| Message ID | 20201209075035.GP3788@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | fold-const: Fix up native_encode_initializer missing field handling [PR98193] | expand |
On Wed, 9 Dec 2020, Jakub Jelinek wrote: > Hi! > > When native_encode_initializer is called with non-NULL mask (i.e. ATM > bit_cast only), it checks if the current index in the CONSTRUCTOR (if any) > is the next initializable FIELD_DECL, and if not, decrements cnt and > performs the iteration with that FIELD_DECL as field and val of zero > (so that it computes mask properly). As the testcase shows, I forgot to > set pos to the byte position of the field though (like it is done > for e.g. index referenced FIELD_DECLs in the constructor. > > Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for > trunk? OK. Richard. > 2020-12-09 Jakub Jelinek <jakub@redhat.com> > > PR c++/98193 > * fold-const.c (native_encode_initializer): Set pos to field's > byte position if iterating over a field with missing initializer. > > * g++.dg/cpp2a/bit-cast7.C: New test. > > --- gcc/fold-const.c.jj 2020-12-04 18:00:47.000000000 +0100 > +++ gcc/fold-const.c 2020-12-08 12:42:53.913529423 +0100 > @@ -8256,6 +8256,7 @@ native_encode_initializer (tree init, un > { > cnt--; > field = fld; > + pos = int_byte_position (field); > val = build_zero_cst (TREE_TYPE (fld)); > if (TREE_CODE (val) == CONSTRUCTOR) > to_free = val; > --- gcc/testsuite/g++.dg/cpp2a/bit-cast7.C.jj 2020-12-08 13:08:39.623341446 +0100 > +++ gcc/testsuite/g++.dg/cpp2a/bit-cast7.C 2020-12-08 13:07:45.443943866 +0100 > @@ -0,0 +1,39 @@ > +// PR c++/98193 > +// { dg-do compile { target c++20 } } > + > +template <typename To, typename From> > +constexpr To > +bit_cast (const From &from) > +{ > + return __builtin_bit_cast (To, from); > +} > + > +struct J > +{ > + long int a, b : 11, h; > +}; > + > +struct K > +{ > + long int a, b : 11, c; > + constexpr bool operator == (const K &x) > + { > + return a == x.a && b == x.b && c == x.c; > + } > +}; > + > +struct L > +{ > + long long int a, b : 11, h; > +}; > +struct M > +{ > + long long int a, b : 11, c; > + constexpr bool operator == (const M &x) > + { > + return a == x.a && b == x.b && c == x.c; > + } > +}; > + > +static_assert (bit_cast <K> (J{}) == K{}, ""); > +static_assert (bit_cast <M> (L{0x0feedbacdeadbeefLL}) == M{0x0feedbacdeadbeefLL}, ""); > > Jakub > >
--- gcc/fold-const.c.jj 2020-12-04 18:00:47.000000000 +0100 +++ gcc/fold-const.c 2020-12-08 12:42:53.913529423 +0100 @@ -8256,6 +8256,7 @@ native_encode_initializer (tree init, un { cnt--; field = fld; + pos = int_byte_position (field); val = build_zero_cst (TREE_TYPE (fld)); if (TREE_CODE (val) == CONSTRUCTOR) to_free = val; --- gcc/testsuite/g++.dg/cpp2a/bit-cast7.C.jj 2020-12-08 13:08:39.623341446 +0100 +++ gcc/testsuite/g++.dg/cpp2a/bit-cast7.C 2020-12-08 13:07:45.443943866 +0100 @@ -0,0 +1,39 @@ +// PR c++/98193 +// { dg-do compile { target c++20 } } + +template <typename To, typename From> +constexpr To +bit_cast (const From &from) +{ + return __builtin_bit_cast (To, from); +} + +struct J +{ + long int a, b : 11, h; +}; + +struct K +{ + long int a, b : 11, c; + constexpr bool operator == (const K &x) + { + return a == x.a && b == x.b && c == x.c; + } +}; + +struct L +{ + long long int a, b : 11, h; +}; +struct M +{ + long long int a, b : 11, c; + constexpr bool operator == (const M &x) + { + return a == x.a && b == x.b && c == x.c; + } +}; + +static_assert (bit_cast <K> (J{}) == K{}, ""); +static_assert (bit_cast <M> (L{0x0feedbacdeadbeefLL}) == M{0x0feedbacdeadbeefLL}, "");