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* explow.c (trunc_int_for_mode): Sign-extend value to mode.

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From-SVN: r39615
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Alexandre Oliva 2001-02-13 06:39:45 +00:00 • committed by Alexandre Oliva
parent 4b01cd8fbf
commit 5b0d91c392
2 changed files with 13 additions and 21 deletions
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gcc/ChangeLog
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@ -1,3 +1,7 @@
2001-02-13 Alexandre Oliva <aoliva@redhat.com>
* explow.c (trunc_int_for_mode): Sign-extend value to mode.
2001-02-12 Geoffrey Keating <geoffk@redhat.com>
* config/rs6000/sysv4.h (MASK_NO_BITFIELD_WORD): New macro.

30
gcc/explow.c
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@ -56,28 +56,16 @@ trunc_int_for_mode (c, mode)
if (mode == BImode)
return c & 1 ? STORE_FLAG_VALUE : 0;
/* We clear out all bits that don't belong in MODE, unless they and our
sign bit are all one. So we get either a reasonable negative
value or a reasonable unsigned value. */
/* Sign-extend for the requested mode. */
if (width < HOST_BITS_PER_WIDE_INT
&& ((c & ((HOST_WIDE_INT) (-1) << (width - 1)))
!= ((HOST_WIDE_INT) (-1) << (width - 1))))
c &= ((HOST_WIDE_INT) 1 << width) - 1;
/* If this would be an entire word for the target, but is not for
the host, then sign-extend on the host so that the number will look
the same way on the host that it would on the target.
For example, when building a 64 bit alpha hosted 32 bit sparc
targeted compiler, then we want the 32 bit unsigned value -1 to be
represented as a 64 bit value -1, and not as 0x00000000ffffffff.
The later confuses the sparc backend. */
if (BITS_PER_WORD < HOST_BITS_PER_WIDE_INT
&& BITS_PER_WORD == width
&& (c & ((HOST_WIDE_INT) 1 << (width - 1))))
c |= ((HOST_WIDE_INT) (-1) << width);
if (width < HOST_BITS_PER_WIDE_INT)
{
HOST_WIDE_INT sign = 1;
sign <<= width - 1;
c &= (sign << 1) - 1;
c ^= sign;
c -= sign;
}
return c;
}