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ranger: Improve a % b operand ranges [PR91029]

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As mentioned in the PR, the previous PR91029 patch was testing
op2 >= 0 which is unnecessary, even negative op2 values will work the same,
furthermore, from if a % b > 0 we can deduce a > 0 rather than just a >= 0
(0 % b would be 0), and it actually valid even for other constants than 0,
a % b > 5 means a > 5 (a % b has the same sign as a and a in [0, 5] would
result in a % b in [0, 5].  Also, we can deduce a range for the other
operand, if we know
a % b >= 20, then b must be (in absolute value for signed modulo) > 20,
for a % [0, 20] the result would be [0, 19].

2020-11-19  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/91029
	* range-op.cc (operator_trunc_mod::op1_range): Don't require signed
	types, nor require that op2 >= 0.  Implement (a % b) >= x && x > 0
	implies a >= x and (a % b) <= x && x < 0 implies a <= x.
	(operator_trunc_mod::op2_range): New method.

	* gcc.dg/tree-ssa/pr91029-1.c: New test.
	* gcc.dg/tree-ssa/pr91029-2.c: New test.
This commit is contained in:
Jakub Jelinek 2020-11-20 00:02:21 +01:00
parent d0d8b5d836
commit d3f2933487
3 changed files with 219 additions and 16 deletions
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69
gcc/range-op.cc
View File

@ -2645,6 +2645,9 @@ public:
virtual bool op1_range (irange &r, tree type,
const irange &lhs,
const irange &op2) const;
virtual bool op2_range (irange &r, tree type,
const irange &lhs,
const irange &op1) const;
} op_trunc_mod;
void
@ -2694,24 +2697,58 @@ operator_trunc_mod::wi_fold (irange &r, tree type,
bool
operator_trunc_mod::op1_range (irange &r, tree type,
const irange &lhs,
const irange &op2) const
const irange &) const
{
// PR 91029. Check for signed truncation with op2 >= 0.
if (TYPE_SIGN (type) == SIGNED && wi::ge_p (op2.lower_bound (), 0, SIGNED))
// PR 91029.
signop sign = TYPE_SIGN (type);
unsigned prec = TYPE_PRECISION (type);
// (a % b) >= x && x > 0 , then a >= x.
if (wi::gt_p (lhs.lower_bound (), 0, sign))
{
unsigned prec = TYPE_PRECISION (type);
// if a % b > 0 , then a >= 0.
if (wi::gt_p (lhs.lower_bound (), 0, SIGNED))
{
r = value_range (type, wi::zero (prec), wi::max_value (prec, SIGNED));
return true;
}
// if a % b < 0 , then a <= 0.
if (wi::lt_p (lhs.upper_bound (), 0, SIGNED))
{
r = value_range (type, wi::min_value (prec, SIGNED), wi::zero (prec));
return true;
}
r = value_range (type, lhs.lower_bound (), wi::max_value (prec, sign));
return true;
}
// (a % b) <= x && x < 0 , then a <= x.
if (wi::lt_p (lhs.upper_bound (), 0, sign))
{
r = value_range (type, wi::min_value (prec, sign), lhs.upper_bound ());
return true;
}
return false;
}
bool
operator_trunc_mod::op2_range (irange &r, tree type,
const irange &lhs,
const irange &) const
{
// PR 91029.
signop sign = TYPE_SIGN (type);
unsigned prec = TYPE_PRECISION (type);
// (a % b) >= x && x > 0 , then b is in ~[-x, x] for signed
// or b > x for unsigned.
if (wi::gt_p (lhs.lower_bound (), 0, sign))
{
if (sign == SIGNED)
r = value_range (type, wi::neg (lhs.lower_bound ()),
lhs.lower_bound (), VR_ANTI_RANGE);
else if (wi::lt_p (lhs.lower_bound (), wi::max_value (prec, sign),
sign))
r = value_range (type, lhs.lower_bound () + 1,
wi::max_value (prec, sign));
else
return false;
return true;
}
// (a % b) <= x && x < 0 , then b is in ~[x, -x].
if (wi::lt_p (lhs.upper_bound (), 0, sign))
{
if (wi::gt_p (lhs.upper_bound (), wi::min_value (prec, sign), sign))
r = value_range (type, lhs.upper_bound (),
wi::neg (lhs.upper_bound ()), VR_ANTI_RANGE);
else
return false;
return true;
}
return false;
}

68
gcc/testsuite/gcc.dg/tree-ssa/pr91029-1.c Normal file
View File

@ -0,0 +1,68 @@
/* PR tree-optimization/91029 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-evrp" } */
void kill (void);
int xx;
void f1 (int i, int j)
{
if ((i % j) == 3)
{
xx = (i < 3);
if (xx)
kill ();
}
}
void f2 (int i, int j)
{
if ((i % j) > 0)
{
xx = (i <= 0);
if (xx)
kill ();
}
}
void f3 (int i, int j)
{
if ((i % j) == -3)
{
xx = (i > -3);
if (xx)
kill ();
}
}
void f4 (int i, int j)
{
if ((i % j) < 0)
{
xx = (i >= 0);
if (xx)
kill ();
}
}
void f5 (int i, int j)
{
if ((i % j) > 42)
{
xx = (i <= 42);
if (xx)
kill ();
}
}
void f6 (int i, int j)
{
if ((i % j) < -124)
{
xx = (i >= -124);
if (xx)
kill ();
}
}
/* { dg-final { scan-tree-dump-not "kill" "evrp" } } */

98
gcc/testsuite/gcc.dg/tree-ssa/pr91029-2.c Normal file
View File

@ -0,0 +1,98 @@
/* PR tree-optimization/91029 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-evrp" } */
void kill (void);
int xx;
void f1 (int i, int j)
{
if ((i % j) == 3)
{
xx = (j <= 3 && j >= -3);
if (xx)
kill ();
}
}
void f2 (int i, int j)
{
if ((i % j) > 0)
{
xx = (j <= 1 && j >= -1);
if (xx)
kill ();
}
}
void f3 (int i, int j)
{
if ((i % j) == -3)
{
xx = (j <= 3 && j >= -3);
if (xx)
kill ();
}
}
void f4 (int i, int j)
{
if ((i % j) < 0)
{
xx = (j <= 1 && j >= -1);
if (xx)
kill ();
}
}
void f5 (int i, int j)
{
if ((i % j) > 42)
{
xx = (j <= 43 && j >= -43);
if (xx)
kill ();
}
}
void f6 (int i, int j)
{
if ((i % j) < -124)
{
xx = (j <= 125 && j >= -125);
if (xx)
kill ();
}
}
void f7 (unsigned int i, unsigned int j)
{
if ((i % j) == 3)
{
xx = (j <= 3);
if (xx)
kill ();
}
}
void f8 (unsigned int i, unsigned int j)
{
if ((i % j) > 0)
{
xx = (j <= 1);
if (xx)
kill ();
}
}
void f9 (unsigned int i, unsigned int j)
{
if ((i % j) >= 124)
{
xx = (j <= 124);
if (xx)
kill ();
}
}
/* { dg-final { scan-tree-dump-not "kill" "evrp" } } */