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ifcombine: factor out inner block viability test

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Bail out early if the inner block has side effects or is otherwise not
eligible for ifcombine.

for  gcc/ChangeLog

	* tree-ssa-ifcombine.c (tree_ssa_ifcombine_bb_1): Factor out
	bb_no_side_effects_p tests...
	(tree_ssa_ifcombine_bb): ... here.

From-SVN: r229691
This commit is contained in:
Alexandre Oliva 2015-11-03 00:31:18 +00:00 • committed by Alexandre Oliva
parent 828ca3d835
commit 067339d220
2 changed files with 10 additions and 9 deletions
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4
gcc/ChangeLog
View file

@ -1,5 +1,9 @@
2015-11-02 Alexandre Oliva <aoliva@redhat.com>
* tree-ssa-ifcombine.c (tree_ssa_ifcombine_bb_1): Factor out
bb_no_side_effects_p tests...
(tree_ssa_ifcombine_bb): ... here.
PR tree-optimization/68083
* tree-ssa-ifcombine.c: Include tree-ssa.h.
(bb_no_side_effects_p): Test for undefined uses too.

15
gcc/tree-ssa-ifcombine.c
View file

@ -576,8 +576,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
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))
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb))
{
/* We have
<outer_cond_bb>
@ -595,8 +594,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
/* 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))
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb))
{
/* We have
<outer_cond_bb>
@ -617,8 +615,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_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))
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb))
{
/* We have
<outer_cond_bb>
@ -635,8 +632,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
/* 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))
&& same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb))
{
/* We have
<outer_cond_bb>
@ -673,7 +669,8 @@ tree_ssa_ifcombine_bb (basic_block inner_cond_bb)
if (a && b)
;
This requires a single predecessor of the inner cond_bb. */
if (single_pred_p (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);