target/5381: __builtin_ia32_pmulhuw seems unknown to compiler

[Richard Henderson]

The following reply was made to PR target/5381; it has been noted by GNATS.

From: Richard Henderson <rth@redhat.com>
To: David.Kastrup@t-online.de
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: target/5381: __builtin_ia32_pmulhuw seems unknown to compiler
Date: Mon, 14 Jan 2002 18:29:54 -0800

 On Mon, Jan 14, 2002 at 08:44:34PM -0000, David.Kastrup@t-online.de wrote:
 > Strangely, while using -mmmx, __builtin_ia32_pmulhuw is unknown to
 > the compiler, while, for example, __builtin_ia32_pmulhw seems known.
 
 Not a bug -- pmulhuw is an SSE instruction, not part of
 the base MMX instruction set.
 
 > Anyhow, as you can see from the generated code, the compiler fails to
 > emit an emmx instruction at the end of the routine, leading to possible
 > floating point errors after return.
 
 Again, not a bug.  The user is responsible for handling emmx.
 
 If the compiler were deciding to emit MMX code on its own, 
 then yes I would agree that it must clean up after itself.
 But this is not the case here.
 
 
 r~