* i386.md (zero_extendsidi2_32): Break out from ...
(zero_extendsidi2): ... here ; turn to expander.
(zero_extendsidi2_rex64): New.
(extendsidi2_32): Break out from ...
(extendsidi2): ... here ; turn to expander.
(extendsidi2_rex64): New.
(zero_extendhidi2, zero_extendqidi2, extendhidi2, extendqidi2): New.
(trunc?f?f splitters): Add 64bit versions.