gcc/gcc13-pr107608.patch

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2023-01-15 12:51:18 +00:00
2023-01-15 Aldy Hernandez <aldyh@redhat.com>
PR tree-optimization/107608
* range-op-float.cc (range_operator_float::fold_range): Avoid
folding into INF when flag_trapping_math.
* value-range.h (frange::known_isinf): Return false for possible NANs.
--- gcc/range-op-float.cc
+++ gcc/range-op-float.cc
@@ -91,6 +91,27 @@ range_operator_float::fold_range (frange &r, tree type,
else
r.clear_nan ();
+ // If the result has overflowed and flag_trapping_math, folding this
+ // operation could elide an overflow or division by zero exception.
+ // Avoid returning a singleton +-INF, to keep the propagators (DOM
+ // and substitute_and_fold_engine) from folding. See PR107608.
+ if (flag_trapping_math
+ && MODE_HAS_INFINITIES (TYPE_MODE (type))
+ && r.known_isinf () && !op1.known_isinf () && !op2.known_isinf ())
+ {
+ REAL_VALUE_TYPE inf = r.lower_bound ();
+ if (real_isneg (&inf))
+ {
+ REAL_VALUE_TYPE min = real_min_representable (type);
+ r.set (type, inf, min);
+ }
+ else
+ {
+ REAL_VALUE_TYPE max = real_max_representable (type);
+ r.set (type, max, inf);
+ }
+ }
+
return true;
}
--- gcc/value-range.h
+++ gcc/value-range.h
@@ -1300,6 +1300,7 @@ inline bool
frange::known_isinf () const
{
return (m_kind == VR_RANGE
+ && !maybe_isnan ()
&& real_identical (&m_min, &m_max)
&& real_isinf (&m_min));
}