The x86_mmx type is used for MMX intrinsics, parameters and
return values where these use MMX registers, and is also
supported in load, store, and bitcast.
Only the above operations generate MMX instructions, and optimizations
do not operate on or produce MMX intrinsics.
MMX-sized vectors <2 x i32> etc. are lowered to XMM or split into
smaller pieces. Optimizations may occur on these forms and the
result casted back to x86_mmx, provided the result feeds into a
previous existing x86_mmx operation.
The point of all this is prevent optimizations from introducing
MMX operations, which is unsafe due to the EMMS problem.
llvm-svn: 115243
transforming it into (add (i32 GPR), 4). This allows us to write type
generic multi patterns and have tblgen automatically drop the bitconvert
in the case when the types align. This allows us to fold an extra load
in the changed testcase.
llvm-svn: 99756
Jakob Stoklund Olesen