return true;
}
+/* Return true if BB is an empty forwarder block to TO_BB. */
+
+static bool
+forwarder_block_to (basic_block bb, basic_block to_bb)
+{
+ return empty_block_p (bb)
+ && single_succ_p (bb)
+ && single_succ (bb) == to_bb;
+}
+
/* Verify if all PHI node arguments in DEST for edges from BB1 or
BB2 to DEST are the same. This makes the CFG merge point
free from side-effects. Return true in this case, else false. */
return false;
}
+/* Helper function for tree_ssa_ifcombine_bb. Recognize a CFG pattern and
+ dispatch to the appropriate if-conversion helper for a particular
+ set of INNER_COND_BB, OUTER_COND_BB, THEN_BB and ELSE_BB.
+ PHI_PRED_BB should be one of INNER_COND_BB, THEN_BB or ELSE_BB. */
+
+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;
+}
+
/* Recognize a CFG pattern and dispatch to the appropriate
if-conversion helper. We start with BB as the innermost
worker basic-block. Returns true if a transformation was done. */
{
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, false, outer_cond_bb, false,
- false);
- }
+ if (tree_ssa_ifcombine_bb_1 (inner_cond_bb, outer_cond_bb,
+ then_bb, else_bb, inner_cond_bb))
+ return true;
- /* And a version where the outer condition is negated. */
- if (recognize_if_then_else (outer_cond_bb, &else_bb, &inner_cond_bb)
- && same_phi_args_p (outer_cond_bb, inner_cond_bb, else_bb)
- && bb_no_side_effects_p (inner_cond_bb))
+ if (forwarder_block_to (else_bb, then_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);
+ /* 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;
}
-
- /* 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_ifandif (inner_cond_bb, true, outer_cond_bb, true,
- true);
- }
-
- /* And a version where the outer condition is negated. */
- if (recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &then_bb)
- && same_phi_args_p (outer_cond_bb, inner_cond_bb, then_bb)
- && bb_no_side_effects_p (inner_cond_bb))
+ else if (forwarder_block_to (then_bb, else_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);
+ /* 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;
}
}