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| author | Alexandre Oliva <aoliva@redhat.com> | 2001-02-13 06:39:45 +0000 |
|---|---|---|
| committer | Alexandre Oliva <aoliva@gcc.gnu.org> | 2001-02-13 06:39:45 +0000 |
| commit | 5b0d91c39237f6a45dcb229620bbf5c144b29c62 (patch) | |
| tree | 7b015877b972e243b2a4efd84b3be03b3d775a5f | |
| parent | 4b01cd8fbf7e5bd516fbebaf4a86910cc88e8566 (diff) | |
| download | gcc-5b0d91c39237f6a45dcb229620bbf5c144b29c62.zip gcc-5b0d91c39237f6a45dcb229620bbf5c144b29c62.tar.gz gcc-5b0d91c39237f6a45dcb229620bbf5c144b29c62.tar.bz2 | |
* explow.c (trunc_int_for_mode): Sign-extend value to mode.
From-SVN: r39615
| -rw-r--r-- | gcc/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/explow.c | 32 |
2 files changed, 14 insertions, 22 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a453776..8761c12 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -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. diff --git a/gcc/explow.c b/gcc/explow.c index b7c0bb9..719421f 100644 --- a/gcc/explow.c +++ b/gcc/explow.c @@ -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. */ - - 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); + /* Sign-extend for the requested mode. */ + + 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; } |