bb)
{
/* The && form is characterized by a common else_bb with
the two edges leading to it mergable. The latter is
guaranteed by matching PHI arguments in the else_bb and
the inner cond_bb having no side-effects. */
if (phi_pred_bb != else_bb
&& recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &else_bb)
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto inner_cond_bb; else goto else_bb;
<inner_cond_bb>
if (p) goto ...; else goto else_bb;
...
<else_bb>
...
*/
return ifcombine_ifandif (inner_cond_bb, false, outer_cond_bb, false,
false);
}
/* And a version where the outer condition is negated. */
if (phi_pred_bb != else_bb
&& recognize_if_then_else (outer_cond_bb, &else_bb, &inner_cond_bb)
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto else_bb; else goto inner_cond_bb;
<inner_cond_bb>
if (p) goto ...; else goto else_bb;
...
<else_bb>
...
*/
return ifcombine_ifandif (inner_cond_bb, false, outer_cond_bb, true,
false);
}
/* The || form is characterized by a common then_bb with the
two edges leading to it mergable. The latter is guaranteed
by matching PHI arguments in the then_bb and the inner cond_bb
having no side-effects. */
if (phi_pred_bb != then_bb
&& recognize_if_then_else (outer_cond_bb, &then_bb, &inner_cond_bb)
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto then_bb; else goto inner_cond_bb;
<inner_cond_bb>
if (q) goto then_bb; else goto ...;
<then_bb>
...
*/
return ifcombine_ifandif (inner_cond_bb, true, outer_cond_bb, true,
true);
}
/* And a version where the outer condition is negated. */
if (phi_pred_bb != then_bb
&& recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &then_bb)
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb)
&& bb_no_side_effects_p (inner_cond_bb))
{
/* We have
<outer_cond_bb>
if (q) goto inner_cond_bb; else goto then_bb;
<inner_cond_bb>
if (q) goto then_bb; else goto ...;
<then_bb>
...
*/
return ifcombine_ifandif (inner_cond_bb, true, outer_cond_bb, false,
true);
}
return false;
}
