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Teach VRP to truncate the case ranges of a switch

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gcc/ChangeLog:

	* tree-vrp.c (simplify_switch_using_ranges): Try to truncate
	the case label ranges that partially overlap with OP's value
	range.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/vrp107.c: New test.
	* gcc.dg/tree-ssa/vrp108.c: New test.
	* gcc.dg/tree-ssa/vrp109.c: New test.

From-SVN: r239157
This commit is contained in:
Patrick Palka 2016-08-05 00:07:16 +00:00
parent 383321ecc9
commit 48abe92225
6 changed files with 206 additions and 1 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2016-08-04 Patrick Palka <ppalka@gcc.gnu.org>
* tree-vrp.c (simplify_switch_using_ranges): Try to truncate
the case label ranges that partially overlap with OP's value
range.
2016-08-04 Uros Bizjak <ubizjak@gmail.com>
PR target/72805

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2016-08-04 Patrick Palka <ppalka@gcc.gnu.org>
* gcc.dg/tree-ssa/vrp107.c: New test.
* gcc.dg/tree-ssa/vrp108.c: New test.
* gcc.dg/tree-ssa/vrp109.c: New test.
2016-08-04 Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>
* gcc.dg/pr70920-4.c: Move dg-require-effective-target before

25
gcc/testsuite/gcc.dg/tree-ssa/vrp107.c Normal file
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@ -0,0 +1,25 @@
/* { dg-options "-O2 -fdump-tree-vrp1" } */
/* { dg-final { scan-tree-dump "case 2:" "vrp1" } } */
/* { dg-final { scan-tree-dump "case 7 ... 8:" "vrp1" } } */
extern void foo (void);
extern void bar (void);
extern void baz (void);
void
test (int i)
{
if (i >= 2 && i <= 8)
switch (i)
{
case 1: /* Redundant label. */
case 2:
bar ();
break;
case 7:
case 8:
case 9: /* Redundant label. */
baz ();
break;
}
}

25
gcc/testsuite/gcc.dg/tree-ssa/vrp108.c Normal file
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@ -0,0 +1,25 @@
/* { dg-options "-O2 -fdump-tree-vrp1" } */
/* { dg-final { scan-tree-dump "case 1:" "vrp1" } } */
/* { dg-final { scan-tree-dump "case 9:" "vrp1" } } */
extern void foo (void);
extern void bar (void);
extern void baz (void);
void
test (int i)
{
if (i < 2 || i > 8)
switch (i)
{
case 1:
case 2: /* Redundant label. */
bar ();
break;
case 7: /* Redundant label. */
case 8: /* Redundant label. */
case 9:
baz ();
break;
}
}

65
gcc/testsuite/gcc.dg/tree-ssa/vrp109.c Normal file
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@ -0,0 +1,65 @@
/* { dg-options "-O2 -fdump-tree-vrp1" } */
/* { dg-final { scan-tree-dump "case 9 ... 10:" "vrp1" } } */
/* { dg-final { scan-tree-dump "case 17 ... 18:" "vrp1" } } */
/* { dg-final { scan-tree-dump "case 27 ... 30:" "vrp1" } } */
extern void foo (void);
extern void bar (void);
void
test1 (int i)
{
if (i != 7 && i != 8)
switch (i)
{
case 1:
case 2:
foo ();
break;
case 7: /* Redundant label. */
case 8: /* Redundant label. */
case 9:
case 10:
bar ();
break;
}
}
void
test3 (int i)
{
if (i != 19 && i != 20)
switch (i)
{
case 1:
case 2:
foo ();
break;
case 17:
case 18:
case 19: /* Redundant label. */
case 20: /* Redundant label. */
bar ();
break;
}
}
void
test2 (int i)
{
if (i != 28 && i != 29)
switch (i)
{
case 1:
case 2:
foo ();
break;
/* No redundancy. */
case 27:
case 28:
case 29:
case 30:
bar ();
break;
}
}

80
gcc/tree-vrp.c
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@ -9593,7 +9593,7 @@ static bool
simplify_switch_using_ranges (gswitch *stmt)
{
tree op = gimple_switch_index (stmt);
value_range *vr;
value_range *vr = NULL;
bool take_default;
edge e;
edge_iterator ei;
@ -9633,6 +9633,84 @@ simplify_switch_using_ranges (gswitch *stmt)
n = gimple_switch_num_labels (stmt);
/* We can truncate the case label ranges that partially overlap with OP's
value range. */
size_t min_idx = 1, max_idx = 0;
if (vr != NULL)
find_case_label_range (stmt, vr->min, vr->max, &min_idx, &max_idx);
if (min_idx <= max_idx)
{
tree min_label = gimple_switch_label (stmt, min_idx);
tree max_label = gimple_switch_label (stmt, max_idx);
if (vr->type == VR_RANGE)
{
/* If OP's value range is [2,8] and the low label range is
0 ... 3, truncate the label's range to 2 .. 3. */
if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
&& CASE_HIGH (min_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (min_label), vr->min) >= 0)
CASE_LOW (min_label) = vr->min;
/* If OP's value range is [2,8] and the high label range is
7 ... 10, truncate the label's range to 7 .. 8. */
if (tree_int_cst_compare (CASE_LOW (max_label), vr->max) <= 0
&& CASE_HIGH (max_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (max_label), vr->max) > 0)
CASE_HIGH (max_label) = vr->max;
}
else if (vr->type == VR_ANTI_RANGE)
{
tree one_cst = build_one_cst (TREE_TYPE (op));
if (min_label == max_label)
{
/* If OP's value range is ~[7,8] and the label's range is
7 ... 10, truncate the label's range to 9 ... 10. */
if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) == 0
&& CASE_HIGH (min_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (min_label), vr->max) > 0)
CASE_LOW (min_label)
= int_const_binop (PLUS_EXPR, vr->max, one_cst);
/* If OP's value range is ~[7,8] and the label's range is
5 ... 8, truncate the label's range to 5 ... 6. */
if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
&& CASE_HIGH (min_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (min_label), vr->max) == 0)
CASE_HIGH (min_label)
= int_const_binop (MINUS_EXPR, vr->min, one_cst);
}
else
{
/* If OP's value range is ~[2,8] and the low label range is
0 ... 3, truncate the label's range to 0 ... 1. */
if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
&& CASE_HIGH (min_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (min_label), vr->min) >= 0)
CASE_HIGH (min_label)
= int_const_binop (MINUS_EXPR, vr->min, one_cst);
/* If OP's value range is ~[2,8] and the high label range is
7 ... 10, truncate the label's range to 9 ... 10. */
if (tree_int_cst_compare (CASE_LOW (max_label), vr->max) <= 0
&& CASE_HIGH (max_label) != NULL_TREE
&& tree_int_cst_compare (CASE_HIGH (max_label), vr->max) > 0)
CASE_LOW (max_label)
= int_const_binop (PLUS_EXPR, vr->max, one_cst);
}
}
/* Canonicalize singleton case ranges. */
if (tree_int_cst_equal (CASE_LOW (min_label), CASE_HIGH (min_label)))
CASE_HIGH (min_label) = NULL_TREE;
if (tree_int_cst_equal (CASE_LOW (max_label), CASE_HIGH (max_label)))
CASE_HIGH (max_label) = NULL_TREE;
}
/* We can also eliminate case labels that lie completely outside OP's value
range. */
/* Bail out if this is just all edges taken. */
if (i == 1
&& j == n - 1