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Re: [PATCH] Add new target-hook truncated_to_mode
- From: Joern RENNECKE <joern dot rennecke at st dot com>
- To: Adam Nemet <anemet at sonic dot net>
- Cc: Richard Sandiford <richard at codesourcery dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 13 Mar 2006 16:47:36 +0000
- Subject: Re: [PATCH] Add new target-hook truncated_to_mode
In http://gcc.gnu.org/ml/gcc-patches/2006-03/msg00732.html, you wrote:
meant by these instructions complementing each other. Or in other
words instead of:
narrowing SUBREG != TRUNCATE
we will now say:
widening SUBREG == SIGN_EXTEND
and try to derive the former property from the latter. But overall I
do agree that it usually carries more information to say what
something _is_ than what it _is not_.
Actually, that is not an accurate description for the SH5. Although an SImode value
in an integer register will be held sign-extended, that is not true of SImode values
in floating point registers.
If you hold an SImode value in a floating point register and want to store it
sign-extended to memory, you have to do a sign-extending copy into an integer
register first (at least that is the most straightforward way to do it).