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[frange] Handle relations in LTGT_EXPR.

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LTGT_EXPR hasn't been handling relations, especially with NANs as a
possibility.  This handles them while documenting how relations work
in a world with NANs.

Basically we need to special case VREL_EQ before calling
frelop_early_resolve.  Note that VREL_EQ on entry to a range-op entry
is really VREL_EQ U NAN, but to make sure about the NAN possibility,
one must look at the operands.  However, even VREL_EQ U NAN is false
for LTGT_EXPR since the latter is just NE_EXPR without a NAN.

After we handle VREL_EQ, we drop down to frelop_early_resolve
pretending to be a NE_EXPR, and everything should just map correctly.

2023-08-28  Aldy Hernandez  <aldyh@redhat.com>

	* range-op-float.cc (fold_range): Handle relations.
This commit is contained in:
Aldy Hernandez 2023-08-25 18:21:16 +02:00
parent c28c579f0d
commit 979e0fbf53
1 changed files with 17 additions and 2 deletions
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19
gcc/range-op-float.cc
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@ -2204,8 +2204,23 @@ class foperator_ltgt : public range_operator
public:
bool fold_range (irange &r, tree type,
const frange &op1, const frange &op2,
relation_trio rel = TRIO_VARYING) const final override
relation_trio trio = TRIO_VARYING) const final override
{
relation_kind rel = trio.op1_op2 ();
// VREL_EQ is really VREL_(UN)EQ because we could have a NAN in
// the operands, but since LTGT_EXPR is really a NE_EXPR without
// the NAN, VREL_EQ & LTGT_EXPR is an impossibility.
if (rel == VREL_EQ)
{
r = range_false (type);
return true;
}
// ...otherwise pretend we're trying to resolve a NE_EXPR and
// everything will "just work".
if (frelop_early_resolve (r, type, op1, op2, trio, VREL_NE))
return true;
if (op1.known_isnan () || op2.known_isnan ())
{
r = range_false (type);
@ -2218,7 +2233,7 @@ public:
if (op2.maybe_isnan ())
op2_no_nan.clear_nan ();
if (!range_op_handler (NE_EXPR).fold_range (r, type, op1_no_nan,
op2_no_nan, rel))
op2_no_nan, trio))
return false;
// The result is the same as the ordered version when the
// comparison is true or when the operands cannot be NANs.