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Re: Feature request: ability to describe x86 register halves as contraints.
- To: Richard Henderson <rth at cygnus dot com>
- Subject: Re: Feature request: ability to describe x86 register halves as contraints.
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Tue, 30 Jun 1998 10:08:52 -0600
- cc: ak at muc dot de, egcs at cygnus dot com
- Reply-To: law at cygnus dot com
In message <19980630004629.A20825@dot.cygnus.com>you write:
> On Mon, Jun 29, 1998 at 06:44:04PM +0200, ak@muc.de wrote:
> > The only way to do this is to use fixed input registers and hardcode the
> > register halves. Unfortunately this adds some compiler version dependencies
> > to my code, and also limits the possibilities of the compiler to do other
> > optimizations.
>
> Incorrect:
>
> b -- print the QImode name of the register for the indicated operand.
> %b0 would print %al if operands[0] is reg 0.
> w -- likewise, print the HImode name of the register.
> k -- likewise, print the SImode name of the register.
> h -- print the QImode name for a "high" register, either ah, bh, ch or dh.>
And does the compiler just assume that the whole register is trashed
since it doesn't ever look at the asm strings?
Maybe we're talking about two different issues.
jeff