This instruction raises #GP, aka SIGSEGV, if the effective address
is not aligned to 16-bytes.
We have assertions in tcg-op-gvec.c that the offset from ENV is
aligned, for vector types <= V128. But the offset itself does not
validate that the final pointer is aligned -- one must also remember
to use the QEMU_ALIGNED() attribute on the vector member within ENV.
PowerPC Altivec has vector load/store instructions that silently
discard the low 4 bits of the address, making alignment mistakes
difficult to discover. Aid that by making the most popular host
visibly signal the error.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>