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Re: x86 MMX/SSE ABI compatibility with ICC

On Mon, Jul 12, 2004 at 01:05:37PM -0700, Richard Henderson wrote:
> On Mon, Jul 12, 2004 at 10:08:09AM -0700, Joe Buck wrote:
> > Nope.  There is an ABI standard that multiple compiler providers,
> > including both GCC and Intel, have agreed to implement.
> For i386?  Yes, but it was written by AT&T in 1980.  It says nothing
> about mmx or sse registers.  We did have some agreement for an abi that
> passed sse types in aligned stack slots, back in 1998/99 when gcc first
> got support for sse.

What crystal ball did they use to write an i386 ABI in 1980, when
the chip was only announced in late 1985, and the next big thing
coming from Intel would be the iAPX432 which was supposed to send 
the 8086 and 80286 into oblivion?

We all know how accurate these predictions turned out to be ;-)

There is at least one big difference between the 16 and 32 bit
APIs that I know: the handling of BX/EBX (preserved across 
calls in 32 bit, not in 16 bit).

> But since then Intel has been making random ABI changes for vector types.

Now that is bad, really.


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