[Bug c++/35004] Adding 4 more tree codes causes a crash in building libstdc++ pre-compiled headers

[michael dot meissner at amd dot com]

------- Comment #6 from michael dot meissner at amd dot com  2008-02-07 17:22 -------
Subject: RE:  Adding 4 more tree codes causes a crash in
 building libstdc++ pre-compiled headers

The problem is there are two different vector shifts.  There is vector
shift by a scalar amount (each element gets shifted the same amount),
and vector shift by a vector (each element gets shifted by the
corresponding element in the vector).

Right now, GCC in tree-vect-transform.c looks at the shift optab and
sees if the second operand is a scalar mode, it believes the machine
only supports the vector shift by scalar mode, and assumes that if the
type is vector mode, that the machine supports vector/vector shifts.

The SSE2 instruction set extension on the x86 has vector/scalar shift
instructions, and the SSE5 instruction set extension adds vector/vector
shifts and rotates.  I want to be able to add support for a machine that
has both types of vector shift, but with the current framework, this was
impossible.

--
Michael Meissner
AMD, MS 83-29
90 Central Street
Boxborough, MA 01719

> -----Original Message-----
> From: bonzini at gnu dot org [mailto:gcc-bugzilla@gcc.gnu.org]
> Sent: Thursday, February 07, 2008 12:11 PM
> To: Meissner, Michael
> Subject: [Bug c++/35004] Adding 4 more tree codes causes a crash in
> building libstdc++ pre-compiled headers
> 
> 
> 
> ------- Comment #5 from bonzini at gnu dot org  2008-02-07 17:10
-------
> Unrelated, but why couldn''t vector/vector shifts/rotates overload
> LSHIFT_EXPR
> instead? :-)
> 
> 
> --
> 
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35004
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35004