[gfortran] Make gfortran pass g77 test f90-intrinsic-bit.f90

[Tobias Schlüter]

This required a number of changes/fixes:
1. ISHFT had an implementation error: in the case where the shift width was
equal to the arguments bit width, we would give an erroneous result, as this
case is not specified for gcc's {L|R}SHIFT_EXPR, but required by the Fortran
standard.  I also removed the shortcut for 0-bit shifts, as I figured that
it's the optimizers job to figure these things out.
2. Our implementation of ISHFT was, even though valid, incompatible with other
compilers: we were doing arithmetic shifts, where other compilers do logical
shifts.  Fixed.  While I was touching this code I also added calls to fold
where appropriate.
3. we didn't have library implementations ISHFTC for INTEGER*1 or INTEGER*2
arguments.  Instead of adding library implementations for these, I chose to
convert the argument to INTEGER*4, and convert the function's result back to
the original type.  While I was doing this, I also cononicalized the second
and third argument to INTEGER*4 where they were previously converted to the
type of the first argument.  While I was touching this code I also added calls
to fold where appropriate.  (I didn't remove the 0-bit shift shortcut here, as
I noticed this only after I had tested the patch.)
4. I added library implementations for the INTEGER*1 and INTEGER*2 variants of
MVBITS.  Unfortunately, this can't be implemented by the same typecasting
trickery as I did for ISHFT, as for some reason I don't understand MVBITS is a
subroutine.

Bubblestrapped and regtested, diff attached. I also attached the new testcase.

Ok?

- Tobi

2004-12-14  Tobias Schlueter  <tobias.schlueter@physik.uni-muenchen.de>

libgfortran/:
	* intrinsics/ishftc.c: Update copyright years.
	(ishftc8): Change 'shift' and 'size' to GFC_INTEGER_4.
	* intrinsics/mvbits.c: Correcty non-ASCII character in my name. Add
	implementations for GFC_INTEGER_{1|2}.
gcc/fortran/:
	* trans-intrinsic.c (gfc_conv_intrinsic_ishft): Change to logical
	shift.  Call fold.  Remove 0-bit shift shortcut.
	(gfc_conv_intrinsic_ishftc): Convert first argument to at least 4
	bytes bits.  Convert 2nd and 3rd argument to 4 bytes.  Convert result
	if width(arg 1) < 4 bytes.  Call fold.
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