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Re: Feature request: ability to describe x86 register halves as contraints.
- To: law at cygnus dot com
- Subject: Re: Feature request: ability to describe x86 register halves as contraints.
- From: Bill Currie <bcurrie at tssc dot co dot nz>
- Date: Wed, 01 Jul 1998 10:12:17 +1200
- CC: ak at muc dot de, egcs at cygnus dot com
- Organization: Telecommunication Systems Support Centre
- References: <15971.899192800@hurl.cygnus.com>
Jeffrey A Law wrote:
> First there'd have to be a way to describe hi/lo halves of registers
> in RTL. I'm not aware of any such mechanism.
Couldn't (subreg:QI (reg:HI 0) 1) or (subreg:QI (reg:SI 0) 1) be used to
represent AH? Trouble is, someone will have to teach egcs to use such
constructs (I'm not well versed on the operation of trees yet,
especially tree->rtl conversion)
Also, how difficult would it be to add eiter a new machine mode or a new
flag/interpretation of existing flags to represent halves of registers?
Bill
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