Date: Mon, 2 Sep 1996 01:22:52 +1000 From: Bruce Evans <bde@zeta.org.au> To: freebsd-hackers@freebsd.org, staff@kyklopen.ping.dk Subject: Re: movsbw question Message-ID: <199609011522.BAA10132@godzilla.zeta.org.au>
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>The pgcc uses the movsbw instruction with a 32 bit oprand and according >to my old i486 assembler book the instraction takes a "r32" oprand but >"as" says it take a reg16 operand. Now what is right? Neither :-). It takes a r/m8 operand and converts it to a r16 result. An Intel assembler book would spell the instruction movsx. The FreeBSD version of gas doesn't really understand this instruction. It generates a superfluous second operand size override for movsbw %al,%bx It emits bytes 0x66, 0x66, 0x0f, 0xbe, 0xd8. This is fixed in GNU assembler version 2.6 (i486-linux), using BFD version 2.6.0.2 Bruce
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