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Re: Patch for bit-field fallout (bug 16437)
- From: Roger Sayle <roger at eyesopen dot com>
- To: "Joseph S. Myers" <jsm at polyomino dot org dot uk>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 10 Jul 2004 19:19:29 -0600 (MDT)
- Subject: Re: Patch for bit-field fallout (bug 16437)
On Sun, 11 Jul 2004, Joseph S. Myers wrote:
> Bugs with the interaction of TREE_CONSTANT_OVERFLOW and integer_zerop
> (cf. <http://gcc.gnu.org/ml/gcc/2004-06/msg00645.html>) are obscure to
> find. TREE_OVERFLOW and TREE_CONSTANT_OVERFLOW have joined
> TREE_COMPLEXITY and NON_LVALUE_EXPR on my little list.
Agreed. The dividend for rewriting C expression parsing is getting
bigger and bigger.
> 2004-07-11 Joseph S. Myers <jsm@polyomino.org.uk>
>
> PR tree-optimization/16437
> * c-common.c (shorten_compare): Don't mark result of conversion to
> narrower signed type as overflowing.
> * fold-const.c (decode_field_reference): Determine whether
> signedness comes from outer type using precision rather than size.
>
> testsuite:
> 2004-07-11 Joseph S. Myers <jsm@polyomino.org.uk>
>
> PR tree-optimization/16437
> * gcc.c-torture/execute/bitfld-4.c: New test.
The fold-const.c changes are OK.
Roger
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