aarch64: Reimplement vmovl_high_* intrinsics using builtins
The vmovl_high_* intrinsics map down to the SXTL2/UXTL2 instructions
that already have appropriately-named patterns and expanders,
so it's straightforward to wire them up.
gcc/ChangeLog:
* config/aarch64/aarch64-simd-builtins.def (vec_unpacks_hi,
vec_unpacku_hi_): Define builtins.
* config/aarch64/arm_neon.h (vmovl_high_s8): Reimplement using
builtin.
(vmovl_high_s16): Likewise.
(vmovl_high_s32): Likewise.
(vmovl_high_u8): Likewise.
(vmovl_high_u16): Likewise.
(vmovl_high_u32): Likewise.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/simd/vmovl_high_1.c: New test.