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Re: New back end ia16: 16-bit Intel x86
- From: rridge at csclub dot uwaterloo dot ca (Ross Ridge)
- To: gcc-patches at gcc dot gnu dot org
- Date: Sat, 18 Aug 2007 16:39:32 -0400 (EDT)
- Subject: Re: New back end ia16: 16-bit Intel x86
Rask Ingemann Lambertsen writes:
>It is not different in your case! You're targetting the i386, so you
>can use i386 addressing modes at just the cost of a 0x67 prefix
You also need to add the cost zero extending the 16-bit pointer values to
32-bits, so using 32-bit addressing modes will only rarely be worthwhile.
Unlike with 16-bit integers, which are available in both 16-bit and
32-bit modes, 16-bit pointers are where in practice real space savings
can be acheived.
>With disp(%esp) being valid on i386, you don't have that problem either.
Only if you can assume the higher 16-bits of ESP are zero.
Ross Ridge