re PR fortran/30381 ([4.1 only] ISHFTC() constant folding is broken.)
PR 30381
PR 30420
* fortran/simplify.c (convert_mpz_to_unsigned): New function.
(convert_mpz_to_signed): New function, largely based on
twos_complement().
(twos_complement): Removed.
(gfc_simplify_ibclr): Add conversions to and from an
unsigned representation before bit-twiddling.
(gfc_simplify_ibset): Same.
(gfc_simplify_ishftc): Add checks for overly large
constant arguments, only check the third argument if
it's present, carry over high bits into the result as
appropriate, and perform the final conversion back to
a signed representation using the correct sign bit.
(gfc_simplify_not): Removed unnecessary masking.
* testsuite/gfortran.dg/
* chkbits.f90: Added IBCLR tests; test calls for
different integer kinds.
* ishft.f90: Renamed to ishft_1.f90...
* ishft_1.f90: ...Renamed from ishft.f90.
* ishft_2.f90: New test.
* ishft_3.f90: New test.
From-SVN: r120634