The ARM backend currently has poor codegen for long sext/zext
operations, such as v8i8 -> v8i32. This patch addresses this
by performing a custom expansion in ARMISelLowering. It also
adds/changes the cost of such lowering in ARMTTI.
This partially addresses PR14867.
Patch by Pete Couperus
llvm-svn: 177380
In r176898 I updated the cost model to reflect the fact that sext/zext/cast on
v8i32 <-> v8i8 and v16i32 <-> v16i8 are expensive.
This test case is so that we make sure to update the cost model once we fix
CodeGen.
llvm-svn: 176955
Renato Golin