From: Jim Wilson <wilson@cygnus.com>
To: John Carr <jfc@mit.edu>
Cc: egcs@cygnus.com
Subject: Re: HOST_WIDE_INT = long long patches
Date: Tue, 21 Apr 1998 23:21:00 -0000 [thread overview]
Message-ID: <199804220053.RAA21350@rtl.cygnus.com> (raw)
In-Reply-To: <199804191934.PAA18086@jfc.>
This change in final.c (split_double) doesn't look like it will work.
! high = GEN_INT (INTVAL (value) << (HOST_BITS_PER_WIDE_INT - 2 * BITS_PER_WORD) >> (HOST_BITS_PER_WIDE_INT - BITS_PER_WORD));
If HOST_BITS_PER_WIDE_INT and BITS_PER_WORD are the same, then you end up with
a negative shift count for the first shift, which is undefined.
This change in reload.c (find_reloads) is unsafe.
! if ((GET_CODE (operand) == CONST_DOUBLE
! || (HOST_BITS_PER_WIDE_INT > BITS_PER_WORD
! && GET_CODE (operand) == CONST_INT))
&& CONST_DOUBLE_OK_FOR_LETTER_P (operand, c))
This is because some ports make the assumption that the input to
CONST_DOUBLE_OK_FOR_LETTER_P is a CONST_DOUBLE, and will fail if it isn't.
For instance, alpha.h references CONST_DOUBLE_{LOW,HIGH} without verifying
that it is a CONST_DOUBLE. Also, if we are going to do this, we should
modify the CONST_DOUBLE_OK_FOR_LETTER_P documentation in tm.texi to indicate
that the operand could be either a CONST_DOUBLE or a CONST_INT.
Likewise, the similar change to recog.c is unsafe.
The emit-rtl.c change looks OK.
Jim
next prev parent reply other threads:[~1998-04-21 23:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-19 15:57 John Carr
1998-04-21 23:21 ` Jeffrey A Law
1998-04-21 23:21 ` Jim Wilson [this message]
1998-04-22 4:19 ` John Carr
1998-04-22 12:13 ` Jim Wilson
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