Hi!
The following patch implements frange multiplication, including the
special case of x * x. The callers don't tell us that it is x * x,
just that it is either z = x * x or if (x == y) z = x * y;
For irange that makes no difference, but for frange it can mean
x is -0.0 and y is 0.0 if they have the same range that includes both
signed and unsigned zeros, so we need to assume result could be -0.0.
The patch causes one regression:
+FAIL: gcc.dg/fold-overflow-1.c scan-assembler-times 2139095040 2
but that is already tracked in PR107608 and affects not just the newly
added multiplication, but addition and other floating point operations
(and doesn't seem like a ranger bug but dce or whatever else).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Once we have division and the reverse ops for all of these, perhaps
we can do some cleanups to share common code, but the way I have division
now partly written doesn't show up many commonalities. Multiplication
is simple, division is a nightmare.
2022-11-10 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/107569
PR tree-optimization/107591
* range-op.h (range_operator_float::rv_fold): Add relation_kind
argument.
* range-op-float.cc (range_operator_float::fold_range): Name
last argument trio and pass trio.op1_op2 () as last argument to
rv_fold.
(range_operator_float::rv_fold): Add relation_kind argument.
(foperator_plus::rv_fold, foperator_minus::rv_fold): Likewise.
(frange_mult): New function.
(foperator_mult): New class.
(floating_op_table::floating_op_table): Use foperator_mult for
MULT_EXPR.
--- gcc/range-op.h.jj 2022-11-10 00:55:09.430219763 +0100
+++ gcc/range-op.h 2022-11-10 11:30:33.594114939 +0100
@@ -123,7 +123,8 @@ public:
const REAL_VALUE_TYPE &lh_lb,
const REAL_VALUE_TYPE &lh_ub,
const REAL_VALUE_TYPE &rh_lb,
- const REAL_VALUE_TYPE &rh_ub) const;
+ const REAL_VALUE_TYPE &rh_ub,
+ relation_kind) const;
// Unary operations have the range of the LHS as op2.
virtual bool fold_range (irange &r, tree type,
const frange &lh,
--- gcc/range-op-float.cc.jj 2022-11-10 00:55:09.318221259 +0100
+++ gcc/range-op-float.cc 2022-11-10 11:31:29.040359082 +0100
@@ -51,7 +51,7 @@ along with GCC; see the file COPYING3.
bool
range_operator_float::fold_range (frange &r, tree type,
const frange &op1, const frange &op2,
- relation_trio) const
+ relation_trio trio) const
{
if (empty_range_varying (r, type, op1, op2))
return true;
@@ -65,7 +65,7 @@ range_operator_float::fold_range (frange
bool maybe_nan;
rv_fold (lb, ub, maybe_nan, type,
op1.lower_bound (), op1.upper_bound (),
- op2.lower_bound (), op2.upper_bound ());
+ op2.lower_bound (), op2.upper_bound (), trio.op1_op2 ());
// Handle possible NANs by saturating to the appropriate INF if only
// one end is a NAN. If both ends are a NAN, just return a NAN.
@@ -103,8 +103,8 @@ range_operator_float::rv_fold (REAL_VALU
const REAL_VALUE_TYPE &lh_lb ATTRIBUTE_UNUSED,
const REAL_VALUE_TYPE &lh_ub ATTRIBUTE_UNUSED,
const REAL_VALUE_TYPE &rh_lb ATTRIBUTE_UNUSED,
- const REAL_VALUE_TYPE &rh_ub ATTRIBUTE_UNUSED)
- const
+ const REAL_VALUE_TYPE &rh_ub ATTRIBUTE_UNUSED,
+ relation_kind) const
{
lb = dconstninf;
ub = dconstinf;
@@ -1868,7 +1868,8 @@ class foperator_plus : public range_oper
const REAL_VALUE_TYPE &lh_lb,
const REAL_VALUE_TYPE &lh_ub,
const REAL_VALUE_TYPE &rh_lb,
- const REAL_VALUE_TYPE &rh_ub) const final override
+ const REAL_VALUE_TYPE &rh_ub,
+ relation_kind) const final override
{
frange_arithmetic (PLUS_EXPR, type, lb, lh_lb, rh_lb, dconstninf);
frange_arithmetic (PLUS_EXPR, type, ub, lh_ub, rh_ub, dconstinf);
@@ -1892,7 +1893,8 @@ class foperator_minus : public range_ope
const REAL_VALUE_TYPE &lh_lb,
const REAL_VALUE_TYPE &lh_ub,
const REAL_VALUE_TYPE &rh_lb,
- const REAL_VALUE_TYPE &rh_ub) const final override
+ const REAL_VALUE_TYPE &rh_ub,
+ relation_kind) const final override
{
frange_arithmetic (MINUS_EXPR, type, lb, lh_lb, rh_ub, dconstninf);
frange_arithmetic (MINUS_EXPR, type, ub, lh_ub, rh_lb, dconstinf);
@@ -1908,6 +1910,123 @@ class foperator_minus : public range_ope
}
} fop_minus;
+/* Wrapper around frange_arithmetics, that computes the result
+ if inexact rounded to both directions. Also, if one of the
+ operands is +-0.0 and another +-INF, return +-0.0 rather than
+ NAN. */
+
+static void
+frange_mult (tree type, REAL_VALUE_TYPE &result_lb, REAL_VALUE_TYPE &result_ub,
+ const REAL_VALUE_TYPE &op1, const REAL_VALUE_TYPE &op2)
+{
+ if (real_iszero (&op1) && real_isinf (&op2))
+ {
+ result_lb = op1;
+ if (real_isneg (&op2))
+ result_lb = real_value_negate (&result_lb);
+ result_ub = result_lb;
+ }
+ else if (real_isinf (&op1) && real_iszero (&op2))
+ {
+ result_lb = op2;
+ if (real_isneg (&op1))
+ result_lb = real_value_negate (&result_lb);
+ result_ub = result_lb;
+ }
+ else
+ {
+ frange_arithmetic (MULT_EXPR, type, result_lb, op1, op2, dconstninf);
+ frange_arithmetic (MULT_EXPR, type, result_ub, op1, op2, dconstinf);
+ }
+}
+
+class foperator_mult : public range_operator_float
+{
+ void rv_fold (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, bool &maybe_nan,
+ tree type,
+ const REAL_VALUE_TYPE &lh_lb,
+ const REAL_VALUE_TYPE &lh_ub,
+ const REAL_VALUE_TYPE &rh_lb,
+ const REAL_VALUE_TYPE &rh_ub,
+ relation_kind kind) const final override
+ {
+ REAL_VALUE_TYPE cp[8];
+ bool is_square
+ = (kind == VREL_EQ
+ && real_equal (&lh_lb, &rh_lb)
+ && real_equal (&lh_ub, &rh_ub)
+ && real_isneg (&lh_lb) == real_isneg (&rh_lb)
+ && real_isneg (&lh_ub) == real_isneg (&rh_ub));
+ // Do a cross-product.
+ frange_mult (type, cp[0], cp[4], lh_lb, rh_lb);
+ if (is_square)
+ {
+ // For x * x we can just do max (lh_lb * lh_lb, lh_ub * lh_ub)
+ // as maximum and -0.0 as minimum if 0.0 is in the range,
+ // otherwise min (lh_lb * lh_lb, lh_ub * lh_ub).
+ // -0.0 rather than 0.0 because VREL_EQ doesn't prove that
+ // x and y are bitwise equal, just that they compare equal.
+ if (real_compare (LE_EXPR, &lh_lb, &dconst0)
+ && real_compare (GE_EXPR, &lh_ub, &dconst0))
+ cp[1] = real_value_negate (&dconst0);
+ else
+ cp[1] = cp[0];
+ cp[2] = cp[0];
+ cp[5] = cp[4];
+ cp[6] = cp[4];
+ }
+ else
+ {
+ frange_mult (type, cp[1], cp[5], lh_lb, rh_ub);
+ frange_mult (type, cp[2], cp[6], lh_ub, rh_lb);
+ }
+ frange_mult (type, cp[3], cp[7], lh_ub, rh_ub);
+ for (int i = 1; i < 4; ++i)
+ {
+ if (real_less (&cp[i], &cp[0])
+ || (real_iszero (&cp[0]) && real_isnegzero (&cp[i])))
+ std::swap (cp[i], cp[0]);
+ if (real_less (&cp[4], &cp[i + 4])
+ || (real_isnegzero (&cp[4]) && real_iszero (&cp[i + 4])))
+ std::swap (cp[i + 4], cp[4]);
+ }
+ lb = cp[0];
+ ub = cp[4];
+
+ // If both operands are the same, then we know it can be +-0.0, or +-INF,
+ // but not both at the same time, so it will never be invalid unless
+ // operand was already NAN.
+ if (is_square)
+ maybe_nan = false;
+ // [+-0, +-0] * [+INF,+INF] (or [-INF,-INF] or swapped is a known NAN.
+ else if ((real_iszero (&lh_lb)
+ && real_iszero (&lh_ub)
+ && real_isinf (&rh_lb)
+ && real_isinf (&rh_ub, real_isneg (&rh_lb)))
+ || (real_iszero (&rh_lb)
+ && real_iszero (&rh_ub)
+ && real_isinf (&lh_lb)
+ && real_isinf (&lh_ub, real_isneg (&lh_lb))))
+ {
+ real_nan (&lb, "", 0, TYPE_MODE (type));
+ ub = lb;
+ maybe_nan = true;
+ }
+ // Otherwise, if one range includes zero and the other ends with +-INF,
+ // it is a maybe NAN.
+ else if (real_compare (LE_EXPR, &lh_lb, &dconst0)
+ && real_compare (GE_EXPR, &lh_ub, &dconst0)
+ && (real_isinf (&rh_lb) || real_isinf (&rh_ub)))
+ maybe_nan = true;
+ else if (real_compare (LE_EXPR, &rh_lb, &dconst0)
+ && real_compare (GE_EXPR, &rh_ub, &dconst0)
+ && (real_isinf (&lh_lb) || real_isinf (&lh_ub)))
+ maybe_nan = true;
+ else
+ maybe_nan = false;
+ }
+} fop_mult;
+
// Instantiate a range_op_table for floating point operations.
static floating_op_table global_floating_table;
@@ -1942,6 +2061,7 @@ floating_op_table::floating_op_table ()
set (NEGATE_EXPR, fop_negate);
set (PLUS_EXPR, fop_plus);
set (MINUS_EXPR, fop_minus);
+ set (MULT_EXPR, fop_mult);
}
// Return a pointer to the range_operator_float instance, if there is
Jakub
