From: Aldy Hernandez <aldyh@redhat.com>
To: GCC patches <gcc-patches@gcc.gnu.org>
Cc: Andrew MacLeod <amacleod@redhat.com>, Aldy Hernandez <aldyh@redhat.com>
Subject: [COMMITTED] range-op: Keep nonzero mask up to date with truncating casts.
Date: Wed, 5 Oct 2022 15:49:32 +0200 [thread overview]
Message-ID: <20221005134932.1584257-1-aldyh@redhat.com> (raw)
gcc/ChangeLog:
* range-op.cc (operator_cast::fold_range): Handle truncating casts
for nonzero masks.
---
gcc/range-op.cc | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 6fa27a8904e..df0735cb42a 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2516,13 +2516,17 @@ operator_cast::fold_range (irange &r, tree type ATTRIBUTE_UNUSED,
return true;
}
- // Pass nonzero mask through the cast.
- if (!truncating_cast_p (inner, outer))
- {
- wide_int nz = inner.get_nonzero_bits ();
- nz = wide_int::from (nz, TYPE_PRECISION (type), TYPE_SIGN (inner.type ()));
- r.set_nonzero_bits (nz);
- }
+ // Update the nonzero mask. Truncating casts are problematic unless
+ // the conversion fits in the resulting outer type.
+ wide_int nz = inner.get_nonzero_bits ();
+ if (truncating_cast_p (inner, outer)
+ && wi::rshift (nz, wi::uhwi (TYPE_PRECISION (outer.type ()),
+ TYPE_PRECISION (inner.type ())),
+ TYPE_SIGN (inner.type ())) != 0)
+ return true;
+ nz = wide_int::from (nz, TYPE_PRECISION (type), TYPE_SIGN (inner.type ()));
+ r.set_nonzero_bits (nz);
+
return true;
}
--
2.37.1
reply other threads:[~2022-10-05 13:49 UTC|newest]
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