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tree-ssa-ifcombine.c (forwarder_block_to): New function.

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* tree-ssa-ifcombine.c (forwarder_block_to): New function.
	(tree_ssa_ifcombine_bb_1): New function.
	(tree_ssa_ifcombine_bb): Use it.  Handle also cases where else_bb
	is an empty forwarder block to then_bb or vice versa and then_bb
	and else_bb are effectively swapped.

	* gcc.dg/tree-ssa/ssa-ifcombine-12.c: New test.
	* gcc.dg/tree-ssa/ssa-ifcombine-13.c: New test.
	* gcc.dg/tree-ssa/phi-opt-2.c: Pass -mbranch-cost=1 if
	possible, only test for exactly one if if -mbranch-cost=1
	has been passed.

From-SVN: r208512
This commit is contained in:
Jakub Jelinek 2014-03-12 13:59:03 +01:00 committed by Jakub Jelinek
parent 7d55b94832
commit bf4787b267
6 changed files with 188 additions and 72 deletions
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8
gcc/ChangeLog
View File

@ -1,3 +1,11 @@
2014-03-12 Jakub Jelinek <jakub@redhat.com>
* tree-ssa-ifcombine.c (forwarder_block_to): New function.
(tree_ssa_ifcombine_bb_1): New function.
(tree_ssa_ifcombine_bb): Use it. Handle also cases where else_bb
is an empty forwarder block to then_bb or vice versa and then_bb
and else_bb are effectively swapped.
2014-03-12 Christian Bruel <christian.bruel@st.com>
PR target/60264

8
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,11 @@
2014-03-12 Jakub Jelinek <jakub@redhat.com>
* gcc.dg/tree-ssa/ssa-ifcombine-12.c: New test.
* gcc.dg/tree-ssa/ssa-ifcombine-13.c: New test.
* gcc.dg/tree-ssa/phi-opt-2.c: Pass -mbranch-cost=1 if
possible, only test for exactly one if if -mbranch-cost=1
has been passed.
2014-03-12 Christian Bruel <christian.bruel@st.com>
PR target/60264

7
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-2.c
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@ -1,5 +1,6 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fdump-tree-optimized" } */
/* { dg-additional-options "-mbranch-cost=1" { target { i?86-*-* x86_64-*-* mips*-*-* s390*-*-* avr*-*-* } } } */
_Bool f1(_Bool a, _Bool b)
{
@ -17,6 +18,8 @@ _Bool f1(_Bool a, _Bool b)
/* There should be only one if, the outer one; the inner one
should have been changed to straight line code with the
value of b (except that we don't fold ! (b != 0) into b
which can be fixed in a different patch). */
/* { dg-final { scan-tree-dump-times "if" 1 "optimized"} } */
which can be fixed in a different patch).
Test this only when known to be !LOGICAL_OP_NON_SHORT_CIRCUIT,
otherwise ifcombine may convert this into return a & b;. */
/* { dg-final { scan-tree-dump-times "if" 1 "optimized" { target { i?86-*-* x86_64-*-* mips*-*-* s390*-*-* avr*-*-* } } } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */

20
gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-12.c Normal file
View File

@ -0,0 +1,20 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fno-tree-vrp -fdump-tree-optimized" } */
/* Testcase for PR31657. */
int f(int x, int a, int b)
{
int t = 0;
int c = 1 << a;
if (!(x & 1))
t = 0;
else
if (x & (1 << 2))
t = 3;
else
t = 0;
return t;
}
/* { dg-final { scan-tree-dump "& 5" "optimized" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */

21
gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-13.c Normal file
View File

@ -0,0 +1,21 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fdump-tree-optimized" } */
/* { dg-additional-options "-mbranch-cost=2" { target { i?86-*-* x86_64-*-* mips*-*-* s390*-*-* avr*-*-* } } } */
_Bool f1(_Bool a, _Bool b)
{
if (a)
{
if (b)
return 1;
else
return 0;
}
return 0;
}
/* For LOGICAL_OP_NON_SHORT_CIRCUIT, this should be optimized
into return a & b;, with no ifs. */
/* { dg-final { scan-tree-dump-not "if" "optimized" { target { i?86-*-* x86_64-*-* mips*-*-* s390*-*-* avr*-*-* } } } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */

196
gcc/tree-ssa-ifcombine.c
View File

@ -135,6 +135,16 @@ bb_no_side_effects_p (basic_block bb)
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. */
@ -561,6 +571,99 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
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. */
@ -585,80 +688,33 @@ tree_ssa_ifcombine_bb (basic_block 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, 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))
else if (forwarder_block_to (then_bb, else_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))
{
/* 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;
}
}